Biodiesel: Cruising On The Fat Of The Land

Four Carleton women trek cross-country in a Chevy Suburban powered by waste frying fat

And, awaaaay we go!

The summer of 2001 saw four Carleton women do what no Carleton student had done before: make a long-distance road trip in a standard American automotive machine without using any petroluem fuel. We'll tell you all about it, but first...

Permit us to introduce ourselves...

We are Emily Fischer, Maria Davidsmeier,
Anna Moseley and Melissa Keevil, all class of 2003.

The Inspiration

The catalyst for the project was an environmental conference at Gustavus Adolphus College in Minnesota that Melissa and Anna attended during their freshman year. One of the presenters talked about a "Veggie Van," a car that ran on biodiesel fuel made from vegetable oil, and Melissa says she knew right away that they would find a way to do it themselves.

"The goal was to see if it was possible to run a car on used vegetable oil," says Melissa. "The test was to go on the road trip and have some fun." They built the processor and took the 25-day road trip, creating their own fuel along the way, without a background in chemistry or engineering, and funded only by their earnings from summer jobs. All the grant applications were rejected on the grounds that the project was not feasible. But Carleton students are not defeated THAT easily by a bunch of desk-bound suits!

Biodiesel, a renewable, cleaner burning alternative to traditional diesel fuel, isn't a new concept. It is manufactured and sold commercially in numerous places around the United States, but usually blended with traditional diesel fuel. It is usually produced on an industrial scale, not in personal-size batches.

To save money, the four women moved into a single studio apartment in Northfield the year before the trip, and they opened a group checking account in which they pooled the money they earned from summer jobs.

It seemed straightforward enough, but limited information - much of it unreliable - made the endeavor more difficult than they had imagined it would be. As they pieced together information from a few web sites and a book about a similar project, they sought out people in Northfield and southern Minnesota who had expertise in car mechanics and welding.

"We ran into a lot of technical problems that made each of us feel like we couldn't do it, but we kept calling up people in Northfield, saying, 'We have this problem. Will you help us?'" Emily recalls. "Sometimes they would say, 'You can't do that, you'll electrocute yourselves!' But some people said, 'Wow! What a great idea!'"

The Equipment

The processor, carried on a trailer behind Emily's '87 Chevy "Bioburban," was a 55-gallon drum with a drill mounted inside to mix the oil and chemicals. A heating element in the processor heated the filtered vegetable oil and sodium methoxide to start the reaction. The equipment also included an industrial size drill for stirring the mixture, a bunch of buckets and cans, and a pump for moving the fuel from the processor to the Bioburban's fuel tank.

By mid-July 2001, the processor and trailer were completed and they headed out for the monthlong road trip from Minnesota to Vermont through southern Ontario, Canada.

Anna shows off the fuel conversion apparatus, the heart of
the biodiesel equipment.

The Process Of Making The Fuel

(The guts of the story)

Creating diesel fuel from used vegetable fat is a multi-step alchemy. When we needed to refuel the Bioburban on our trip from Northfield, Minnesota to Vermont (through Canada), we cruised highway retail strips looking for restaurants with waste oil bins out behind. When we found one and had secured permission to take some of their waste oil, we carried the oil to a campground where we would process it and spend the night.

The art of recognizing quality used oil is a stomach strengthening skill. The oil, found in dumpster-like bins behind restaurants, is gross, and we had to filter it through our high-tech cheese cloth and embroidery hoop filter to remove the chicken and french-fry bits.

A small test batch of biodiesel must be made with each collection of oil. The pH varies between oils and a titration is done to calculate how much catalyst is needed.

lye + methanol produces sodium methoxide

sodium methoxide + vegetable oil
(when heated and stirred for several hours)
produces biodiesel + glycerin

The glycerin (which is heavier than the biodiesel fuel) is decanted from the processor through the valve at the bottom. Some of this stuff is hazardous so appropriate gear is a wise choice.

Every batch of used frying oil is different so we had to make test batches of biodiesel to figure out the recipe for the final product. Other campers in the campgrounds were often mystified by what we were doing.

The contrast between lye and flower gardens is riveting.

Continue on to page 2 of the Bioburban saga!

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