26.07.2013 Views

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

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

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

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!