Article. Energy in fokus - from Kyoto to Copenhagen. - AgroTech
Article. Energy in fokus - from Kyoto to Copenhagen. - AgroTech
Article. Energy in fokus - from Kyoto to Copenhagen. - AgroTech
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ENERGY IN FOCUS<br />
EnErgy <strong>in</strong> Focus<br />
- From <strong>Kyo<strong>to</strong></strong> <strong>to</strong> copenhagen<br />
Institute for Agri Technology and Food Innovation<br />
gartner<br />
tidende
NOT ONLY GREEN<br />
ON THE OUTSIDE<br />
For further <strong>in</strong>formation about bus<strong>in</strong>ess development<br />
and susta<strong>in</strong>able greenhouses of the future please<br />
visit our website agrotech.dk/plantpower.<br />
Institute for Agri Technology and Food Innovation
Jesper Mazanti Aaslyng<br />
Head of Department, <strong>AgroTech</strong><br />
– Institute for Agri Technology<br />
and Food Innovation<br />
We need PlantPower<br />
<strong>Energy</strong> is one of our most important resources, and it will cont<strong>in</strong>ue <strong>to</strong> be so <strong>in</strong> the future.<br />
We’ve been hear<strong>in</strong>g this for a long time, so what’s different now?<br />
The greenhouse sec<strong>to</strong>r, technology companies and knowledge <strong>in</strong>stitutions have been reduc<strong>in</strong>g energy<br />
consumption for many years. Several projects are extremely promis<strong>in</strong>g. Now we are <strong>in</strong> a phase mov<strong>in</strong>g <strong>from</strong><br />
research <strong>to</strong> <strong>in</strong>novation. Development is still necessary, but we must also reap the rewards of our experience so<br />
far, and results must be implemented.<br />
We believe that the time is ripe <strong>to</strong> br<strong>in</strong>g <strong>in</strong><strong>to</strong> use many of the technologies which have been developed<br />
and which are still be<strong>in</strong>g developed. External fac<strong>to</strong>rs such as high energy prices and government demands for<br />
reduced energy consumption by the sec<strong>to</strong>r are also call<strong>in</strong>g for this change process.<br />
We must th<strong>in</strong>k <strong>in</strong>novatively and reduce energy consumption <strong>in</strong> every way conceivable. Changes <strong>in</strong> climate<br />
regulation, LED lights, new sensors, new plant species, new curta<strong>in</strong>s, and better climate screens are just some<br />
of the possibilities. We have <strong>to</strong> adjust ideas <strong>from</strong> the closed greenhouse concept, and cont<strong>in</strong>ue harvest<strong>in</strong>g and<br />
exploit<strong>in</strong>g the surplus energy generated <strong>in</strong> greenhouses dur<strong>in</strong>g the summer.<br />
Under the PlantPower banner, the Danish company <strong>AgroTech</strong> – Institute for Agri Technology and Food<br />
Innovation, has <strong>in</strong>itiated several projects aim<strong>in</strong>g at creat<strong>in</strong>g the susta<strong>in</strong>able, energy-produc<strong>in</strong>g greenhouse.<br />
Many enterprises and knowledge <strong>in</strong>stitutions are <strong>in</strong>volved, as only through concerted efforts can we meet this<br />
challenge.<br />
It must be possible <strong>to</strong> build the greenhouse of the future with the same pride as CO2-neutral <strong>to</strong>wns are<br />
be<strong>in</strong>g built <strong>to</strong>day throughout the world. Greenhouses should not be mere CO2-neutral production areas, they<br />
must also have a positive CO2 account and they must be a high-quality product which is an <strong>in</strong>tegral part of a<br />
biological cycle. This must be the long-term goal of the sec<strong>to</strong>r.<br />
Several projects have already started <strong>to</strong> achieve this goal and ’<strong>Energy</strong> <strong>in</strong> focus, <strong>from</strong> <strong>Kyo<strong>to</strong></strong> <strong>to</strong> <strong>Copenhagen</strong>’<br />
is provid<strong>in</strong>g some of the first results of these projects. Let us <strong>to</strong>gether harvest PlantPower for the future.<br />
The projects are sponsored by the participat<strong>in</strong>g companies and <strong>in</strong>stitutions, Region South Denmark, the European<br />
Regional Fund and the Danish Agency for Science, Technology and Innovation under the M<strong>in</strong>istry of Science.<br />
4 Hjortebjerg greenhouse nursery<br />
6 Towards a semiclosed greenhouse<br />
8 Development of future greenhouse climate control<br />
10 Optimisation of climate management with Climate Check and Plant Check<br />
11 Environmental sensors for harsh environments<br />
12 <strong>Energy</strong> sav<strong>in</strong>gs <strong>in</strong> Danish greenhouse production<br />
14 Ventila<strong>to</strong>rs save energy<br />
16 <strong>Energy</strong> extraction <strong>from</strong> greenhouse companies with district heat<strong>in</strong>g<br />
17 What can we use NIR curta<strong>in</strong>s for?<br />
18 Dynamic management of supplemental light<br />
19 Artificial light<strong>in</strong>g and light<strong>in</strong>g control of the future<br />
20 The sun as a potential source of energy<br />
22 Purchase electricity when it is cheapest – au<strong>to</strong>matically<br />
23 Renewable energy and the s<strong>to</strong>rage issue<br />
24 Dynamic climate control works – worldwide<br />
28 Two organizations work<strong>in</strong>g for the same cause<br />
30 Plants on wheels reduce the carbon footpr<strong>in</strong>t<br />
33 Intelligent us of <strong>Energy</strong> <strong>in</strong> Greenhouses<br />
M<strong>in</strong>i symposium / Workshop 6-7 Oc<strong>to</strong>ber 2009 Odense<br />
Publisher: <strong>AgroTech</strong> A/S, Udkærsvej 15, 8200 Aarhus N, Denmark • Production: Gartner Tidende / MarkT<strong>in</strong>g a/s • Pr<strong>in</strong>t: Rosendahls
Ole Skov, oes@agrotech.dk and Janni B. Lund, jbl@agrotech.dk, consultants, <strong>AgroTech</strong><br />
Hjortebjerg greenhouse<br />
– a demonstration facility for new energy technologies<br />
What can we do right now <strong>to</strong> reduce<br />
the consumption of fossil fuels <strong>in</strong><br />
the greenhouse sec<strong>to</strong>r? What technologies<br />
should we concentrate on <strong>in</strong> the future?<br />
Researchers, consultants and technology<br />
enterprises work<strong>in</strong>g with the greenhouse<br />
sec<strong>to</strong>r have tried <strong>to</strong> answer these questions<br />
<strong>in</strong> collaboration with the sec<strong>to</strong>r.<br />
An <strong>in</strong>novation consortium, a demonstration<br />
project and various other cooperation<br />
projects have been started <strong>in</strong> this<br />
connection, and these mean that <strong>to</strong>day a<br />
4,000 m2 demonstration greenhouse has<br />
been set up at Hjortebjerg. Furthermore,<br />
an exhibition has been set up at Hjortebjerg<br />
which shows the technologies which<br />
can be used right now and <strong>in</strong> the future.<br />
Our short-term goal is energy sav<strong>in</strong>gs<br />
of 60 percent and the long term goal is <strong>to</strong><br />
make the greenhouse sec<strong>to</strong>r a net energy<br />
producer.<br />
The owners of Hjortebjerg would like<br />
<strong>to</strong> make production more energy friendly<br />
- But it must also be f<strong>in</strong>ancially viable<br />
and we won’t compromise on the quality<br />
of the plants, says Steen Thomsen, jo<strong>in</strong>t<br />
owner and responsible for energy management<br />
at the production plant.<br />
The demonstration greenhouse is<br />
located as an extension of the production<br />
sections. The greenhouse is a standard<br />
Venlo Block with s<strong>in</strong>gle glaz<strong>in</strong>g <strong>in</strong> the<br />
roof surfaces and two-layer channel plates<br />
<strong>in</strong> the sides and gables, supplied by<br />
Viemose-Driboga.<br />
Exhibition<br />
at Hjortebjerg<br />
Extraction and s<strong>to</strong>rage<br />
of surplus heat<br />
We know that if the heat <strong>from</strong> the summer<br />
could be s<strong>to</strong>red until the w<strong>in</strong>ter, greenhouses<br />
could be self-sufficient <strong>in</strong> energy.<br />
The challenge is <strong>to</strong> s<strong>to</strong>re the heat as energy<br />
which can be reused. There are several<br />
energy-s<strong>to</strong>rage possibilities, and for this<br />
project it was decided <strong>to</strong> s<strong>to</strong>re the energy<br />
underground.<br />
Studies show that much of the Danish<br />
subsurface could be used for this type<br />
of s<strong>to</strong>rage. The Netherlands has a lot of<br />
experience with this type of plant. In<br />
Denmark, <strong>in</strong> order <strong>to</strong> <strong>in</strong>stall such a plant,<br />
a permit must be obta<strong>in</strong>ed <strong>from</strong> the local<br />
authorities.<br />
The plant at Hjortebjerg can be considered<br />
a semi closed system because experience<br />
has shown that it is best not <strong>to</strong> have<br />
the w<strong>in</strong>dows closed all the time which<br />
would also require a very large cool<strong>in</strong>g<br />
capacity on hot summer days.<br />
The climate <strong>in</strong>side the greenhouses is<br />
managed accord<strong>in</strong>g <strong>to</strong> pr<strong>in</strong>ciples developed<br />
over a number of years, such as<br />
dynamic climate control, which will provide<br />
the possibility for optimal plant production<br />
and energy reductions <strong>in</strong> heat<strong>in</strong>g<br />
of at least 50 %.<br />
It is usually necessary <strong>to</strong> drill down <strong>to</strong><br />
70-100 m, but at Hjortebjerg 40 m was<br />
enough. Drill<strong>in</strong>g was carried out by a<br />
Danish firm, Enopsol, while the extraction<br />
units, compris<strong>in</strong>g 24 JSK units located bet-<br />
From Oc<strong>to</strong>ber <strong>to</strong> January, there is an exhibition<br />
at Hjortebjerg of the technologies currently be<strong>in</strong>g used,<br />
as well as future technologies such as LED light<strong>in</strong>g.<br />
It is possible <strong>to</strong> arrange a visit <strong>to</strong> Hjortebjerg<br />
Contact: Janni B. Lund, project manager<br />
jbl@agrotech.dk +45 2338 0559<br />
ween the columns <strong>in</strong> the greenhouse, were<br />
supplied by the Dutch company Wilk van<br />
der Sande.<br />
In order <strong>to</strong> extract as high temperature<br />
as possible, ‘chimneys’ were built <strong>from</strong><br />
the extraction plant and up <strong>to</strong> the ridge,<br />
where the temperature is more than 40°C<br />
for long periods. The energy extracted is<br />
s<strong>to</strong>red <strong>in</strong> the underground magaz<strong>in</strong>e at an<br />
average temperature of 30°C. When the<br />
energy extracted is <strong>to</strong> be reused, the water<br />
is heated <strong>from</strong> the 30°C <strong>to</strong> 70°C via a CO2<br />
-based heat pump, supplied by Advansor.<br />
New types of curta<strong>in</strong>s<br />
Two curta<strong>in</strong>s have been set up <strong>in</strong> the<br />
demonstration greenhouse. Both curta<strong>in</strong>s<br />
are <strong>from</strong> Ludvig Svensson. One curta<strong>in</strong><br />
is for <strong>in</strong>sulation and shade (LS16), and<br />
the other is a new curta<strong>in</strong>, an NIR (Near<br />
Infrared Reflect<strong>in</strong>g) curta<strong>in</strong>, which reflects<br />
large parts of the heat radiation <strong>in</strong> the<br />
near-<strong>in</strong>frared area of the spectrum (heat<br />
radiation) and allows the pho<strong>to</strong>synthesisactive<br />
light <strong>to</strong> pass through.<br />
LS 16 has a shade rate of 60 % for the<br />
whole spectrum, while the NIR curta<strong>in</strong> has<br />
a shade rate of 20 % for pho<strong>to</strong>synthesisactive<br />
light and 80 % t for heat radiation<br />
<strong>from</strong> 800 nm <strong>to</strong> 1200 nm. The curta<strong>in</strong>s<br />
are controlled so that they ensure optimal<br />
climate conditions for the plants, and so<br />
that, dur<strong>in</strong>g extraction, the air circulation<br />
creates optimises the extraction of heat<br />
<strong>from</strong> the air. Dur<strong>in</strong>g extraction, the NIR<br />
curta<strong>in</strong> must be used <strong>to</strong> separate the layer<br />
above and below the curta<strong>in</strong>. The curta<strong>in</strong> is<br />
opened with slits of at least 15% t <strong>in</strong> order<br />
<strong>to</strong> ensure the required air circulation.<br />
Optimal climate control<br />
A climate control computer (LCC Completa)<br />
<strong>from</strong> Senmatic was <strong>in</strong>stalled <strong>in</strong> the<br />
new section, with software developed <strong>in</strong><br />
a collaboration between Senmatic, The<br />
University of Southern Denmark, Aarhus<br />
University and <strong>AgroTech</strong>.<br />
The new software is <strong>to</strong> ensure optimal<br />
use of the energy with respect <strong>to</strong> plant<br />
growth. In order <strong>to</strong> optimize management,<br />
better measurements of the climate con-<br />
4 ENERGY IN FOCUS
nursery<br />
ditions for the plants are required. In the<br />
demonstration house, new sensors are<br />
be<strong>in</strong>g tested which are under development<br />
at Danfoss IXA Sensor Technologies<br />
<strong>in</strong> cooperation with Senmatic, DELTA and<br />
<strong>AgroTech</strong>. The aim is <strong>to</strong> make cheap, reliable,<br />
durable cordless sensors, and these<br />
are expected <strong>to</strong> be commercially available<br />
<strong>in</strong> a few years.<br />
Other <strong>in</strong>itiatives at Hjortebjerg<br />
In addition <strong>to</strong> tak<strong>in</strong>g part <strong>in</strong> the projects<br />
<strong>in</strong>volv<strong>in</strong>g the demonstration greenhouse,<br />
Hjortebjerg have also reduced the energy<br />
costs by hav<strong>in</strong>g a Climate Check carried<br />
out by <strong>AgroTech</strong>.<br />
This resulted <strong>in</strong> reductions <strong>in</strong> energy<br />
consumption of 35 % <strong>from</strong> 2007-2008.<br />
Moreover, one of the three Caterpillar<br />
mo<strong>to</strong>rs <strong>in</strong> Hjortebjerg’s comb<strong>in</strong>ed heat<br />
and power plant has been replaced with a<br />
more energy-efficient mo<strong>to</strong>r.<br />
What the future will br<strong>in</strong>g for Hjortebjerg<br />
is as yet uncerta<strong>in</strong> but, as Steen<br />
Thomsen says, “we will keep a watchful<br />
eye on solar cell technology, which we<br />
expect we will be able <strong>to</strong> comb<strong>in</strong>e with<br />
underground energy s<strong>to</strong>rage. We are also<br />
keep<strong>in</strong>g an eye on the <strong>in</strong>creas<strong>in</strong>g demands<br />
<strong>to</strong> m<strong>in</strong>imise resources, which <strong>in</strong> the future<br />
will <strong>in</strong>volve far more than just energy”.<br />
<br />
Hjortebjerg I/S<br />
The his<strong>to</strong>ry of Hjortebjerg goes back<br />
<strong>to</strong> 1933 and <strong>to</strong>day it is one of Denmark’s<br />
largest suppliers of the pot<br />
plants Sa<strong>in</strong>t Paulia and Euphorbia<br />
milii. Five-six million pot plants are<br />
produced each year on about 51,000<br />
m 2 , of which 80 % are exported. The<br />
plant is extremely modern, with a<br />
high degree of au<strong>to</strong>mation. The enterprise<br />
is owned by Jørgen Thomsen<br />
and his sons, Gert, Alex and Steen.<br />
The Danish Nursery Hjortebjerg has taken<br />
a huge step <strong>in</strong><strong>to</strong> the future with the establishment<br />
of a demonstration greenhouse for test<strong>in</strong>g<br />
of new energy sav<strong>in</strong>g technology<br />
ENERGY IN FOCUS 5
Silke Hemm<strong>in</strong>g, Wagen<strong>in</strong>gen UR Greenhouse Horticulture, The Netherlands, silke.hemm<strong>in</strong>g@wur.nl<br />
Towards the semiclosed<br />
The liberalisation of the energy market<br />
has <strong>in</strong>creased the awareness of<br />
the energy consumption. This free market<br />
implies that growers do not pay a fixed<br />
price per unit of natural gas anymore, but<br />
that prices are greatly determ<strong>in</strong>ed by the<br />
maximum supply capacity of the gas contract.<br />
Therefore, it is important <strong>to</strong> reduce<br />
peaks <strong>in</strong> energy use.<br />
Improved energy efficiency<br />
In view of the <strong>Kyo<strong>to</strong></strong> pro<strong>to</strong>col several<br />
governments have set goals for energy use<br />
and CO2 emission. In the Netherlands, the<br />
horticultural sec<strong>to</strong>r and government have<br />
agreed <strong>to</strong> improve the energy efficiency<br />
(production per unit of energy) by 65% <strong>in</strong><br />
2010 compared <strong>to</strong> 1980 and <strong>to</strong> <strong>in</strong>crease<br />
the contribution of susta<strong>in</strong>able energy <strong>to</strong><br />
4%. Over the period 1980 - 2005, energy<br />
efficiency <strong>in</strong> Dutch greenhouse <strong>in</strong>dustry<br />
has more than doubled. However, <strong>to</strong>tal<br />
energy use per square meter of greenhouse<br />
hardly changed. Efficiency improvement<br />
resulted <strong>from</strong> a more than doubl<strong>in</strong>g <strong>in</strong><br />
yield per m 2 caused by amongst others<br />
improved greenhouse transmission, cultivars<br />
and cultivation techniques.<br />
The use of fossil energy can be reduced<br />
by limit<strong>in</strong>g the energy demand, higher<br />
<strong>in</strong>sulation and by <strong>in</strong>telligent control of climate,<br />
by <strong>in</strong>creas<strong>in</strong>g the energy efficiency<br />
and by us<strong>in</strong>g susta<strong>in</strong>able energy sources.<br />
<strong>Energy</strong> sav<strong>in</strong>g of<br />
greenhouse systems<br />
<strong>Energy</strong> losses occur through the ventilation<br />
but also greenhouse cover<strong>in</strong>g. Greenhouse<br />
covers with higher <strong>in</strong>sulat<strong>in</strong>g values and<br />
energy screens highly limits the energy<br />
loss. Increased <strong>in</strong>sulation can be obta<strong>in</strong>ed<br />
by modern greenhouse materials, where<br />
new coat<strong>in</strong>gs (low emission and antireflection)<br />
are applied. <strong>Energy</strong> sav<strong>in</strong>g of<br />
25-30% seems <strong>to</strong> be possible with the<br />
new materials without loss of light. If additional<br />
CO2 is applied production will not<br />
decrease, <strong>in</strong> spite of considerable energy<br />
sav<strong>in</strong>gs.<br />
In current greenhouse horticulture, next <strong>to</strong> high production,<br />
levels, quality and timel<strong>in</strong>ess of production are important.<br />
6 ENERGY IN FOCUS
greenhouse<br />
If screens are used almost permanently,<br />
they can reduce the energy use by more<br />
than 35%. Due <strong>to</strong> restrictions for clos<strong>in</strong>g<br />
<strong>in</strong> commercial practice, reduction <strong>in</strong><br />
energy use by thermal screens is restricted<br />
<strong>to</strong> 20%. Efficient screen<strong>in</strong>g strategies can<br />
save energy while ma<strong>in</strong>ta<strong>in</strong><strong>in</strong>g crop production<br />
level.<br />
Semi-closed greenhouse concepts<br />
The last years several greenhouse concepts<br />
were developed. It started with us<strong>in</strong>g the<br />
greenhouse itself as solar collec<strong>to</strong>r (solar<br />
greenhouse “Zonnekas”), followed by fully<br />
closed greenhouses, <strong>to</strong>wards energy produc<strong>in</strong>g<br />
greenhouses (“Kas als energiebron”)<br />
and latest developments <strong>to</strong>ward electricity<br />
produc<strong>in</strong>g greenhouses (“Elkas”). In closed<br />
greenhouses, the excess of solar energy<br />
<strong>in</strong> summer is collected and s<strong>to</strong>red e.g. <strong>in</strong><br />
aquifers <strong>to</strong> be reused <strong>in</strong> w<strong>in</strong>ter <strong>to</strong> heat the<br />
greenhouse. These concepts result <strong>in</strong> a<br />
reduction <strong>in</strong> primary energy use of 33%.<br />
But <strong>to</strong> reduce <strong>in</strong>vestment costs, growers<br />
tend <strong>to</strong> choose a semi closed system.<br />
Cool<strong>in</strong>g capacity of this system is lower<br />
and <strong>in</strong>sufficient <strong>to</strong> keep the temperature<br />
below the maximum, so ventilation w<strong>in</strong>dows<br />
will be opened. CO2 emission <strong>in</strong><br />
(semi)closed greenhouses is considerably<br />
lower than <strong>in</strong> open greenhouses. In a<br />
recent experiment, <strong>in</strong> which <strong>to</strong>ma<strong>to</strong>es<br />
were grown at a maximum concentration<br />
of 1000 ppm, the open greenhouse used<br />
54.7 kg CO2 m-2 <strong>in</strong> contrast 14.4 kg CO2<br />
m-2 <strong>in</strong> the closed greenhouse.<br />
Susta<strong>in</strong>able greenhousees<br />
Specific characteristics of climate <strong>in</strong> (semi)<br />
closed greenhouses are: high CO2 concentrations,<br />
vertical temperature gradients,<br />
high humidities, comb<strong>in</strong>ed conditions of<br />
high light <strong>in</strong>tensity and high CO2 concentration<br />
and <strong>in</strong>creased rates of air movement.<br />
Yield <strong>in</strong>crease is due <strong>to</strong> the effects<br />
of elevated CO2 concentration at high<br />
irradiance, and the optimum temperature<br />
for crop pho<strong>to</strong>synthesis <strong>in</strong>creased with<br />
CO2 concentration.<br />
The follow<strong>in</strong>g concepts are shown at<br />
the Innovation and Demonstration Centre<br />
<strong>in</strong> Bleiswijk and <strong>in</strong>vestigated by Wagen<strong>in</strong>gen<br />
UR Greenhouse Horticulture. These<br />
and future concepts might even create a<br />
surplus of energy <strong>to</strong> be used <strong>in</strong> the surround<strong>in</strong>gs.<br />
Sunergy Greenhouse<br />
The objective is <strong>to</strong> obta<strong>in</strong> the greatest possible<br />
light transmittance. A double screen<br />
traps heat <strong>to</strong> reduce the greenhouse’s own<br />
heat consumption. This greenhouse comb<strong>in</strong>es<br />
the best of the exist<strong>in</strong>g technologies<br />
now be<strong>in</strong>g applied <strong>in</strong> horticulture. The<br />
roof of the greenhouse is anti-reflective<br />
glass (GroGlass). The greenhouse is seven<br />
metres with an ultra-lightweight substructure<br />
(Tw<strong>in</strong>light) but no roof vents. Heat loss<br />
is limited by a double screen<strong>in</strong>g system<br />
with a new slid<strong>in</strong>g system prevent<strong>in</strong>g<br />
leak<strong>in</strong>g gaps. The concept is developed<br />
by Wagen<strong>in</strong>gen UR and P.L.J. Bom greenhouse<br />
builders.<br />
Sun W<strong>in</strong>d Greenhouse<br />
Many pot plants are shade plants that<br />
require a high degree of screen<strong>in</strong>g dur<strong>in</strong>g<br />
the summer. An <strong>in</strong>novative paneled screen<br />
<strong>in</strong>stalled <strong>in</strong> the Sun-W<strong>in</strong>d Greenhouse collects<br />
energy <strong>in</strong> the form of warm water and<br />
prevents direct sunlight <strong>from</strong> enter<strong>in</strong>g. The<br />
warm water is then s<strong>to</strong>red <strong>in</strong> a special buffer<br />
under the greenhouse but with a conventional<br />
climate control. The greenhouse<br />
roof faces south and consists of adjustable<br />
solar collec<strong>to</strong>r panels sandwiched between<br />
double glaz<strong>in</strong>g at a 35° slope. The<br />
north side of the greenhouse consists of<br />
acrylic sheets with a slope of 60° and onesided<br />
cont<strong>in</strong>uous roof ventilation. The post<br />
height is three meters, ridge height n<strong>in</strong>e<br />
meters and trellis girder 11.80 meters. This<br />
concept is developed by Thermotech and<br />
Gakon greenhouse builders.<br />
FlowDeck Greenhouse<br />
The greenhouse roof consists of hollowcore<br />
polycarbonate sheet<strong>in</strong>g through<br />
which water flows <strong>from</strong> the gutter <strong>to</strong><br />
the ridge and back. Light transmittance<br />
through Flowdeck is equal <strong>to</strong> conventional<br />
acrylic sheet<strong>in</strong>g but when filled with<br />
water is equal <strong>to</strong> normal s<strong>in</strong>gle horticultural<br />
glass. The greenhouse has a Venlo<br />
structure with a gutter height of 7 metres<br />
and an extended span of 6.40 metres. The<br />
greenhouse has roof vents on the sheltered<br />
side. An air-handl<strong>in</strong>g unit is connected <strong>to</strong><br />
an air distribution system with perforated<br />
flexible pipes <strong>in</strong>stalled under the cultivat<strong>in</strong>g<br />
systems. Forced-air heat<strong>in</strong>g/cool<strong>in</strong>g<br />
units are <strong>in</strong>stalled. The greenhouse is also<br />
equipped with a s<strong>in</strong>gle shade cloth. This<br />
concept is developed by Climeco Eng<strong>in</strong>eer<strong>in</strong>g<br />
and Maurice greenhouse builders.<br />
<strong>Energy</strong> efficient<br />
climate control<br />
With<strong>in</strong> semi-closed greenhouse concepts,<br />
an energy efficient climate control leads <strong>to</strong><br />
further reduction <strong>in</strong> energy consumption<br />
and/or <strong>in</strong>crease of production. New grow<strong>in</strong>g<br />
strategies are currently developed for<br />
several crops. The aim of such concepts is<br />
<strong>to</strong> reduce energy consumption dramatically<br />
without production losses. In the new<br />
grow<strong>in</strong>g strategy for <strong>to</strong>ma<strong>to</strong> e.g. the energy<br />
consumption has <strong>to</strong> drop <strong>from</strong> 40 m 3 <strong>to</strong><br />
26 m 3 gas per m 2 greenhouse area. Other<br />
concepts are developed for other crops.<br />
There are several possibilities <strong>to</strong> decrease<br />
energy consumption <strong>in</strong> greenhouse<br />
horticulture <strong>in</strong> the future. The challenge is<br />
<strong>to</strong> reach it with low-cost solutions.<br />
Semi-closed greenhouse concepts are<br />
permanently <strong>in</strong> development <strong>in</strong> order <strong>to</strong><br />
optimize the systems concern<strong>in</strong>g costs and<br />
performance. In order <strong>to</strong> apply new greenhouse<br />
concepts and grow<strong>in</strong>g strategies<br />
<strong>in</strong><strong>to</strong> horticultural practice cooperation, an<br />
active exchange of knowledge between<br />
growers, horticultural <strong>in</strong>dustry, extension<br />
service and research is necessary.<br />
<br />
ENERGY IN FOCUS 7
Oliver Körner, consultant, <strong>AgroTech</strong>, oko@agrotech.dk • Mads Andersen, Senmatic, DGT Volmatic, maa@senmatic.com<br />
Bo Nørregaard Jørgensen, The Maersk Mc-K<strong>in</strong>ney Moller Institute, University of Southern Denmark, bnj@mip.sdu.dk<br />
Development of future<br />
greenhouse climate control<br />
Next <strong>to</strong> production of high quality plants, the greenhouses of the future<br />
will have <strong>to</strong> produce energy <strong>to</strong>o. In order <strong>to</strong> ensure optimal output,<br />
there should be improved au<strong>to</strong>mation of the climate control system<br />
Such au<strong>to</strong>mation requires climate control<br />
software based on models that can<br />
predict the actual plant reactions <strong>to</strong> the<br />
ongo<strong>in</strong>g changes <strong>in</strong> the greenhouse climate<br />
(as a consequence of comb<strong>in</strong>ed plant<br />
and energy production), and the complexity<br />
of this issue demands a different way of<br />
plann<strong>in</strong>g and th<strong>in</strong>k<strong>in</strong>g when design<strong>in</strong>g the<br />
climate control software.<br />
In a cooperation <strong>in</strong>clud<strong>in</strong>g <strong>AgroTech</strong>,<br />
University of Southern Denmark (SDU),<br />
and Senmatic DGT Volmatic, future climate<br />
control software will be planned,<br />
built up and tested.<br />
The system<br />
Future greenhouses will at least be CO2<br />
neutral and they will also produce energy.<br />
Research has shown that climate conditions<br />
<strong>in</strong> closed and semi-closed greenhouses<br />
demand new climate strategies.<br />
Luckily, <strong>in</strong> parallel with the development<br />
of these types greenhouse, there have been<br />
rapid developments <strong>in</strong> greenhouse climate<br />
control. The long discussed speak<strong>in</strong>g-plant<br />
approach <strong>to</strong> fill the greenhouse with a lot<br />
of sensors, measure everyth<strong>in</strong>g possible on<br />
and around the plants, and then control<br />
the greenhouse climate <strong>to</strong> meet the needs<br />
of the plants, is com<strong>in</strong>g closer. Development<br />
of <strong>in</strong>expensive wireless microsensors<br />
is well on the way, and the quality of<br />
calculation models for <strong>in</strong>terpretation and<br />
further use of the measured data has been<br />
greatly improved.<br />
The system is modular<br />
All these possibilities place high demands<br />
on the climate control software platform.<br />
The platform must be flexible so that new<br />
options can be added as soon as they are<br />
available <strong>from</strong> research.<br />
In order <strong>to</strong> achieve the necessary flexibility,<br />
the climate control software must be<br />
based on <strong>in</strong>dependent control modules,<br />
and the <strong>in</strong>dividual commands <strong>from</strong> these<br />
modules for the greenhouse climate must<br />
be coord<strong>in</strong>ated by a higher <strong>in</strong>tegrat<strong>in</strong>g<br />
decision unit.<br />
The decision unit is programmed with<br />
goals for plant quality, energy consumption<br />
and so on. The higher <strong>in</strong>tegrat<strong>in</strong>g<br />
