Energy balances of biodiesel production from soybean and canola in Canada

Biodiesel is currently produced in Canada mostly from recycled oils and animal fats. If biodiesel is to supply 5% of diesel usage, a government objective, first-time vegetable, likely from canola and soybean, oil will also be required to provide adequate feedstocks. In this review, we estimate the life cycle energy balances for biodiesel produced from soybean and canola oil under Canadian conditions. The three broad areas of energy inputs were crop production, oil extraction, and transesterification of the vegetable oil into biodiesel. Per unit seed yield, farm production energy inputs for canola were about three times higher than for soybean, mostly because of higher nitrogen fertilizer requirements for canola. Energy required for processing and oil extraction, per unit oil, was higher for soybean. Energy allocation for co-products was allocated using a system expansion approach. Protein meal was assigned about 12% of the energy expended for canola to grow the crop and extract the oil, and about 37% for soybean. Glycerine produced during the transesterification process was allocated energy on a weight basis (11.4%). The ratio of biodiesel energy produced per energy input ranged from 2.08 to 2.41. The energy ratio was similar for soybean and canola; soybean required less energy inputs, but also produced less oil than canola, for a given weight of seed.