Oil that fries your food in a restaurant could be what powers your car's engine

The use of biodiesel has increased "greatly" over the past five years, dropping off, though, over the past year and a half due to the cost of the plant oil, said Dennis Miller, a professor of chemical engineering at Michigan State University.

Unlike Santa Cruz's fuel, most biodiesel comes from soybeans, canola and other sources, all of which have increased dramatically in price because of increased demand and speculation on demand, he said.

Locally, there is a "small but passionate group of individuals" running their vehicles on biodiesel, said Maggie Striz Calnin, program coordinator of Greater Lansing Area Clean Cities, a nonprofit coalition of local governments and businesses.

"For one, they see the connection between the environment and public health and alternative fuels," she said. "They're also starting to see the benefit of using domestically produced fuel rather than imported fuel, because our lives are so interconnected with transportation."

Santa Cruz estimates that to fill the 25-gallon tank of his 2004 Dodge Sprinter van with regular diesel fuel, it would cost $125.

But by using 50 percent biodiesel in the van's tank, he's only paying half the price, saving him anywhere from $300 to $400 a month on fuel costs.

"I'm a green-feeling person," Santa Cruz said. "I take this with sincerity: We're in a real crisis, and I think we need to look at alternative means." Got grease?

Biodiesel isn't the only alternative that's attracting interest.

Sales have increased for Greasecar Vegetable Fuel Systems, which bills itself as the nation's largest retailer and manufacturer of vegetable oil kits, said Justin Carven, founder and owner of the company based out of Easthampton, Mass.

The fuel system allows diesel vehicles retrofitted with conversion kits to run on straight vegetable oil, or grease, often obtained from restaurants for free.

Carven said slightly more than 5,000 kits have been sold in the last eight years, most of which were sold in the last two years.

As fuel prices climb, he said, so has interest in the system.

"There's not too many places for people to turn, and this is a relatively straightforward and affordable way to go," Carven said.

In 2007, he said, Greasecar sold just fewer than 1,000 kits. Carven expects 2,000 kits to be sold by the end of this year.