decision unit coord<strong>in</strong>ates and decides for<br />
any given situation, which of the modules<br />
are <strong>to</strong> control the greenhouse actua<strong>to</strong>rs.<br />
The modules may be physical sensors, soft<br />
sensors or soft controllers.<br />
Different modules can send conflict<strong>in</strong>g<br />
commands <strong>to</strong> the actua<strong>to</strong>rs and thus<br />
coord<strong>in</strong>ation is necessary. Without a well<br />
structured unit this would result <strong>in</strong> serious<br />
errors. Consequently, the system asks<br />
for clearly def<strong>in</strong>ed stand-alone modules,<br />
as <strong>in</strong>terdependency among the modules<br />
<strong>in</strong>duces a high risk that the whole system<br />
will not work correctly.<br />
At the Mærsk McK<strong>in</strong>ney Møller Institute<br />
at SDU, research is be<strong>in</strong>g carried out <strong>in</strong><strong>to</strong><br />
software technologies that can handle<br />
these so-called feature <strong>in</strong>teractions. The<br />
use of <strong>in</strong>dependent modules is <strong>in</strong> the long<br />
run a basic need <strong>to</strong> utilise and implement<br />
<strong>in</strong>ternational research results <strong>in</strong> climate<br />
control without re-design<strong>in</strong>g the system.<br />
The future climate control platform thus<br />
enables faster implementation of research<br />
<strong>in</strong><strong>to</strong> practice.<br />
Models for climate control<br />
The modules for the future greenhouse<br />
climate control platform are typically sensors,<br />
soft sensors or soft controllers. Soft<br />
sensors will be developed <strong>in</strong> areas where<br />
physical sensors are not appropriate, are<br />
<strong>to</strong>o expensive, or do not exist, or where<br />
basic measurements need <strong>to</strong> be analysed<br />
further. Soft sensors are typically mathematical<br />
models that are used <strong>to</strong> further<br />
compute measured data for more value<br />
usage.<br />
Soft sensors are under development for<br />
a number of processes <strong>in</strong> the greenhouse<br />
such as plant temperature or condensation.<br />
For climate control, cont<strong>in</strong>uous data<br />
are necessary, and appropriate sensors are<br />
often not available.<br />
For example, measur<strong>in</strong>g pho<strong>to</strong>synthe-<br />
8 ENERGY IN FOCUS
sis is rout<strong>in</strong>e, but it is impossible <strong>to</strong> get<br />
detailed pho<strong>to</strong>synthesis measurements of<br />
the whole greenhouse, and at any given<br />
time, without <strong>in</strong>vest<strong>in</strong>g <strong>in</strong> very expensive<br />
measur<strong>in</strong>g equipment.<br />
In this case, a model can produce<br />
a pho<strong>to</strong>synthesis soft sensor by calculat<strong>in</strong>g<br />
actual pho<strong>to</strong>synthesis <strong>from</strong> measured<br />
microclimate po<strong>in</strong>t measurements. Such<br />
a soft sensor implemented <strong>in</strong> the control<br />
circuit is called a soft controller.<br />
A typical and simple soft controller<br />
used <strong>in</strong> daily practice is temperature <strong>in</strong>tegration.<br />
A typical soft sensor/controller<br />
system is an early warn<strong>in</strong>g system for<br />
stress. Soft-sensors can help <strong>to</strong> identify<br />
plant stress before it can be seen and actually<br />
damage the plant. The greenhouse<br />
actua<strong>to</strong>rs can then be controlled <strong>in</strong> order<br />
<strong>to</strong> avoid crop damage.<br />
<strong>AgroTech</strong> develops these model-based<br />
soft sensors and soft controllers. They have<br />
been implemented <strong>in</strong> co-operation with<br />
SDU and Senmatic.<br />
Interpretation<br />
of measurements<br />
Models are not only used <strong>in</strong> soft-sensors<br />
and soft controllers. Soon there will be<br />
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products for cool production and with low heat<strong>in</strong>g requirements.<br />
Bestil til v<strong>in</strong>ter og forårsproduktion;<br />
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Antirrh<strong>in</strong>um - Floral Showers<br />
Begonia - Ambassador, Emperor, Fortune, Queen<br />
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Gypsophila – Gypsy, Festival<br />
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Og mange andre sorter….<br />
many new sensors available and with the<br />
new software systems, it will be child’s<br />
play <strong>to</strong> fit these <strong>to</strong> the climate control<br />
platform.<br />
But, what should we do with the sensor<br />
data when their <strong>in</strong>terpretation is somewhat<br />
unclear? The danger is that we will make<br />
the wrong decisions. How can we be sure<br />
whether a measurement is good or bad?<br />
Here, models are very helpful for data<br />
<strong>in</strong>terpretation.<br />
Everybody knows when temperature,<br />
relative humi-dity, light or CO2 is <strong>to</strong>o<br />
low or <strong>to</strong>o high. But how can we use<br />
measurements of s<strong>to</strong>mata conductance,<br />
pho<strong>to</strong>synthesis or transpiration? What is<br />
low and what is high and when is it as it<br />
should be? In these questions, models can<br />
help <strong>to</strong> f<strong>in</strong>d the right <strong>in</strong>terpretation of the<br />
measurements.<br />
When will the future<br />
climate control be available?<br />
A part of the ongo<strong>in</strong>g projects focuses on<br />
implement<strong>in</strong>g research and development<br />
<strong>in</strong> practice. The actual projects <strong>in</strong>clude:<br />
• Intelligent <strong>Energy</strong> Management<br />
<strong>in</strong> Greenhouses, Greenhouse<br />
Concept 2017<br />
M<strong>in</strong>dre energi - Lavere omkostn<strong>in</strong>ger – Øget <strong>in</strong>dtjen<strong>in</strong>g.<br />
Cool Crops – <strong>Energy</strong> savers.<br />
Kontakt d<strong>in</strong> GASA Young Plants sælger for yderligere <strong>in</strong>fo.<br />
Contact your GASA Young Plants sales representative for further <strong>in</strong>fo.<br />
GASA Young Plants A/S<br />
Lavsenvænget 1<br />
5200 Odense V<br />
t: +45 65 48 14 00<br />
f: +45 63 12 96 31<br />
e: <strong>in</strong>fo@gasayoungplants.dk<br />
www.gasayoungplants.dk<br />
ENERGY IN FOCUS 9<br />
<strong>Energy</strong><br />
costs<br />
• Technology for susta<strong>in</strong>able greenhouse<br />
production, PREDICT – Towards<br />
spread<strong>in</strong>g of <strong>in</strong>telligent climate<br />
control <strong>to</strong> the greenhouse<br />
horticultural <strong>in</strong>dustry.<br />
These projects are based on different elements<br />
of research with<strong>in</strong> dynamic climate<br />
control and the aim is <strong>to</strong> create a substantial<br />
reduction <strong>in</strong> energy consumption<br />
without compromis<strong>in</strong>g plant quality. New<br />
developments with<strong>in</strong> dynamic climate<br />
control are be<strong>in</strong>g transferred <strong>to</strong> practice<br />
<strong>in</strong> all the projects. The newly created climate<br />
software is cont<strong>in</strong>uously be<strong>in</strong>g tested<br />
<strong>in</strong> the participat<strong>in</strong>g greenhouse production<br />
plants. Software developed with<strong>in</strong> the<br />
scope of the projects will be available for<br />
evaluation by other producers when the<br />
projects term<strong>in</strong>ate.<br />
In general, <strong>in</strong> the future Danish greenhouse<br />
producers will experience the<br />
benefits of new features <strong>in</strong> climate control<br />
software when the ongo<strong>in</strong>g flux of<br />
research, development and new knowledge<br />
is implemented <strong>in</strong> com<strong>in</strong>g versions<br />
of exist<strong>in</strong>g software packages.<br />
<br />
<strong>Energy</strong><br />
savers
Peter Rasmussen, per@agrotech.dk • Jens Rystedt, jor@agrotech.dk • Jakob Skov Pedersen, jap@agrotech.dk, consultants, <strong>AgroTech</strong> A/S<br />
Optimisation of climate management<br />
with Climate Check and Plant Check<br />
Is the greenhouse nursery spend<strong>in</strong>g more money than necessary on energy?<br />
What will happen if we change <strong>to</strong> dynamic climate management?<br />
Should I <strong>in</strong>ject more CO2 and cut down on growth light<strong>in</strong>g <strong>in</strong>stead?<br />
Is it worth <strong>in</strong>vest<strong>in</strong>g <strong>in</strong> new curta<strong>in</strong> systems or lights?<br />
There is a lot of questions, and the decisions<br />
are often hard <strong>to</strong> make, but there<br />
is money <strong>to</strong> be saved, if you make the<br />
right decisions. Many people are reluctant<br />
<strong>to</strong> change cultivation practices or climate<br />
strategy because it is difficult <strong>to</strong> see how<br />
chang<strong>in</strong>g a sett<strong>in</strong>g will affect heat<strong>in</strong>g bills<br />
or how well plants grow. However, the<br />
high energy prices <strong>in</strong> summer 2008 caused<br />
many producers <strong>to</strong> look for quick sav<strong>in</strong>gs,<br />
and at <strong>AgroTech</strong> we saw a need <strong>to</strong> develop<br />
services <strong>to</strong> optimise greenhouse production.<br />
We came up with Climate Check and<br />
Plant Check.<br />
Climate Check and the<br />
new opportunities<br />
In brief, Climate Check <strong>in</strong>volves collect<strong>in</strong>g<br />
all the relevant data <strong>in</strong> the greenhouses, for<br />
example data on climate management and<br />
energy consumption. This data is entered<br />
<strong>in</strong><strong>to</strong> a model which uses the data <strong>to</strong> calculate<br />
ongo<strong>in</strong>g energy consumption. The<br />
calculations are adapted <strong>to</strong> the <strong>in</strong>dividual<br />
greenhouse and they can be carried out<br />
at short <strong>in</strong>tervals, for example every five<br />
m<strong>in</strong>utes. This makes it possible <strong>to</strong> look<br />
more closely at the climate management<br />
sett<strong>in</strong>gs <strong>in</strong> relation <strong>to</strong> energy consumption.<br />
It also makes it possible <strong>to</strong> simulate alternative<br />
climate management strategies with<br />
new sett<strong>in</strong>gs, and it is possible <strong>to</strong> calculate<br />
the new energy consumption figures and<br />
the new climate.<br />
<strong>AgroTech</strong> has implemented Climate<br />
Did you know that ...<br />
Climate boxes at KU Life be<strong>in</strong>g used for Plant Check. The boxes here<br />
are be<strong>in</strong>g used <strong>to</strong> study cucumbers.<br />
Check at ten greenhouse companies with<br />
a <strong>to</strong>tal of 500,000 m 2 under glass. On<br />
average, proposals for energy sav<strong>in</strong>gs of 12<br />
per cent have been put forward.<br />
S<strong>in</strong>ce autumn 2008, <strong>AgroTech</strong> has<br />
developed Climate Check further with<br />
a greenhouse simulation model known<br />
as AgroClimate. This makes it possible<br />
<strong>to</strong> simulate plant growth, pho<strong>to</strong>synthesis,<br />
temperature, humidity as well as energy<br />
processes <strong>in</strong> the greenhouse. With<br />
much better time resolution than previous<br />
models, the new model can analyse the<br />
complex relationship between humidity,<br />
transpiration, ventilation and dosage of<br />
CO2. The aim is <strong>to</strong> be able <strong>to</strong> predict<br />
• Heat loss <strong>from</strong> greenhouses <strong>in</strong>creases exponentially with the difference between<br />
<strong>in</strong>side and outside temperature?<br />
• If the greenhouse curta<strong>in</strong> is opened at low light limits early <strong>in</strong> the morn<strong>in</strong>g, a<br />
significant proportion of the daily energy consumption is used immediately after?<br />
It is important <strong>to</strong> f<strong>in</strong>d the right balance between light and energy consumption.<br />
• It is a good idea <strong>to</strong> log climate data - it may be worth its weight <strong>in</strong> gold! A climate<br />
check makes optimal use of climate data go<strong>in</strong>g back over up <strong>to</strong> two years.<br />
• Plants have a higher rate of pho<strong>to</strong>synthesis with diffuse light than with direct light.<br />
new strategies for a specific production<br />
and <strong>to</strong> ensure compliance with growth<br />
requirements for humidity, temperature<br />
and light.<br />
Plant Check<br />
But climate management and energy<br />
consumption is one th<strong>in</strong>g. Quite another<br />
aspect is the plants. When do they grow<br />
best? How much light, heat or cold can<br />
they <strong>to</strong>lerate? This is where Plant Check<br />
comes <strong>in</strong><strong>to</strong> play. Plant Check can establish<br />
the plants’ limits for optimal growth,<br />
for example <strong>to</strong>lerance limits for cold<br />
and heat. It also establishes how plants’<br />
pho<strong>to</strong>synthesis and growth are affected<br />
by the cultivation climate and light<strong>in</strong>g.<br />
Plant Check can be anyth<strong>in</strong>g <strong>from</strong> advanced<br />
cultivation trials <strong>in</strong> climate cham-<br />
bers or climate boxes <strong>to</strong> simpler proces-<br />
ses <strong>to</strong> measure pho<strong>to</strong>synthesis on <strong>in</strong>divi-<br />
dual leaves under various climate con-<br />
ditions. Imag<strong>in</strong>e what would happen if<br />
energy prices rose <strong>to</strong> the same levels as <strong>in</strong><br />
August 2008. Wouldn’t it be nice <strong>to</strong> know<br />
how much you can reduce the temperature<br />
at night? A few degrees can easily<br />
mean sav<strong>in</strong>gs of 15-20 per cent.<br />
If you would like <strong>to</strong> f<strong>in</strong>d out more, you<br />
are always welcome <strong>to</strong> contact us.<br />
<br />
10 ENERGY IN FOCUS
Jens Møller Jensen, CTO, Danfoss IXA A/S, jensen@danfoss.com and Bent S. Bennedsen, Agrotech A/S, bsb@agrotech.dk<br />
Environmental sensors<br />
for harsh environments<br />
– a novel approach <strong>to</strong> multiple parameter sensors for greenhouses<br />
Sensors for environmental parameters are numerous and widespread, and the<br />
number of applications <strong>in</strong> which such sensors are applied is constantly ris<strong>in</strong>g.<br />
One application of <strong>in</strong>terest is greenhouse production, <strong>in</strong> which the application<br />
of multiple distributed sensors can serve <strong>to</strong> drastically reduce energy<br />
consumption and improve growth control<br />
However, this approach implies<br />
requirements that are not fulfilled<br />
with exist<strong>in</strong>g sensors, namely requirements<br />
that the sensors function cont<strong>in</strong>uously<br />
and stably and with little or no ma<strong>in</strong>tenance<br />
requirement <strong>in</strong> a harsh environment<br />
likely <strong>to</strong> contam<strong>in</strong>ate the sensors.<br />
Additional requirements are that the sensors<br />
can operate wirelessly <strong>in</strong> order <strong>to</strong><br />
enable use of multiple sensors without<br />
obstructions and expensive cabl<strong>in</strong>g, and<br />
that they can do so at an energy consumption<br />
level low enough <strong>to</strong> be powered by<br />
energy harvest<strong>in</strong>g, avoid<strong>in</strong>g the need for<br />
recurrent battery exchange.<br />
New sensors needed<br />
Currently available sensors are <strong>in</strong> general<br />
not specifically designed for harsh environments,<br />
and <strong>in</strong> most cases standard<br />
sensors are therefore applied with various<br />
additional measures <strong>to</strong> protect them and<br />
with limited position<strong>in</strong>g options <strong>to</strong> compensate<br />
for the harsh environment impact.<br />
Moreover, different sensors<br />
are needed for the various<br />
environment parameters. This<br />
means the sensors are even less<br />
applicable, less durable and less<br />
accurate than needed <strong>in</strong> order<br />
<strong>to</strong> efficiently provide measurement<br />
data for optimum energy<br />
management and environment<br />
control.<br />
Such control requires moni<strong>to</strong>r<strong>in</strong>g<br />
of the environment <strong>in</strong> close<br />
proximity <strong>to</strong> the plants, and the<br />
sensors therefore should be placed<br />
amongst the plants, preferably<br />
on a multiple distributed<br />
basis. The sensors should be able<br />
<strong>to</strong> withstand close impacts <strong>from</strong><br />
the various plant-care activities<br />
while at the same time not requir<strong>in</strong>g<br />
tedious time and effort consum<strong>in</strong>g <strong>in</strong>stallation<br />
and ma<strong>in</strong>tenance, which impedes<br />
daily work rout<strong>in</strong>es.<br />
Obta<strong>in</strong><strong>in</strong>g these features requires<br />
sensors that are actually designed for<br />
the purpose. They must be reliable and<br />
durable and designed for maximum usability<br />
<strong>in</strong> the specific application, and they<br />
must require no or very little service and<br />
ma<strong>in</strong>tenance. They must also be able <strong>to</strong><br />
communicate data wirelessly <strong>in</strong> order <strong>to</strong><br />
facilitate easy and dynamic position<strong>in</strong>g<br />
and handl<strong>in</strong>g.<br />
Novel approach<br />
All this calls for a novel approach <strong>to</strong><br />
greenhouse sensors <strong>in</strong> technology, conception<br />
and design. Danfoss IXA A/S,<br />
<strong>to</strong>gether with partners of the Greenhouse<br />
Concept 2017, is develop<strong>in</strong>g such sensors,<br />
based on novel and patented optical pr<strong>in</strong>ciples<br />
<strong>in</strong>corporat<strong>in</strong>g nanotechnology.<br />
Danfoss IXA A/S has developed and<br />
patented a novel optical measurement<br />
pr<strong>in</strong>ciple and novel nano-coat<strong>in</strong>g pr<strong>in</strong>ciples<br />
which, <strong>to</strong>gether with application<br />
targeted design, enable sensors with all<br />
the required properties. The sensors simultaneously<br />
measure CO2, absolute and<br />
relative humidity, <strong>in</strong>clud<strong>in</strong>g dew po<strong>in</strong>t,<br />
various temperatures and light; they are<br />
faster than exist<strong>in</strong>g sensors, they are self<br />
clean<strong>in</strong>g and hermetically sealed, they<br />
are powered by energy-harvest<strong>in</strong>g, and<br />
they communicate wirelessly <strong>in</strong> a multiple-node<br />
network which enables huge<br />
improvements <strong>in</strong> both greenhouse energy<br />
consumption and growth control. At the<br />
same time the sensors impose no additional<br />
ma<strong>in</strong>tenance and service requirements<br />
on the users. The sensors can withstand<br />
direct exposure <strong>to</strong> the various daily plantcare<br />
activities and handl<strong>in</strong>g and they<br />
are specifically designed for optimum<br />
usability and efficiency <strong>in</strong> professio-<br />
nal greenhouse production plants.<br />
<br />
ENERGY IN FOCUS 11
Ole Skov, oes@agrotech.dk and Jens Rystedt, jor@agrotech.dk, consultants <strong>AgroTech</strong><br />
<strong>Energy</strong> sav<strong>in</strong>gs <strong>in</strong> Danish<br />
greenhouse production<br />
For a number of years, there has been focus on energy sav<strong>in</strong>gs <strong>in</strong> greenhouse<br />
nurseries, and this has led <strong>to</strong> a general reduction <strong>in</strong> energy consumption<br />
of 25-30 percent over the past 10 years. Today, the average annual<br />
energy consumption per m 2 of greenhouse is about 400 kWh<br />
The large reduction <strong>in</strong> energy consumption<br />
is due <strong>to</strong> a wide range of <strong>in</strong>itiatives<br />
<strong>from</strong> researchers, advisors, and not least<br />
the greenhouse producers themselves.<br />
Despite great efforts, however, energy<br />
consumption rema<strong>in</strong>s high and <strong>in</strong>creas<strong>in</strong>g<br />
prices for energy and CO2 allowances<br />
can have significant consequences.<br />
If energy prices aga<strong>in</strong> exceed USD 140 per<br />
<strong>to</strong>nne, energy consumption will have <strong>to</strong> be<br />
halved <strong>in</strong> a very few years, as a m<strong>in</strong>imum,<br />
if competitiveness is <strong>to</strong> be reta<strong>in</strong>ed.<br />
Therefore, it is proposed that greenhouse<br />
companies launch and carry out an<br />
action plan <strong>to</strong> make energy consumption<br />
more efficient.<br />
This should be over a number of years,<br />
with gradual utilisation and <strong>in</strong>troduction<br />
of the newest technologies and <strong>in</strong>itiatives<br />
<strong>from</strong> research and development. Most<br />
important are mak<strong>in</strong>g the greenhouse climate<br />
more efficient, energy improvements<br />
<strong>to</strong> the climate screens <strong>in</strong> greenhouses, and<br />
exploitation of surplus heat.<br />
More efficient greenhouse<br />
climate (Climate Check)<br />
This could be via the greenhouse nursery’s<br />
own climate data, where the <strong>in</strong>teraction<br />
between temperature, curta<strong>in</strong> control,<br />
growth light<strong>in</strong>g and so on is analysed us<strong>in</strong>g<br />
a modell<strong>in</strong>g program which tests the exist<strong>in</strong>g<br />
management strategy.<br />
This provides knowledge about when<br />
energy is used <strong>in</strong> the greenhouse. On this<br />
basis, a number of suggested changes <strong>to</strong><br />
the management system are listed which<br />
will lead <strong>to</strong> reduced energy consumption.<br />
Experience so far shows a sav<strong>in</strong>gs potential<br />
of 10 <strong>to</strong> 30 percent.<br />
Improvements of the climate screens<br />
<strong>in</strong> greenhouses (<strong>Energy</strong> Check)<br />
This is primarily about <strong>in</strong>stall<strong>in</strong>g new<br />
mobile curta<strong>in</strong> equipment. Preferably two<br />
types; one thick curta<strong>in</strong> for <strong>in</strong>sulation at<br />
night, and another for shade with a maximum<br />
shade effect of 20 percent.<br />
It is also about replac<strong>in</strong>g s<strong>in</strong>gle-glazed<br />
panes <strong>in</strong> the greenhouse with channel<br />
plates with several layers of glaz<strong>in</strong>g. This<br />
will lead <strong>to</strong> a reduction <strong>in</strong> heat transmission<br />
through the new plates of about 60<br />
percent, as well as a reduction <strong>in</strong> the <strong>in</strong>flux<br />
of light as channel plates with several layers<br />
have somewhat lower light transmission<br />
than s<strong>in</strong>gle-glazed panes.<br />
However, replacement <strong>in</strong> many of the<br />
greenhouse surfaces will not lead <strong>to</strong> significant<br />
reductions <strong>in</strong> the <strong>in</strong>flux of light,<br />
for example gables and outer walls. With<br />
respect <strong>to</strong> older DEG standard greenhouses<br />
with leaky or draughty glass rails, it<br />
is suggested that the glass <strong>in</strong> roof surfaces<br />
fac<strong>in</strong>g north also be replaced with channel<br />
plates with several layers, while the<br />
glass <strong>in</strong> the south-fac<strong>in</strong>g surfaces should<br />
be replaced with new four-sided supported<br />
glass rails.<br />
Such replacement will give reductions<br />
<strong>in</strong> energy consumption of more than 50<br />
percent. However, you should beware of<br />
the reduction <strong>in</strong> light conditions.<br />
Exploitation of surplus heat<br />
When the surfaces of a greenhouse are<br />
<strong>in</strong>sulated, more effective management of<br />
the greenhouse climate is required, particularly<br />
humidity can be a problem. It might<br />
be necessary <strong>to</strong> fit ventilation equipment<br />
which can rapidly even out differences <strong>in</strong><br />
temperature and humidity <strong>in</strong> the greenhouse.<br />
And this could be the start of a full<br />
extraction system, where surplus heat <strong>from</strong><br />
the <strong>in</strong>flux of sunlight and growth light<strong>in</strong>g<br />
can be extracted, s<strong>to</strong>red and reused when<br />
the energy is needed. Such systems have<br />
several stages, depend<strong>in</strong>g on how much of<br />
the surplus energy is <strong>to</strong> be s<strong>to</strong>red and for<br />
how long. With the right dimensions, the<br />
greenhouse nursery could become almost<br />
<strong>in</strong>dependent of fossil fuels.<br />
There is no s<strong>in</strong>gle solution <strong>to</strong> the energy<br />
challenge. Several balls must come <strong>in</strong><strong>to</strong><br />
play and it is important <strong>to</strong> set a long-term<br />
strategy for how the <strong>in</strong>dividual greenhouse<br />
company can make itself <strong>in</strong>dependent of<br />
expensive energy.<br />
<br />
12 ENERGY IN FOCUS
Pottemask<strong>in</strong>e<br />
Pottemask<strong>in</strong>en består af<br />
en basisenhed, som kan<br />
monteres med magas<strong>in</strong>er,<br />
boreenhed og transportbånd.<br />
Magas<strong>in</strong>er og boreenhed<br />
fremstilles til forskellige<br />
pottetyper og fabrikater.<br />
For eksempel runde, støbte<br />
potter, termoformede potter,<br />
Jiffy potter og firkantede,<br />
støbte potter.<br />
Pottemask<strong>in</strong>en har en s<strong>to</strong>r<br />
kapacitet og er opbygget som<br />
en kompakt og arbejdsvenlig<br />
enhed.<br />
På fo<strong>to</strong>et er vist en pottemask<strong>in</strong>e<br />
med boreenhed,<br />
transportbånd og stativ<br />
til småplanter.<br />
Topfmasch<strong>in</strong>e<br />
Die Topfmasch<strong>in</strong>e besteht<br />
aus e<strong>in</strong>er Basise<strong>in</strong>heit, die mit<br />
Magaz<strong>in</strong>en, Bohrsystem und<br />
Förderband ausgestattet werden<br />
kann.<br />
Magaz<strong>in</strong>e und Bohrsystem<br />
werden für verschiedene<br />
Topftypen und Topffabrikate<br />
hergestellt, wie z. B. runde<br />
Spritzgusstöpfe, Thermoform-<br />
Töpfe, Jiffy-Töpfe und viereckige<br />
Spritzgusstöpfe.<br />
Die Topfmasch<strong>in</strong>e verfügt über<br />
e<strong>in</strong>e große Kapazität und ist als<br />
kompakte und arbeitsfreundliche<br />
E<strong>in</strong>heit konzipiert.<br />
Das Bild zeigt e<strong>in</strong>e Topfmasch<strong>in</strong>e<br />
mit Bohrsystem, Förderband und<br />
e<strong>in</strong>em Ständer für Jungpflanzen.<br />
Pott<strong>in</strong>g mach<strong>in</strong>e<br />
The pott<strong>in</strong>g mach<strong>in</strong>e consists<br />
of a basic unit which can<br />
be fitted with magaz<strong>in</strong>es, a<br />
drill<strong>in</strong>g unit and a conveyor-<br />
belt.<br />
Magaz<strong>in</strong>es and drill<strong>in</strong>g unit<br />
are made for different pot<br />
types and makes.<br />
For example round, moulded<br />
pots, thermoformed pots, Jiffy<br />
pots and square, moulded<br />
pots.<br />
This high-capacity pott<strong>in</strong>g<br />
mach<strong>in</strong>e is designed as a<br />
compact, work-friendly unit.<br />
The pho<strong>to</strong> shows a pott<strong>in</strong>g<br />
mach<strong>in</strong>e with a drill<strong>in</strong>g unit, a<br />
conveyorbelt and a frame<br />
for small plants.<br />
Bekidan a/S<br />
Erhvervsvangen 18<br />
DK-5792 Årslev<br />
Telefon +45 65 99 16 35<br />
Telefax +45 65 99 16 90<br />
E-mail: bekidan@bekidan.dk<br />
www.bekidan.dk<br />
ENERGY IN FOCUS 13
By: Lotte Bjarke, edi<strong>to</strong>r, Gartner Tidende, post@lottebjarke.dk<br />
Ventila<strong>to</strong>rs save energy<br />
Experiences <strong>from</strong> this grow<strong>in</strong>g season proves that it is possible <strong>to</strong> save<br />
about 10 percent of energy for <strong>to</strong>ma<strong>to</strong> grow<strong>in</strong>g by the use of ventila<strong>to</strong>rs <strong>in</strong> the<br />
greenhouse and at the same time achieve a better climate <strong>in</strong> the greenhouse<br />
Normally ventila<strong>to</strong>rs <strong>in</strong> greenhouses<br />
consume energy. But <strong>in</strong> the Danish<br />
<strong>to</strong>ma<strong>to</strong> nursery, Alfred Pedersen & Son, a<br />
set of new ventila<strong>to</strong>rs actually helps the<br />
nursery <strong>to</strong> save energy.<br />
The ventila<strong>to</strong>rs were <strong>in</strong>stalled <strong>in</strong> week<br />
6 this year and have s<strong>in</strong>ce proven that by<br />
a m<strong>in</strong>or energy consumption <strong>to</strong> keep the<br />
ventila<strong>to</strong>rs runn<strong>in</strong>g it is actually possible<br />
<strong>to</strong> achieve so big advantages regard<strong>in</strong>g<br />
the greenhouse climate, that substantial<br />
sav<strong>in</strong>gs on the <strong>to</strong>tal energy consumption<br />
is achievable.<br />
Traditionally ventila<strong>to</strong>rs are <strong>in</strong>stalled<br />
under the greenhouse roof, but these are<br />
<strong>in</strong>stalled under the plants and that is what<br />
makes the difference.<br />
In the nursery the <strong>to</strong>ma<strong>to</strong>es are grown<br />
<strong>in</strong> trenches thus mak<strong>in</strong>g it possible <strong>to</strong><br />
<strong>in</strong>stall the ventila<strong>to</strong>rs below the <strong>to</strong>ma<strong>to</strong><br />
crop and thereby <strong>to</strong> create movements of<br />
the entire greenhouse atmosphere.<br />
- We have placed the ventila<strong>to</strong>rs at<br />
<strong>in</strong>tervals throughout the greenhouse. They<br />
