Põllumajandusministeeriumi ja Maaelu ... - bioenergybaltic

When growing biomass on large areas, a grass harvesting conveyer should be formed
with the species of the different speed of development. When calculating the area of sowing,
we should proceed from the time of harvesting of a single species field which must not be
longer than five days. The amount of biogas received from biomass digestion is closely
connected with the phase of development of the herbage plants and it decreases when the
herbage ages and this is why late mowing decreases the productivity of biogas. The list of
recommended species in the order of the speed of development in spring, starting from the
quickest one, is the following: cocksfoot grass, reed canary grass, smooth bromegrass, tall
fescue, timothy. In making the conveyer we should bear in mind that the speed of
development of reed canary grass, brome grass and tall fescue is rather similar and this is why
the difference in the optimal harvesting time is only a couple of times.
Field Crops Production of bioenergy from field crops
Corn (Zea mays L. ssp.) is the most widely spread culture for producing biogas in
Europe. From corn a big amount of biomass is received per hectar and it is ensilaged well.
Most evidently corn is one of the best cultures of biogas for us.
Potato (Solanum tuberosum) as a culture rich in starch can be used both for producing
bioethanol and biogas. In Estonian conditions the area of growing potatoes is decreasing each
year and in 2007 it was only 10,200 ha. This is why to grow potatoes for producing ethanol is
not reasonable. Potato growing is connected with a rather big use of energy and because of
that energy output is modest 0.8 – 1.6. When it is decided to produce bioethanol from potatoes
the high yield and rich in starch cultivars, or specially bred industrial GMO cultivars, must be
selected for growing in local conditions. In Estonia, there is no starch production resulting in
big amounts of wastes. Growing potatoes as an energy culture, all the agrotechnological
methods should be applied- correct soil tilling, fertilization with both organic and mineral
fertilizers, early planting, timely plant protection, even watering. When using all these
requirements, it is possible to receive big yields of tubers rich in starch.
Sugar beet (Beta vulgaris saccharifera) is an important energy culture both globally
and in the whole of Europe. In Estonian conditions growing sugar beet is minimal, connected
with a big energy and human labour need. This is why the Estonian list of cultivars does not
contain a single cultivar. For growing sugar beet as an energy culture, such cultivars which are
grown by our close neighbours Latvia and Lithuania should be recommended. Annually sugar
beet gives 240 GJ/ha of energy, out of which 45% or 108 GJ/ha can be made into ethanol. The
energy potential of the local sugar beet in producing ethanol is on average 58 t/ha of beets, the
yield of ethanol 93 l/t and 5400 l/ha and the amount of energy 115.0 GJ/ha. Up to 90% sugars
of the beet can fermented into ethanol. From the tops of the beet and the side product of
ethanol production it is possible to produce valuable biogas. One kilogramme of dry matter
may give 230-400 l of biogas. In energy beet N, Na and K are important influencing sugar
extraction.
Rape (Brassica napus) and biennial turnip rape (Brassica rapa oleifera) are also the
major field crops in Estonia which can be used for producing high quality biodiesel fuel. From
the point of view of energy management, the production of biodiesel fuel from rape seeds is
useful. When taking into consideration all the energy costs connected with production, it is
possible to produce 1.3-1.6 times more energy from a hectare. The production can be used
both as food and a source of energy. By 2007, the area of growing rape and biennial turnip
rape is already 72,500 hectares. Later there may be problems with the fields of growing
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