Some people say Tara Sieg’s vintage Volkswagen Rabbit diesel smells more like french fries or tacos as it motors by, but she doesn’t mind a bit.

The 30-something environmental scientist and self-described “hippie” is proud of doing her part to reduce greenhouse gases by running the 1981 compact on biodiesel fuel she makes herself on her farm south of St. Marys from recycled cooking oil she gets for free from a Mexican restaurant and a french fry wagon.

With fuel prices for gas and diesel around a buck a litre and predicted to climb higher, many motorists would be green with envy that it costs her about 30 cents a litre for the homemade fuel. But she insisted economics isn’t her motivation.

“My reason for doing it was environmental, really,” she said at CARE Stratford’s third annual Symposium on the Environment at Northwestern Secondary School Saturday.

She demonstrated how to make the alternative fuel using a glass jar and two-litre pop bottle to mix together the used cooking oil, methane and lye.

Biodiesel is the name of a clean-burning alternative fuel made from renewable resources, often vegetable oil. It contains no petroleum but can be blended with petroleum diesel to create a biodiesel blend. Biodiesel is biodegradable and non-toxic.

Stratford is currently experimenting with running some of its public transit buses on biodiesel. It’s a trend across North America and Europe as municipalities look for ways to save money and cut down on smog.

Biodiesel, which burns about 90 per cent cleaner than gasoline or traditional diesel, starts out looking like thick orange juice and ends up looking like ice tea when it’s done.

On her farm, Ms. Sieg mixes the fuel in bigger batches outdoors using an old water heater scavenged from a landfill.

She attracted a small but curious crowd with the demonstration.

“If you put 100 per cent of that stuff in, would your car still go?” asked one man.

“A lot of people run 100 per cent,” she replied.

At the moment, she uses between 20 and 50 per cent biodiesel mixed with regular diesel bought at the pumps. Her goal is to run 100 per cent biodiesel.

To do that, she will need to replace the rubber fuel lines in her car with metal lines because biodiesel degrades the rubber over time, she explained.

It’s one of the few minor drawbacks to biodiesel, although most late model cars don’t use rubber fuel lines any more.

Another is biodiesel’s higher gel point, which makes it harder to use in winter when the temperature is colder.

People can get around the problem by installing a block heater and fuel filter warmer, she said.

Besides the smell of french fries or tacos, the licence plate on the mint Rabbit is a giveaway the driver is someone willing to seek out new frontiers and boldly go where most people don’t. The Star Trek fan’s plates carry the Federation symbol from the groundbreaking science-fiction TV series and movies.

“I really believe in the whole idea of using technology to make life better without a big cost,” she said.

The VW enthusiast recalled reading an article a decade ago about a high school student who was running his Volkswagen on vegetable oil. “It sort of led me to research that alternative fuel idea.”

Ms. Sieg has a master’s degree in environmental science and said she is considering doing a PhD in alternative fuels.

For instructions on how to make biodiesel, see www.biodieselcommunity.org.