Another renewable fuel is biodiesel, a fuel made from vegetable oil that can be used to power diesel engines. According to statistics published by the U.S. Department of Energy’s National Renewable Energy Laboratory, the United States has the capacity to produce about 900 million gallons of biodiesel a year. That’s enough to supplant less than 1% of the gasoline used in the country.

Straight vegetable oil can also burn in diesel engines. But any car, truck or SUV must have a diesel engine before it can be converted to burn vegetable oil. A diesel car would need a separate fuel tank for the oil and a preheating system to keep it from congealing, cost to do so ranges from $800 to several thousand dollars, plus installation.

Still, some retailers have incorporated biodiesel where it makes sense.

“Kum & Go was an early adopter of higher biofuels blends,” said Ken Kleemeier, vice president of fuels at Kum & Go, Des Moines, Iowa. “In addition to standard fuel grades, we offer E15, E85 and biodiesel blends at many of our locations to ensure our customers have a wide selection of options when fueling.”