are each connected <strong>to</strong> <strong>in</strong>flatable tubes<br />
along the rows of plants. The tubes have<br />
holes <strong>in</strong> the sides which adds <strong>to</strong> the movement<br />
of the air, expla<strong>in</strong>s Poul Erik Lund,<br />
who is production manager of the nursery.<br />
Mov<strong>in</strong>g the air<br />
The trick is that the ventila<strong>to</strong>rs are placed<br />
with <strong>in</strong>terchang<strong>in</strong>g direction of air <strong>in</strong>take.<br />
This creates an s-shaped movement of<br />
the air horizontally and thanks <strong>to</strong> the air<br />
blown, out through the holes <strong>in</strong> the tubes<br />
this movement is transmitted also <strong>to</strong> the<br />
vertical plane. In short all the air <strong>in</strong> the<br />
nursery is constantly mov<strong>in</strong>g but without<br />
any feel<strong>in</strong>g of w<strong>in</strong>d <strong>in</strong> the greenhouse.<br />
- The idea orig<strong>in</strong>ates <strong>from</strong> the Dutch<br />
closed-greenhouse projects. They have<br />
ventila<strong>to</strong>rs under each s<strong>in</strong>gle row of plants<br />
while we only have placed them with a<br />
certa<strong>in</strong> <strong>in</strong>terval, says Poul Erik Lund, who<br />
is pleased with the improved climate <strong>in</strong><br />
the greenhouse follow<strong>in</strong>g the <strong>in</strong>stallation<br />
of the ventila<strong>to</strong>rs.<br />
- We ma<strong>in</strong>ly expected that we could<br />
achieve sav<strong>in</strong>gs on the energy consumption<br />
<strong>in</strong> w<strong>in</strong>tertime when we produce <strong>to</strong>ma-<br />
<strong>to</strong>es by additional lightn<strong>in</strong>g, because the<br />
movement of the air let the heat<strong>in</strong>g surplus<br />
created by the lamps come <strong>to</strong> the benefit<br />
of the plants thus mak<strong>in</strong>g less demands<br />
for the heat<strong>in</strong>g system, expla<strong>in</strong>s Poul Erik<br />
Lund.<br />
But actually there is also potential energy<br />
sav<strong>in</strong>gs <strong>to</strong> achieve <strong>in</strong> summertime.<br />
- We use quite some energy <strong>to</strong> keep<br />
the humidity under control <strong>in</strong> the morn<strong>in</strong>g<br />
even <strong>in</strong> summer. Heat is necessary<br />
<strong>to</strong> remove humidity <strong>in</strong> order <strong>to</strong> get the<br />
evaporation of the plants go<strong>in</strong>g and <strong>in</strong><br />
order <strong>to</strong> lower the risk of diseases. But the<br />
movement of the air now means that it is<br />
possible <strong>to</strong> control humidity with far less<br />
use of heat<strong>in</strong>g, underl<strong>in</strong>es Poul Erik Lund.<br />
Plants at work<br />
Alfred Pedersen & Son expect that a <strong>to</strong>tal<br />
sav<strong>in</strong>g of about 10% of the energy consumption<br />
will be possible thanks <strong>to</strong> the<br />
ventila<strong>to</strong>rs.<br />
- We now have <strong>to</strong> learn how <strong>to</strong> optimize<br />
the use of the ventila<strong>to</strong>rs. For <strong>in</strong>stance we<br />
must learn how much we can lower the<br />
heat for humidity control <strong>in</strong> the morn<strong>in</strong>g.<br />
But I am quite confident that the potential<br />
is big, says Poul Erik Lund who even<br />
expects possible raise of production thanks<br />
<strong>to</strong> the improved climate of the greenhouse<br />
also on grey and ra<strong>in</strong>y days.<br />
- It is all about gett<strong>in</strong>g the plants <strong>to</strong> work<br />
as much as possible and apparently the<br />
constant movement of the air is mak<strong>in</strong>g<br />
them keep up the work because the humidity<br />
is cont<strong>in</strong>uously removed <strong>from</strong> the<br />
plant surface thus optimiz<strong>in</strong>g evaporation,<br />
he expla<strong>in</strong>s.<br />
So far the ventila<strong>to</strong>rs have been <strong>in</strong>stalled<br />
<strong>in</strong> a greenhouse where w<strong>in</strong>ter <strong>to</strong>ma<strong>to</strong>es<br />
are produced by artificial lightn<strong>in</strong>g.<br />
But a new project is com<strong>in</strong>g up and the<br />
nursery will also use the achieved experience<br />
for production of w<strong>in</strong>ter cucumbers<br />
by artificial lightn<strong>in</strong>g.<br />
- We believe <strong>in</strong> the potential <strong>in</strong> <strong>to</strong>ma<strong>to</strong>es<br />
as well as other plants but there is a<br />
need for more experience s<strong>in</strong>ce different<br />
plants respond differently as well as different<br />
grow<strong>in</strong>g systems mean different<br />
potential, underl<strong>in</strong>es Poul Erik Lund.<br />
<br />
14 ENERGY IN FOCUS
A C<br />
D<br />
ACF<br />
F<br />
ENERGY IN FOCUS 15<br />
D C<br />
C E<br />
C<br />
AC<br />
F E<br />
F<br />
F<br />
D E AC<br />
• Here, suppliers <strong>in</strong> the sec<strong>to</strong>r present their companies,<br />
products and new items.<br />
• This is where your cus<strong>to</strong>mers will ga<strong>in</strong> an overview of what<br />
the market has <strong>to</strong> offer <strong>in</strong> the way of possibilities.<br />
• This is the showcase for contemporary trends <strong>to</strong> provide<br />
<strong>in</strong>spiration for future <strong>in</strong>vestments.<br />
This is the place where all the new items are presented, trends<br />
for the new garden<strong>in</strong>g season are revealed <strong>in</strong> earnest and the<br />
sec<strong>to</strong>r’s buyers meet <strong>to</strong> plan the upcom<strong>in</strong>g season and ga<strong>in</strong><br />
new <strong>in</strong>spiration <strong>to</strong> take away with them.<br />
Dan-Gar-Tek was held under the same roof as the Fagmessen<br />
for the first time <strong>in</strong> 2006. Br<strong>in</strong>g<strong>in</strong>g them <strong>to</strong>gether has<br />
created a new, <strong>in</strong>spir<strong>in</strong>g forum across the horticulture<br />
<strong>in</strong>dustry throughout the Nordic region.<br />
F<br />
D E AC<br />
It’s easy <strong>to</strong><br />
get <strong>to</strong> Denmark<br />
by plane or<br />
by tra<strong>in</strong>!<br />
Come and be part of creat<strong>in</strong>g the future of horticulture <strong>in</strong><br />
Denmark, Norway, Sweden and F<strong>in</strong>land.<br />
Telephone +45 65560284 | Fax +45 65560299 | e-mail: jbm@ose.dk | www.dan-gar-tek.com | www.fagmessen.dk<br />
D E AC<br />
D<br />
You can f<strong>in</strong>d out more at www.dan-gar-tek.com,<br />
www.fagmessen.dk, or by call<strong>in</strong>g +45 6556 0284
Jan Hass<strong>in</strong>g, Gartneriernes Fjernvarmeforsyn<strong>in</strong>g,<br />
janhass<strong>in</strong>g@energifyn.jay.net<br />
(organization of producers with district heat<strong>in</strong>g) •<br />
Jan Strømvig, FjernvarmeFyn (Funen district heat<strong>in</strong>g),<br />
js@fjernvarmefyn.dk •<br />
Jens Rystedt, <strong>AgroTech</strong>, jor@agrotech.dk<br />
<strong>Energy</strong> extraction<br />
<strong>from</strong> greenhouse<br />
nurseries with<br />
district heat<strong>in</strong>g<br />
A research project is focus<strong>in</strong>g on how<br />
it is possible <strong>to</strong> use the surplus energy<br />
<strong>from</strong> greenhouses thus mak<strong>in</strong>g the<br />
greenhouse nurseries energy producers<br />
rather than energy consumers<br />
Over a s<strong>in</strong>gle year, a greenhouse<br />
receives more solar energy than it<br />
needs for heat<strong>in</strong>g and controll<strong>in</strong>g humidity.<br />
So, every year there is an energy<br />
surplus <strong>in</strong> a greenhouse. The problem is<br />
just that so far it has not been possible <strong>to</strong><br />
extract the surplus energy and s<strong>to</strong>re it for<br />
later use, for example <strong>from</strong> day until night,<br />
or even better, <strong>from</strong> summer until w<strong>in</strong>ter.<br />
In recent years, new technologies have<br />
made it possible <strong>to</strong> extract surplus energy.<br />
The energy conditions <strong>in</strong> an “average<br />
greenhouse” can be outl<strong>in</strong>ed as below:<br />
When the energy is extracted, it must<br />
be possible <strong>to</strong> either use it immediately<br />
or <strong>to</strong> s<strong>to</strong>re it, for example <strong>in</strong> a groundwater<br />
aquifer or energy s<strong>to</strong>rage ponds.<br />
The <strong>in</strong>vestment required for s<strong>to</strong>rage is very<br />
high, however, and not all locations are<br />
suitable for underground s<strong>to</strong>rage.<br />
The district heat<strong>in</strong>g area around Odense<br />
<strong>Energy</strong> conditions <strong>in</strong> an “average greenhouse”<br />
has 151 greenhouse producers with a <strong>to</strong>tal<br />
of 1.8 million m² under glass. These greenhouses<br />
are all connected <strong>to</strong> the district<br />
heat<strong>in</strong>g network.<br />
An obvious question is whether it is possible<br />
<strong>to</strong> send the surplus energy directly<br />
out <strong>to</strong> the district heat<strong>in</strong>g network, <strong>in</strong>stead<br />
of s<strong>to</strong>r<strong>in</strong>g it <strong>in</strong> expensive seasonal s<strong>to</strong>rage<br />
facilities.<br />
<strong>Energy</strong> for 20.000 households<br />
This year, the district heat<strong>in</strong>g company<br />
on Funen, (Fjernvarme Fyn), Gartnernes<br />
Fjernvarmeselskaber and <strong>AgroTech</strong> are<br />
look<strong>in</strong>g at the possibilities of exploit<strong>in</strong>g<br />
the surplus heat <strong>from</strong> nurseries. Prelim<strong>in</strong>ary<br />
calculations show that the <strong>to</strong>tal potential<br />
energy extraction <strong>from</strong> the nurseries<br />
amounts <strong>to</strong> about 2.2 million GJ per year,<br />
correspond<strong>in</strong>g <strong>to</strong> the energy consumption<br />
of about 20,000 households. However,<br />
KWh per m2 Radiation out<br />
greenhouse per year<br />
1040<br />
Radiation <strong>in</strong>flux <strong>to</strong> a greenhouse 900<br />
<strong>Energy</strong> consumption <strong>in</strong> a greenhouse (standard year) 400 – 450<br />
<strong>Energy</strong> surplus 450 – 500<br />
Potential energy extraction 350 - 400<br />
this assumes that all nurseries extract all<br />
their surplus energy and that the district<br />
heat<strong>in</strong>g network can take all the energy.<br />
The calculations show more realistically<br />
that if 25 percent of the nurseries practice<br />
energy extraction, the district heat<strong>in</strong>g<br />
network will immediately be able <strong>to</strong> take<br />
all the energy without s<strong>to</strong>rage for longer<br />
periods.<br />
Before this can become a reality, however,<br />
there are some technical challenges <strong>to</strong><br />
be overcome - most importantly that the<br />
temperature <strong>from</strong> the energy extraction by<br />
the nurseries is <strong>to</strong>o low <strong>to</strong> be immediately<br />
sent <strong>in</strong><strong>to</strong> the district heat<strong>in</strong>g network. The<br />
temperature must be <strong>in</strong>creased <strong>from</strong> 35°C<br />
<strong>to</strong> about 70°C, us<strong>in</strong>g either solar heat<strong>in</strong>g<br />
plant, heat pumps or the exist<strong>in</strong>g boilers at<br />
the nurseries.<br />
The whole issue of f<strong>in</strong>anc<strong>in</strong>g, costs and<br />
taxation has not yet been resolved.<br />
Nevertheless, the greenhouse companies<br />
do have an energy surplus which could<br />
be recovered and which could transform<br />
greenhouses <strong>from</strong> energy consumers <strong>to</strong><br />
energy producers.<br />
The project is be<strong>in</strong>g funded by Gartneribrugets<br />
Afsætn<strong>in</strong>gsudvalg, a foundation <strong>to</strong><br />
enhance development of the horticultutral<br />
sec<strong>to</strong>r, and will be completed with an<br />
overall analysis at the end of 2009.<br />
<br />
16 ENERGY IN FOCUS
Anker Kuehn, <strong>AgroTech</strong>, ank@agrotech.dk • Eva Rosenqvist, KU-Life, ero@life.ku.dk •<br />
Hans Andersson, LS, haa@ludvigsvensson.com and Jørn Rosager, jr@dgssupply.dk<br />
What can we<br />
use NIR curta<strong>in</strong>s for?<br />
NIR curta<strong>in</strong>s are the newest type of curta<strong>in</strong> <strong>from</strong> Ludvig Svensson.<br />
Near <strong>in</strong>frared reflect<strong>in</strong>g curta<strong>in</strong>s that reflect some of the heat radiation<br />
and allow almost all pho<strong>to</strong>synthesis-active light <strong>to</strong> pass through.<br />
Can plants <strong>to</strong>lerate more light when the heat radiation is reduced?<br />
When we shade plants <strong>from</strong><br />
high <strong>in</strong>fluxes of radiation <strong>from</strong><br />
the sun, it is usually not <strong>to</strong> reduce the<br />
amount of light, but rather <strong>to</strong> avoid scorch<strong>in</strong>g<br />
the plants. When the <strong>in</strong>flux of<br />
visible light is high, the level of <strong>in</strong>visible<br />
NIR is also high. NIR radiation is<br />
heat radiation that plants cannot utilise <strong>in</strong><br />
their pho<strong>to</strong>synthesis and because, <strong>in</strong> most<br />
cases, greenhouses are warm enough as it<br />
is, the heat is a waste product.<br />
In pr<strong>in</strong>ciple most plants can withstand<br />
high exposures <strong>to</strong> light, as many of the<br />
species grown <strong>in</strong> Danish greenhouse<br />
nurseries love the sun, however they<br />
must be kept cool dur<strong>in</strong>g exposure. If the<br />
leaf temperature becomes <strong>to</strong>o high, the<br />
plant cannot keep up with the vapour<br />
pressure, mean<strong>in</strong>g that the water that<br />
evaporates <strong>from</strong> the leaves is not replaced<br />
quickly enough. The plant protects<br />
itself <strong>from</strong> dehydrat<strong>in</strong>g by clos<strong>in</strong>g its pores,<br />
lead<strong>in</strong>g <strong>to</strong> the arrest of pho<strong>to</strong>synthesis. If<br />
the plant is exposed <strong>to</strong> <strong>in</strong>creased vapour<br />
pressure, the outer layer of cells on its leaves<br />
will be damaged; what we call leaf<br />
scorch. When the pores are closed, temperature<br />
<strong>in</strong>creases can lead <strong>to</strong> scorch<strong>in</strong>g<br />
of the middle part of the leaf.<br />
We can prevent this damage <strong>to</strong> leaves<br />
if we provide shade for the plants,<br />
and regular curta<strong>in</strong>s, e.g. XLS16, block<br />
64% of the radiation <strong>in</strong>flux and reflect it<br />
out <strong>from</strong> the greenhouse. Unfortunately<br />
this type of curta<strong>in</strong> also blocks 64% of<br />
the visible (and pho<strong>to</strong>synthesis-active)<br />
light out, thereby prevent<strong>in</strong>g pho<strong>to</strong>synthesis.<br />
NIR curta<strong>in</strong>s<br />
The new NIR curta<strong>in</strong> differentiates between<br />
the visible part of the spectrum<br />
(380-750nm, where plants use 400-700nm<br />
<strong>in</strong> the pho<strong>to</strong>synthesis) and the near <strong>in</strong>frared<br />
(NIR) area (800-1200nm). The NIR<br />
area also makes up a large part of what we<br />
call heat radiation.<br />
So, these curta<strong>in</strong>s can block out up <strong>to</strong><br />
80% of heat radiation while at the same<br />
time only block<strong>in</strong>g out 20 % of the visible<br />
and pho<strong>to</strong>synthesis-active light.<br />
This means that we block out less pho<strong>to</strong>synthesis-active<br />
light while at the same<br />
time prevent<strong>in</strong>g overheat<strong>in</strong>g of the greenhouse.<br />
In this way CO2 can be adm<strong>in</strong>istered<br />
over a longer period, and we can<br />
achieve more pho<strong>to</strong>synthesis and growth.<br />
The curta<strong>in</strong>s look like regular lightshad<strong>in</strong>g<br />
curta<strong>in</strong>s because the shade rate<br />
is for the part of the spectrum that we<br />
cannot see.<br />
We expect NIR curta<strong>in</strong>s will allow for<br />
<strong>in</strong>creased growth without risk of scorch<strong>in</strong>g.<br />
Hopefully we will also see lower<br />
leaf temperatures under NIR curta<strong>in</strong>s.<br />
Test<strong>in</strong>g NIR curta<strong>in</strong>s<br />
Together with a diffuse curta<strong>in</strong>, NIR<br />
curta<strong>in</strong>s are currently be<strong>in</strong>g tested at<br />
KU-Life <strong>in</strong> cooperation with Ludvig Svensson.<br />
The tests will be look<strong>in</strong>g at room and<br />
leaf temperatures under the different curta<strong>in</strong>s.<br />
First chrysanthemums, potted roses,<br />
begonias and kalanchoë are be<strong>in</strong>g used<br />
as test plants, as they have different types<br />
of leaves and therefore their water balance<br />
and control of leaf temperature with regard<br />
<strong>to</strong> radiation also differs.<br />
NIR curta<strong>in</strong>s have also been <strong>in</strong>stalled<br />
<strong>in</strong> the demonstration facility at Hjorte-<br />
bjerg greenhouse nursery, where they are<br />
on public display. See the article about<br />
the Hjortebjerg plant – a demonstration<br />
facility for new energy technologies.<br />
<br />
ENERGY IN FOCUS 17
Carl-Ot<strong>to</strong> Ot<strong>to</strong>sen, Department of Horticulture, Aarhus University, co.ot<strong>to</strong>sen@agrsci.dk •<br />
Bo Nørregaard Jørgensen, The Maersk Mc-K<strong>in</strong>ney Moller Institute, University of Southern Denmark, bnj@mip.sdu.dk<br />
Dynamic management<br />
of supplemental light<br />
As the natural light even <strong>in</strong> w<strong>in</strong>ter a sunny day might be adequate <strong>to</strong> substitute<br />
supplemental light, we have decided <strong>to</strong> comb<strong>in</strong>e <strong>in</strong>formation about the weather<br />
forecasts, the actual forecasted electricity prices and the pho<strong>to</strong>synthetic<br />
performance of the actual species <strong>in</strong><strong>to</strong> one context<br />
This is the core of an R&D project between<br />
Department of Horticulture and<br />
The Maersk Mc-K<strong>in</strong>ney Moller Institute<br />
with fund<strong>in</strong>g <strong>from</strong> regional energy producers<br />
(<strong>Energy</strong> Fyns Fond) and more recently<br />
commercial growers and national fund<strong>in</strong>g<br />
(The Danish Food Agency Services).<br />
Optimal ga<strong>in</strong> of pho<strong>to</strong>synthesis<br />
To reach this target a software package has<br />
been developed that <strong>in</strong>stalled on a PC connected<br />
<strong>to</strong> the Internet and with access <strong>to</strong> a<br />
climate computer will calculate the most<br />
efficient time <strong>to</strong> turn on the supplemental<br />
light based on the weather forecast, the<br />
energy prices and the pho<strong>to</strong>synthesis sum<br />
<strong>from</strong> <strong>in</strong>dividual plant species.<br />
In this way we not only overcome the<br />
traditional rather conservative set po<strong>in</strong>ts<br />
for use of supplemental light, but also<br />
secures that the use of supplemental light<br />
takes place <strong>in</strong> periods where the ga<strong>in</strong> <strong>in</strong><br />
terms of pho<strong>to</strong>synthesis per light hours is<br />
the best.<br />
The control of supplemental light is<br />
predictive rather than the traditional retrospect<br />
analysis of light sums. The consequence<br />
is that light use is moved <strong>from</strong><br />
peak <strong>to</strong> low load periods.<br />
The decision support <strong>in</strong> the program is<br />
based of the IntelliGrow concepts of dynamic<br />
climate management, but added more<br />
knowledge about the different species<br />
ability <strong>to</strong> cope with fluctuations <strong>in</strong> light<br />
and perhaps even use supplemental light.<br />
The software requires currently Super-<br />
L<strong>in</strong>k4 (Senmatic), but we are test<strong>in</strong>g methods<br />
<strong>to</strong> communicate with Priva systems.<br />
Results<br />
Experiments with different pho<strong>to</strong>syn-<br />
thesis sums us<strong>in</strong>g dynamic light control<br />
vs. traditional light controls based of set<br />
po<strong>in</strong>t of supplemental light and pho<strong>to</strong>synthesis<br />
sums, have been performed <strong>in</strong><br />
spr<strong>in</strong>g 2009.<br />
The dynamic supplemental light control<br />
was used <strong>in</strong> comb<strong>in</strong>ation with dynamic<br />
climate control us<strong>in</strong>g potted m<strong>in</strong>iature<br />
roses, Hibiscus rosa-s<strong>in</strong>ensis and<br />
Euphorbia milii showed that a reduction<br />
of more than 10% of the supplemental<br />
light use was possible. If it was comb<strong>in</strong>ed<br />
with dynamic climate control both the cost<br />
for heat<strong>in</strong>g and electricity was reduced<br />
with an improved plant performance (often<br />
more compact plants).<br />
Pho<strong>to</strong>synthesis measurements of the<br />
species reveal large differences <strong>in</strong> response<br />
times <strong>to</strong> light, which <strong>in</strong>dicate several<br />
additional possibilities for reduc<strong>in</strong>g<br />
electricity costs us<strong>in</strong>g different ignit<strong>in</strong>g<br />
patterns for the lamps. This knowledge<br />
will be <strong>in</strong>cluded <strong>in</strong> the software and ongo<strong>in</strong>g<br />
work on the software will <strong>in</strong>clude a<br />
better prediction of the climate <strong>to</strong> improve<br />
the pho<strong>to</strong>synthesis calculation, but also<br />
<strong>in</strong>clude suggestion for different uses of the<br />
<strong>in</strong>stalled supplementary light <strong>in</strong> different<br />
situations.<br />
Test<strong>in</strong>g supplemental light<br />
use on the web<br />
The results are developed with the <strong>in</strong>volved<br />
nurseries, but a novel web based<br />
application is available for all. If growers<br />
upload climate date on the homepage<br />
http://SoftwareLab.sdu.dk/DynaLight <strong>in</strong>formation<br />
about possible energy sav<strong>in</strong>gs will<br />
be shown.<br />
<br />
The screen shows an example of<br />
supplemental light control, where the<br />
light is on 6 hrs dur<strong>in</strong>g the night (lower<br />
left). The graph shows times of light on<br />
(red), price of electricity (light blue)<br />
and work<strong>in</strong>g light (yellow). The green<br />
l<strong>in</strong>e is natural light and light green l<strong>in</strong>e<br />
is the pho<strong>to</strong>synthetic activity.<br />
18 ENERGY IN FOCUS
Anker Kuehn, <strong>AgroTech</strong>, ank@agrotech.dk, • Eva Rosenqvist, KU-Life, ero@life.ku.dk • Stig Gejl, Philips Light<strong>in</strong>g, stig.gejl@philips.com<br />
Artificial light<strong>in</strong>g and<br />
light<strong>in</strong>g control of the future<br />
Light<strong>in</strong>g diodes are becom<strong>in</strong>g <strong>in</strong>creas<strong>in</strong>gly efficient. In a few years time they<br />
are expected <strong>to</strong> be even more efficient than SON-T lights, and prices will have<br />
dropped so much that they can compete with other types of light<strong>in</strong>g.<br />
It should also be mentioned that LED lights have a longer life-time<br />
So there are many advantages <strong>to</strong> us<strong>in</strong>g<br />
light<strong>in</strong>g diodes. The question is, are<br />
there other advantages <strong>to</strong> us<strong>in</strong>g LED<br />
lights? One of the advantages is that you<br />
can change the colour composition and<br />
thereby affect the growth of plants. For<br />
example, colour composition affects the<br />
way a plant stretches and when it flowers.<br />
Effectiveness of pho<strong>to</strong>synthesis<br />
Chlorophyll is the most important pigment<br />
and its function is <strong>to</strong> absorb light <strong>in</strong> plants’<br />
pho<strong>to</strong>synthesis. It absorbs most light <strong>in</strong> the<br />
red and blue area. Plants are green because<br />
they reflect much of the green light and<br />
absorb other colours <strong>in</strong> the light spectrum.<br />
In pr<strong>in</strong>ciple, a plant can use light of any<br />
colour <strong>in</strong> its pho<strong>to</strong>synthesis because light<br />
is absorbed by different pigments, and<br />
energy <strong>from</strong> the light is then transferred <strong>to</strong><br />
the pho<strong>to</strong>synthesis reaction centre.<br />
Blue light conta<strong>in</strong>s more energy than<br />
red light, although both colour wavelengths<br />
contribute equally <strong>to</strong> pho<strong>to</strong>synthesis.<br />
In terms of energy, the same amount of<br />
Watts will render more red light rays than<br />
blue. That is, as regards pho<strong>to</strong>synthesis, it<br />
is “cheaper” <strong>to</strong> use red light than blue.<br />
Flower<strong>in</strong>g<br />
The flower<strong>in</strong>g pattern of many plants is<br />
governed by the available light. Some<br />
plants flower when there is enough light,<br />
that is when there is a pho<strong>to</strong>synthesis<br />
“surplus”, while the flower<strong>in</strong>g pattern of<br />
other plants is regulated by the length of<br />
daylight. In plants that are regulated by<br />
daylight, the length of night is the most<br />
important. Plants conta<strong>in</strong> a substance called<br />
pho<strong>to</strong>chrome that can appear <strong>in</strong> two<br />
forms, active and <strong>in</strong>active, and it is this<br />
substance that determ<strong>in</strong>es whether the<br />
plant will flower. Pho<strong>to</strong>chrome can be<br />
converted between its active and <strong>in</strong>active<br />
forms by us<strong>in</strong>g light <strong>in</strong> the red and farred<br />
region. We know that we can br<strong>in</strong>g<br />
po<strong>in</strong>settias <strong>to</strong> flower a week early if we<br />
draw the curta<strong>in</strong>s before the sun sets.<br />
This is because the amount of light <strong>from</strong><br />
the far-red region that normally sh<strong>in</strong>es on<br />
the plants just before the onset of night is<br />
reduced.<br />
Shape and height<br />
There is much more far-red light than red<br />
light <strong>in</strong> a woodland area (the leaves <strong>in</strong> the<br />
tree crowns are very efficient at absorb<strong>in</strong>g<br />
red light), and this acts as a signal <strong>to</strong> the<br />
pho<strong>to</strong>chrome <strong>in</strong> the leaves below, lead<strong>in</strong>g<br />
these plants <strong>to</strong> stretch <strong>to</strong>ward the light. We<br />
also see this <strong>in</strong> plants that are exposed <strong>to</strong><br />
<strong>in</strong>candescent lamps, as these also irradiate<br />
a lot of far-red light.<br />
In addition <strong>to</strong> this phenomenon, blue<br />
light also affects the shape of plants. Plants<br />
that are exposed <strong>to</strong> more blue light are<br />
more compact and produce more side<br />
shoots. This is due <strong>to</strong> the similar conditions<br />
<strong>to</strong> plants grow<strong>in</strong>g freely under a blue sky.<br />
Correspond<strong>in</strong>gly, plants that are exposed<br />
<strong>to</strong> UV light thus stretch less.<br />
Artificial light<strong>in</strong>g can<br />
be controlled but it is only<br />
supplementary light<strong>in</strong>g<br />
When we know how plants react, we<br />
can control the light and the colours of<br />
the light, <strong>to</strong> match the plants’ needs. This<br />
means that we do not need the same light<br />
composition all of the time; sometimes<br />
only extra pho<strong>to</strong>synthesis is needed, and<br />
<strong>in</strong> such situations it would be cheaper <strong>to</strong><br />
use red light, while at other times we need<br />
<strong>to</strong> affect the shape of the plant and therefore<br />
other light colours are needed.<br />
The question is, how do we make this<br />
work <strong>in</strong> practice, given that most of the<br />
current knowledge has been obta<strong>in</strong>ed <strong>from</strong><br />
climate chambers and experiments <strong>in</strong> the<br />
lab? In the Innovation Consortium project,<br />
Greenhouse Concept 2017, we are test<strong>in</strong>g<br />
the LED technology <strong>in</strong> the greenhouse.<br />
However, there are lots of light combi-<br />
nation possibilities, and lots of different<br />
plant reactions, so we will probably see<br />
many different LED comb<strong>in</strong>ations, possibly<br />
<strong>in</strong> the same lamp cab<strong>in</strong>et.<br />
We must remember that daylight is<br />
the most important light source and that<br />
artificial light is merely supplementary<br />
light. We know <strong>from</strong> SON-T lights that<br />
yellow-orange light is a useful supplement<br />
<strong>to</strong> daylight, however it does not work<br />
very well on its own because it results <strong>in</strong><br />
undesirable stretch<strong>in</strong>g. When we use the<br />
lights as supplementary light<strong>in</strong>g, they must<br />
be well suited for pho<strong>to</strong>synthesis, but we<br />
can achieve even more by us<strong>in</strong>g new light<br />
colour comb<strong>in</strong>ations. And the expected<br />
<strong>in</strong>crease <strong>in</strong> efficiency and the longer lifetime<br />
of the LED lights is added bonus.<br />
ENERGY IN FOCUS 19
The sun<br />
as a potential source of energy<br />
In the long term there are likely <strong>to</strong> be demands for CO2-friendly or perhaps<br />
even CO2 neutral production. There is no simple method of solv<strong>in</strong>g this<br />
problem. Several solutions have <strong>to</strong> be brought <strong>in</strong><strong>to</strong> play at the same time,<br />
