Möjligheter att använda halmeldning till energiförsörjningen i Mälardalen
The purpose of this project is to find out where straw can be used as a fuel and, in those cases where straw is not a suitable energy source, to find out the reason. The reasons could be lack of straw, that the town already is tied to some other fuel, or even lack of interest or negative attitudes from the town politicians and official employees. Most towns and larger villages in the counties of Stockholm, Uppsala, Södermanland and Västmanland have been studied. The problems and possibilities concerning straw as a fuel has been mentioned and three different large scale straw combustion systems have been presented: Nordfab’s straw feeding with pusher, the Vølund "cigar"-method and The Johnson biocombustor, which in Sweden is marketed by Studsvik Energy. All of these three methods use baled straw; pellets and wafers are so much more expensive, they will have great difficulties competing with other fuels. The prerequisities for profitable straw combustion have been brought up, but no calculations occur in this document. The project was carried through as follows: Town officials and farmers were contacted and the municipal energy plans were read. The available amounts of straw were calculated from statistics over the use of arable area. 20 km was used as the maximum transport distance and an average straw harvest of 500 kg/ha was estimated. Only straw of wheat, rye, barley and oil plants has been considered usable for energy. In some towns/villages, where the prerequisities for using straw as a fuel seemed good, a meeting was arranged, at which straw burning was discussed with a group of farmers. The conclusion from this work is that straw could be used as a fuel much more in the area. The straw supply is in most cases good and the farmers are in common very interested in delivering straw for energy. The reason why so few straw fired district heating plants exist today probably mainly depend on the fact that well functioning reference plants are missing in the area and that the Swedish energy policies have mistreated bio energy and let the prices of oil, coal and electricity go down, in spite of the environmental consequences. We can here compare with Denmark, who let the prices of fossil fuels and electricity stay high, where today straw burning is usual. Another fact that today stops straw fired district heating plants from being built is that the large towns already are tied up by other cheap fuels as coal, waste heat, or combustion of refuse. The smaller places have no distribution nets for hot water and it is today not considered economical to build new ones, specially as the towns/ villages often are very sparsely built. Among both types of towns/villages there are some who think of natural gas as the only fuel for the future. Many towns have negative attitudes against combustion of straw, mainly due to technical problems with early prototype plants. Of the 53 studied towns and villages 10 could start burning straw immediately and further 21 had straw supplies enough to make combustion of straw an interesting energy alternative for the future.
straw; byproducts; energy sources; energy generation; fuel crops; solid fuels; combustion; heating
Rapport - Sveriges lantbruksuniversitet, Institutionen för lantbruksteknik
Publisher: Institutionen för lantbruksteknik, Sveriges lantbruksuniversitet
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