On average, fast-food restaurants in any major U.S. city generate about 22 pounds of waste grease each year per city resident, according to a 1998 study by the National Renewable Energy Laboratory (NREL). The National Biodiesel Board, a trade group in Jefferson City, Missouri, estimates that more than 2.5 billion pounds of waste cooking grease are available annually—enough to make 100 million gallons of biodiesel.
Of course, America's appetite for petroleum is huge: 2004 consumption was nearly 315 billion gallons, including 139 billion in gasoline and 41 billion diesel. Robert McCormick, a fuels engineer at NREL, says that biodiesel could displace 5 percent of the petrodiesel used in the United States within ten years. To replace more will require growing vegetable crops specifically for fuel—and America's soybean farmers are standing by. Some proponents envision growing aquatic algae—richer in oil than any other plant—in pools next to electric power stations. In an ecological two-for-one, the smokestack carbon dioxide would feed the algae, which would churn out biodiesel.
Grass-roots fans aren't waiting. Kantor, who paid $1,400 to outfit her VW diesel with a second fuel tank, says she gets nearly 200 miles per petrodiesel gallon. "This is not about money," says Kantor, who speaks at schools about protecting the environment. "I'm doing this to set an example."