and exploit<strong>in</strong>g the heat <strong>from</strong> the sun is a strong contender<br />
Ole Skov oes@agrotech.dk, and Jens Rystedt jor@agrotech.dk, consultants, <strong>AgroTech</strong><br />
Solar radiation is potentially an enormous<br />
source of energy, and <strong>in</strong> a greenhouse<br />
the annual <strong>in</strong>flux of energy is about<br />
850 kWh/m2 (measured on a horizontal<br />
surface <strong>in</strong>side the greenhouse); approximately<br />
twice as much as the greenhouse’s<br />
own energy consumption.<br />
In pr<strong>in</strong>ciple, a greenhouse is one big<br />
solar panel, and it will become <strong>in</strong>creas<strong>in</strong>gly<br />
common <strong>to</strong> collect some of the<br />
surplus energy <strong>from</strong> the greenhouse and<br />
s<strong>to</strong>re it for later use. However, so far the<br />
<strong>in</strong>vestment required has been <strong>to</strong>o big <strong>to</strong><br />
make this possible. S<strong>to</strong>rage of the large<br />
amounts of energy for use <strong>in</strong> the w<strong>in</strong>ter is<br />
a great challenge.<br />
Perhaps better <strong>in</strong>sulation of greenhouses<br />
would be a good start, as this would<br />
reduce the amount of energy which would<br />
have <strong>to</strong> be s<strong>to</strong>red. With better <strong>in</strong>sulation, it<br />
is not unrealistic <strong>to</strong> halve the energy need.<br />
After this we can tackle exploitation of the<br />
sun’s energy, either directly <strong>in</strong> the greenhouse,<br />
or by us<strong>in</strong>g solar panels, or through<br />
a comb<strong>in</strong>ation of the two.<br />
Harvest of solar energy<br />
Great challenges have <strong>to</strong> be overcome<br />
before we can meet all our needs us<strong>in</strong>g<br />
solar energy: How is the energy <strong>to</strong> be harvested,<br />
and how is it <strong>to</strong> be s<strong>to</strong>red?<br />
The plants seen so far, mostly <strong>in</strong> the<br />
Netherlands, uses ventilation units <strong>to</strong> harvest<br />
the energy by transferr<strong>in</strong>g it <strong>from</strong> the<br />
air <strong>in</strong> the greenhouses <strong>to</strong> water, which is<br />
often s<strong>to</strong>red underground. This method<br />
works at relatively low temperatures, especially<br />
<strong>in</strong> the s<strong>to</strong>rage facilities. The energy<br />
has <strong>to</strong> be transferred back <strong>to</strong> the greenhouse<br />
<strong>from</strong> the water <strong>to</strong> the air.<br />
The surplus energy <strong>from</strong> the sun can<br />
be harvested and s<strong>to</strong>red <strong>in</strong> many different<br />
ways. The method <strong>to</strong> be chosen depends<br />
on the exist<strong>in</strong>g equipment and on the<br />
percentage of the energy consumption <strong>to</strong><br />
be covered <strong>in</strong>itially by the surplus energy.<br />
At many sites, buffer tanks and other<br />
types of water s<strong>to</strong>rage have been <strong>in</strong>stalled<br />
which can be used as energy s<strong>to</strong>res for<br />
short periods – e.g. <strong>from</strong> day <strong>to</strong> night or<br />
over a few days. For example, if the surplus<br />
energy is collected on a daily basis via a<br />
ventilation plant <strong>in</strong> which the water temperature<br />
is heated <strong>to</strong> 70°C and then s<strong>to</strong>red<br />
<strong>in</strong> a 500 m 2 buffer tank, this can be enough<br />
<strong>to</strong> cover the energy consumption of a 5000<br />
m 2 greenhouse for four <strong>to</strong> five summer<br />
months. This corresponds <strong>to</strong> about 20 percent<br />
of the annual energy consumption.<br />
Water is either heated us<strong>in</strong>g traditional<br />
solar panels, or us<strong>in</strong>g a heat pump.<br />
New possibilities<br />
So, even with a small heat s<strong>to</strong>rage facility,<br />
it is possible <strong>to</strong> reduce the use of fossil<br />
fuels. In comb<strong>in</strong>ation with <strong>in</strong>stallation of<br />
ventilation equipment, this provides new<br />
opportunities <strong>to</strong> secure energy supplies,<br />
and ventilation equipment <strong>in</strong> the greenhouse<br />
means it is possible <strong>to</strong> control and<br />
adjust the greenhouse climate by even<strong>in</strong>g<br />
out the differences <strong>in</strong> temperature and<br />
humidity.<br />
If we want <strong>to</strong> <strong>in</strong>crease the percentage of<br />
our energy which comes <strong>from</strong> solar heat<strong>in</strong>g,<br />
we have <strong>to</strong> th<strong>in</strong>k <strong>in</strong> terms of larger s<strong>to</strong>rage<br />
capacity. For example, underground<br />
s<strong>to</strong>rage, or <strong>in</strong> heat s<strong>to</strong>rage ponds, which<br />
are like large ra<strong>in</strong>water bas<strong>in</strong>s covered<br />
with <strong>in</strong>sulat<strong>in</strong>g material.<br />
There is still some way <strong>to</strong> go before we<br />
can say that we are <strong>in</strong>dependent of fossil<br />
fuels, but energy directly <strong>from</strong> the sun is<br />
certa<strong>in</strong>ly one of the possibilities we should<br />
keep our eye on.<br />
<br />
20 ENERGY IN FOCUS
Energiforbrug<br />
Dækmaterialer<br />
• Glas<br />
• Dobbeltglas<br />
• Termoglas<br />
• Polycarbonat<br />
• Termopaneler<br />
Gard<strong>in</strong>er<br />
• Et eller <strong>to</strong> lags<br />
• S<strong>to</strong>ftyper<br />
Der kan bygges<br />
på mange måder<br />
Dæklister<br />
• Gummitætn<strong>in</strong>gslister<br />
ved glas<br />
Grønnegyden 105<br />
DK-5270 Odense N<br />
Phone: +45 6614 5070<br />
Telefax: +45 6614 5084<br />
E-mail: gpl@gpl.dk<br />
http:/www.gpl.dk<br />
Lad os se på<br />
dit væksthusprojekt<br />
Applikation and adm<strong>in</strong>istration of:<br />
Plant Breeders’ Right / Plant Patents<br />
Trade Marks and Utility Patents<br />
Odensevej 38 • Vern<strong>in</strong>ge • 5690 Tommerup • Tlf. +45 6475 2000 • Fax: +45 6475 2470 • <strong>in</strong>fo@viemose-driboga.dk • www.viemose-driboga.dk<br />
ENERGY IN FOCUS 21
Jan Agnoletti Pedersen, Vik<strong>in</strong>gegaarden A/S, jap@vik<strong>in</strong>gegaarden.com • Mads Andersen, Senmatic, DGT-Volmatic, maa@senmatic.dk •<br />
Jens Rystedt, <strong>AgroTech</strong>, jor@agrotech.dk<br />
Purchase electricity when<br />
it is cheapest – au<strong>to</strong>matically<br />
More than 20 percent of the energy consumption <strong>in</strong> Denmark is covered by w<strong>in</strong>d<br />
turb<strong>in</strong>es, and it is estimated this will <strong>in</strong>crease dramatically <strong>in</strong> the future. The successful<br />
implementation of a high coverage of green electricity presents some huge challenges,<br />
but it also opens up for some great opportunities. The w<strong>in</strong>d turb<strong>in</strong>es produce electricity<br />
when the w<strong>in</strong>d is blow<strong>in</strong>g, no matter if there are consumers who can use it or not.<br />
To obta<strong>in</strong> the balance between electricity<br />
production and electricity consumption,<br />
a “balance” system has been<br />
set up with decentral standby electrical<br />
consumers/producers and vary<strong>in</strong>g electricity<br />
prices as the essential elements.<br />
When purchas<strong>in</strong>g electricity on the<br />
spot market, it is possible <strong>to</strong> purchase<br />
the electricity at the actual market price,<br />
which varies hour by hour. The variations<br />
are huge, rang<strong>in</strong>g <strong>from</strong> free of charge <strong>to</strong><br />
very expensive <strong>in</strong> periods with high consumption.<br />
The free of charge periods are typically<br />
periods where the w<strong>in</strong>d is blow<strong>in</strong>g and<br />
consumption of electrical power is at a<br />
m<strong>in</strong>imum. Consumers with an electrical<br />
consumption which can be moved <strong>from</strong><br />
one period of the day <strong>to</strong> another, and with<br />
a m<strong>in</strong>imum of disturbance, can profit <strong>from</strong><br />
this system.<br />
As a rule of thumb it is possible <strong>to</strong> save<br />
up <strong>to</strong> 10-15 percent on the electricity bill,<br />
as the electricity prices can vary <strong>from</strong> free<br />
of charge <strong>to</strong> EUR 0.9-1.0 per kWh. This<br />
large variation gives great opportunities for<br />
significant sav<strong>in</strong>gs on operat<strong>in</strong>g costs.<br />
Change time of consumption<br />
One condition <strong>to</strong> exploit the variations <strong>in</strong><br />
the electricity prices is that it must be possible<br />
<strong>to</strong> change the hours <strong>in</strong> which electricity<br />
is consumed, with no loss of production.<br />
Many <strong>in</strong>dustrial companies are<br />
locked <strong>to</strong> work<strong>in</strong>g hours, as the production<br />
must run when the personnel is present.<br />
However, there is a vast number of<br />
<strong>in</strong>dustries with the option <strong>to</strong> change their<br />
consumption pattern. For example cold<br />
s<strong>to</strong>res, <strong>in</strong>dustrial processes and pump units<br />
can benefit <strong>from</strong> chang<strong>in</strong>g their consumption<br />
<strong>to</strong> the hours with cheap electricity.<br />
Vik<strong>in</strong>gegaarden A/S manufactures webbased<br />
control equipment, <strong>in</strong>clud<strong>in</strong>g a<br />
module enabl<strong>in</strong>g the possibility <strong>to</strong> utilize<br />
electricity when it is cheapest - Elspot.<br />
The module can be programmed <strong>to</strong><br />
switch on a plant for the eight cheapest<br />
hours, or only <strong>to</strong> switch on when the price<br />
is below a certa<strong>in</strong> price level.<br />
Elspot system for growth light<br />
Senmatic, <strong>AgroTech</strong> and Vik<strong>in</strong>gegaarden<br />
A/S have teamed up and are <strong>in</strong> the process<br />
of adapt<strong>in</strong>g and <strong>in</strong>tegrat<strong>in</strong>g the Elspot<br />
system so that it can be used <strong>in</strong> connection<br />
with growth light and optional electrical<br />
heaters.<br />
The system <strong>from</strong> Vik<strong>in</strong>gegaarden A/S<br />
retrieves the hourly prices of electri-<br />
city by means of the GSM/GPRS net work.<br />
Those hourly prices are transferred <strong>to</strong> the<br />
SuperL<strong>in</strong>k 4 <strong>from</strong> Senmatic for use <strong>in</strong> the<br />
advanced control system.<br />
This means that electricity prices are<br />
part of the optimization program, assur<strong>in</strong>g<br />
the most optimum match between the<br />
lowest possible electrical prices and the<br />
maximum growth of the plants, assur<strong>in</strong>g<br />
the horticultural sec<strong>to</strong>r the most profitable<br />
bus<strong>in</strong>ess.<br />
The systems <strong>from</strong> Senmatic and Vik<strong>in</strong>gegaarden<br />
A/S are now be<strong>in</strong>g implemented<br />
and will later be tested at a nursery <strong>to</strong><br />
determ<strong>in</strong>e functionality and the f<strong>in</strong>ancial<br />
benefits.<br />
The system is expected <strong>to</strong> be launched<br />
on the market later this year, for use <strong>in</strong> the<br />
forthcom<strong>in</strong>g growth light season.<br />
<br />
22 ENERGY IN FOCUS
Flemm<strong>in</strong>g Ulbjerg • Chief consultant, Rambøll, fu@ramboll.dk<br />
Renewable energy<br />
and the s<strong>to</strong>rage issue<br />
Full conversion <strong>to</strong> renewable energy requires <strong>in</strong>novation and development.<br />
For example, “production” and “consumption” do not always go hand <strong>in</strong> hand for<br />
renewable energy. If we want <strong>to</strong> use more renewable energy than we do <strong>to</strong>day, we have<br />
<strong>to</strong> be able <strong>to</strong> s<strong>to</strong>re energy over long periods of time; and this presents a challenge<br />
The Danish Government’s long-term target<br />
is <strong>to</strong> be able <strong>to</strong> cover most Danish<br />
energy consumption requirements with<br />
renewable energy.<br />
The renewable energy sources currently<br />
commercially available are large-scale<br />
solar heat<strong>in</strong>g and w<strong>in</strong>d power both offshore<br />
and onshore. In addition, biomass <strong>in</strong><br />
the shape of chipp<strong>in</strong>gs and straw etc. is a<br />
well known energy source, although supplies<br />
are limited.<br />
Large scale solar heat<strong>in</strong>g<br />
Large scale solar heat<strong>in</strong>g has been <strong>in</strong>stalled<br />
at a large number of district heat<strong>in</strong>g<br />
plants supply<strong>in</strong>g natural-gas fired heat<strong>in</strong>g.<br />
Partly because of the taxes on natural gas,<br />
solar heat<strong>in</strong>g is an extremely profitable<br />
alternative <strong>to</strong> current supplies <strong>from</strong> natural<br />
gas.<br />
The cost of heat <strong>from</strong> a large solar heat<strong>in</strong>g<br />
plant for the first year can typically<br />
be around DKK 250 per MWh heat, compared<br />
with natural gas which costs about<br />
DKK 500 per MWh, <strong>in</strong>clud<strong>in</strong>g tax.<br />
These solar heat<strong>in</strong>g plants usually cover<br />
between 15 and 20 percent of annual<br />
energy consumption.<br />
Not until heat-s<strong>to</strong>rage technologies are<br />
commercially mature and tested will the<br />
way be paved <strong>to</strong> expand these solar heat<strong>in</strong>g<br />
plants <strong>to</strong> cover somewhere between 50<br />
and 75 percent of the annual consumption<br />
of heat at a specific district heat<strong>in</strong>g plant.<br />
Geothermics as a s<strong>to</strong>rage method<br />
Today, geothermics are usually associated<br />
with direct heat supply such as that <strong>in</strong><br />
<strong>Copenhagen</strong>, for example, <strong>in</strong> which hot<br />
water is obta<strong>in</strong>ed <strong>from</strong> very deep boreholes<br />
- often around two kilometres deep<br />
- and then used for direct heat<strong>in</strong>g.<br />
However, geothermics are also a promis<strong>in</strong>g<br />
s<strong>to</strong>rage method. In some green-<br />
houses heat is s<strong>to</strong>red <strong>in</strong> aqueous sand<br />
layers at a depth of about 100-200 metres.<br />
Dutch greenhouse companies are <strong>in</strong>creas<strong>in</strong>gly<br />
us<strong>in</strong>g this method. The heat is<br />
extracted <strong>from</strong> the greenhouse <strong>in</strong> the summer<br />
us<strong>in</strong>g a heat pump, and it is led back<br />
<strong>in</strong> the w<strong>in</strong>ter via the same heat pump.<br />
Underground s<strong>to</strong>rage is not possible<br />
everywhere, so short-term s<strong>to</strong>rage <strong>in</strong> steel<br />
tanks is attractive, and just as effective<br />
as geothermic s<strong>to</strong>rage. However, both<br />
geothermic s<strong>to</strong>rage and other forms of<br />
s<strong>to</strong>rage <strong>in</strong> lagoons or heat s<strong>to</strong>rage ponds<br />
must be further developed before they can<br />
be used commercially.<br />
Need for <strong>in</strong>novation<br />
It is likely that future heat supply for<br />
greenhouses and heat<strong>in</strong>g other build<strong>in</strong>gs<br />
will come <strong>from</strong> a comb<strong>in</strong>ation of different<br />
sources, with w<strong>in</strong>d and solar energy play<strong>in</strong>g<br />
a large part. However, before we get<br />
there, there is a great need for <strong>in</strong>novation<br />
<strong>in</strong> the development of cheap heat s<strong>to</strong>rage.<br />
ENERGY IN FOCUS 23
Ole Bærenholdt-Jensen • Advisor, Danish Advisory Service, obj@landscentret.dk<br />
Dynamic climate control works<br />
– worldwide<br />
The <strong>in</strong>ternational GreenSys 2009 Conference <strong>in</strong> Canada <strong>in</strong> June conta<strong>in</strong>ed new<br />
research results <strong>from</strong> all around the world. A major part of the conference<br />
was about the latest developed ideas concern<strong>in</strong>g energy sav<strong>in</strong>gs. One method<br />
for sav<strong>in</strong>g energy, Dynamic Climate Control, which gets a lot of attention<br />
<strong>in</strong> Denmark, was backed up by several presentations<br />
Some presentations <strong>from</strong> the conference<br />
revealed that many people are<br />
research<strong>in</strong>g the same elements which are<br />
<strong>in</strong>cluded <strong>in</strong> the Danish Dynamic Climate<br />
Control Concept.<br />
Results <strong>from</strong> the “Intelligrow” project<br />
research go<strong>in</strong>g on <strong>in</strong> the period 1998-2002<br />
gave an idea of the potential for energy<br />
sav<strong>in</strong>g <strong>from</strong> this k<strong>in</strong>d of climate control.<br />
The Intelligrow research has created a base<br />
for a great part of the later development<br />
concern<strong>in</strong>g climate control <strong>in</strong> Denmark.<br />
One important element <strong>in</strong> Dynamic<br />
Climate Control is <strong>to</strong> allow bigger fluctuations<br />
<strong>in</strong> the temperature <strong>in</strong> the greenhouse,<br />
which gives you the highest possible part<br />
of the heat <strong>from</strong> the irradiation, and as<br />
little as possible <strong>from</strong> heat<strong>in</strong>g unit based<br />
on fossil fuel (nature gas, coal, oil).<br />
Modest, aggressive and extended<br />
control <strong>in</strong> Great Brita<strong>in</strong><br />
Steve Adams, Great Brita<strong>in</strong> presented<br />
results <strong>from</strong> his research <strong>in</strong> energy sav<strong>in</strong>gs<br />
us<strong>in</strong>g different levels of flexible temperature<br />
control, based on TI, Temperature<br />
Integration. There was calculated on three<br />
levels: Modest, aggressive and extended<br />
TI.<br />
Results and explanation <strong>from</strong> the calculations<br />
of energy use can be seen on<br />
monthly base <strong>in</strong> figure 1.<br />
Trials were made us<strong>in</strong>g these methods<br />
<strong>in</strong> <strong>to</strong>ma<strong>to</strong>es, pot-chrysanthemum, pansy<br />
and petunia, on Warwick research station.<br />
The results <strong>in</strong> <strong>to</strong>ma<strong>to</strong> production were<br />
good us<strong>in</strong>g TI with a day temperature setpo<strong>in</strong>t<br />
on 14°C, and the yearly harvest was<br />
not affected.<br />
Also <strong>in</strong> pot plants the results were good,<br />
with only 1-2 days extension <strong>in</strong> production<br />
time us<strong>in</strong>g temperature setpo<strong>in</strong>ts at 12°C<br />
and ventilation setpo<strong>in</strong>t at 26°C.<br />
Low temperature three<br />
hours post-night<br />
From Canada Mr. X. Hao et. al. reported<br />
<strong>from</strong> trials <strong>in</strong> Ontario <strong>in</strong> <strong>to</strong>ma<strong>to</strong>es. Low<br />
Figure 1. Calculated monthly energy consumption. Conventional control (black) day/<br />
night 18/18°C, ventilation at 20°C. You see 8% energy sav<strong>in</strong>g at modest TI control (light<br />
grey, d/n 16/16°C, vent 23°C), 13% by aggressive TI control (White, d/n 12/12°C, vent<br />
26°C), and 18% energy sav<strong>in</strong>g by extended TI control (dark grey, control as the former<br />
plus fixed low day temp setpo<strong>in</strong>t). Note that only at the extended TI control it is possible <strong>to</strong><br />
save energy <strong>in</strong> November-February. And <strong>in</strong> June-august you can see energy consumption<br />
at almost zero at aggressive and extended TI control.<br />
temperature late night, comb<strong>in</strong>ed with<br />
temperature <strong>in</strong>tegration gave an <strong>in</strong>creased<br />
temperature dur<strong>in</strong>g daytime <strong>to</strong> compensate<br />
for the night time period with low<br />
temperature.<br />
The conventional treatment weas 17°C<br />
dur<strong>in</strong>g the three hours, <strong>to</strong> compare with<br />
the treatment <strong>in</strong> the trial with 13,5°C<br />
dur<strong>in</strong>g the three hours.<br />
There was no energy sav<strong>in</strong>g <strong>in</strong> February,<br />
but 6-8% sav<strong>in</strong>g <strong>in</strong> march-may. Dew po<strong>in</strong>t<br />
temperature at the 13,5°C treatment was<br />
lower compared <strong>to</strong> conventional, so there<br />
was no humidity problems concern<strong>in</strong>g the<br />
treatment. The trials did not show major<br />
differences <strong>in</strong> harvest level (except for one<br />
variety).<br />
Dynamic <strong>to</strong>ma<strong>to</strong>es <strong>in</strong> France<br />
Trials <strong>in</strong> <strong>to</strong>ma<strong>to</strong> grow<strong>in</strong>g <strong>in</strong> West-France<br />
us<strong>in</strong>g Dynamic climate control (Temperature<br />
<strong>in</strong>tegration and higher/lower setpo<strong>in</strong>ts)<br />
was described by Serge le Quillec<br />
et. al. There was references also <strong>to</strong> the<br />
Danish Intelligrow concept.<br />
Description and results are seen <strong>in</strong> figure<br />
2. You can see energy sav<strong>in</strong>g around 5%<br />
- 15% without loss of harvest, if you assure<br />
that the temperature don’t get lower than<br />
13°C and not beyond 29°C. The weight<br />
pr fruit becomes 10% higher. It was also<br />
stated that you get higher CO2 level dur<strong>in</strong>g<br />
the day, hav<strong>in</strong>g a slightly lower consumption,<br />
because of more closed w<strong>in</strong>dows.<br />
But it was also po<strong>in</strong>ted out that you<br />
have <strong>to</strong> be aware of us<strong>in</strong>g an effective<br />
humidity control because of Botrytis risk,<br />
and that you should look for more temperature<br />
<strong>to</strong>lerant varieties, <strong>to</strong> reach bigger<br />
energy sav<strong>in</strong>g results by us<strong>in</strong>g dynamic<br />
climate control.<br />
Several Dutch trials<br />
J. A. Dieleman et. al. described <strong>in</strong> a wide<br />
range presentation the research go<strong>in</strong>g on<br />
<strong>in</strong> the latest years <strong>in</strong> Holland, concern<strong>in</strong>g<br />
energy sav<strong>in</strong>g <strong>from</strong> greenhouse technique,<br />
climate control and plant physiology.<br />
24 ENERGY IN FOCUS
Figure 2. Dynamic climate control <strong>to</strong>ma<strong>to</strong> trials <strong>in</strong> France. <strong>Energy</strong><br />
consumption and sav<strong>in</strong>g <strong>in</strong> 2006-2007. At IT1 the Temperature<br />
<strong>in</strong>tegration had 2-5°C extra space <strong>from</strong> highest/lowest setpo<strong>in</strong>ts,<br />
compared <strong>to</strong> control. At IT2 it was 3-8°C.<br />
She described that the essential element<br />
<strong>in</strong> energy effectiveness by change <strong>in</strong><br />
climate control is <strong>to</strong> allow big difference<br />
between highest and lowest temperature<br />
<strong>in</strong> a “band-width”, <strong>to</strong> allow higher humidity<br />
level, and <strong>to</strong> use dynamic changes of<br />
the setpo<strong>in</strong>ts <strong>in</strong> the control.<br />
It was stated that results <strong>from</strong> several<br />
trials where many different cultivars were<br />
used, show that most cultivars are <strong>to</strong>lerant<br />
<strong>to</strong> temperature fluctuations, if you assure<br />
<strong>to</strong> keep track of the average temperature<br />
by us<strong>in</strong>g temperature <strong>in</strong>tegration control.<br />
This is well known knowledge, but here<br />
Anja Dielemann said that this assumption<br />
is based on documentation <strong>from</strong> research,<br />
and not just a “rule of thumb”. Results<br />
<strong>from</strong> some trials show energy sav<strong>in</strong>g <strong>from</strong><br />
3% <strong>to</strong> 13% us<strong>in</strong>g a band-width on 10°C<br />
<strong>in</strong> the temperature <strong>in</strong>tegration control, as<br />
an example <strong>from</strong> the research <strong>in</strong> Holland.<br />
Low temperature for Anthurium<br />
grown <strong>in</strong> Belgium<br />
If you want <strong>to</strong> use dynamic climate control<br />
you have <strong>to</strong> decide the limit for the<br />
allowed, lowest temperature. This can be<br />
due <strong>to</strong> the danger of leaf wetness caused<br />
by high humidity, if the humidity control<br />
can’t catch up with the temperature<br />
fluctua-tions. It can also depend on which<br />
temperature <strong>to</strong>lerance the cultivars are<br />
“born with” <strong>from</strong> their orig<strong>in</strong>, and still not<br />
loos<strong>in</strong>g quality.<br />
Trials that should help <strong>to</strong> state the<br />
lowest acceptable temperature were<br />
described on a poster <strong>from</strong> Els S<strong>to</strong>rme et.<br />
al. <strong>from</strong> Belgium.<br />
Grow<strong>in</strong>g Tropical plants often requires<br />
fairly high temperatures, therefore energy<br />
use can be high. Therefore it is especially<br />
important <strong>to</strong> try <strong>to</strong> save energy, for<br />
example by us<strong>in</strong>g dynamic climate control<br />
with low temperature setpo<strong>in</strong>ts. But how<br />
low? The trials were made on Anthurium<br />
‘Limoria’ (C3 plant), set <strong>in</strong> different temperature<br />
regimes, <strong>from</strong> high <strong>to</strong> low. Measur<strong>in</strong>g<br />
on different processes <strong>in</strong> the crop,<br />
they found that temperatures under 12°C<br />
did affect the processes negative.<br />
High temperature for po<strong>in</strong>settia<br />
On the other hand you also have <strong>to</strong> get<br />
<strong>to</strong> fairly high temperature, especially <strong>in</strong><br />
Research <strong>from</strong> different places shows that it is also possible <strong>to</strong> use dynamic<br />
climate control <strong>in</strong> <strong>to</strong>ma<strong>to</strong>es if you choose appropriate setpo<strong>in</strong>ts.<br />
Anthurium. Research shows that the processes <strong>in</strong> the<br />
plant are affected at temperatures below 12°C.<br />
the middle of the day, where you can harvest<br />
more free energy form the sun if you<br />
allow high temperatures. But you can also<br />
decide <strong>to</strong> use high temperatures if you can<br />
buy cheep energy <strong>in</strong> certa<strong>in</strong> periods.<br />
In Germany there has been trials on this<br />
for Po<strong>in</strong>settia. N. Gruda et. al. used day/<br />
night setpo<strong>in</strong>ts fixed on 25°C/16°C, plus<br />
a period <strong>in</strong> the morn<strong>in</strong>g us<strong>in</strong>g even lower<br />
temperature (12°C).<br />
The control day/night were 18°C/16°C.<br />
Results were good. Plant quality was good,<br />
with bigger leaf area and same height<br />
development, although they became a<br />
little higher. Conclusion was that it is possible<br />
also <strong>to</strong> use higher temperatures <strong>to</strong><br />
produce good quality po<strong>in</strong>settia, <strong>in</strong> periods<br />
where you have “luxury heat”, cheap<br />
or free, and thereby save energy and/or<br />
money.<br />
Dynamic climate control<br />
will rema<strong>in</strong><br />
The elements <strong>from</strong> dynamic climate control<br />
are described <strong>in</strong> an article by the<br />
present writer <strong>in</strong> Gartner Tidende no. 12<br />
<strong>from</strong> June 2009. A wide range of results<br />
<strong>from</strong> research <strong>in</strong> other countries supports<br />
that dynamic climate control works, gives<br />
energy sav<strong>in</strong>gs and states that the climate<br />
control course <strong>in</strong> Denmark is right.<br />
In several of the projects, described <strong>in</strong><br />
other articles <strong>in</strong> this magaz<strong>in</strong>e, is dynamic<br />
climate control <strong>in</strong>volved. One example<br />
is <strong>from</strong> the project “Intelligent use of<br />
energy”, where the climate control <strong>in</strong><br />
the demonstration greenhouse at “Hjortebjerg”,<br />
Funen, is <strong>in</strong>clud<strong>in</strong>g the “Intelligrow”<br />
climate control concept.<br />
In my op<strong>in</strong>ion we are go<strong>in</strong>g <strong>in</strong> the right<br />
direction, but <strong>to</strong> be backed up by research<br />
results <strong>from</strong> all over the world confirms<br />
the concept. Dynamic climate control has<br />
come and will rema<strong>in</strong>.<br />
<br />
ENERGY IN FOCUS 25
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For years Dal<strong>in</strong>a have been breed<strong>in</strong>g Osteospermum,<br />
and we are happy with the results they<br />
have achieved.<br />
There are now 15 Dal<strong>in</strong>a® Osteospermum<br />
cultivars available, <strong>in</strong> beautiful colours.<br />
The Dal<strong>in</strong>a cultivars are grower friendly, with<br />
good garden performance.<br />
Young Flowers present –<br />
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Meet us at<br />
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Hall 7 stand 0816<br />
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We have a wide range of products <strong>in</strong> our<br />
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26 ENERGY IN FOCUS
The World of Dal<strong>in</strong>a® 2010<br />
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As a result of Dal<strong>in</strong>a’s <strong>in</strong>tensive breed<strong>in</strong>g<br />
programme, they have created a number of<br />
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Dal<strong>in</strong>a® Dahlia cultivars are both healthy and<br />
