| Energy self-reliance and a closed nutrient cycle are basic principles of organic farming ever since. Engineering sciences methods in energy accounting may support efforts to introduce these principles into praxis. A method to calculate efficiency of energy crop production including sun energy, direct and indirect energy for cultivation, processing, and conversion into fuel is demonstrated using rape and derived fuels as an example. Every production and conversion step is a process and calculated separately. The overall efficiency includes energy input and output of all processes. The process effi-ciency of rape cultivation reaches in Finland up to 1100%. However, the overall en-ergy efficiency of rape methyl ester (RME) is 1 to 2 ‰ only. The production of... |
