Everyday Environmentalist

Run Your Car on Vegetable Oil

"As of 2000, the United States was producing in excess of 11 billion liters of waste vegetable oil annually."

Gabe Cahalan, land steward for The Nature Conservancy’s Maryland/DC program

By Gabe Cahalan

Before taking a job at The Nature Conservancy, I worked as a seasonal field biologist counting birds. I went wherever the work took me — and this often meant migrating with the birds all over the country.

So I decided I should try to lessen the impact of all that travel on the environment.

A hybrid vehicle was a little out of a traveling intern’s budget, but it turns out there are alternatives. A diesel vehicle can be made to run on waste vegetable oil (WVO) with some modifications — and a Google search will yield plenty of companies that make kits for various cars.

Why You Should Consider WVO

If you’ve read the recent Science article about biofuels co-authored by Nature Conservancy scientist Joe Fargione, you may know that biofuels made from corn and other food by-products have serious drawbacks — namely, land conversion from forest to agriculture creates a huge carbon debt.

While WVO is by no means the answer to all our transportation problems, it does have some redeeming qualities:

  • Emissions testing of WVO shows that it produces lower levels of CO and PM (particulate matter) than diesel when tested in the same vehicle (tested by the conversion company Greasecar).
  • WVO is a recycled waste product that releases carbon drawn down by the plants grown to make the oil. On the other hand, burning petroleum releases carbon drawn down millions of years ago.
  • And the plants that WVO is made from come from existing agricultural lands, so there’s no additional conversion of habitat.

When I tell people about using WVO in my car, they usually ask me: Should everyone do this? Of course, there's not enough used vegetable oil around to fuel the whole U.S. vehicle fleet. But consider this: As of 2000, the United States was producing in excess of 11 billion liters of waste vegetable oil annually — mainly from restaurants, snack food factories and deep fryers in potato processing plants, according to Wikipedia.

How I Did It

I custom built my first vegetable-oil conversion for an old 1983 Volvo. That car took me across the country twice on used vegetable oil I got from restaurants.

I went to the restaurant managers and explained that I was using the oil in my car. Although some gave me a blank stare, most managers were happy to give it to me and pointed me towards their dumpster or barrels in the back.

My latest conversion is a kit made for the Volkswagon Jetta. With a little mechanical know-how, I installed the kit into my car in one afternoon.

This conversion is best for longer trips because you have to warm up the engine by driving 15-20 minutes before switching to vegetable oil. I mostly use it on weekend getaways since my commute to the office is only two miles and I bike there whenever possible. The conversion includes a second fuel tank for vegetable oil that’s heated by coolant from the engine.

Of course, there are some minor inconveniences to using WVO:

  • I have to warm up the engine for up to 15 minutes before I can switch to veggie oil.
  • It takes some dedication to pick-up and pre-filter the oil when most of us are so used to pulling up to the nearest gas pump.
  • There are many ways to pre-filter vegetable oil including just pouring it through old clothes or rags. I use a pump and a water filter that keeps the process contained and clean. It takes about 20-30 minutes to filter 5 gallons.

My gas mileage on vegetable oil is comparable to what I would get on regular diesel fuel — 37 miles per gallon in city driving and 41 mpg on the highway. There's no noticeable difference in driving power, either. With an engine tune-up, I could probably get closer to 45 mpg for highway driving in my Jetta.

And WVO is now available across the country. Municipal websites can also be helpful — the Maryland county I live in now has a used vegetable oil exchange web site where converted car owners can be matched to restaurants with oil.

It feels good to pick up my carryout and fuel at the same place and to know that the fuel is relatively non-toxic. At the same time, I know that this is just a small step and that much bigger changes are needed in our transportation system.

The opinions expressed in this article are the author's and do not represent those of The Nature Conservancy.