vigorous, m<strong>in</strong>imis<strong>in</strong>g production problems.<br />
The short production time optimises efficient<br />
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There are now four different stra<strong>in</strong>s <strong>to</strong> choose<br />
<strong>from</strong>:<br />
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ENERGY IN FOCUS 27<br />
Tel.: +45 6317 0495 · <strong>in</strong>fo@youngflowers.dk · www.youngflowers.dk
Lotte Bjarke, edi<strong>to</strong>r, Gartner Tidende, post@lottebjarke.dk<br />
Two organisations<br />
work<strong>in</strong>g for the same cause<br />
Danish Horticulture and the largest trade union <strong>in</strong> Denmark, 3F,<br />
are <strong>in</strong> close dialogue with each other and often back up each other’s views.<br />
Safeguard<strong>in</strong>g the future of the horticultural bus<strong>in</strong>ess and preserv<strong>in</strong>g<br />
jobs are some of the organisations’ common goals.<br />
When the future of the horticultural<br />
bus<strong>in</strong>ess is threatened, Danish Horticulture<br />
and 3F move closer <strong>to</strong>gether as<br />
was the case <strong>in</strong> the early spr<strong>in</strong>g when the<br />
two organisations received the Tax Commission’s<br />
proposal for a new Tax reform.<br />
- We have no doubt that a quick reaction<br />
and a jo<strong>in</strong>t statement <strong>from</strong> our two<br />
organisations made a difference so that<br />
the f<strong>in</strong>al result of the tax proposal ended<br />
up not be<strong>in</strong>g as bad as expected, agrees<br />
Jesper Lund-Larsen, 3F’s consultant for<br />
environment and work<strong>in</strong>g environment,<br />
and consultant <strong>in</strong> Danish Horticulture, Leif<br />
Marienlund.<br />
Involve staff<br />
The two consultants can give several<br />
examples of cases where the organisati-<br />
ons have mutual <strong>in</strong>terests among which<br />
the most important ones are climate and<br />
energy.<br />
- Obviously, the energy issue is very<br />
crucial for the greenhouse nurseries.<br />
We are more than will<strong>in</strong>g <strong>to</strong> take part<br />
<strong>in</strong> fulfill<strong>in</strong>g the climate goals set out by<br />
the Danish State. Long-term survival is<br />
dependent on future reductions of the<br />
energy level. But at the same time we must<br />
remember that the horticultural bus<strong>in</strong>ess<br />
has already reducet its energy consumption<br />
by 26% <strong>from</strong> 1996 <strong>to</strong> 2008, says<br />
Leif Marienlund, who po<strong>in</strong>ts out that this<br />
reduction is due <strong>to</strong> close and focused cooperation<br />
between management and staff<br />
<strong>in</strong> the <strong>in</strong>dividual greenhouses. This is a<br />
very important issue for 3F.<br />
- It is of great significance that the staff<br />
is <strong>in</strong>volved <strong>in</strong> the whole process as this<br />
will result <strong>in</strong> bigger profits and happy<br />
employees, and it helps valuable experience<br />
<strong>to</strong> be passed on <strong>from</strong> one nursery <strong>to</strong><br />
the colleagues <strong>in</strong> the other nursery, says<br />
Jesper Lund-Larsen.<br />
Common conditions <strong>in</strong> the EU<br />
The organisations are keep<strong>in</strong>g a sharp eye<br />
on the present development on tax changes<br />
<strong>in</strong> Denmark.<br />
- There is no doubt that the energy<br />
bill will <strong>in</strong>crease, and it is important that<br />
the greenhouses keep focus on energy<br />
sav<strong>in</strong>gs. We would like <strong>to</strong> take part <strong>in</strong><br />
discussions on how <strong>to</strong> reduce energy<br />
consumption, but at the same time we<br />
have <strong>to</strong> ensure that we are not punished<br />
afterwards. If this situation becomes reality,<br />
the whole Danish horticultural sec<strong>to</strong>r<br />
will be clos<strong>in</strong>g down, Jesper Lund-Larsen<br />
po<strong>in</strong>ts out.<br />
- It is a fundamental problem <strong>to</strong> provide<br />
funds for development and one of our<br />
greatest challenges. We are very pleased<br />
that the Danish M<strong>in</strong>ister for Food, Agriculture<br />
and Fisheries Eva Kjer Hansen has<br />
made a contribution of DKK 50 million<br />
<strong>to</strong> the horticultural sec<strong>to</strong>r (“gartnerikonvolutten”)<br />
<strong>to</strong> support projects concern<strong>in</strong>g<br />
<strong>in</strong>novation, energy, water consumption<br />
etc. But it is a bit disappo<strong>in</strong>t<strong>in</strong>g that di-<br />
strict heat<strong>in</strong>g is not <strong>in</strong>cluded <strong>in</strong> this grant,<br />
says Leif Marienlund. He adds that of course<br />
new technology can create jobs, but at<br />
the same time it is important <strong>to</strong> remember<br />
<strong>to</strong> use and develop already exist<strong>in</strong>g technologies.<br />
Leif Marienlund and Jesper Lund-Larsen<br />
wish the Danish and the European horticultural<br />
<strong>in</strong>dustry all the best and hope<br />
that the future will br<strong>in</strong>g uniform work<strong>in</strong>g<br />
conditions for all growers with<strong>in</strong><br />
the framework of the EU <strong>to</strong> avoid Da-<br />
nish growers look<strong>in</strong>g upon their Dutch<br />
colleagues <strong>in</strong> the future with envy when<br />
they are receiv<strong>in</strong>g state guaranteed loans<br />
and other means of subsidies.<br />
<br />
28 ENERGY IN FOCUS
P<strong>in</strong>dstrup products are sold<br />
worldwide and delivered <strong>in</strong><br />
bulk, Big Bales, compressed<br />
bales or loose-filled bags.<br />
Transport arranged by trailer,<br />
conta<strong>in</strong>ers or shiploads as<br />
required by the cus<strong>to</strong>mer.<br />
P<strong>in</strong>dstrup · DK-8550 Ryomgaard · Denmark<br />
Tel.: + 45 89 74 74 89 · Fax: + 45 89 74 75 70<br />
www.p<strong>in</strong>dstrup.com · E-mail: p<strong>in</strong>dstrup@p<strong>in</strong>dstrup.dk<br />
ENERGY IN FOCUS 29
Af: Søren Møller Sørensen • COO (Chief Operations Officer), Conta<strong>in</strong>er Centralen a/s, s.sorensen@conta<strong>in</strong>er-centralen.com<br />
Plants on wheels reduce the<br />
S<strong>in</strong>ce 1976, pot plants <strong>in</strong> Europe have <strong>in</strong>creas<strong>in</strong>gly been transported<br />
on trolleys – the CC Conta<strong>in</strong>ers <strong>from</strong> Conta<strong>in</strong>er Centralen (CC).<br />
This has optimised horticultural logistics tremendously<br />
In the beg<strong>in</strong>n<strong>in</strong>g, transportation costs<br />
and waste due <strong>to</strong> damaged plants and a<br />
lot of one-way packag<strong>in</strong>g were the major<br />
concerns.<br />
In the 21st century, the environmental ga<strong>in</strong>s<br />
of reusable transportation items have also<br />
become a focal po<strong>in</strong>t on the agenda.<br />
Standard for plant logistics<br />
To optimise horticultural logistics, the largest<br />
plant exporters <strong>in</strong> Denmark came<br />
<strong>to</strong>gether <strong>in</strong> the mid 1970s <strong>to</strong> develop a<br />
transportation unit and a complementary<br />
management system. This resulted <strong>in</strong> the<br />
reusable CC Conta<strong>in</strong>er and the CC Pool<br />
System, which is now the lead<strong>in</strong>g transportation<br />
system for pot plants <strong>in</strong> Europe,<br />
<strong>in</strong>clud<strong>in</strong>g <strong>in</strong>ter-cont<strong>in</strong>ental flows, e.g. <strong>from</strong><br />
Asia or Lat<strong>in</strong> America. CC Conta<strong>in</strong>ers are<br />
produced <strong>in</strong> Asia, and they are loaded<br />
with young plants on their maiden voyage<br />
<strong>to</strong> Europe. Transportation of empty CC<br />
Conta<strong>in</strong>ers is avoided, and comb<strong>in</strong><strong>in</strong>g<br />
the transportation of new CC Conta<strong>in</strong>ers<br />
and young plants reduces CO2 emissions<br />
immensely.<br />
The CC Conta<strong>in</strong>er was developed <strong>to</strong><br />
fully use the space <strong>in</strong> a cooled truck. At<br />
the same time, the <strong>in</strong>troduction of the CC<br />
Pool System made it possible <strong>to</strong> exchange<br />
empty conta<strong>in</strong>ers for full and vice versa.<br />
sThis decreased the need for transportation<br />
of empty conta<strong>in</strong>ers. When empty<br />
conta<strong>in</strong>ers now and then have <strong>to</strong> be transported<br />
– e.g. when sent for repair and<br />
ma<strong>in</strong>tenance – they can be disassembled<br />
and condensed <strong>to</strong> a fraction (1/10) of their<br />
loaded volume.<br />
Further improvements<br />
Needless <strong>to</strong> say, the CC Conta<strong>in</strong>ers can<br />
be used over and over aga<strong>in</strong>, elim<strong>in</strong>at<strong>in</strong>g<br />
the need for one-way packag<strong>in</strong>g that contributes<br />
negatively <strong>to</strong> the CO2 account<br />
due <strong>to</strong> more production, waste disposal,<br />
and a poorer utilisation of space <strong>in</strong> cooled<br />
trucks.<br />
Also, space utilisation <strong>in</strong> warehouses is<br />
better s<strong>in</strong>ce there is no need <strong>to</strong> allow for<br />
space for the forklift handl<strong>in</strong>g, reduc<strong>in</strong>g<br />
energy for light, heat<strong>in</strong>g, etc.<br />
Thus the CC Pool System, <strong>in</strong>clud<strong>in</strong>g the<br />
When the CC Conta<strong>in</strong>er was developed <strong>in</strong> the mid 1970s, the aim was <strong>to</strong> reduce costs <strong>in</strong> the logistic cha<strong>in</strong>s.<br />
An extra bonus of optimised logistics is the reduction of the carbon footpr<strong>in</strong>t. The CC Conta<strong>in</strong>er has contributed <strong>to</strong> this s<strong>in</strong>ce 1976.<br />
30 ENERGY IN FOCUS
carbon footpr<strong>in</strong>t<br />
CC Conta<strong>in</strong>er, has contributed <strong>to</strong> a reduction<br />
<strong>in</strong> CO2 emissions long before climate<br />
changes became a global concern.<br />
From February 2010, all CC Conta<strong>in</strong>ers<br />
will be equipped with RFID tags (Radio<br />
Frequency IDentification). Us<strong>in</strong>g RFID for<br />
Track & Trace further improves logistics,<br />
lead<strong>in</strong>g <strong>to</strong> even larger CO2 – and cost<br />
sav<strong>in</strong>gs <strong>in</strong> the future.<br />
More <strong>in</strong>formation:<br />
www.conta<strong>in</strong>er-centralen.com<br />
www.cc-rfid.com<br />
This is how the CC Conta<strong>in</strong>er<br />
reduces the carbon footpr<strong>in</strong>t<br />
<strong>in</strong> horticultural transportation<br />
• S<strong>in</strong>ce the CC Conta<strong>in</strong>er is a returnable transport item, cont<strong>in</strong>uous production<br />
and waste of disposable packag<strong>in</strong>g are avoided.<br />
• The <strong>in</strong>troduction of RFID on CC Conta<strong>in</strong>ers <strong>in</strong> 2010 will optimise logistics and<br />
thus reduce CO 2 emissions further.<br />
• The CC Conta<strong>in</strong>er has been developed <strong>to</strong> utilise all available space <strong>in</strong> cooled /<br />
traditional “flower” trucks <strong>to</strong> avoid transportation of “air”.<br />
• CC Conta<strong>in</strong>ers can be exchanged full for empty and vice versa <strong>in</strong> the CC Pool<br />
System, and therefore don’t have <strong>to</strong> travel empty over long distances.<br />
• Conta<strong>in</strong>er Centralen also ensures that the trucks don’t travel empty on their<br />
return trips. Average utilisation of truck space on CC controlled transportation<br />
of CC Conta<strong>in</strong>ers is about 97% (<strong>in</strong>clud<strong>in</strong>g empty trucks <strong>in</strong> transit), versus the<br />
Danish average of only 38% (source: A recent analysis published by e.g.: http://<br />
www.dr.dk).<br />
• Whenever empty CC Conta<strong>in</strong>ers have <strong>to</strong> be transported, they can be condensed<br />
<strong>to</strong> a fraction of their loaded volume (1/10).<br />
• New CC Conta<strong>in</strong>ers are loaded for the first time already <strong>in</strong> their country of orig<strong>in</strong><br />
for their maiden voyage – so right <strong>from</strong> the start they don’t travel empty.<br />
Complete horticultural<br />
eng<strong>in</strong>eer<strong>in</strong>g<br />
Wilk van der Sande is specialised <strong>in</strong> heat<strong>in</strong>g, greenhouse cool<strong>in</strong>g, electrical eng<strong>in</strong>eer<strong>in</strong>g, irrigation<br />
and closed greenhouses. Wilk van der Sande is a very <strong>in</strong>novative company, cont<strong>in</strong>uously<br />
develop<strong>in</strong>g new solutions for improved energy sav<strong>in</strong>g systems. You will nd no other supplier<br />
with such vast expertise, particularly <strong>in</strong> the eld of closed greenhouses. The comb<strong>in</strong>ation of<br />
discipl<strong>in</strong>es takes a lot of work off your hands.<br />
ENERGY IN FOCUS 31
Optimal Irrigation Solutions<br />
Years of experience and<br />
advanced new products<br />
make us a leader<br />
<strong>in</strong> cus<strong>to</strong>mized<br />
irrigation systems<br />
<strong>in</strong> Northern Europe<br />
Optimal Irrigation Solutions ensure precise and correct amounts<br />
of water and energy <strong>in</strong> environmental friendly applications<br />
Vestre 32 Kongevej 7 • 8260 Viby J. Denmark • Tel: +45-86 10 71 37 • Fax: +45-86 10 71 67 • Mobile: ENERGY +45-26 IN 74 FOCUS 71 37<br />
• www.orev.dk • post@orev.dk<br />
Sp<strong>in</strong>Net SD application pho<strong>to</strong> by OREV PTS09
M<strong>in</strong>i symposium / workshop<br />
Intelligent use of <strong>Energy</strong><br />
<strong>in</strong> Greenhouses<br />
<br />
6 - 7 Oc<strong>to</strong>ber 2009<br />
at<br />
University of Southern Denmark, Odense, Denmark<br />
THE EUROPEAN UNION<br />
The European Regional<br />
Development Fund<br />
Invest<strong>in</strong>g <strong>in</strong> your future
Welcom<strong>in</strong>g message<br />
The greenhouse horticulture sec<strong>to</strong>r is under pressure of the huge energy expenses.<br />
The sec<strong>to</strong>r’s energy consumption needs <strong>to</strong> be reduced, and efforts are be<strong>in</strong>g made<br />
<strong>to</strong> f<strong>in</strong>d solutions, which will both reduce costs and benefit the environment. Reduc<strong>in</strong>g<br />
energy consumption often reduces the quality of plants, and new technological<br />
solutions and <strong>in</strong>creased understand<strong>in</strong>g of the physiological reactions of plants<br />
will be necessary <strong>to</strong> achieve energy reduction while ma<strong>in</strong>ta<strong>in</strong><strong>in</strong>g plant quality but<br />
actually also <strong>to</strong> <strong>in</strong>crease and diversify the production<br />
In Denmark there has been a long his<strong>to</strong>ry of research and development with<strong>in</strong><br />
the area of energy sav<strong>in</strong>g. Most of the Danish work has been centred on the physiologically<br />
based ideas of dynamic climate management (IntelliGrow), which has<br />
been one of the causes of the decl<strong>in</strong>e <strong>in</strong> energy use <strong>in</strong> Danish nurseries.<br />
Two projects have been granted, “Greenhouse Concept 2017” and “Intelligent<br />
Use of <strong>Energy</strong> <strong>in</strong> Greenhouses”. The technologies, which will be <strong>in</strong>vestigated as<br />
part of these projects, <strong>in</strong>clude s<strong>to</strong>rage of surplus energy <strong>in</strong> an aquifer, physiology of<br />
plants dynamic climate control, light-emitt<strong>in</strong>g diodes and a number of other technologies,<br />
which may contribute <strong>to</strong> energy efficiency <strong>in</strong> greenhouses. Results are<br />
tested and demonstrated at Hjortebjerg Nursery <strong>in</strong> Søndersø. “Greenhouse Concept<br />
2017” was established as an <strong>in</strong>novation consortium f<strong>in</strong>anced by the Danish<br />
Agency for Science, Technology and Innovation under the M<strong>in</strong>istry of Science,<br />
and the “Intelligent Use of <strong>Energy</strong> <strong>in</strong> Greenhouses” project is sponsored by Region<br />
South Denmark and the European Regional Fund.<br />
In the future, the horticultural sec<strong>to</strong>r, universities, ATS companies (Authorised<br />
Technology Service) and other technological companies need work <strong>to</strong>gether <strong>to</strong> f<strong>in</strong>d<br />
a solution for the <strong>in</strong>dustry and associated bus<strong>in</strong>esses. This will require novel use of<br />
ideas and methods that currently is not <strong>in</strong> use <strong>in</strong> the greenhouse <strong>in</strong>dustry.<br />
On the other hand the potential for energy production <strong>from</strong> the five million<br />
square meter might be important <strong>in</strong> the longer scale, but will require more <strong>in</strong>teraction<br />
between growers, energy and technology suppliers.<br />
On behalf of the Danish partners <strong>in</strong> the project beh<strong>in</strong>d the workshop – welcome<br />
Carl-Ot<strong>to</strong> Ot<strong>to</strong>sen<br />
Convener<br />
34 ENERGY IN FOCUS
Program<br />
Tuesday Oc<strong>to</strong>ber 6<br />
9.30 Open<strong>in</strong>g<br />
Carl Holst, Chair of Region South Denmark<br />
9.45 Keynote<br />
Towards the semi-closed greenhouse? Dr. Silke Hemm<strong>in</strong>g, WUR, NL<br />
10.30 Coffee<br />
10.50 Topic 1: The closed or semi closed greenhouse<br />
Modera<strong>to</strong>r Carl-Ot<strong>to</strong> Ot<strong>to</strong>sen, DK<br />
10.50 Novarbo – Closed Greenhouse Cool<strong>in</strong>g, Huttunen, F<strong>in</strong>land<br />
11.10 The <strong>in</strong>telligent greenhouse concept, Lund et al, DK<br />
11.30 Thema<strong>to</strong> air heat<strong>in</strong>g moni<strong>to</strong>r<strong>in</strong>g study, Ch<strong>in</strong>-Kon-Sung et al. NL<br />
11.50 Us<strong>in</strong>g Novarbo cool<strong>in</strong>g with cucumber, <strong>to</strong>ma<strong>to</strong> and sweet pepper <strong>in</strong> summer 2009,<br />
Kaukoranta et al. F<strong>in</strong>land<br />
12.15 Lunch<br />
13.20 Topic 2: Climate control <strong>in</strong> the future<br />
Modera<strong>to</strong>r, Janni Lund, DK<br />
13.40 Improv<strong>in</strong>g productivity of cucumber, <strong>to</strong>ma<strong>to</strong> and cut rose <strong>in</strong> semi-closed greenhouse<br />
<strong>in</strong> F<strong>in</strong>land, Särkkä et al. FI.<br />
14.00 Predict – climate management software for dynamic climate control, Nørregård Jørgensen et al. DK<br />
14.20 How do we pass on new ideas like Dynamic climate control and new greenhouse<br />
ICT <strong>to</strong> the grower? Bærenholdt-Jensen, DK<br />
14.45 Coffee<br />
15.15 Topic 3: Technology <strong>in</strong> greenhouses<br />
Modera<strong>to</strong>r: Andreas Ulbrect, DE.<br />
15.15 Multilayer screen<strong>in</strong>g system <strong>in</strong> greenhouse with screen materials with different properties<br />
<strong>to</strong> enhance energy sav<strong>in</strong>g, Andersson & Skov, DK<br />
15.35 Innovative roof<strong>in</strong>g materials for <strong>in</strong>creased plant quality and energy consumption, Lambrecht et al. DE<br />
15.55 Environmental Sensors for Harsh Environments – a Novel Approach <strong>to</strong> Multiple Parameter<br />
Sensors for Greenhouses, Jensen & Bennedsen, DK<br />
16.15 Dynamic management of supplemental light, Ot<strong>to</strong>sen et al. DK<br />
16.35 The effect of screen material on leaf and air temperature, Rosenqvist et al. DK<br />
17.00 General discussion – how can we l<strong>in</strong>k the greenhouses <strong>to</strong> the energy grid?<br />
18.00- D<strong>in</strong>ner at SDU<br />
Wednesday Oc<strong>to</strong>ber 7<br />
9.00 Departure <strong>to</strong> Hjortebjerg Nursery (on your own or organized by the workshop)<br />
10.00 Exhibition and presentation of projects <strong>in</strong> the commercial nursery and exhibition<br />
of technical equipment associated with energy sav<strong>in</strong>g<br />
11.30 Quick lunch and return <strong>to</strong> city<br />
ENERGY IN FOCUS 35
Silke Hemm<strong>in</strong>g, Wagen<strong>in</strong>gen UR Greenhouse Horticulture, P.O. Box 644,<br />
6700 AP Wagen<strong>in</strong>gen, The Netherlands. E-mail: silke.hemm<strong>in</strong>g@wur.nl<br />
Towards the semi-closed greenhouse?<br />
In current greenhouse horticulture, next<br />
<strong>to</strong> high production levels, quality and<br />
timel<strong>in</strong>ess of production are important.<br />
This can be reached by optimal control<br />
of greenhouse climate for which energy<br />
is of major importance. More conditioned<br />
greenhouses are preferable. Next <strong>to</strong><br />
that the need for (energy) cost reduction<br />
has become higher, s<strong>in</strong>ce with <strong>in</strong>creas<strong>in</strong>g<br />
prices of natural gas <strong>in</strong> the last decade,<br />
energy forms a substantial fraction of the<br />
<strong>to</strong>tal production costs. The liberalisation of<br />
the energy market for Dutch growers s<strong>in</strong>ce<br />
2002 has <strong>in</strong>creased the growers awareness<br />
of the energy consumption of their cropp<strong>in</strong>g<br />
systems. This free market implies that<br />
growers do not pay a fixed price per unit<br />
of natural gas anymore, but that prices are<br />
greatly determ<strong>in</strong>ed by the maximum supply<br />
capacity of the gas contract. Therefore,<br />
it is important <strong>to</strong> reduce peaks <strong>in</strong> energy<br />
use. In view of the <strong>Kyo<strong>to</strong></strong> pro<strong>to</strong>col several<br />
governments have set goals for energy use<br />
and CO emission. In the Netherlands, the<br />
2<br />
horticultural sec<strong>to</strong>r and government have<br />
agreed <strong>to</strong> improve the energy efficiency<br />
(production per unit of energy) by 65% <strong>in</strong><br />
2010 compared <strong>to</strong> 1980 and <strong>to</strong> <strong>in</strong>crease<br />
the contribution of susta<strong>in</strong>able energy <strong>to</strong><br />
4%. Over the period 1980 – 2005, energy<br />
efficiency <strong>in</strong> Dutch greenhouse <strong>in</strong>dustry<br />
has more than doubled. However, <strong>to</strong>tal<br />
energy use per square meter of greenhouse<br />
hardly changed. Efficiency improvement<br />
resulted <strong>from</strong> a more than doubl<strong>in</strong>g <strong>in</strong><br />
yield per m2 caused by amongst others<br />
improved greenhouse transmission, cultivars<br />
and cultivation techniques.<br />
<strong>Energy</strong> <strong>in</strong> the greenhouse is primarily<br />
used for temperature control, reduction<br />
of air humidity, <strong>in</strong>crease of light <strong>in</strong>tensity<br />
and <strong>to</strong> a lesser extent for CO supply.<br />
2<br />
The use of fossil energy can be reduced<br />
by limit<strong>in</strong>g the energy demand of the<br />
system and decreas<strong>in</strong>g energy losses (higher<br />
<strong>in</strong>sulation), by <strong>in</strong>telligent control of<br />
(micro)climate, by <strong>in</strong>creas<strong>in</strong>g the energy<br />
efficiency of the crop and by replac<strong>in</strong>g<br />
fossil energy sources by susta<strong>in</strong>able ones.<br />
In this paper, recent developments concern<strong>in</strong>g<br />
reduction of energy consumption<br />
<strong>in</strong> greenhouse production systems will be<br />
presented, as well as the consequences for<br />
crop management.<br />
<strong>Energy</strong> sav<strong>in</strong>g of<br />
greenhouse systems<br />
<strong>Energy</strong> requirement of the greenhouse can<br />
be lowered by reduc<strong>in</strong>g energy losses.<br />
<strong>Energy</strong> losses occur through the ventilation<br />
as sensible and latent heat, but also<br />
through the greenhouse cover<strong>in</strong>g by convection<br />
and radiation. Us<strong>in</strong>g greenhouse<br />
covers with higher <strong>in</strong>sulat<strong>in</strong>g values and<br />
the use of energy screens highly limits<br />
the amount of energy losses. Increased<br />
<strong>in</strong>sulation can be obta<strong>in</strong>ed by modern<br />
greenhouse materials, where new coat<strong>in</strong>gs<br />
(low emission and anti-reflection) are<br />
applied. <strong>Energy</strong> sav<strong>in</strong>g of 25-30% seem <strong>to</strong><br />
be possible with the new double materials<br />
compared <strong>to</strong> a greenhouse with s<strong>in</strong>gle<br />
glass and energy screen. A prerequisite is<br />
that new <strong>in</strong>sulat<strong>in</strong>g materials should not<br />
<strong>in</strong>volve considerable light loss, s<strong>in</strong>ce this<br />
would result <strong>in</strong> a loss of production, s<strong>in</strong>ce<br />
1% additional light results <strong>in</strong> 0.8-1% more<br />
production. With new double materials<br />
loss of light is not <strong>to</strong> be expected. If additional<br />
CO 2 is applied and attention is paid<br />
<strong>to</strong> humidity control, production will not<br />
decrease, <strong>in</strong> spite of considerable energy<br />
sav<strong>in</strong>gs.<br />
Thermal screens add an additional barrier<br />
between the greenhouse environment<br />
and its surround<strong>in</strong>gs. When movable, it<br />
has less impact on the light transmission<br />
compared <strong>to</strong> fixed screens. If they are used<br />
almost permanently, screens can reduce<br />
the energy use by more than 35%, depend<strong>in</strong>g<br />
on the material. In practice, movable<br />
screens are closed only part of the cropp<strong>in</strong>g<br />
season depend<strong>in</strong>g on the criteria for<br />
open<strong>in</strong>g and clos<strong>in</strong>g. Due <strong>to</strong> restrictions<br />
for clos<strong>in</strong>g, generally enforced by criteria<br />
related <strong>to</strong> humidity and light, <strong>in</strong> commercial<br />
practice reduction <strong>in</strong> energy use by<br />
thermal screens is restricted <strong>to</strong> 20%. Efficient<br />
screen<strong>in</strong>g strategies can save energy<br />
sav<strong>in</strong>g while ma<strong>in</strong>ta<strong>in</strong><strong>in</strong>g crop production<br />
level. Delay<strong>in</strong>g the screen open<strong>in</strong>g <strong>to</strong> out-<br />
side radiation levels above 50-150 W m -2<br />
energy sav<strong>in</strong>gs can be reached <strong>in</strong> practice<br />
without production losses.<br />
Semi-closed greenhouse concepts<br />
Semi-closed greenhouse concepts contribute<br />
<strong>to</strong> energy sav<strong>in</strong>g. The last years<br />
several greenhouse concepts were developed.<br />
It started with us<strong>in</strong>g the greenhouse<br />
itself as solar collec<strong>to</strong>r (solar greenhouse<br />
“Zonnekas”), followed by fully closed<br />
greenhouses, <strong>to</strong>wards energy produc<strong>in</strong>g<br />
greenhouses (“Kas als energiebron”) and<br />
latest developments <strong>to</strong>ward electricity produc<strong>in</strong>g<br />
greenhouses (“Elkas”). In closed<br />
greenhouses, the excess of solar energy<br />
<strong>in</strong> summer is collected and s<strong>to</strong>red e.g. <strong>in</strong><br />
aquifers <strong>to</strong> be reused <strong>in</strong> w<strong>in</strong>ter <strong>to</strong> heat the<br />
greenhouse. These concepts result <strong>in</strong> a<br />
reduction <strong>in</strong> primary energy use of 33%,<br />
based on 1/3 of the area with closed<br />
greenhouse and 2/3 with traditional greenhouse<br />
with ventilation w<strong>in</strong>dows. Besides<br />
aquifers for seasonal energy s<strong>to</strong>rage, the<br />
technical concept consists of a heat pump,<br />
daytime s<strong>to</strong>rage, heat exchangers and air<br />
treatment units which either br<strong>in</strong>g the cold<br />
air directly <strong>in</strong><strong>to</strong> the <strong>to</strong>p of the greenhouse<br />
or do so via air distribution ducts below<br />
the gutters. In this concept, ventilation<br />
w<strong>in</strong>dows are closed. Thereby, CO 2 levels,<br />
temperature and humidity can be controlled<br />
<strong>to</strong> the needs of the crop. To reduce<br />
<strong>in</strong>vestment costs, <strong>in</strong> practice growers<br />
tend <strong>to</strong> choose for a semi closed system.<br />
Cool<strong>in</strong>g capacity of this system is lower<br />
than that of a closed greenhouse. Therefore,<br />
when the active cool<strong>in</strong>g capacity is<br />
<strong>in</strong>sufficient <strong>to</strong> keep the temperature below<br />
the maximum, ventilation w<strong>in</strong>dows will<br />
be opened. CO 2 emission <strong>in</strong> (semi)closed<br />
greenhouses is considerable lower than <strong>in</strong><br />
open greenhouses. In a recent experiment,<br />
<strong>in</strong> which <strong>to</strong>ma<strong>to</strong>es were grown with a CO 2<br />
supply capacity of 230 kg ha -1 h -1 up <strong>to</strong><br />
a maximum concentration of 1000 ppm,<br />
<strong>in</strong> the open greenhouse 54.7 kg CO 2 m -2<br />
was supplied whereas <strong>in</strong> the closed greenhouse<br />
this was 14.4 kg CO 2 m -2 .<br />
Specific characteristics of climate <strong>in</strong><br />
36 ENERGY IN FOCUS
(semi)closed greenhouses with cool<strong>in</strong>g<br />
ducts under the gutters are: high CO 2<br />
concentrations, vertical temperature gradients,<br />
high humidities, comb<strong>in</strong>ed conditions<br />
of high light <strong>in</strong>tensity and high<br />
CO 2 concentration, and <strong>in</strong>creased rates<br />
of air movement. Investigations showed<br />
that air circulation did not change the<br />
pho<strong>to</strong>synthesis light-response curves. Yield<br />
