Pleasant Ridge residents David and Joleen Gardner consider themselves on the "bleeding edge" of environmental activism, but perhaps "frying edge" is more accurate.

The family got sizzling mad over the price of fuel about this time last year and took drastic steps, converting a diesel Jetta car to run on cooking oil.

They are among only 15 families in Ohio and six in Kentucky who have made the switch to the readily available alternative fuel source.

For the Gardners, it was as easy as buying a new fuel injector system and a tank to hold the cooking oil fuel and finding a regular supply of cooking oil.

"We do what we can afford and what makes sense for us," said Gardner.

Joleen Gardner drives a 2005 Prius, a gasoline/electric hybrid that gets about 52 miles per gallon of gasoline because it runs at times on a battery and electric motor.

David Gardner's 2001 Volkswagen Jetta gets 48 miles a gallon on diesel - or when it runs on the used fryer oil that Gardner collects for free from the cafeteria at Midland Co. in Amelia, where he works as a computer programmer.

Gardner says he was motivated to make the change when the price of unleaded gasoline hit $2 a gallon last year and he decided it was time his family reduce its dependence on foreign oil.

"We believe in pocketbook activism," said Gardner.

He paid $840 for a kit from www.greasecar.com that will reconfigure a diesel-powered car's fuel system so it can burn vegetable oil. Soon Gardner was his own mechanic and, later, his own petroleum transfer technician.

"I spent four very meticulous weekends converting the car," he says. "I was doing it very, very carefully."

"I thought David was rather ambitious to do himself," adds his wife. "I'm just so impressed that he was able to take apart this car and put it back together again."

And it worked.

Since late last summer, about three times a month, Gardner picks up a 5-gallon bucket full of oil from the Midland cafeteria and takes it home, where he pours it into a cooler in the garage attic (although these days he is using a neighbor's garage because strong winds blew a tree into the Gardner garage and wrecked the rafters). From the cooler the oil drips through a filter that removes food bits and other debris.

Flipping a switch

After drip-filtering the oil, Gardner pours it into a tank in his car's trunk that was built into the space that formerly held a spare tire.

When Gardner flips a switch on his dash - after the engine has warmed up the cooking oil through yet another device - the car can run. It works in winter, too, because a warmer prevents the cooking oil from congealing.

Gardner figures the system will pay for itself in about three years. He usually drives about 250 miles a week on the cooking oil and could go farther but hasn't had the time or inclination to locate another source of oil.

He figures he saves about $15 to $20 a week when compared to a car that runs on unleaded gas.

"As far as I'm concerned, when I'm burning vegetable oil, it's all good," he said. Nitrous oxide emissions from cooking oil is equal to diesel, but cooking oil exhaust has 26 percent less carbon monoxide and 40 percent fewer particulate materials than diesel.

Cincinnati safety officials say there are no laws prohibiting the filtering of cooking oil, although they stopped short of endorsing Gardner's method.

"It seems like it's a safe situation, but we've not seen it so I can't make a judgment call on it," said Fredrick Prather, Cincinnati district fire chief.

Fuel from a fryer

A 1985 Roger Bacon High School graduate and 1989 Miami University graduate with a degree in systems analysis, Gardner has long had an interest in environmental living.

After graduating from Miami, he rode his bicycle through Europe and then along the West Coast of the United States.

"Being overseas, you can really compare how much of a consumer society we have become," he said. "We use energy at a rate that the rest of the world just can't fathom. But if you look around here, it seems normal because everybody is doing it."

Usually restaurants with fryers contract with a service to pick up their used cooking oil, said Lee Briante, customer support specialist at Grease Car, an Easthampton, Mass., firm that sold Gardner the technology to convert the diesel car into a cooking oil burner.

Two years ago, the company sold about 10 units a month. Today the firm sells 100 a month - and Briante fields about 30 telephone calls an hour. Finding cooking oil is usually not a challenge.

"Most restaurants pay more to have it picked up than they do to have it delivered fresh," Briante said, although that's not how it works at Camp Washington Chili, for instance. Owner John Johnson says a service comes at least once a week to remove the used oil for free.

Johnson said staff at his restaurant replace the fryer oil twice a week. That's 52 pounds of oil, or about 7 gallons a week. So far no one has approached him about using the old cooking oil for a car or truck, but Johnson wouldn't be surprised if it happens soon.

"Right now, with the way fuel price keep going up, any energy use for the old cooking oil would be good," Johnson said.

Griffin Industries, based in Cold Spring, collects fats and oils, purifies it and converts into biodiesel, similar to but not the same as straight vegetable oil, so it can be sold to fuel distributors. Those companies then blend it with regular diesel fuel to sell to industrial users, including truck fleets and school bus systems.

"The industry is growing very rapidly in this country, but it's still in its infancy," said Jim Conway, vice president of sales and marketing at Griffin Industries. "But it's a very viable option in the U.S. to replace foreign oil."

Burning used cooking oil in a car does have at least one other benefit, Gardner said.

"When I'm on the vegetable oil, you have nice-smelling exhaust," he said. "It smells like french fries."