Photos: Revving up on fast food

The Big Green Bus from Dartmouth College runs on vegetable oil from deep fat fryers.

The engine of the Big Green Bus. To run on vegetable oil, the oil first has to be heated to 150 degrees Fahrenheit.

Nascar has corporate sponsors, so why not a vegetable oil-burning bus? Lonely Planet is another sponsor.

The engine first runs on standard diesel until the vegetable oil comes to temperature. This is the control panel that shuts off the diesel and monitors other vital signs.

The back of the bus serves as a dorm. People also sleep outside.

The requisite college reading material. The bus has a flat-screen TV too.

Visitors tour the inside of the bus.

Paul Renpen of Sacramento has converted his Mercedes diesel to run on vegetable oil. "I don't pay anything for it," he said.