Vegetable Oil Fuels Cal Poly Students' VW Rabbit
By Collin Hester
Mustang Daily (California Poly State U.)
05/29/2002

(U-WIRE) SAN LUIS OBISPO, Calif. — Most vehicles on the road today require either gasoline or diesel fuel to provide power. However, there are some that are specially equipped to run on methanol, natural gas or electric power, which many people believe to be safer for the environment. But what would the environmental implications be for vehicles that could be powered by a simple cooking product found in most all kitchens — vegetable oil?

For their senior project, California Polytechnic State University mechanical engineering seniors Obadiah Bartholomy and Jason Fuller successfully converted their diesel 1982 Volkswagen Rabbit to run solely on vegetable oil. Their intent was to address the possibilities of powering vehicles with unconventional fuels in order to improve emissions.

"We wanted to try and show that we can use renewable fuels and that they're cleaner alternatives," Bartholomy said.

The vegetable oil needs to be warmed up to around 160º F before it can be run in the engine or else it's too gummy, Bartholomy said. To achieve this, the car is started and run for several minutes on a tank filled with biodiesel, which is a fuel that contains methanol and vegetable oil.

Meanwhile, plain vegetable oil from another tank in the rear of the car gets heated as it passes through hoses that lead to the engine, Fuller said. The heat is provided by radiator coolant, two heat exchangers and an electric inline heater. Once the vegetable oil is at the right temperature, the driver flips a switch on the dash to allow the vegetable oil to be fed through the engine. From this point on, the car can be run entirely on vegetable oil. But before the car can be shut off for any length of time, the engine must be switched back over to biodiesel.

"(This process) purges the fuel system of all the vegetable oil so there's only biodiesel back in the system," Fuller said. "If you try to start the engine on just cold vegetable oil, you're not going to get it to start."

The students' idea originated from people who have experimented with running diesel vehicles on biodiesel fuel for the purposes of reducing pollution, Bartholomy said.

In fall 2001, Bartholomy and Fuller chose to take this concept one step further by beginning to convert the car to run on straight vegetable oil, a task that has been done by fewer people.

Fuller said that most of the conversion involved replacing rubber fuel hoses with synthetic hoses, adding heat exchangers, electrical relays, switches and a separate fuel tank for the vegetable oil. The total expense of the project was nearly $2,000.

A large portion of their time and money was also spent on building a biodiesel refinery, Fuller said. The refinery is an enclosed trailer that is towed behind the car with all the necessary components to make their own biodiesel fuel.

"It consists of one tank with an electric motor used for mixing methanol and lye and a larger tank used for mixing vegetable oil with the methanol lye," Fuller said.

The students haven't yet done a lot of testing to determine the effects of vegetable oil on the car's engine performance and emission ratings. Bartholomy said that diesel engines typically lose 20 percent of their power when using vegetable oil.

"The only place that we noticed (a loss of power) was getting onto the freeway, where it seemed to be a little bit slower," Bartholomy said, "But we still got up to almost the same speed."

Their eventual goal is to run the car on waste vegetable oil, which could be obtained free from any fast food restaurant, Bartholomy said. Vegetable oil is a renewable fuel that, when burned, doesn't contribute to excessive greenhouses gases like carbon dioxide.

"The fuel is grown, so you're not putting any more carbon dioxide into the atmosphere than what was taken in as the plants were growing and absorbing it," he said.

After all the testing is finished, Bartholomy is looking to publish their research in an alternative energy journal called Home Power.

"(We're) trying to get people to realize that this fuel is out there and consider switching their car over or making a push for more widespread use of biodiesel as a way to improve emissions," he said.

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