Biodiesel

Biodiesel is either a derivative of triglycerides resulting in a fatty acid methyl ester (FAME) or the result of thermochemical conversion of biomass. The feedstock for FAME biodiesel is typically soybean oil in the USA or rapeseed/canola in Europe or Canada, although waste grease and fat from food operations can serve as feedstocks. However, the conversion technology to produce the FAME is the very mature, low-cost chemical transesterification process, which permits little opportunity for alternative processes such as enzymatic esterification. The process entails blending a triglyceride with an alcohol, usually methanol, in molar excess with an alkaline catalyst such as methoxide that caused the methanol to replace glycerol ester to the fatty acid yielding free glycerol and a FAME. The most significant opportunity for process and product improvement lies in the selection of alternative crop species beyond soybeans, and canola fills this niche to some extent. However, the prime driver for alternative crop species is both high yield of oil per acre and an optimal degree of unsaturation. Soybeans typically yield about 376 lb per acre of oil whereas canola produces about twice that amount per acre.

The degree of unsaturation is important in order to provide a degree of cold tolerance when blended with petroleum diesel at the 20% level, but oxidative instability is caused by the excessive double bond content. Canola is nearly 92% unsaturated but 63% of the fatty acids have only one double bond compared with 84% and 25% for soybean oil, respectively. Ideal plant species, such as an improved canola that has higher productivity and is able to be grown at in warmer mid-latitudes, should be the subject of plant breeding and bioengineering. Recent
production expansion aims at producing 1.8 billion US gallons, but only 0.33 billion gallons are in production at present. Unfortunately, the current cost of soybean oil has risen from $0.31 to $0.55 per pound, causing plants to reconsider operation.Germany, the largest producer of biodiesel, is facing market problems for very different reasons as of January 2008 due to large Federal tax increases, and this threatens the otherwise huge production from canola/rapeseed.