<strong>in</strong>crease was therefore attributable only <strong>to</strong><br />
the <strong>in</strong>stantaneous effects of elevated CO 2<br />
concentration. It was also shown that at<br />
high irradiance, the optimum temperature<br />
for crop pho<strong>to</strong>synthesis <strong>in</strong>creased with<br />
CO 2 concentration.<br />
The higher humidities cause a reduction<br />
<strong>in</strong> transpiration, and thereby <strong>in</strong>creased<br />
temperatures of the <strong>to</strong>p of the canopy. In<br />
systems where cool<strong>in</strong>g ducts are below the<br />
gutters, temperature differences of 5°C between<br />
roots and <strong>to</strong>p of the plant can occur.<br />
This affects the time necessary for fruits <strong>to</strong><br />
mature. At lower temperatures, fruits need<br />
more time <strong>to</strong> ripen. Toma<strong>to</strong> fruits were<br />
found <strong>to</strong> be more sensitive <strong>to</strong> temperature<br />
<strong>in</strong> their later stages of maturation at which<br />
they are at lower temperatures <strong>in</strong> (semi)<br />
closed greenhouses.<br />
Development of new greenhouse concepts<br />
is ongo<strong>in</strong>g. Current examples are<br />
greenhouse systems which even create<br />
a surplus of energy <strong>to</strong> be delivered <strong>to</strong><br />
neighbor greenhouses, other <strong>in</strong>dustries or<br />
houses. Concepts like Sunergy Greenhouse,<br />
Sun W<strong>in</strong>d Greenhouse or Flow-<br />
Deck Greenhouse are examples for that.<br />
With different technological concepts an<br />
energy surplus has <strong>to</strong> be generated. Currently<br />
these three concepts are shown at<br />
the Innovation and Demonstration Centre<br />
<strong>in</strong> Bleiswijk. The <strong>in</strong>novations are <strong>in</strong>tended<br />
<strong>to</strong> <strong>in</strong>spire commercial operations <strong>to</strong> take<br />
advantage of susta<strong>in</strong>able solutions for climate<br />
neutral production. The performance<br />
of the systems is currently <strong>in</strong>vestigated by<br />
Wagen<strong>in</strong>gen UR Greenhouse Horticulture.<br />
Sunergy Greenhouse<br />
The sunlight that enters the greenhouse is<br />
absorbed by plants and heats the greenhouse<br />
air. Dur<strong>in</strong>g the summer, this energy<br />
can be collected <strong>from</strong> the greenhouse air<br />
by means of heat exchangers. The heated<br />
water is then s<strong>to</strong>red <strong>in</strong> an aquifer until it<br />
can be used dur<strong>in</strong>g the w<strong>in</strong>ter <strong>to</strong> provide<br />
energy <strong>to</strong> a heat pump of the greenhouse<br />
and those of third parties. The objective<br />
of the Sunergy Greenhouse is <strong>to</strong> obta<strong>in</strong><br />
the greatest possible light transmittance.<br />
A double screen traps heat <strong>to</strong> reduce<br />
the greenhouse’s own heat consumption.<br />
This greenhouse comb<strong>in</strong>es the best of the<br />
exist<strong>in</strong>g technologies now be<strong>in</strong>g applied <strong>in</strong><br />
horticulture.<br />
The roof of the greenhouse is equipped<br />
with anti-reflective glass (GroGlass).<br />
The greenhouse is seven metres <strong>in</strong> height<br />
and has an ultra-lightweight substructure<br />
(Tw<strong>in</strong>light). There are no roof vents. The<br />
climate is controlled by means of pipe rail<br />
heat<strong>in</strong>g, an air-treatment unit with slurves<br />
under the gullies, and overhead cool<strong>in</strong>g<br />
units (1/100 m 2 ). Heat loss is limited by<br />
a double screen<strong>in</strong>g system consist<strong>in</strong>g of a<br />
transparent screen (XLS 10 ultra plus) and<br />
an alum<strong>in</strong>ized screen<strong>in</strong>g material (XLS<br />
18). A new slid<strong>in</strong>g system prevents leak<strong>in</strong>g<br />
gaps. The transparent screen is closed at<br />
night and dur<strong>in</strong>g cold days. The alum<strong>in</strong>ized<br />
screen is closed dur<strong>in</strong>g the night and<br />
when the outside temperature drops below<br />
12 0C. Dehumidification is accomplished<br />
by draw<strong>in</strong>g <strong>in</strong> outside air. This greenhouse<br />
concept is based on s<strong>to</strong>r<strong>in</strong>g heat collected<br />
dur<strong>in</strong>g the summer <strong>in</strong> an aquifer.<br />
The concept is developed by Wagen<strong>in</strong>gen<br />
UR and P.L.J. Bom greenhouse builders.<br />
Sun W<strong>in</strong>d Greenhouse<br />
Many pot plants are shade plants that<br />
require a high degree of screen<strong>in</strong>g dur<strong>in</strong>g<br />
the summer. A shade cloth can prevent<br />
solar energy <strong>from</strong> enter<strong>in</strong>g the greenhouse,<br />
and light not transmitted <strong>in</strong><strong>to</strong> the greenhouse<br />
can be collected with a screen that<br />
acts as a solar collec<strong>to</strong>r. An <strong>in</strong>novative<br />
paneled screen <strong>in</strong>stalled <strong>in</strong> the Sun-W<strong>in</strong>d<br />
Greenhouse collects energy <strong>in</strong> the form of<br />
warm water and prevents direct sunlight<br />
<strong>from</strong> enter<strong>in</strong>g the greenhouse. The warm<br />
water is then s<strong>to</strong>red <strong>in</strong> a special buffer<br />
under the greenhouse for re-use dur<strong>in</strong>g<br />
the w<strong>in</strong>ter.<br />
The greenhouse roof faces south and<br />
consists of adjustable solar collec<strong>to</strong>r<br />
panels sandwiched between double glaz<strong>in</strong>g<br />
at a 35° slope. The north side of the<br />
greenhouse consists of acrylic sheets with<br />
a slope of 60° and one-sided cont<strong>in</strong>uous<br />
roof ventilation. The post height is three<br />
meters, ridge height n<strong>in</strong>e meters and trellis<br />
girder 11.80 meters. Climate control<br />
is conventional. When heat is required,<br />
the greenhouse is heated with water <strong>from</strong><br />
the buffer delivered by means of a standard<br />
heat<strong>in</strong>g system. For a commercial<br />
operation, a w<strong>in</strong>d turb<strong>in</strong>e will generate<br />
the electricity for the pumps. The excess<br />
electricity will be delivered <strong>to</strong> the power<br />
grid. Dur<strong>in</strong>g calm periods, electricity will<br />
be drawn <strong>from</strong> the power grid.<br />
This concept is developed by Thermotech<br />
and Gakon greenhouse builders.<br />
FlowDeck Greenhouse<br />
Dur<strong>in</strong>g cold periods, the greatest loss of<br />
heat occurs through the greenhouse roof<br />
and sides. Dur<strong>in</strong>g the summer, the reverse<br />
occurs and the greenhouse collects a great<br />
deal of solar energy. A roof consist<strong>in</strong>g of a<br />
double layer ‘Flowdeck’, is better <strong>in</strong>sulated<br />
than a standard glass greenhouse. Dur<strong>in</strong>g<br />
very sunny periods, pre-treated water can<br />
flow between these layers <strong>to</strong> improve<br />
light transmittance <strong>to</strong> benefit the crop.<br />
The greenhouse roof also collects heat;<br />
this keeps the greenhouse climate cooler<br />
and promotes the dehumidification of the<br />
greenhouse. The heated water is s<strong>to</strong>red <strong>in</strong><br />
an aquifer for re-use dur<strong>in</strong>g the w<strong>in</strong>ter.<br />
The greenhouse roof consists of hollow-core<br />
polycarbonate sheet<strong>in</strong>g through<br />
which water flows <strong>from</strong> the gutter <strong>to</strong> the<br />
ridge and back. The supply and dra<strong>in</strong>age<br />
system is <strong>in</strong>tegrated <strong>in</strong><strong>to</strong> the gutter. Light<br />
transmittance through a Flowdeck is equal<br />
<strong>to</strong> that of conventional acrylic sheet<strong>in</strong>g but<br />
when filled with water is equal <strong>to</strong> normal<br />
s<strong>in</strong>gle horticultural glass. The greenhouse<br />
has a traditional Venlo structure with a gutter<br />
height of seven metres and an extended<br />
span of 6.40 metres. The greenhouse has<br />
ENERGY IN FOCUS 37
oof vents on the sheltered side. Humidity<br />
is controlled by the ClimecoVent system.<br />
An air-handl<strong>in</strong>g unit for heat recovery<br />
(the Rega<strong>in</strong> unit) is connected <strong>to</strong> an air<br />
distribution system with perforated flexible<br />
pipes <strong>in</strong>stalled under the cultivat<strong>in</strong>g<br />
systems. This enables dehumidification by<br />
means of heat recovery. The greenhouse is<br />
equipped with pipe rail heat<strong>in</strong>g and wall<br />
heat<strong>in</strong>g. Forced-air heat<strong>in</strong>g/cool<strong>in</strong>g units<br />
are <strong>in</strong>stalled over the aisle. The greenhouse<br />
is also equipped with a s<strong>in</strong>gle shade cloth<br />
(LS 10).<br />
This concept is developed by Climeco<br />
Eng<strong>in</strong>eer<strong>in</strong>g and Maurice greenhouse builders.<br />
<strong>Energy</strong> efficient climate control<br />
With<strong>in</strong> semi-closed greenhouse concepts,<br />
an energy efficient climate control leads<br />
<strong>to</strong> further reduction <strong>in</strong> energy consumption<br />
and/or <strong>in</strong>crease of production. Possibilities<br />
are: temperature <strong>in</strong>tegration, drop<br />
strategies, reduction of transpiration by<br />
reduction of leaf area, higher setpo<strong>in</strong>ts<br />
for relative humidity and us<strong>in</strong>g diffuse<br />
light. New grow<strong>in</strong>g strategies are currently<br />
developed for several crops. The aim of<br />
such concepts is <strong>to</strong> reduce energy consumption<br />
dramatically without production<br />
losses. In the new grow<strong>in</strong>g strategy for<br />
<strong>to</strong>ma<strong>to</strong> e.g. the energy consumption has <strong>to</strong><br />
drop <strong>from</strong> 40m 3 <strong>to</strong> 26 m 3 gas per m 2 greenhouse<br />
area. This is done by high <strong>in</strong>sulation<br />
us<strong>in</strong>g a double screen. The first screen is a<br />
transparent screen, which is closed until<br />
250 W/m 2 outside radiation. The second<br />
screen is alum<strong>in</strong>ized and highly <strong>in</strong>sulat<strong>in</strong>g.<br />
It is closed when the outside temperature<br />
is below 8 o C. The heat<strong>in</strong>g temperature is<br />
lowered by 1 o C, the ventilation setpo<strong>in</strong>t is<br />
Jukka Huttunen, Biolan Oy, PL 2, FI- 27500 Kauttua, F<strong>in</strong>land, jukka.huttunen@biolan.fi<br />
<strong>in</strong>creased. Above 85% humidity the ventilation<br />
is opened. It seems that the goal can<br />
be reached <strong>in</strong> a demonstration trial. Other<br />
concepts are developed for other crops.<br />
There are several possibilities <strong>to</strong> decrease<br />
energy consumption <strong>in</strong> greenhouse<br />
horticulture <strong>in</strong> the future. The challenge<br />
is <strong>to</strong> reach that with low-cost solutions.<br />
More conditioned greenhouse are certa<strong>in</strong>ly<br />
necessary <strong>in</strong> the future. Semi-closed<br />
greenhouse concepts are permanently <strong>in</strong><br />
development <strong>in</strong> order <strong>to</strong> optimize the<br />
systems concern<strong>in</strong>g costs and performance.<br />
In order <strong>to</strong> apply new greenhouse<br />
concepts and grow<strong>in</strong>g strategies <strong>in</strong><strong>to</strong> horticultural<br />
practice cooperation and active<br />
exchange of knowledge between growers,<br />
horticultural <strong>in</strong>dustry, extension service<br />
and research is necessary.<br />
<br />
Novarbo – Closed Greenhouse Cool<strong>in</strong>g<br />
Keywords:<br />
High yield, CO 2 , condensation<br />
Abstract<br />
High CO 2 dur<strong>in</strong>g high light conditions is<br />
possible <strong>in</strong> a closed greenhouse. Clos<strong>in</strong>g<br />
also helps plant protection and prevents<br />
the heat loss, which occurs when ventilat<strong>in</strong>g<br />
excess humidity, especially when<br />
us<strong>in</strong>g artificial lightn<strong>in</strong>g <strong>in</strong> a cold climate.<br />
The result of clos<strong>in</strong>g is <strong>in</strong>creased yield and<br />
decreased energy use per product.<br />
Novarbo is a novel cool<strong>in</strong>g method for<br />
closed greenhouse. Inside the greenhouse<br />
is a water droplet curta<strong>in</strong>, which transfers<br />
the energy directly <strong>from</strong> the warm and<br />
humid greenhouse air <strong>to</strong> the cool<strong>in</strong>g water<br />
by condensation of the latent heat and<br />
conductivity of the sensible heat. Only<br />
the heated water is then led out, where<br />
an evapora<strong>to</strong>r sprays water through outside<br />
air, evaporat<strong>in</strong>g and thus cool<strong>in</strong>g the<br />
water, which is then pumped back <strong>to</strong> cool<br />
the greenhouse.<br />
Two years of commercial use shows<br />
the coefficient of performance <strong>in</strong> <strong>in</strong>side<br />
cool<strong>in</strong>g (COP) was 60 –200, which is very<br />
high, compared <strong>to</strong> normal heat pump COP<br />
3-8. The F<strong>in</strong>nish Agrifood Research center<br />
has grow<strong>in</strong>g results with cucumbers: better<br />
crop +(25-41) %, with cut roses: +<br />
25 % with <strong>to</strong>ma<strong>to</strong>es +10 %. This method<br />
maximizes the growth and m<strong>in</strong>imizes the<br />
environmental impact, especially <strong>in</strong> wellequipped<br />
greenhouses.<br />
<br />
38 ENERGY IN FOCUS
Janni Bjerregaard Lund, Ole Skov and Bent S. Bennedsen, <strong>AgroTech</strong> A/S<br />
The <strong>in</strong>telligent greenhouse concept<br />
The vision beh<strong>in</strong>d our concept is a 60%<br />
reduction <strong>in</strong> energy <strong>from</strong> fossil fuel<br />
when produc<strong>in</strong>g potted plants <strong>in</strong> a one<br />
layer greenhouse and without any negative<br />
effect on the quantity or quality of the<br />
produce.<br />
This objective will be achieved through a<br />
comb<strong>in</strong>ation of;<br />
• Improved strategies for climate<br />
control<br />
• Extraction of surplus heat and<br />
s<strong>to</strong>r<strong>in</strong>g it <strong>in</strong> ground water reservoirs<br />
• Improved curta<strong>in</strong> systems<br />
• Introduction of a novel wireless<br />
sensor system<br />
• Further improvements of the<br />
climate control software, <strong>in</strong> order<br />
<strong>to</strong> utilize the potentials <strong>in</strong> the<br />
new sensor technology, heat<br />
extraction, LED light<strong>in</strong>g, and curta<strong>in</strong>s.<br />
The concept is be<strong>in</strong>g implemented and<br />
tested on the greenhouse production<br />
plant “Hjortebjerg” located 23 kilometres<br />
north-west of Odense at Funen Island<br />
(Latitude 55° N). The ma<strong>in</strong> production is<br />
potted Euphorba milii Des. Moul.<br />
The first step was carried out <strong>in</strong> 2007<br />
and consisted of a climate check. This<br />
<strong>in</strong>volves construction of a mathematical<br />
model, which simulates the greenhouses,<br />
and computes the energy consumption<br />
at different climate control strategies. The<br />
result was that by <strong>in</strong>troduc<strong>in</strong>g dynamic<br />
climate control, an energy reduction of<br />
at least 21% could be obta<strong>in</strong>ed. Dur<strong>in</strong>g<br />
2008, the actual reduction was 35%, <strong>from</strong><br />
375 kWh/m 2 <strong>in</strong> 2007 <strong>to</strong> 241 kWh/m 2 <strong>in</strong><br />
2008.<br />
Calculations have shown, that the irradiance,<br />
received by a greenhouse over<br />
the year, is twice the energy requirement<br />
dur<strong>in</strong>g the same period. However, there is<br />
a surplus dur<strong>in</strong>g the summer, which is lost<br />
through ventilation and a deficiency <strong>in</strong> the<br />
w<strong>in</strong>ter, which is supplemented by heat<strong>in</strong>g.<br />
In our concept, we extract heat <strong>from</strong> hot<br />
air, collected below the roof ridge of the<br />
greenhouses, and s<strong>to</strong>re it <strong>in</strong> groundwater<br />
reservoirs. Dur<strong>in</strong>g the summer, ground<br />
water of 10 o C is passed through an air <strong>to</strong><br />
liquid heat exchanger, which raises the<br />
water temperature <strong>to</strong> an average of 30 o C<br />
with a maximum of 35°C.<br />
The water is then pumped back <strong>in</strong><strong>to</strong><br />
the ground water reservoir, at a depth of<br />
40 m, where it will ma<strong>in</strong>ta<strong>in</strong> its temperature,<br />
albeit with a slight loss, until w<strong>in</strong>ter.<br />
The process is reversed dur<strong>in</strong>g w<strong>in</strong>ter by<br />
pump<strong>in</strong>g the water up and cool<strong>in</strong>g it by<br />
means of heat pumps. This generates 70<br />
– 80 o C water for heat<strong>in</strong>g the greenhouses.<br />
The system is not able <strong>to</strong> fully extract heat<br />
on hot summer days and will be comparable<br />
<strong>to</strong> what is known as the semi-closed<br />
greenhouse.<br />
The comb<strong>in</strong>ed effect of optimized climate<br />
control and heat s<strong>to</strong>rage will be a<br />
50% energy reduction.<br />
Further reductions will be achieved by<br />
<strong>in</strong>troduc<strong>in</strong>g new curta<strong>in</strong>s and improved<br />
sensor technologies for more accurate<br />
climatic <strong>in</strong>formation and further improved<br />
climate control.<br />
A system of two layers of curta<strong>in</strong> will be<br />
<strong>in</strong>troduced <strong>to</strong> improve the <strong>in</strong>sulation and<br />
thereby reduce heat radiation. The “NIR<br />
curta<strong>in</strong>” and a LS16 curta<strong>in</strong> (AB Ludvig<br />
Svensson) will be <strong>in</strong>stalled <strong>in</strong> the demonstrations<br />
house at Hjortebjerg.<br />
The new sensor system, which is be<strong>in</strong>g<br />
developed by Danfoss IXA Sensor Technologies,<br />
will comprise a relatively large<br />
number of small, wireless sensors, which<br />
will measure temperature, relative humidity,<br />
CO 2 level, radiation and leaf temperature.<br />
The sensors will be located <strong>in</strong> the<br />
foliage of the plants, and hence give more<br />
accurate and detailed <strong>in</strong>formation about<br />
the actual conditions, which the plants are<br />
experienc<strong>in</strong>g. This will permit the grower<br />
<strong>to</strong> f<strong>in</strong>e tune his climate control, and thus<br />
reduce the energy <strong>in</strong>put.<br />
The projects will cont<strong>in</strong>ue until 2012,<br />
by which time, we are confident that the<br />
objective of a 60% energy reduction will<br />
be achieved for the Hjortebjerg plant.<br />
Further, based on the knowledge acquired<br />
dur<strong>in</strong>g the projects, other greenhouse production<br />
plants will be able <strong>to</strong> achieve the<br />
same amount of reduction of energy and<br />
CO 2 emission.<br />
<br />
ENERGY IN FOCUS 39
Roël Ch<strong>in</strong>-Kon-Sung, TNO Bouw en Ondergrond, The Netherlands<br />
Thema<strong>to</strong> air heat<strong>in</strong>g moni<strong>to</strong>r<strong>in</strong>g study<br />
Introduction<br />
TNO is a Dutch knowledge <strong>in</strong>stitute that<br />
applies scientific knowledge <strong>to</strong> strengthen<br />
the <strong>in</strong>novative power of <strong>in</strong>dustry and<br />
government. Our core areas are: Quality<br />
of Life; Defence, Security & Safety;<br />
Science & Industry; Built Environment &<br />
Geosciences; ICT. By encourag<strong>in</strong>g effective<br />
<strong>in</strong>teraction between knowledge areas,<br />
we generate creative and practical<br />
<strong>in</strong>novations <strong>in</strong> the form of new products,<br />
new services and new processes.<br />
Greenhouse horticulture is a major eng<strong>in</strong>e<br />
of the Dutch economy. The sec<strong>to</strong>r also<br />
enjoys a lead<strong>in</strong>g <strong>in</strong>ternational position,<br />
which has been built through constant<br />
<strong>in</strong>novation. TNO and Horticulture is<br />
mak<strong>in</strong>g an active contribution <strong>to</strong> <strong>in</strong>novation<br />
<strong>in</strong> the greenhouse horticulture sec<strong>to</strong>r<br />
<strong>in</strong> cooperation with various players, <strong>in</strong>clu-<br />
d<strong>in</strong>g growers, suppliers, mach<strong>in</strong>e builders<br />
and advisors.<br />
Our mission has been described as<br />
follows: TNO and Horticulture applies<br />
scientific knowledge <strong>from</strong> various discipl<strong>in</strong>es<br />
with<strong>in</strong> and outside the agrarian sec<strong>to</strong>r<br />
with the aim of strengthen<strong>in</strong>g the competitive<br />
power and <strong>in</strong>novative character of<br />
<strong>in</strong>dustry <strong>in</strong> greenhouse horticulture.<br />
In horticulture, the use of <strong>in</strong>stallation<br />
techniques <strong>to</strong> achieve climate control <strong>in</strong><br />
greenhouses is <strong>in</strong>creas<strong>in</strong>gly widespread.<br />
Due <strong>to</strong> ris<strong>in</strong>g energy prices, greenhouse<br />
horticulture is always look<strong>in</strong>g for new<br />
energy-efficient climate concepts. The<br />
knowledge of <strong>in</strong>stallation concepts used <strong>in</strong><br />
commercial and <strong>in</strong>dustrial build<strong>in</strong>gs such<br />
as air-condition<strong>in</strong>g and dehumidification<br />
is now be<strong>in</strong>g applied <strong>in</strong> greenhouses. Such<br />
a new climate concept is now be<strong>in</strong>g tested<br />
at a grower’s enterprise. Together with the<br />
<strong>to</strong>ma<strong>to</strong> grower, an <strong>in</strong>stalation manufacturer<br />
and a plant research <strong>in</strong>stitute, TNO is<br />
evaluat<strong>in</strong>g this system. The climate fac<strong>to</strong>rs<br />
temperature, relative humidity, CO2 concentration<br />
and air movement <strong>in</strong> the greenhouse<br />
are moni<strong>to</strong>red.<br />
The ma<strong>in</strong> project goal is <strong>to</strong> achieve<br />
energy sav<strong>in</strong>g and <strong>in</strong>creased <strong>to</strong>ma<strong>to</strong> production.<br />
The climate control system registers<br />
measured and calculated data such as vent<br />
position, heat<strong>in</strong>g, energy consumption etc.<br />
and setpo<strong>in</strong>ts. The greenhouse climate fac<strong>to</strong>rs<br />
are moni<strong>to</strong>red accord<strong>in</strong>g <strong>to</strong> a detailed<br />
measur<strong>in</strong>g plan. Prelim<strong>in</strong>ary results are<br />
presented.<br />
<br />
40 ENERGY IN FOCUS
Timo Kaukoranta and Juha Näkkilä, MTT Agrifood Research F<strong>in</strong>land, Horticulture<br />
Toivonl<strong>in</strong>nantie 518, 21500 Piikkiö, F<strong>in</strong>land, e-mail: timo.kaukoranta@mtt.fi, juha.nakkila@mtt.fi<br />
Us<strong>in</strong>g Novarbo cool<strong>in</strong>g with cucumber,<br />
<strong>to</strong>ma<strong>to</strong> and sweet pepper<br />
<strong>in</strong> summer 2009<br />
key component of an energy efficient<br />
A greenhouse is a system that removes<br />
humidity and heat <strong>from</strong> the greenhouse<br />
<strong>to</strong> allow it <strong>to</strong> operate without ventilation<br />
when deemed economically mean<strong>in</strong>gful.<br />
Novarbo system by Biolan Company, F<strong>in</strong>land,<br />
performs that task by creat<strong>in</strong>g a<br />
curta<strong>in</strong> of fall<strong>in</strong>g, cool water droplets that<br />
extract <strong>from</strong> greenhouse air sensitive heat<br />
by convection and humidity by condensation.<br />
In the configuration <strong>in</strong>stalled at our<br />
greenhouse at MTT Agrifood Research F<strong>in</strong>land,<br />
at Piikkiö, the droplets are led <strong>to</strong> an<br />
outside bas<strong>in</strong> <strong>to</strong> be re-cooled by a Waterix<br />
evaporative water cooler. The bas<strong>in</strong> serves<br />
also as a buffer <strong>in</strong> the system that allows<br />
the droplet curta<strong>in</strong> and water cooler <strong>to</strong><br />
operate separately. Electrical energy is<br />
consumed by the system for pump<strong>in</strong>g cool<br />
water <strong>from</strong> the bas<strong>in</strong> <strong>in</strong><strong>to</strong> the greenhouse<br />
and for operat<strong>in</strong>g the Waterix cooler.<br />
In an experiment <strong>in</strong> 2009 we aimed <strong>to</strong><br />
fully closed greenhouse, constantly high<br />
carbon dioxide concentration (CO 2 ), and<br />
high radiation, supplemented by moderate<br />
<strong>in</strong>ter-row (169, 175, 125 W/m 2 ) and<br />
over-<strong>to</strong>p light<strong>in</strong>g (169, 175, 125 W/m 2 ) by<br />
HPS lights whenever <strong>to</strong>tal solar radiation<br />
outside falls below 200 W/m 2 except for<br />
a break <strong>in</strong> the night. In the table below<br />
is summarized <strong>to</strong>tal cool<strong>in</strong>g (sensitive +<br />
latent), electricity consumption of the<br />
Novarbo droplet curta<strong>in</strong>, and electricity<br />
consumption of the Waterix cooler <strong>in</strong> three<br />
different weather periods and three crops,<br />
each grown <strong>in</strong> a compartment of 130 m 2 .<br />
The goal of fully closed greenhouse<br />
lead <strong>to</strong> rather high electricity consumption,<br />
which however could be economically<br />
justified. High maximum temperature (28-<br />
30°C) and humidity (85%) sett<strong>in</strong>gs led<br />
<strong>to</strong> clearly lower energy consumption <strong>in</strong><br />
Cucumber Toma<strong>to</strong> Sweet pepper<br />
Weather 2009 C<strong>to</strong>t Drops Wix C<strong>to</strong>t Drops Wix C<strong>to</strong>t Drops Wix<br />
Cool dry, May 12-18 - - - 2.0 0.03 0.15 2.1 0.04 0.16<br />
Cool ra<strong>in</strong>y, Jun 7-13 3.4 0.06 0.10 5.3 0.13 0.13 5.1 0.06 0.13<br />
Warm humid, Jul 21-27 4.8 0.13 0.12 5.6 0.17 0.14 6.5 0.14 0.16<br />
cucumber production than lower sett<strong>in</strong>gs<br />
<strong>in</strong> <strong>to</strong>ma<strong>to</strong> (27°C, 75-80%), and sweet pepper<br />
(28°C, 80-90%) production. Aim<strong>in</strong>g at<br />
fully closed greenhouse with cucumber<br />
and pepper may not be economically the<br />
most optimal goal. In fact, it is often not<br />
even practical. Temperature can be quite<br />
easily controlled by cool<strong>in</strong>g but humidity<br />
control is less straightforward. In a sunny<br />
morn<strong>in</strong>g, ventilation with some heat<strong>in</strong>g<br />
is needed for mov<strong>in</strong>g air <strong>to</strong> prevent condensation<br />
of humidity on fruits. Dur<strong>in</strong>g<br />
daytime, lower<strong>in</strong>g humidity and temperature<br />
<strong>to</strong> ensure poll<strong>in</strong>ation of <strong>to</strong>ma<strong>to</strong><br />
flowers can lead <strong>to</strong> a control spiral where<br />
absolute humidity and temperature fall<br />
simultaneously with no decrease <strong>in</strong> relative<br />
humidity. To cut the spiral, ventilation<br />
is needed.<br />
<br />
Table 1. Daily mean of sum of sensitive and latent heat extracted <strong>from</strong> a greenhouse compartment by Novarbo<br />
(C<strong>to</strong>t), electricity consumption by droplet curta<strong>in</strong> (Drops) and by Waterix water cooler a (Wix) allocated <strong>to</strong> each<br />
crop. All units kWh/day/m 2 of greenhouse. Dur<strong>in</strong>g cool weather daily maximum temperature was 12 <strong>to</strong> 15°C, dur<strong>in</strong>g<br />
warm weather 20 <strong>to</strong> 25°C.<br />
ENERGY IN FOCUS 41
Liisa Särkkä, Eeva-Maria Tuhkanen, Ti<strong>in</strong>a Hovi-Pekkanen and Ris<strong>to</strong> Tahvonen<br />
Improv<strong>in</strong>g productivity of cucumber,<br />
<strong>to</strong>ma<strong>to</strong> and cut rose <strong>in</strong> semi-closed<br />
greenhouse <strong>in</strong> F<strong>in</strong>land<br />
Improv<strong>in</strong>g<br />
M<br />
productivity of cucumber, <strong>to</strong>ma<strong>to</strong> and cut rose <strong>in</strong> semi-closed greenhouse <strong>in</strong> F<strong>in</strong>land<br />
TT Agrifood Research F<strong>in</strong>land, Plant<br />
Liisa Särkkä, Production Eeva-Maria Research, Tuhkanen, Toivonl<strong>in</strong>nan- Ti<strong>in</strong>a Hovi-Pekkanen and Ris<strong>to</strong> Tahvonen<br />
tie 518, 21500 Piikkiö, F<strong>in</strong>land, e-mail<br />
MTT liisa.sarkka@mtt.fi Agrifood Research F<strong>in</strong>land, Plant Production Research, Toivonl<strong>in</strong>nantie 518, 21500 Piikkiö,<br />
F<strong>in</strong>land, Despite e-mail the good liisa.sarkka@mtt.fi<br />
light environment for<br />
plants, a year-round greenhouse produc-<br />
Despite tion suffers the good <strong>from</strong> lower light environment yields <strong>in</strong> summer for plants, a year-round greenhouse production suffers <strong>from</strong><br />
lower than dur<strong>in</strong>g yields the <strong>in</strong> other summer times than of the dur<strong>in</strong>g year. Tra- the other times of the year. Traditional climate control <strong>in</strong> the<br />
greenhouse ditional climate with control roof vents <strong>in</strong> the is greenhouse not sufficient and this weakens growth fac<strong>to</strong>rs. A new cool<strong>in</strong>g system<br />
was<br />
with<br />
developed<br />
roof vents<br />
allow<strong>in</strong>g<br />
is not sufficient<br />
the roof<br />
and<br />
vents<br />
this<br />
<strong>to</strong> be closed most of the time. Therefore carbon dioxide<br />
concentration could be kept high and both air temperature and air humidity could be controlled <strong>in</strong><br />
