Testing started in 2002 at the university, which has successfully run its steam plant on chicken fat, fryer grease, white pork fat, and beef tallow, he said.
Compared with fossil fuel, "environmentally it's much better to use the fat or plant oil because it's nontoxic," Adams said. "You can eat or drink this stuff."
While it's not quite time for big oil to panic, market volatility and price - grease can cost about half as much as heating oil - are stimulating the field.
Philadelphia Fry-o-Diesel, a spin-off of the nonprofit Energy Cooperative, is using a $369,696 state grant to determine whether it can harvest trap grease, the gunk poured down the city's restaurant sinks.
"It's a mess. There's really no good use for it right now," Fry-o-Diesel chief Nadia Adawi said.
Shipments for testing come in 2,000-gallon trucks, Adawi said. She hopes the project, which will involve small-scale production, shows that even the least desirable waste oil can become an economical heating source. Soybeans - now added to home heating oil to create so-called bioheat - might be the fuel produced on farms while restaurant waste, she said, could be the urban answer.
"Our crop here in Philadelphia is restaurant grease," Adawi said.
Trap grease or yellow grease, the stuff that turns potatoes into french fries, could become more commonly used if prices for heating oil and natural gas remain high, she said.
Barring a hitch, New Jersey's Department of Environmental Protection is within a couple of weeks of approving its first application to burn yellow grease for heat.
Darling International is seeking permission to use the waste it hauls from restaurants to fuel boilers at the Cardolite Corp.'s plant in Newark, N.J. Cardolite makes cashew-shell-based products for such applications as brake linings and printing.
"There is interest in using these products for fuel," said Ross Hamilton, Darling's government affairs director.
