Energy analysis of reed canary grass for solid fuel and ley for biogas

摘要

Considering the large interest there is in Sweden for alternative use of land set aside and the production of renewable fuels this study was carried out to evaluate the suitability of reed canary grass (Phalaris arundinacea) and a ley of red clover (Trifolium pratense) and timothy grass (Phleum pratense) as energy crops. The typical production systems for each crop was established, a set of assumptions were also agreed upon and all inputs and outputs were identified, quantified and expressed in MJ/ha. Reed canary grass was to last ten years and the harvest is done in the spring. A four year rotation was established for the ley with barley as a nurse crop in the first year. As outputs of the ley system the following were considered: barley grain, barley straw, biogas and nitrogen in the digesters residues which are assumed spread on the field. As parameters of efficiency Net Energy Gain (N.E.G) and the output/input ratio were calculated. The main results showed a N.E.G of 56417 MJ/ha and year and an output/input ratio of 7.4 for the reed canary grass; biogas production from the ley gave a N.E.G of 53000 MJ/ha and year and an output/input ratio of 2.9.