If you smell Chinese food on campus, your first thought might be that the Prothro staff is whipping up an Asian food buffet. The culprit, however, might be Shannon Cotulla driving to or from his job at the Virginia Department of Transportation.
Shannon Cotulla at work on his biodiesel.Earlier this semester, Cotulla, husband of Sweet Briar Ourdoor Programs (SWEBOP) director Laura Staman, converted his 1985 Mercedes diesel to run on biofuel, more specifically used vegetable oil gleaned from a local restaurant. The veggie oil-powered car officially hit the road on Oct. 1.
He completed the project with help from a do-it-yourself Web site and Faculty Row neighbor Matthias Glauser. Glauser is an electrical engineer with a Ph.D. and husband of assistant professor of engineering Dorsa Sanadgol.
“[Matthias] is now working on some microchip temperature controls and sensors for the project,” Cotulla, a civil engineer at VDOT, said. “He has also been a great resource on all the electrical wiring stuff, which I am pretty ignorant on. I have had to learn tons of stuff about diesel engines, Mercedes vacuum systems and electrical wiring.”
The project was born out of Cotulla’s desire to conserve gas without forgoing one of his passions — whitewater kayaking. As many local rivers are suffering from the drought, he has had to drive to neighboring states to find good rapids.
“While we have some great local rivers, when they are out of water I need to travel to West Virginia, North Carolina or Pennsylvania,” he said. “I hate burning all that gas just for recreation. It seems like such an indulgence and so wasteful. So I started looking for a better way.”
Diesel cars, which will run on vegetable oil without engine modifications, started catching Cotulla’s eye. Eventually he bought a Mercedes 300D Turbo from a mechanic’s shop in Raleigh, N.C. and went to work on the conversion.
He estimates the project, including the car’s $650 price tag, has cost him about $2,500 so far.
Because “the car still has some bugs,” Cotulla will have to funnel more money into the vehicle before it’s all said and done. “It is running much better than when I first bought it, but these issues have nothing to do with the veggie oil,” he said.
“I have a bit of an air leak in the veggie oil fuel system, which results in it running rough at low speeds around town. It runs fine at highway speeds. It has the same power and fuel economy as on diesel.”
At least the fuel is free, although Cotulla had a little trouble at first convincing the restaurant to relinquish the yellow liquid. “They were a bit confused and did not understand what I wanted the oil for,” Cotulla said.
“I explained that I was doing an experiment the first time, and I tested the oil and discovered that it was great quality. I returned the following week and explained that I wanted to take their oil every week and they hesitantly agreed with the condition that I not tell anyone where I get the oil.”
Cotulla leaves two five-gallon buckets at the restaurant and returns the next day to pick them up. He then filters the fuel before putting it into his car.
“I drain it through bag filters made out of old blue jeans and through a bulk fuel filter that farmers use,” he said. “I have this set-up on a 55-gallon drum with a heater that allows particulates and water to settle out.”
The trickiest part of the process, however, has been getting the oil to heat to at least 140 degrees Fahrenheit so it will vaporize when it passes through the fuel injectors.
“Getting it hot is the challenge,” he said. “I do this mostly by using the excess heat from the engine via coolant. I spliced into the coolant lines and use it in a series of heat exchangers and electrical heaters to get the temperature I need. It is pretty simple, and is easier to see than describe.”
– By
Suzanne Ramsey,
SBC staff writer
