In 2004, the United States consumed 140 billion gallons of gasoline and 40 billion gallons of diesel for on-road transportation (Annual Energy Outlook, 2007; http://www.eia.doe.gov/oifa/aeo/). In an effort to reduce dependence on petroleum-based fuel products and reduce their negative impact on the environment (Hill et al., 2006), production of biofuels from renewable energy sources has experie...