Costs of bioethanol production from winter cereals: the effect of growing conditions and crop production intensity levels

Costings of bioethanol production are estimated based on biennial field trials conducted at two locations in southwest Germany. Winter cereals (rye cultivar ‘Farino’, triticale cv. ‘Modus’, wheat cv. ‘Batis’) were grown under different crop production conditions and intensity levels with emphasis on reinforcing grain carbohydrate rather than grain protein accumulation in order to improve bioethanol conversion. For both cost saving and minimizing the energy input, previous legume crops (pea, grass-clover) and/or grain stillage substituted for mineral fertilizer nitrogen. Stillage is a liquid residue from bioethanol processing containing nitrogen in organic form. Along with the costs of cultivation and conversion, the total costs per hectare and the costs per liter of ethanol produced were considered. Calculations were cut off at the factory gate of the conversion plant. As crop production intensity increased, total costs per hectare rose. However, when the intensification improved grain yield, the costs per liter of bioethanol produced fell because the increase in bioethanol yield per hectare outweighed the extra costs in intensifying crop husbandry. Comparing the species investigated, triticale crops were most economical in terms of costs per liter of bioethanol produced due to the highest bioethanol yields per hectare. The lowest costs per liter of bioethanol produced (0.70 DM at least) were determined with crops grown after a previous pea crop. In contrast, stillage manuring was the most expensive procedure (1.27 DM per liter in maximum) to provide bioethanol. Our results indicate that appropriate bioethanol grain production is a substantial source of cost savings in bioethanol production. This could give some impetus to a competitive fuel-ethanol production in the years ahead.