Joe Carney, left, a cafeteria employee, and Josh Pasqual, a student, cook french fries with the canola oil that will power the shuttle bus.

The Providence Journal / Frieda Squires

BRISTOL — There’s a lot to like about Roger Williams University’s refurbished shuttle bus. Of course, there’s the fact that it’s an eco-friendly vehicle, retrofitted to use canola oil rather than diesel fuel. But there’s also the odor that wafts from the engine — French fries. Yum.

The explanation for that enticing aroma is ingenious. All the oil that fuels the 16-passenger bus is recycled from the campus’s Dining Commons. That’s right, it comes straight from the fryolator.

Yesterday, members of the university’s Recycling and Sustainability Committee, a group of students and staff, unveiled the converted Ford F-350 at a noon event outside the library, celebrating with what else but French fries and sweet potato fries cooked in oil that will eventually be used to power the bus.

About 150 members of the campus community came out to see the unique vehicle. They also got a chance to see university president Roy J. Nirschel take it on an inaugural spin.

The bus is different from most vehicles that run on alternative fuel. It doesn’t use biodiesel, an increasingly common mixture that’s 80 percent diesel and 20 percent oil. The university’s shuttle runs on 100 percent canola oil.

“To our knowledge, RWU is the only university in Rhode Island — and one of just a handful in the U.S. — to power a passenger vehicle with straight canola oil,” said Scott Yonan, staff co-chair of the Recycling and Sustainability Committee.

Yonan, special assistant and ombudsman to the office of the president, said he and other members of the committee have been working on ideas for an environmentally friendly vehicle for the past two years.

David Smith, a 2006 graduate, came forward with the proposal for a bus that runs on biodiesel, but Yonan said he was more attracted to engines that run entirely on cooking oil.

“I wanted to go straight to vegetable oil,” he said.

So the school got in touch with consultant Mark Howards whose Sharon, Mass., company, AltEnergy Oasis, specializes in engines that run on alternative fuels.

University mechanics were able to do most of the work on the bus themselves with input from Howards. The total cost of the project was about $10,000, but the conversion kit alone was only about $3,000. The rest of the money went to Howards’ fee and to building a special pumping station. Retrofitting other vehicles would be much cheaper.

“The idea was to start with one,” said university spokesman Brian E. Clark. “There is talk of expanding this to other vehicles.”

It makes financial sense. Yonan said that last year, before it was converted, the F-350 traveled 17,000 miles on $6,900 worth of diesel. With the cost of diesel rising, this year, it would have cost $8,000 to fuel the bus.

Instead, it will cost very little. The bus has two tanks, one for canola and one for diesel. Because canola oil is thicker than diesel, it needs to be heated up before it can be used. So when a driver turns the ignition on the converted bus, it initially runs on diesel. When the engine is warm enough, a process which takes about 10 minutes, it switches to oil.

Each evening, when the bus is shut down, it again changes back to diesel as the engine cools down and the canola oil is flushed back into its tank. An onboard engine controls the changes.

Yonan said the bus will likely use only 110 gallons of diesel this year at a cost of a few hundred dollars. But he said that investing in the new engine wasn’t just about economics. It was also about finding a clean source of fuel.

“This vehicle is about as carbon-neutral as you can get,” he said.

The bus is already shuttling students around campus and up to dormitories and the supermarket off Metacom Avenue.

“The aroma of French fries,” said Yonan, “is in the air.”

akuffner@projo.com