weakens growth fac<strong>to</strong>rs. A new cool<strong>in</strong>g<br />
a proper way.<br />
system was developed allow<strong>in</strong>g the roof<br />
Cultivation vents <strong>to</strong> be trials closed were most made of the with time. cucumber, The- <strong>to</strong>ma<strong>to</strong> and cut roses. In semi-closed greenhouse the<br />
yield refore of carbon cucumber dioxide <strong>in</strong>creased concentration <strong>in</strong> the could first summer by 24 % and <strong>in</strong> the second summer by 40 % compared<br />
be kept <strong>to</strong> the high traditional and both climate air temperature control (Fig. 1). The reduced need for ventilation <strong>in</strong> semi-closed<br />
greenhouse and air humidity allowed could ma<strong>in</strong>ta<strong>in</strong><strong>in</strong>g be controlled of <strong>in</strong> constant a higher CO2 concentration (cucumber average 1000<br />
ppm, proper <strong>to</strong>ma<strong>to</strong> way. and cut rose 700-800 ppm) than <strong>in</strong> traditional greenhouse (cucumber and cut rose<br />
average Cultivation 400 ppm, trials <strong>to</strong>ma<strong>to</strong> were 500 made ppm) with (Fig. 2). In semi-closed greenhouse, the summer yield (weeks<br />
23-35) cucumber, of <strong>to</strong>ma<strong>to</strong> and was <strong>in</strong>creased cut roses. In while sem<strong>in</strong>ot<br />
the spr<strong>in</strong>g yield (weeks 13-22). The yield quality of cut<br />
roses closed was greenhouse improved the but yield not of the cucumber number of flowers compared <strong>to</strong> traditional greenhouse. All trials<br />
were <strong>in</strong>creased illum<strong>in</strong>ated <strong>in</strong> the first year summer round by by 24 HPS % and lamps. Moreover, <strong>to</strong>ma<strong>to</strong> had 31% <strong>in</strong>terlight<strong>in</strong>g of 170 W/m<br />
<strong>in</strong> the second summer by 40 % compared<br />
<strong>to</strong> the traditional climate control (Fig.<br />
1). The reduced need for ventilation <strong>in</strong><br />
2<br />
Fig 2. 2. Climate for for cucumber <strong>in</strong> <strong>in</strong> the the semi-closed (cool<strong>in</strong>g) (cool<strong>in</strong>g) greenhouse greenhouse and <strong>in</strong> and the traditional <strong>in</strong> the greenhouse<br />
traditional<br />
(control)<br />
greenhouse<br />
<strong>in</strong> August<br />
(control)<br />
as mean values<br />
<strong>in</strong> August<br />
of each<br />
as mean<br />
hours of<br />
values<br />
the days.<br />
of each hours of the days.<br />
semi-closed greenhouse allowed ma<strong>in</strong>tai- greenhouse (cucumber and cut rose ave-<br />
<strong>in</strong>stalled lights.<br />
n<strong>in</strong>g of constant higher CO concentration rage 400 ppm, <strong>to</strong>ma<strong>to</strong> 500 ppm) (Fig. 2).<br />
2<br />
(cucumber average 1000 ppm, <strong>to</strong>ma<strong>to</strong> and In semi-closed greenhouse, the summer<br />
Pho<strong>to</strong>synthesis measurements showed that plants benefited <strong>from</strong> high carbon dioxide concentration.<br />
The plant structure was also affected by<br />
cut<br />
the<br />
rose<br />
semi-closed<br />
700-800 ppm)<br />
greenhouse<br />
than <strong>in</strong> traditional<br />
environment.<br />
yield (weeks 23-35) of <strong>to</strong>ma<strong>to</strong> was <strong>in</strong>creased<br />
while not the spr<strong>in</strong>g yield (weeks<br />
Further trials are needed <strong>to</strong> optimize the greenhouse climate. Our cool<strong>in</strong>g system makes 13-22). it possible The yield quality of cut roses was<br />
<strong>to</strong> f<strong>in</strong>d out the most beneficial climates <strong>to</strong> each plant species for optimal production. improved but not the number of flowers<br />
compared <strong>to</strong> traditional greenhouse. All<br />
trials were illum<strong>in</strong>ated year round by HPS<br />
lamps. Moreover, <strong>to</strong>ma<strong>to</strong> had 31% <strong>in</strong>terlight<strong>in</strong>g<br />
of 170 W/m2 <strong>in</strong>stalled lights.<br />
Pho<strong>to</strong>synthesis measurements showed<br />
that plants benefited <strong>from</strong> high carbon<br />
dioxide concentration. The plant structure<br />
was also affected by the semi-closed<br />
greenhouse environment.<br />
Further trials are needed <strong>to</strong> optimize the<br />
greenhouse climate. Our cool<strong>in</strong>g system<br />
makes it possible <strong>to</strong> f<strong>in</strong>d out the most<br />
beneficial climates <strong>to</strong> each plant species<br />
for optimal production.<br />
<br />
Fig 1. Yield of cucumber <strong>in</strong> semi-closed (cool<strong>in</strong>g) greenhouse and traditional roof<br />
Fig 1. Yield of cucumber <strong>in</strong> semi-closed (cool<strong>in</strong>g) greenhouse and traditional roof ventilated<br />
ventilated greenhouse (control). Summer yield <strong>in</strong> the first year was <strong>from</strong> 12 weeks<br />
greenhouse (control). Summer yield <strong>in</strong> the first year was <strong>from</strong> 12 weeks and second year <strong>from</strong> 14<br />
and second year <strong>from</strong> 14 weeks. The lower case shows statistical difference of the<br />
weeks. The lower case shows statistical difference of the same classes <strong>in</strong> different treatments. Block<br />
letters same classes show difference <strong>in</strong> different between treatments. <strong>to</strong>tal Block yields. letters show difference between <strong>to</strong>tal yields.<br />
42 ENERGY IN FOCUS
Mart<strong>in</strong> Lykke Rytter Jensen and Bo Nørregaard Jørgensen, University of Southern Denmark, The Maersk Mc-K<strong>in</strong>ney Moller Institute,<br />
Campusvej 55, DK-5230 Odense M, Denmark<br />
Oliver Körner, <strong>AgroTech</strong>, Højbakkegaard Allé 21, DK-2630 Taastrup, Denmark, Carl-Ot<strong>to</strong> Ot<strong>to</strong>sen, University of Aarhus,<br />
Faculty of Agricultural Sciences, Department of Horticulture, Kirst<strong>in</strong>ebjergvej 10, Postboks 102, DK-5792 Aarslev, Denmark<br />
is caused by lack of CO2. The graph also shows the maximum pho<strong>to</strong>synthesis we can expect <strong>in</strong> the<br />
near future (green dashed l<strong>in</strong>e). This pho<strong>to</strong>synthesis is cont<strong>in</strong>uously calculated based on irradiation<br />
data <strong>from</strong> the most current weather forecast. When a cloudy day is expected, the control system wil<br />
au<strong>to</strong>matically turn on artificial light earlier <strong>in</strong> an attempt <strong>to</strong> achieve a specified light sum. The<br />
PREDICT – A component-based<br />
software platform for<br />
dynamic climate control<br />
grower can use the forecast <strong>to</strong> see how much artificial light will be needed and potentially adapt the<br />
light strategy before it is executed. The transition of this version of the PREDICT software <strong>in</strong><strong>to</strong><br />
commercial greenhouses was planned as a three-phase process. In the first phase, the software was<br />
tested and demonstrated <strong>to</strong> growers <strong>in</strong> a greenhouse research facility. Here, the software gives the<br />
growers advice on optimal climate control with respect <strong>to</strong> production rate. In the second phase, the<br />
software was <strong>in</strong>stalled at Danish Growers. To start with, the software runs <strong>in</strong> simulated mode; that is<br />
the software only computes the climate set po<strong>in</strong>ts, it does not effectuate them. The primary purpose<br />
of this phase is <strong>to</strong> allow the growers <strong>to</strong> become familiar with the software, how it operates, and understand<br />
the effect of dynamic climate control. The f<strong>in</strong>al phase is active control where the PRE-<br />
DICT software takes control of the climate based on overall goals set by the grower. Through the<br />
The dynamic model-based development climate of COa new that maximises component-based pho<strong>to</strong>synthesis software at the platform Proven for successful dynamic <strong>in</strong> climate small setups, control, the the PRE-<br />
2<br />
control concept IntelliGrow DICT has project been has present contributed light level with <strong>in</strong> the extended greenhouse. knowledge The next of step the was implication <strong>to</strong> try the of IntelliGrow <strong>in</strong>creas<strong>in</strong>g conthe<br />
ab-<br />
developed <strong>in</strong> Denmark s<strong>in</strong>ce straction 1996. The level result of climate is then control. translated This <strong>to</strong> set knowledge po<strong>in</strong>ts appli- is crucial cept <strong>in</strong> for commercial develop<strong>in</strong>g greenhouses. the next Howe- generation of<br />
concept aims at improv<strong>in</strong>g <strong>in</strong>telligent the energy climate-control cable by the components.<br />
specific climate computer. ver, whereas the orig<strong>in</strong>al IntelliGrow soft-<br />
efficiency of greenhouse production by Comb<strong>in</strong>ed with temperature <strong>in</strong>tegration ware was designed as a research pro<strong>to</strong>type<br />
adjust<strong>in</strong>g the greenhouse climate References dynami- control, this optimization reduces the use applicable <strong>to</strong> an experimental sett<strong>in</strong>g, the<br />
cally <strong>to</strong> the present weather Hansen situation. JM, To Ehler of additional N, Karlsen heat<strong>in</strong>g P, Høgh-Schmidt of the greenhouse. K, Rosenqvist move <strong>to</strong>wards E. (1996). full-scale A computer production controlled <strong>in</strong><br />
do so, IntelliGrow <strong>in</strong>corporates chamber a determisystem<br />
The designed concept has for been greenhouse proved <strong>to</strong> microclimate work <strong>in</strong> commercial modell<strong>in</strong>g greenhouses and control. required Acta a Hort. new<br />
nistic leaf-pho<strong>to</strong>synthesis model 440:310-315.<br />
based on climate-chamber experiments (Hansen et software platform. For this reason, the<br />
Farquhar et al. (1980) and Gijzen Aaslyng, (1994) J.M., al., Lund, 1996) J.B., as well Ehler, as <strong>in</strong> N. small and Rosenqvist, greenhouse E. PREDICT (2003) project IntelliGrow: was undertaken a greenhouse <strong>in</strong> 2006. compo-<br />
as presented by Körner (2004) nent-based <strong>to</strong> ensure climate experiments control with system. many different Environmental cultivars Modell<strong>in</strong>g The primary & goal Software of the 18: PREDICT 657-666 project<br />
maximum pho<strong>to</strong>synthetic performance. Gijzen H. By (1994) of pot Ontwikkel<strong>in</strong>g plants (Aaslyng van et al., een 2003), simulatiemodel resul- was voor <strong>to</strong> provide transpiratie such a en software wateropname platform. en van<br />
us<strong>in</strong>g this model, it is possible een <strong>to</strong> <strong>in</strong>tegral deter- gewasmodel. t<strong>in</strong>g <strong>in</strong> energy (Development sav<strong>in</strong>gs up <strong>to</strong> 40%, of a depen- simulation A primary model design for transpiration concern of the and PREDICT water uptake<br />
m<strong>in</strong>e the comb<strong>in</strong>ation of temperature and an and <strong>in</strong>tegral d<strong>in</strong>g crop on model), the season. AB-DLO, Wagen<strong>in</strong>gen, The project Netherlands. focused on advanc<strong>in</strong>g pp. 90. the orig<strong>in</strong>al<br />
Farquhar G.D., Von Caemmerer S., Berry J.A. (1980) A biochemical model of pho<strong>to</strong>synthetic CO2<br />
assimilation <strong>in</strong> leaves of C3 species. Planta 149:78-90.<br />
Körner O. (2004) Evaluation of crop pho<strong>to</strong>synthesis models for dynamic climate control. Acta<br />
Horticulturae 654:295-302.<br />
Figure 1.<br />
ENERGY IN FOCUS 43
IntelliGrow concept <strong>to</strong> <strong>in</strong>clude weather<br />
forecasts <strong>in</strong> the computations of climate<br />
set po<strong>in</strong>ts. Where the IntelliGrow concept<br />
uses his<strong>to</strong>rical sensor-data read<strong>in</strong>gs<br />
for irradiance, temperature and CO 2 , the<br />
PREDICT concept should use weather<br />
forecasts as well. Thus, <strong>in</strong> the PREDICT<br />
project, special emphasis is put on design<br />
that utilizes local weather forecasts for<br />
energy- sav<strong>in</strong>g purposes while ensur<strong>in</strong>g<br />
tim<strong>in</strong>g of the production. Another important<br />
design concern of the PREDICToncept<br />
focused on elaborat<strong>in</strong>g the idea of modularity<br />
<strong>in</strong> climate control. In the IntelliGrow<br />
project, the responsibility of controll<strong>in</strong>g<br />
the climate is assigned <strong>to</strong> different components.<br />
In the PREDICT project, this idea<br />
has been developed further <strong>in</strong> order <strong>to</strong><br />
allow for new climate-control components<br />
<strong>to</strong> be easily added. The idea is <strong>to</strong> allow<br />
growers <strong>to</strong> download new climate control<br />
components <strong>from</strong> a central server when<br />
these are available. However, this openness<br />
<strong>to</strong>wards new climate-control components<br />
may make it harder for growers <strong>to</strong><br />
understand who is <strong>to</strong> be held responsible<br />
for a decision and therefore the PREDICT<br />
software is not only a control system, it<br />
is also a decision support system. In the<br />
short run the control system can make<br />
sound decisions - start ventilation when it<br />
becomes <strong>to</strong>o hot, add CO 2 when it limits<br />
plant pho<strong>to</strong>synthesis etc. However, the<br />
many decisions made by a mixture of<br />
climate-control components are far <strong>to</strong>o<br />
complicated <strong>to</strong> be made au<strong>to</strong>matically <strong>in</strong><br />
the long run. It is, therefore, essential that<br />
PREDICT is capable of not just execut<strong>in</strong>g<br />
but also expla<strong>in</strong><strong>in</strong>g those decisions.<br />
The goal of such explanations is <strong>to</strong> support<br />
the grower <strong>in</strong> tak<strong>in</strong>g long-term decisions<br />
beyond the reason<strong>in</strong>g capabilities of<br />
the control system. To facilitate explanation<br />
of control decisions, the system is open<br />
not only <strong>to</strong> new control components, but<br />
also <strong>to</strong> new portals capable of expla<strong>in</strong><strong>in</strong>g<br />
various aspects of the climate control. The<br />
pho<strong>to</strong>synthesis portal shown <strong>in</strong> figure 1 is<br />
an example. The speedometer <strong>in</strong> the <strong>to</strong>p<br />
right corner of the portal shows the current<br />
pho<strong>to</strong>synthesis rate – the current pho<strong>to</strong>synthesis<br />
as a percentage of the maximum<br />
pho<strong>to</strong>synthesis possible under the cur-<br />
rent light conditions. The control system<br />
attempts <strong>to</strong> achieve a target rate specified<br />
by the grower. S<strong>in</strong>ce the calculated temperature<br />
optimum for leaf pho<strong>to</strong>synthesis at<br />
elevated CO 2 is often above the plant temperature<br />
accepted for high quality plant<br />
production, the theoretical maximum of<br />
100% pho<strong>to</strong>synthesis is commonly reduced<br />
<strong>to</strong> around 80% <strong>to</strong> 90% and the lower<br />
temperature value is chosen for control.<br />
In the figure the system currently achieves<br />
66.9% which is below the target rate.<br />
This <strong>in</strong>formation encourages the grower <strong>to</strong><br />
take a closer look at the system. The graph<br />
at the bot<strong>to</strong>m shows the actual pho<strong>to</strong>synthesis<br />
achieved <strong>in</strong> the past (blue l<strong>in</strong>e) and<br />
the maximum pho<strong>to</strong>synthesis that could<br />
theoretically have been achieved us<strong>in</strong>g the<br />
light conditions at the time (green l<strong>in</strong>e).<br />
The bigger the distance between the<br />
two l<strong>in</strong>es, the lower pho<strong>to</strong>synthesis optimization<br />
rate was achieved at the time.<br />
When the grower does not understand a<br />
pattern <strong>in</strong> the graphs, he can select a po<strong>in</strong>t<br />
<strong>in</strong> time and get a detailed textual description<br />
of relevant control decisions.<br />
That is, if he selects 2:30 AM he will see<br />
that the <strong>in</strong>crease <strong>in</strong> pho<strong>to</strong>synthesis dur<strong>in</strong>g<br />
the night was caused by the artificial lights<br />
be<strong>in</strong>g turned on. If he selects current time<br />
he will see that the low pho<strong>to</strong>synthesis<br />
rate is caused by lack of CO 2 . The graph<br />
also shows the maximum pho<strong>to</strong>synthesis<br />
we can expect <strong>in</strong> the near future (green<br />
dashed l<strong>in</strong>e). This pho<strong>to</strong>synthesis is cont<strong>in</strong>uously<br />
calculated based on irradiation<br />
data <strong>from</strong> the most current weather<br />
forecast. When a cloudy day is expected,<br />
the control system will au<strong>to</strong>matically turn<br />
on artificial light earlier <strong>in</strong> an attempt <strong>to</strong><br />
achieve a specified light sum.<br />
The grower can use the forecast <strong>to</strong> see<br />
how much artificial light will be needed<br />
and potentially adapt the light strategy<br />
before it is executed. The transition of this<br />
version of the PREDICT software <strong>in</strong><strong>to</strong><br />
commercial greenhouses was planned as<br />
a three-phase process. In the first phase,<br />
the software was tested and demonstrated<br />
<strong>to</strong> growers <strong>in</strong> a greenhouse research facility.<br />
Here, the software gives the growers<br />
advice on optimal climate control with<br />
respect <strong>to</strong> production rate. In the second<br />
phase, the software was <strong>in</strong>stalled at Danish<br />
Growers. To start with, the software runs <strong>in</strong><br />
simulated mode; that is, the software only<br />
computes the climate set po<strong>in</strong>ts, it does<br />
not effectuate them. The primary purpose<br />
of this phase is <strong>to</strong> allow the growers <strong>to</strong><br />
become familiar with the software, how<br />
it operates, and understand the effect of<br />
dynamic climate control. The f<strong>in</strong>al phase is<br />
active control where the PREDICT software<br />
takes control of the climate based on overall<br />
goals set by the grower. Through the<br />
development of a new component-based<br />
software platform for dynamic climate<br />
control, the PREDICT project has contributed<br />
with extended knowledge of the<br />
implication of <strong>in</strong>creas<strong>in</strong>g the abstraction<br />
level of climate control. This knowledge is<br />
crucial for develop<strong>in</strong>g the next generation<br />
of <strong>in</strong>telligent climate-control components.<br />
References<br />
Hansen JM, Ehler N, Karlsen P, Høgh-<br />
Schmidt K, Rosenqvist E. (1996). A computer<br />
controlled chamber system designed<br />
for greenhouse microclimate modell<strong>in</strong>g<br />
and control. Acta Hort. 440:310-315.<br />
Aaslyng, J.M., Lund, J.B., Ehler, N. and<br />
Rosenqvist, E. (2003) IntelliGrow: a greenhouse<br />
component-based climate control<br />
system. Environmental Modell<strong>in</strong>g & Software<br />
18: 657-666.<br />
Gijzen H. (1994) Ontwikkel<strong>in</strong>g van een<br />
simulatiemodel voor transpiratie en wateropname<br />
en van een <strong>in</strong>tegral gewasmodel.<br />
(Development of a simulation model for<br />
transpiration and water uptake and an<br />
<strong>in</strong>tegral crop model), AB-DLO, Wagen<strong>in</strong>gen,<br />
The Netherlands. pp. 90.<br />
Farquhar G.D., Von Caemmerer S.,<br />
Berry J.A. (1980) A biochemical model of<br />
pho<strong>to</strong>synthetic CO2 assimilation <strong>in</strong> leaves<br />
of C3 species. Planta 149:78-90.<br />
Körner O. (2004) Evaluation of crop<br />
pho<strong>to</strong>synthesis models for dynamic climate<br />
control. Acta Horticulturae 654:295-<br />
302.<br />
44 ENERGY IN FOCUS
Ole Bærenholdt-Jensen, Advisor, Horticultural Advisory Service, Denmark. obj@landscentret.dk<br />
Company / address: Dansk Landbrugsrådgivn<strong>in</strong>g, GartneriRådgivn<strong>in</strong>gen, Hvidkærvej 29, 5250 Odense SV.<br />
How do we pass on new ideas like<br />
Dynamic climate control and<br />
new greenhouse ICT <strong>to</strong> the grower?<br />
In Denmark, there has been energy<br />
sav<strong>in</strong>g projects <strong>in</strong> the last many years<br />
with results, that should be implemented<br />
as much as possible at the grower. In The<br />
Horticultural advisory service we have<br />
been the partner <strong>in</strong> most of the project <strong>to</strong><br />
make the <strong>in</strong>formation and implementation<br />
part. We have also been a part of the<br />
development <strong>in</strong> the projects - the best possible<br />
background for giv<strong>in</strong>g Information.<br />
Information has been done with articles<br />
<strong>in</strong> Growers Magaz<strong>in</strong>e, <strong>in</strong>formation days,<br />
and by meet<strong>in</strong>gs <strong>in</strong> more than 100 nurseries<br />
<strong>to</strong> give them results and presentations<br />
adjusted <strong>to</strong> the specific nursery – their<br />
cultures and energy sav<strong>in</strong>g possibilities.<br />
Implementation: The results are an <strong>in</strong>tegrated<br />
part of the advice we give at the<br />
grower, and <strong>in</strong> climate control courses we<br />
are giv<strong>in</strong>g. Therefore ideas <strong>from</strong> e.g. the<br />
dynamic climate control project already<br />
are adapted at many growers. The results<br />
dur<strong>in</strong>g the years has also been implemented<br />
<strong>in</strong> the Danish greenhouse “energy<br />
manual”, that most of the growers have<br />
followed, because they have made an<br />
“energy agreement”, with the government.<br />
Example on <strong>in</strong>formation/ implementation<br />
for the com<strong>in</strong>g period is: <strong>AgroTech</strong><br />
and GartneriRådgivn<strong>in</strong>gen are releas<strong>in</strong>g a<br />
brand new www energy <strong>in</strong>formation platform<br />
this autumn.<br />
<br />
ENERGY IN FOCUS 45
N.E. Andersson 1 and O. Skov 2 , 1 University of Aarhus, Faculty of Agricultural Sciences, Department of Horticulture,<br />
Kirst<strong>in</strong>ebjergvej 10, DK-5792 Aarslev, Denmark, Phone: +45 89991900, Fax: +45 89993490, e-mail: Niels.Andersson@agrsci.dk<br />
2 <strong>AgroTech</strong>, Højbakkegård Allé 21, DK-2630 Taastrup, Denmark, Phone: +45 87438400, Fax: +45 36440533, e-mail: oes@agrotech.dk<br />
Multilayer screen<strong>in</strong>g system<br />
<strong>in</strong> greenhouse with screen materials<br />
with different properties<br />
<strong>to</strong> enhance energy sav<strong>in</strong>g<br />
Mobile screens <strong>in</strong> greenhouses play an<br />
important role <strong>in</strong> energy sav<strong>in</strong>g and<br />
the control of the radiation environment <strong>in</strong><br />
the greenhouse. The control of the screens<br />
is base on light, a fac<strong>to</strong>r which makes<br />
control for both energy sav<strong>in</strong>g and shad<strong>in</strong>g<br />
possible. A s<strong>in</strong>gle layer screen is common<br />
<strong>in</strong> greenhouses because the screen<br />
material has the properties that make it<br />
applicable for energy sav<strong>in</strong>g and shad<strong>in</strong>g.<br />
However, such materials are not optimal<br />
for both shad<strong>in</strong>g and energy sav<strong>in</strong>g and the<br />
performance of the screen<strong>in</strong>g system could<br />
be enhanced by a multilayer system.<br />
A test set-up consist<strong>in</strong>g of 5 frames of<br />
1×2×0.25 m was build of plywood and<br />
stacked <strong>to</strong>gether <strong>to</strong> a <strong>to</strong>tal height of 1.25<br />
m and with a ground area of 2 m2 . On the<br />
<strong>to</strong>p frame was placed a glass pane with a<br />
thickness of 4 mm m and <strong>in</strong> the bot<strong>to</strong>m<br />
frame was a sand layer with a thickness<br />
of 0.15 m. In the sand layer was placed a<br />
heat<strong>in</strong>g cable with a length of 20 m and<br />
with a heat dissipation of 15 Wm-1 . In the<br />
three frames <strong>in</strong> the middle of the test setup<br />
different comb<strong>in</strong>ations of screen materials<br />
were <strong>in</strong>stalled. The screen materials<br />
were XLS Obscura A/B+B/B, XLS Obscura<br />
Fig. 1. Heat loss (Q) <strong>from</strong> the uppermost frame <strong>in</strong> regard screen comb<strong>in</strong>ations.<br />
Fig. 1. Heat loss (Q) <strong>from</strong> the uppermost frame<br />
<strong>in</strong> regard screen comb<strong>in</strong>ations.<br />
Firebreak A/A+B/W, XLS NIR, XLS 10<br />
Ultra, and XLS 55 Harmony. The test set-up<br />
was placed <strong>in</strong> a greenhouse compartment<br />
at a m<strong>in</strong>imum air temperature of 5°C. The<br />
experiment was conducted at two <strong>in</strong>ternal<br />
temperatures <strong>in</strong> the test set-up of 15 and<br />
20 °C and data was collected every 5<br />
m<strong>in</strong>utes, but only data dur<strong>in</strong>g night was<br />
used <strong>in</strong> the analysis.<br />
The energy loss (Q) <strong>from</strong> the uppermost<br />
frame depends on the difference <strong>in</strong> air<br />
temperature between <strong>in</strong>side and outside<br />
the test set-up. A high <strong>in</strong>sulation effect of<br />
the screen comb<strong>in</strong>ation results <strong>in</strong> a low<br />
temperature <strong>in</strong> the uppermost frame of the<br />
test set-up and the temperature difference<br />
between <strong>in</strong>side and outside becomes<br />
small. Increas<strong>in</strong>g number of layers reduced<br />
the heat loss <strong>from</strong> the test set-up, but the<br />
reduction <strong>in</strong> energy loss <strong>from</strong> the uppermost<br />
part of the test set-up was not equal<br />
for the different comb<strong>in</strong>ations of screen<br />
materials (Fig. 1). The heat loss depends<br />
on the set po<strong>in</strong>t and was always highest<br />
at the highest set po<strong>in</strong>t of 20 °C. At a set<br />
po<strong>in</strong>t of 20 °C the heat loss for the comb<strong>in</strong>ation<br />
XLS Obscura A/B+B/B and XLS NIR<br />
is not significant different for a triple layer<br />
comb<strong>in</strong>ation consist<strong>in</strong>g of the same two<br />
materials <strong>to</strong>gether with a shad<strong>in</strong>g screen<br />
type of material (XLS 10 Ultra or XLS 55<br />
Harmony). However, the lowest heat loss<br />
<strong>from</strong> the test set-up was always obta<strong>in</strong>ed<br />
by a triple layer system <strong>in</strong>dependent of the<br />
set po<strong>in</strong>t.<br />
Increas<strong>in</strong>g the number of layers decreased<br />
the heat transmission coefficient (U),<br />
but <strong>in</strong>troduc<strong>in</strong>g a second layer did not<br />
always result <strong>in</strong> a significant lower heat<br />
transmission coefficient (Fig. 2). There was<br />
always a significant lower heat transmission<br />
coefficient with a triple layer system<br />
compared <strong>to</strong> a s<strong>in</strong>gle layer system.<br />
The <strong>in</strong>dividual screen material has different<br />
ability <strong>to</strong> reduce energy loss, and<br />
the differences should be found <strong>in</strong> the<br />
transmittance of the materials. Some of<br />
the materials are opaque while others are<br />
transparent, which <strong>in</strong>fluences the long<br />
wave radiation heat loss. Another possible<br />
fac<strong>to</strong>r that might <strong>in</strong>fluence the energy loss<br />
is the permeability of the screen materials.<br />
A higher permeability will <strong>in</strong>crease mass<br />
and heat transport.<br />
<br />
Fig. 2. The heat transmission coefficient (U) of the system <strong>in</strong> regard <strong>to</strong> screen comb<strong>in</strong>ations.<br />
Fig. 2. The heat transmission coefficient (U)<br />
of the system <strong>in</strong> regard <strong>to</strong> screen comb<strong>in</strong>ations.<br />
46 ENERGY IN FOCUS
1 S. Lambrecht, s.lambrecht@fz-juelich.de<br />
1 S. Tittmann, s.tittmann@fz-juelich.de<br />
2 H. Behn, helen_behn@uni-bonn.de<br />
2 G.Reis<strong>in</strong>ger, grei@uni-bonn.de<br />
1 A. Walter, a.walter@fz-juelich.de<br />
3 T. Hofmann, Thomas.Hofmann@centrosolarglas.com<br />
4 H.-J.Tantau, tantau@bgt.uni-hannover.de<br />
4 B. von Elsner, elsner@bgt.uni-hannover.de<br />
Innovative roof<strong>in</strong>g materials<br />
for <strong>in</strong>creased plant quality<br />
and reduced energy consumption<br />
Introduction<br />
Light is a determ<strong>in</strong><strong>in</strong>g fac<strong>to</strong>r for optimum<br />
quality <strong>in</strong> plants. Scientific and commercial<br />
plant cultivation takes place <strong>in</strong> part<br />
<strong>in</strong> greenhouses, which <strong>in</strong>volves reduced<br />
light quality and high energy consumption.<br />
<strong>Energy</strong> consumption <strong>in</strong> greenhouses<br />
can be almost halved by us<strong>in</strong>g <strong>in</strong>novative<br />
roof<strong>in</strong>g materials. In contrast <strong>to</strong> the past,<br />
energy sav<strong>in</strong>gs and high transmissions can<br />
be achieved simultaneously. Our goal is<br />
<strong>to</strong> obta<strong>in</strong> low energy consumption and<br />
<strong>in</strong>creased quality of plant products at the<br />
same time.<br />
Pr<strong>in</strong>ciples of glass-film<br />
comb<strong>in</strong>ation (GFC)<br />
In contrast <strong>to</strong> double and triple layers of<br />
