During the biodiesel production
process, oils/fats (triglycerides) are mixed with methyl alcohol
and alkaline catalysts to produce esters of free fatty acids, with
glycerol as a primary by-product. In general, production of
100 kg of biodiesel yields approximately 10 kg of glycerol
(National Renewable Energy Laboratory, http://www.eere.
energy.gov/afdc/progs/vwbs2.cgi?9626), which is impure and
of low economic value.