Biodiesel is safer for the environment because it produces lower emissions and is made from renewable sources, say supporters. But the snag for morally motivated vegetarians is that those renewable sources can include cows, pigs, and chickens.
Biodiesel is an alternative to petroleum diesel and can be used to power cars, trucks, and buses. It is usually made from soy bean oil but can also be made from beef tallow, pork lard, and chicken grease. According to Render Magazine, animal fats may be a cheaper and better raw material than soy bean oil.
So not only will morally squeamish green consumers worry about whether the soy product in their tank is genetically modified, but they will also worry about whether they have contributed to the suffering of animals.
David G. B. Boocock, professor of chemical engineering at the University of Toronto, has suggested making biodiesel from ‘mad cows.’ According to Boocock, the spread of Bovine Spongiform Encephalopathy (BSE, or mad cow disease) has left many countries with cow carcasses they are unable to use. Render Magazine is already assuring the public that "The possibility that humans could develop vCJD from the use of biodiesel is extremely small"