Second-generation biodiesels

As traditional fuels become more expensive and scarce, the biofuels industry is scrambling to develop more sustainable sources from nonfood agriculture.

Governments and consumers are increasingly pinning their hopes for reduced dependence on foreign oil, improved stability of fuel supply, and reduced environmental impact on biofuels such as biodiesel. Biodiesel is particularly attractive, because unlike ethanol, biodiesel production clearly produces much more fuel than it consumes.

The fuel returns 3.2 units of energy for each unit of fossil fuel consumed in its production and distribution, according to the U.S. National Renewable Energy Laboratory (NREL), while petroleum-based diesel consumes 1.2 units of energy for each unit produced. Tailpipe emissions-not considering the effects of aftertreatment systems-are much lower for biodiesel, with a 68% reduction in particulate matter and a 46% reduction of carbon dioxide. Sulfur dioxide is eliminated entirely because there is no sulfure present in biodiesel, NREL reports.