When Sam Bryant fills up the gas cans that fuel his diesel truck, he can’t help but think of doughnuts and french fries.

Bryant doesn’t gas up the usual way. A fuel entrepreneur and chemistry hobbiest, he is Whidbey Island’s only distributor of biodiesel.

In the garage of his rural Oak Harbor home, Bryant has been converting restaurant grease into a diesel-like automotive fuel since last fall, and has been using that fuel to run the diesel truck he drives for his day job at a Port Townsend paper mill.

After finding a recipe on the Internet last Thanksgiving for converting grease from deep-fat fryers into fuel, he immediately started driving around Oak Harbor to collect as much grease as restaurateurs would give him.

Processed with a mixture of methanol and Red Devil Lye, the resulting biodiesel looks, feels and smells much like vegetable oil — because that is, essentially, what it is.

Technically referred to as methyl esthers, biodiesel is one of three products made during processing. Separated out of the mixture are glycerine and fatty acids, components that cause grease to solidify. Once these are removed from biodiesel, the fuel flows as a liquid in temperatures as low as 10 degrees Fahrenheit.

Despite its resemblance to the bottle of Wesson oil in his kitchen, the first batch of biodiesel to come out of Bryant’s garage immediately went into his truck’s fuel tank. He wasn’t worried.

“Diesel engines burn anything,” Bryant said.

A few weeks of test runs convinced him biodiesel was as good in the tank as regular diesel and far better out. Little spills in his garage — which were par for the course since he transports the fuel to Port Townsend in 20-gallon jugs — have never been a problem, except for the day his wife was inexorably and repeatedly drawn to the garage by the smell of doughnuts.

Having fuel that smells like food could be a mixed blessing, Bryant said, especially at rush hour.

“It makes my exhaust smell like french fries,” he said, noting that the smell could send drivers to the nearest fast-food restaurant.

Bryant had enough success in his early trials to convince him to start marketing biodiesel fuel. After all, the raw material — the grease — was free. Restaurateurs were happy to give the grease away, since they normally have to pay a fee to dispose of it.

Even so, the numbers did not work out profitably. Though by this spring Bryant was processing batches of 100 liters at a time and was getting some commercial interest from potential customers in Oak Harbor, Port Townsend and South Whidbey, the $1.85 a gallon he had to charge barely covered his business liability insurance and processing costs.

“Obviously, operating out of a garage is difficult,” he said.

But he did not want to give up. Listing biodiesel’s advantages — low carbon emissions, biodegradability and low toxicity — Bryant is a true believer in the fuel. To stay in the business and promote the fuel on and around Whidbey Island, he became a dealer for large-scale biodiesel producer World Energy under the business name Sound Oil.

He is not waiting for customers to come to him. In July, Bryant made a pitch for the fuel to the Port Townsend Chamber of Commerce, proposing that the city’s fleet of transit buses start using a mix of diesel and biodiesel fuel.

He is also looking for a place to install the equivalent of a biodiesel gas pump, to make filling up convenient. Currently, island biodiesel users must order jugs of the fuel from Bryant and wait for them to be delivered either by him or through Federal Express.

Though he doesn’t see himself getting rich or even making a living off biodiesel sales, Bryant recently purchased a fuel truck for transporting large amounts of biodiesel to a future biodiesel “gas station.” He said he will stay in the business as long as he can generate interest in the fuel.

“It’s not for everybody right now,” he said.

But he hopes more drivers are willing to try the fuel, especially now as small, efficient compact diesel cars like the Volkswagen Golf TDI are becoming popular with the mileage-conscious. The fuel, he said, should work just as well in these high-tech vehicles as it does in an old pickup truck.

Like any other commodity or product, biodiesel’s future will be decided by consumers.

“It’s going to be voted on by the public,” Bryant said. “I believe in it.”