roof<strong>in</strong>g materials consist<strong>in</strong>g of the same<br />
components (only glass or only film),<br />
Forschungszentrum Jülich has created an<br />
<strong>in</strong>novative roof<strong>in</strong>g system with different<br />
materials. This system comb<strong>in</strong>es a microstructured<br />
white glass (Centrosolar) and<br />
an ethylene tetrafluoroethylene (ETFE) film<br />
(Asahi Glass). The film is either p<strong>in</strong>ched<br />
or glued <strong>to</strong> the edge of the glass. By us<strong>in</strong>g<br />
a ventilation system, an air cushion is<br />
created which separates the film <strong>from</strong> the<br />
glass. The air cushion of approximately<br />
25mm represents an <strong>in</strong>sulation layer which<br />
results <strong>in</strong> lower energy consumption.<br />
Fenstertechnik at Rosenheim (ift; Institute<br />
for W<strong>in</strong>dow Technologies). The applied<br />
<strong>in</strong>vestigation was conducted <strong>in</strong> a model<br />
system, the so-called “hot box”, which<br />
represents similar greenhouse conditions<br />
with respect <strong>to</strong> air humidity and heat<strong>in</strong>g.<br />
Basically, the GFC was tested <strong>in</strong> different<br />
fixation systems (glued and p<strong>in</strong>ched with<br />
PVC profile) under both sets of conditions<br />
<strong>in</strong> comparison <strong>to</strong> s<strong>in</strong>gle-layer glass (i.e.<br />
float glass).<br />
The U-value for s<strong>in</strong>gle layer glass (5.9<br />
W/m 2 K) accord<strong>in</strong>g <strong>to</strong> the manufacturer`s<br />
2 G. Noga, nogag@uni-bonn.de<br />
1 U. Schurr, u.schurr@fz-juelich.de<br />
1 A. Ulbrich, a.ulbrich@fz-juelich.de<br />
1 Forschungszentrum Jülich, Phy<strong>to</strong>sphere Institute<br />
2 University of Bonn: INRES,<br />
3 Centrosolar, Fürth<br />
4 Leibniz University Hannover, BGT<br />
<strong>in</strong>formation is twice the value of GFC<br />
(PVC profile) under labora<strong>to</strong>ry conditions<br />
(2.9 W/m 2 K). From an energetic po<strong>in</strong>t of<br />
view, double-layer glass (manufacturer`s<br />
<strong>in</strong>formation: 3.0 W/m 2 K) and GFC (PVC<br />
profile; labora<strong>to</strong>ry conditions, 2.9 W/m 2 K)<br />
display very similar U-values. The glued<br />
variant of the GFC has a lower effect on<br />
energy sav<strong>in</strong>gs. The heat transmission coefficient<br />
is 3.6 W/m 2 K. The labora<strong>to</strong>ry conditions<br />
do not reflect the real conditions<br />
of a greenhouse (e.g. air humidity, heat<strong>in</strong>g,<br />
w<strong>in</strong>d velocity). Investigations under<br />
Heat transmission coefficient<br />
To verify the energy efficiency potential of<br />
the GFC, the heat transmission coefficient Figure Figure 1: Determ<strong>in</strong>ation 1: Determ<strong>in</strong>ation of of the the heat heat transmission coefficient “ U” “ U” on on the the basis basis of of the the manufac-<br />
“U” was determ<strong>in</strong>ed. With respect <strong>to</strong> the turer’ Figure turer’ s 1: <strong>in</strong>formation s Determ<strong>in</strong>ation <strong>in</strong>formation and and <strong>in</strong>vestigations of <strong>in</strong>vestigations the heat transmission under under labora<strong>to</strong>ry coefficient as well as “ well U” as applied as on applied the basis conditions of the for manufac- for different<br />
problem of evaluat<strong>in</strong>g the heat transmissi-<br />
roof<strong>in</strong>g turer’ roof<strong>in</strong>g s <strong>in</strong>formation materials. The and The manufacturer`s <strong>in</strong>vestigations manufacturer`s under <strong>in</strong>formation labora<strong>to</strong>ry represents as well average as average applied values values conditions for for commercially<br />
for different<br />
Figure available roof<strong>in</strong>g available 1: Determ<strong>in</strong>ation<br />
materials. glaz<strong>in</strong>gs (Pilk<strong>in</strong>g<strong>to</strong>n, The (Pilk<strong>in</strong>g<strong>to</strong>n, manufacturer`s<br />
of the Sa<strong>in</strong>t-Goba<strong>in</strong>, heat Sa<strong>in</strong>t-Goba<strong>in</strong>, transmission<br />
<strong>in</strong>formation Glas Glas Trösch, coefficient<br />
represents Trösch, Interpane, average<br />
“U” on Arcon). values<br />
the Arcon). basis<br />
for Measurements commercially<br />
of the manu- at the at the<br />
on coefficient <strong>in</strong> commercial greenhouses, facturer’s Institut available Institut für <strong>in</strong>formation glaz<strong>in</strong>gs für Fenstertechnik (Pilk<strong>in</strong>g<strong>to</strong>n, and <strong>in</strong>vestigations at Rosenheim at Sa<strong>in</strong>t-Goba<strong>in</strong>, Rosenheim (ift) under (ift) Glas can can labora<strong>to</strong>ry be Trösch, be found found Interpane, <strong>in</strong> as the <strong>in</strong> well the labora<strong>to</strong>ry as Arcon). applied section. Measurements section. conditions The The section at for the on on<br />
we decided <strong>to</strong> exam<strong>in</strong>e the U-value under different applied Institut applied roof<strong>in</strong>g für conditions Fenstertechnik materials. represents at The Rosenheim measurements manufacturer`s measurements (ift) <strong>in</strong> can a <strong>in</strong> hot be <strong>in</strong>formation a hot found box box <strong>to</strong> <strong>in</strong> simulate <strong>to</strong> the simulate represents labora<strong>to</strong>ry environmental average section. conditions values The conditions section for on<br />
labora<strong>to</strong>ry and applied conditions. The comparable<br />
commercially<br />
applied comparable conditions <strong>to</strong> those <strong>to</strong> those<br />
available<br />
represents of of a greenhouse. a greenhouse.<br />
glaz<strong>in</strong>gs<br />
measurements<br />
(Pilk<strong>in</strong>g<strong>to</strong>n,<br />
<strong>in</strong><br />
Sa<strong>in</strong>t-Goba<strong>in</strong>,<br />
a hot box <strong>to</strong> simulate<br />
Glas Trösch,<br />
environmental<br />
Interpane,<br />
conditions<br />
Arcon).<br />
comparable <strong>to</strong> those of a greenhouse.<br />
labora<strong>to</strong>ry test<strong>in</strong>g was performed accor- Measurements Light Light transparency at the Institut für Fenstertechnik at Rosenheim (ift) can be found <strong>in</strong> the<br />
d<strong>in</strong>g <strong>to</strong> German <strong>in</strong>dustrial standards (EN labora<strong>to</strong>ry Basically, Light Basically, transparency section. both both materials The section (microstructured on applied white white conditions glass glass and and represents an an ethylene measurements tetrafluoroethylene <strong>in</strong> a (ETFE) hot (ETFE)<br />
ISO 12567-1:2009-09) at the Institut für box<br />
film) Basically,<br />
<strong>to</strong><br />
film)<br />
simulate<br />
display both <strong>in</strong>creased<br />
environmental<br />
materials <strong>in</strong>creased transparency (microstructured transparency<br />
conditions<br />
<strong>to</strong> pho<strong>to</strong>synthetically <strong>to</strong> white pho<strong>to</strong>synthetically<br />
comparable<br />
glass and<br />
<strong>to</strong><br />
an active<br />
those<br />
ethylene active radiation<br />
of<br />
radiation tetrafluoroethylene<br />
a greenhouse.<br />
(PAR; (PAR; approx. (ETFE) 92 92 per per<br />
cent), film) cent), display UV-A UV-A radiation <strong>in</strong>creased radiation (above transparency (above 80 80 per per cent) <strong>to</strong> pho<strong>to</strong>synthetically cent) and and UV-B UV-B radiation active (up radiation (up <strong>to</strong> 80 <strong>to</strong> 80 per (PAR; per cent) cent) approx. <strong>in</strong> comparison <strong>in</strong> comparison 92 per <strong>to</strong> <strong>to</strong><br />
s<strong>in</strong>gle-layer cent), s<strong>in</strong>gle-layer UV-A glass radiation glass roof<strong>in</strong>g (above (approx. 80 per 90 cent) 90 per per cent, and cent, UV-B 70 70 per radiation per cent cent and and (up 0 per 0 <strong>to</strong> per 80 cent, cent, per respectively). cent) respectively). <strong>in</strong> comparison The The comcom- <strong>to</strong><br />
b<strong>in</strong>ation s<strong>in</strong>gle-layer b<strong>in</strong>ation of of the glass the two roof<strong>in</strong>g two materials (approx. (<strong>in</strong><strong>to</strong> (<strong>in</strong><strong>to</strong> a 90 GFC a per GFC system cent, system 70 as per described as described cent and above) 0 above) per leads cent, leads <strong>to</strong> respectively). a <strong>to</strong> light a light transparency The com-<br />
ENERGY IN FOCUS of b<strong>in</strong>ation of the the pho<strong>to</strong>synthetically of pho<strong>to</strong>synthetically the two materials active active (<strong>in</strong><strong>to</strong> radiation a radiation GFC of system of almost almost as 90 described 90 per per cent, cent, above) and and UV-A leads UV-A <strong>to</strong> of a of approximately light approximately transparency 47 70. 70.<br />
These of These the values pho<strong>to</strong>synthetically values are are comparable active with radiation with the the ones ones of of almost of floatglas. 90 per The The cent, UV-B UV-B and transmission UV-A transmission of approximately values values for for float float 70.<br />
glass These glass are values are 0 <strong>in</strong> 0 are comparison <strong>in</strong> comparison comparable <strong>to</strong> 17 <strong>to</strong> with 17 per the per cent ones cent for of for GFC. floatglas. GFC. All All measurements The measurements UV-B transmission were were conducted values under for under float greengreenhouse glass house are conditions. 0 conditions.<br />
<strong>in</strong> comparison <strong>to</strong> 17 per cent for GFC. All measurements were conducted under green-
applied conditions make this difficulty<br />
very clear. The U-values for both GFC<br />
variants are higher under applied conditions<br />
compared <strong>to</strong> labora<strong>to</strong>ry conditions.<br />
Nevertheless, the energy sav<strong>in</strong>g potential<br />
represents approximately 40 per cent <strong>in</strong><br />
contrast <strong>to</strong> float glass.<br />
Light transparency<br />
Basically, both materials (microstructured<br />
white glass and an ethylene tetrafluoroethylene<br />
(ETFE) film) display <strong>in</strong>creased<br />
transparency <strong>to</strong> pho<strong>to</strong>synthetically active<br />
radiation (PAR; approx. 92 per cent), UV-A<br />
radiation (above 80 per cent) and UV-B<br />
radiation (up <strong>to</strong> 80 per cent) <strong>in</strong> comparison<br />
<strong>to</strong> s<strong>in</strong>gle-layer glass roof<strong>in</strong>g (approx.<br />
90 per cent, 70 per cent and 0 per cent,<br />
respectively). The comb<strong>in</strong>ation of the two<br />
materials (<strong>in</strong><strong>to</strong> a GFC system as described<br />
above) leads <strong>to</strong> a light transparency of<br />
the pho<strong>to</strong>synthetically active radiation of<br />
almost 90 per cent, and UV-A of approximately<br />
70. These values are comparable<br />
with the ones of floatglas. The UV-B<br />
transmission values for float glass are 0<br />
<strong>in</strong> comparison <strong>to</strong> 17 per cent for GFC.<br />
All measurements were conducted under<br />
greenhouse conditions.<br />
Plant product quality<br />
After confirm<strong>in</strong>g the improved light conditions<br />
under GFC roof<strong>in</strong>g, it is necessary<br />
<strong>to</strong> verify the <strong>in</strong>fluence of the <strong>in</strong>creased<br />
transparency of PAR and UV-A as well as<br />
UV-B on plant growth and development.<br />
Investigations on plant development were<br />
made under s<strong>in</strong>gle-layer roof<strong>in</strong>g consist<strong>in</strong>g<br />
of white glass, ETFE and float glass. These<br />
exam<strong>in</strong>ations were conducted <strong>in</strong> commercial<br />
greenhouses as well as <strong>in</strong> small<br />
research units. The improved light conditions<br />
led <strong>to</strong> the desired optimization of<br />
plant growth and product quality both <strong>in</strong><br />
research greenhouses and also at a commercial<br />
plant grower’s. The example of<br />
red leaf lettuce plants showed the decisive<br />
<strong>in</strong>fluence of the UV-B transmission properties<br />
of the roof<strong>in</strong>g material. This led <strong>to</strong> a<br />
reduction <strong>in</strong> leaf length and width, which<br />
brought about a more compact growth<br />
form al<strong>to</strong>gether.<br />
With respect <strong>to</strong> product quality, a considerably<br />
more <strong>in</strong>tensive colouration of the<br />
plants was visibly identifiable. The analysis<br />
of the plants confirmed this impression<br />
based on an <strong>in</strong>creased content of significant<br />
secondary metabolites. For <strong>in</strong>stance,<br />
the anthocyan content of red leaf lettuce<br />
showed a significantly higher value under<br />
UV-B-transmitt<strong>in</strong>g roof<strong>in</strong>g material (white<br />
glass and ETFE film).<br />
Outlook<br />
Further <strong>in</strong>vestigations are necessary <strong>to</strong><br />
evaluate the energy sav<strong>in</strong>g potential <strong>in</strong><br />
commercial greenhouses consider<strong>in</strong>g the<br />
problems of relative air humidity. In this<br />
context, it is important <strong>to</strong> develop an <strong>in</strong>telligent<br />
regulation and control algorithm for<br />
operat<strong>in</strong>g the air cushion.<br />
For example, there is no air cushion<br />
without ventilation, so the film attaches <strong>to</strong><br />
the glass. This state is comparable <strong>to</strong> s<strong>in</strong>gle<br />
layer roof<strong>in</strong>g which enables condensation<br />
and the relative air humidity decreases.<br />
But the consequences are reduced energy<br />
sav<strong>in</strong>gs.<br />
<br />
48 ENERGY IN FOCUS
Jens Møller Jensen, CTO, Danfoss IXA A/S, jensen@danfoss.com, Bent S. Bennedsen, Agrotech A/S, bsb@agrtech.dk<br />
Environmental Sensors for Harsh<br />
Environments - a Novel Approach<br />
<strong>to</strong> Multiple Parameter Sensors<br />
for Greenhouses<br />
Sensors for environmental parameters<br />
are numerous and widespread, and<br />
the number of applications <strong>in</strong> which such<br />
sensors are applied are constantly ris<strong>in</strong>g.<br />
One application of <strong>in</strong>terest is greenhouse<br />
production, <strong>in</strong> which the application of<br />
multiple distributed sensors can serve <strong>to</strong><br />
drastically reduce energy consumption<br />
and improved growth control. However,<br />
this approach implies requirements that<br />
are not fulfilled with the currently exist<strong>in</strong>g<br />
sensors, namely those of the ability of<br />
the sensors <strong>to</strong> function cont<strong>in</strong>uously and<br />
stable and with little or no service requirement<br />
<strong>in</strong> a harsh environment likely <strong>to</strong><br />
contam<strong>in</strong>ate the sensors, the ability <strong>to</strong><br />
operate wirelessly <strong>in</strong> order <strong>to</strong> enable use<br />
of multiple sensors without obstruct<strong>in</strong>g<br />
and expensive cabl<strong>in</strong>g, and the ability <strong>to</strong><br />
do so at a energy consumption level low<br />
enough for power<strong>in</strong>g by energy harvest<strong>in</strong>g,<br />
avoid<strong>in</strong>g the need for recurrent battery<br />
exchange.<br />
Currently available sensors are <strong>in</strong> general<br />
not specifically designed for harsh<br />
environments, and <strong>in</strong> most cases standard<br />
sensors are therefore applied with various<br />
additional measures taken <strong>in</strong> terms of<br />
artificial protection and limited position<strong>in</strong>g<br />
options <strong>to</strong> compensate for the harsh<br />
environment impact. Moreover, different<br />
sensors are needed for the various environment<br />
parameters. This leaves the sensors<br />
still less applicable, less durable and less<br />
accurate than needed <strong>in</strong> order <strong>to</strong> efficiently<br />
provide measurement data for optimum<br />
energy management and environment<br />
control. Such control requires moni<strong>to</strong>r<strong>in</strong>g<br />
of the environment <strong>in</strong> proximity of the<br />
plants, and the sensors therefore should<br />
be placed amongst the plants, preferably<br />
on a multiple distributed basis, and be<br />
able <strong>to</strong> withstand close impact <strong>from</strong> the<br />
various nurs<strong>in</strong>g activities while at the same<br />
time not requir<strong>in</strong>g tedious time-and-effort<br />
consum<strong>in</strong>g <strong>in</strong>stallation and ma<strong>in</strong>tenance<br />
which impede daily work rout<strong>in</strong>es and<br />
bus<strong>in</strong>ess. Obta<strong>in</strong><strong>in</strong>g these features require<br />
sensors that are really designed for the purpose.<br />
They must be reliable and durable<br />
and designed for maximum usability <strong>in</strong> the<br />
specific application, and they must require<br />
no or very little service and ma<strong>in</strong>tenance<br />
and must communicate their data wire-<br />
lessly <strong>in</strong> order <strong>to</strong> facilitate easy and dynamic<br />
position<strong>in</strong>g and handl<strong>in</strong>g.<br />
This all calls for a novel approach <strong>to</strong><br />
greenhouse sensors <strong>in</strong> technology, concept<br />
and design. Danfoss IXA A/S <strong>to</strong>gether with<br />
partners of the Greenhouse Concept 2017<br />
is develop<strong>in</strong>g such sensors, based on novel<br />
and patented optical pr<strong>in</strong>ciples <strong>in</strong>corporat<strong>in</strong>g<br />
nanotechnology.<br />
Danfoss IXA A/S has developed and<br />
patented a novel optical measurement<br />
pr<strong>in</strong>ciple and novel nano-coat<strong>in</strong>g pr<strong>in</strong>ciples<br />
which <strong>to</strong>gether with application<br />
targeted design enable sensors with all the<br />
required properties. The sensors simultaneously<br />
measure CO 2 , absolute and relative<br />
humidity, <strong>in</strong>clud<strong>in</strong>g dew po<strong>in</strong>t, various<br />
temperatures and light, they are faster than<br />
exist<strong>in</strong>g sensors, they are self-clean<strong>in</strong>g and<br />
hermetically sealed, they are powered<br />
by energy harvest<strong>in</strong>g and they communicate<br />
wirelessly <strong>in</strong> a multiple-node network<br />
which enables huge improvements<br />
<strong>in</strong> both greenhouse energy consumption<br />
and growth control. At the same time the<br />
sensors impose no additional ma<strong>in</strong>tenance<br />
and service requirements on the users. The<br />
sensors can withstand direct exposure <strong>to</strong><br />
the various daily nurs<strong>in</strong>g activities and<br />
handl<strong>in</strong>g and they are specifically designed<br />
for optimum usability and efficiency<br />
<strong>in</strong> professional greenhouse production<br />
plants.<br />
<br />
ENERGY IN FOCUS 49
Carl-Ot<strong>to</strong> Ot<strong>to</strong>sen, Department of Horticulture, Kirst<strong>in</strong>ebjergvej 10, 5792 Aarslev, Aarhus University DENMARK, co.ot<strong>to</strong>sen@agrsci.dk<br />
Bo Nørregaard Jørgensen, The Maersk Mc-K<strong>in</strong>ney Moller Institute, University of Southern Denmark, Campusvej 55<br />
DK-5230 Odense M, DENMARK, bnj@mip.sdu.dk<br />
Dynamic management<br />
of supplemental light<br />
Introduction<br />
Even the most advanced control <strong>in</strong> greenhouse<br />
does not <strong>in</strong>clude species differences<br />
adjustment. In terms of supplemental light<br />
use, the plant species might differ dramatically<br />
<strong>in</strong> terms of light response – both <strong>in</strong><br />
level and <strong>in</strong> time. In an attempt <strong>to</strong> address<br />
not only the challenges of efficiency of<br />
light use we have tried <strong>to</strong> comb<strong>in</strong>e physiological<br />
knowledge, weather forecast<br />
and actual energy prices <strong>to</strong> control the<br />
light use.<br />
The state-of-the-art dynamic climate<br />
control system IntelliGrow is based on<br />
the pho<strong>to</strong>synthesis response of plants has<br />
hither<strong>to</strong> not <strong>in</strong>cluded the control of supplemental<br />
light control besides fixed set<br />
po<strong>in</strong>ts. While the <strong>in</strong>itial aim was <strong>to</strong> reduce<br />
the heat<strong>in</strong>g costs as much as possible,<br />
so a natural step is f<strong>in</strong>d solutions <strong>to</strong> the<br />
<strong>in</strong>creas<strong>in</strong>g use of electricity for the supplemental<br />
light use <strong>in</strong> commercial green-<br />
houses – both vegetables and ornamentals.<br />
As the natural light even <strong>in</strong> darkest part of<br />
the year on a sunny day might be enough<br />
we have decided <strong>to</strong> comb<strong>in</strong>e <strong>in</strong>formation<br />
about the weather forecasts, the actual<br />
forecasted electricity prices and the pho<strong>to</strong>synthetic<br />
performance of the actual species<br />
<strong>in</strong><strong>to</strong> one context.<br />
Idea<br />
To reach this target a software package has<br />
been developed, that <strong>in</strong>stalled on a PC<br />
connected <strong>to</strong> the Internet and with access<br />
<strong>to</strong> a climate computer will calculate the<br />
most efficient time <strong>to</strong> turn on the supplemental<br />
light based on the weather forecast,<br />
the energy prices and the pho<strong>to</strong>synthesis<br />
sum <strong>from</strong> <strong>in</strong>dividual plant species. In this<br />
way we not only overcome the traditional<br />
rather conservative set po<strong>in</strong>ts for use of<br />
supplemental light, but also secures that<br />
The screen shows an example of supplemental light control, where the light is on 6 hrs<br />
dur<strong>in</strong>g the night (lower left). The graph shows times of light on (red), price of electricity<br />
(light blue) and work<strong>in</strong>g light (yellow). The green l<strong>in</strong>e is natural light and light green l<strong>in</strong>e<br />
is the pho<strong>to</strong>synthetic activity.<br />
the use of supplemental light takes place<br />
<strong>in</strong> periods where the ga<strong>in</strong> <strong>in</strong> terms of pho<strong>to</strong>synthesis<br />
per light hours are the best. The<br />
control of supplemental light is predictive<br />
rather than the traditional retrospect analysis<br />
of light sums.<br />
Results<br />
Experiments with different pho<strong>to</strong>synthesis<br />
sums us<strong>in</strong>g dynamic light control vs. traditional<br />
light controls based of set po<strong>in</strong>t<br />
of supplemental light has been performed<br />
<strong>in</strong> Spr<strong>in</strong>g 2009. The dynamic supplemental<br />
light control was use <strong>in</strong> comb<strong>in</strong>ation<br />
with dynamic climate control us<strong>in</strong>g potted<br />
m<strong>in</strong>iature roses, Hibiscus rosa-s<strong>in</strong>ensis and<br />
Euphorbia milii showed that a reduction of<br />
more than 10% of the supplemental light<br />
use was possible. If it was comb<strong>in</strong>ed with<br />
dynamic climate control both the cost for<br />
heat<strong>in</strong>g and electricity was reduced with<br />
an improved plant performance (often<br />
more compact plants).<br />
Pho<strong>to</strong>synthesis measurements of the<br />
species reveal large differences <strong>in</strong> response<br />
times <strong>to</strong> light, which <strong>in</strong>dicate several<br />
additional possibilities for reduc<strong>in</strong>g electricity<br />
costs us<strong>in</strong>g different ignit<strong>in</strong>g patterns<br />
for the lamps. This knowledge will<br />
be <strong>in</strong>cluded <strong>in</strong> the software and on go<strong>in</strong>g<br />
work on the software will <strong>in</strong>clude a better<br />
prediction of the climate <strong>to</strong> improve<br />
the pho<strong>to</strong>synthesis calculation, but also<br />
<strong>in</strong>clude suggestion for different uses of the<br />
<strong>in</strong>stalled supplementary light <strong>in</strong> different<br />
situations.<br />
Conclusions<br />
The software that enables the l<strong>in</strong>k between<br />
actual costs of electricity and the weather<br />
forecast is as such an effective <strong>to</strong>ol for<br />
greenhouse growers <strong>to</strong> reduce the energy<br />
cost as it illustrates clearly the actual costs<br />
for provid<strong>in</strong>g light for the plants. When it is<br />
comb<strong>in</strong>ed with the species specific <strong>in</strong>formation<br />
about the required pho<strong>to</strong>synthesis<br />
and the response rates of the plants it will<br />
enable growers <strong>to</strong> reduce the energy costs,<br />
by mov<strong>in</strong>g energy use <strong>from</strong> peak <strong>to</strong> low<br />
peak periods, which on the other hand is<br />
beneficial for the energy providers.<br />
<br />
50 ENERGY IN FOCUS
Eva Rosenqvist 1 , Anker Kuehn 2 , Jakob Skov Pedersen 2 , Per Holgersson 3 and Hans Andersson 3<br />
1 Dept. of Agriculture and Ecology, University of <strong>Copenhagen</strong>, Højbakkegård Allé 9, 2630 Tåstrup, Denmark, ero@life.ku.dk<br />
2 Agrotech, Højbakkegård Allé 21, 2630 Tåstrup, Denmark, 3 AB Ludvig Svensson, 511 82 K<strong>in</strong>na, Sweden<br />
The effect of screen material<br />
on air and leaf temperature<br />
The present development of greenhouse<br />
production is much focused on new<br />
climate control strategies and new technical<br />
solution for energy management.<br />
Here the development of new screen<br />
material will play an important role s<strong>in</strong>ce<br />
the screens have a great impact on both<br />
the micro climate experienced by the crop<br />
and the temperature distribution <strong>in</strong> the<br />
greenhouse, which will be important for<br />
the possibilities for heat extraction aim<strong>in</strong>g<br />
at s<strong>to</strong>r<strong>in</strong>g energy harvested dur<strong>in</strong>g warm<br />
periods of time for use dur<strong>in</strong>g cold periods<br />
of time.<br />
In an experiment run dur<strong>in</strong>g June – September<br />
2009 we have compared radiation<br />
and temperature parameters under three<br />
permanently closed screens: (1) a traditional<br />
ventilated screen with one alum<strong>in</strong>ium<br />
strip, on clear transparent strip and two<br />
open strips, (2) a dense pro<strong>to</strong>type of NIR<br />
screen, with clear strips that transmits less<br />
near <strong>in</strong>fra-red radiation than the traditional<br />
transparent strips does and (3) a dense<br />
diffus<strong>in</strong>g screen with one white and two<br />
diffus<strong>in</strong>g transparent strips. Each screen<br />
was sewn <strong>in</strong><strong>to</strong> a tent measur<strong>in</strong>g 1.8 x 6.2<br />
m, be<strong>in</strong>g 1.2 m high <strong>to</strong> the south and 1.6<br />
m high <strong>to</strong> the north, <strong>to</strong>wards the wall (fig.<br />
1). In the tents and (4) on a control bench<br />
without any screen the follow<strong>in</strong>g climate<br />
parameters were measured; global radiation,<br />
pho<strong>to</strong>synthetic active radiation (PAR),<br />
air temperature and leaf temperature by<br />
four thermocouples <strong>in</strong>serted <strong>in</strong><strong>to</strong> the leaves.<br />
The leaf temperature was measured<br />
on Chrysanthemum, pot roses, Begonias<br />
and Kalanchoë.<br />
Data <strong>from</strong> June show that the three<br />
permanent screens decrease the global<br />
radiation by 33–36 %, i.e. they all have<br />
comparable filtration <strong>in</strong> the spectral range<br />
of 400–1100 nm. In the PAR region screen<br />
1 and 3 removes 27–30 % of the light<br />
while the NIR screen (2) only removes<br />
19 % of the light thus potentially <strong>in</strong>creas<strong>in</strong>g<br />
the rate of pho<strong>to</strong>synthesis <strong>in</strong> the<br />
crop compared <strong>to</strong> the other screens. The<br />
screens decreased the mean air temperature<br />
<strong>in</strong> the range 0.3–0.9 °C while the<br />
mean leaf temperature of Chrysanthemum<br />
only varied with +/- 0.3 °C i.e. the effects<br />
of the different screens on the two mean<br />
temperature parameters were limited. It<br />
should be kept <strong>in</strong> m<strong>in</strong>d, though, that the<br />
screens were permanently on and not<br />
ventilated more that what the screen material<br />
itself allowed. However, when look<strong>in</strong>g<br />
at the daily temperature course several<br />
<strong>in</strong>terest<strong>in</strong>g patterns are revealed where<br />
the screens can decrease the leaf temperature<br />
with up <strong>to</strong> 5 °C, compared <strong>to</strong> the<br />
control, and these differences and the<br />
effect of the various screen materials will<br />
be shown and discussed.<br />
<br />
Fig. 1. The experimental setup <strong>in</strong> a greenhouse at University of <strong>Copenhagen</strong>, Tåstrup. From left are screen (1) a traditional<br />
ventilated screen with one alum<strong>in</strong>ium strip, on clear transparent strip and two open strips, (2) a dense pro<strong>to</strong>type of NIR<br />
screen, with clear strips that transmits less near <strong>in</strong>fra-red radiation than the traditional transparent strips does, (3) a dense<br />
diffus<strong>in</strong>g screen with one white and two diffus<strong>in</strong>g transparent strips and (4) a control bench <strong>to</strong> the east without any screen.<br />
ENERGY IN FOCUS 51
<strong>Energy</strong> Saver Curta<strong>in</strong><br />
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