Burger and fries to go

How to convert a car to run on leftover vegetable oil from your local greasy spoon.

Published August 13, 2008 10:52AM (EDT)

Hey, you, environmentalist: Want the greenest wheels going but find yourself lacking $109,000 for a Tesla Roadster? Despair not! There's a vehicular option that makes a Prius seem like a gas guzzler and can save you major bucks, too. (Here's the only catch: This option may not be strictly legal under the federal Clean Air Act. But more on that later.)

The vehicle in question is a grease car, a ride capable of lowering your motoring greenhouse gas emissions by 78 to 87 percent over regular gasoline. A grease car is a diesel car, truck or Jeep that runs on waste vegetable oil from your local greasy spoon or fine-dining establishment. A grease car also significantly reduces a bevy of environmental badness -- asthma-triggering particulate matter, smog-forming carbon monoxide, likely carcinogenic polycyclic aromatic hydrocarbons and the sulfur emissions that lead to acid rain. The only environmental downside is a small increase in smog-forming nitrogen oxide.

Sold? Good. The first thing you need is, of course, a diesel vehicle. Old Mercedeses and V.W. Rabbits and Jettas -- costing about 2,000 to 4,000 bucks -- are popular among greasers. Or, if you're feeling flush, you might want to spring for one of the V.W.s, Mercedes or Jeeps in showrooms now.

Next you need grease. Local restaurants and other food service establishments -- cafeterias, caterers, hotels -- are all good sources of what, in greaser parlance, is known as WVO, waste vegetable oil. "Just go into a restaurant during nonbusy hours and ask to speak with the manager," advises California environmental consultant and greaser Stephanie Collins. The food folks usually give it up for free.

Your next step is to decide between two fueling options. Straight vegetable oil (SVO) or biodiesel. SVO is filtered WVO; to use it, you usually have to modify your car's fuel system. Biodiesel is WVO catalyzed with methanol and lye. Biodiesel can be used in many diesel engines without modification. But making the stuff necessitates using and storing caustic and combustible chemicals.

"Modifying the car to run straight vegetable oil is great, and if you have just one vehicle, it makes more sense because it's simpler," says Lyle Rudensey, owner of Seattle's BioLyle's Biodiesel Workshop, which offers instruction on making your own fuel.

Key to success is careful filtration of your French fry grease. Otherwise you risk clogging your vehicle's fuel injector and damaging the engine. Filtration systems run from low-cost/low-tech solutions that sell for next to nothing to mechanized systems that can cost as much as $1,500.

To make sure his grease is engine safe, SVO user Chuck Wyatt, a Holliston, Mass., Web developer, lets the oil he has collected sit in containers for a week or two, so most of the water and food remnants settle out. Then he pours the grease into a large hanging filter positioned above a 55-gallon drum. After the first filtering, he heats the grease with an electric heater and pumps it through a diesel-fuel filter into a second drum. "It's not glamorous, but it works," Wyatt says. Higher-priced mechanized systems can do all the work for you.

If you're disinclined to get your hands dirty, you can purchase ready-to-use vegetable oil from a relatively small number of biofuels co-ops and fueling stations, such as Ithaca Biodiesel, in upstate New York.

Because SVO is more viscous than regular diesel fuel, you'll probably need to have a mechanic install a kit that creates two fuel lines for your car -- one for regular diesel, one for vegetable oil. You switch between one line and the other once the vegetable oil has been heated by the car's engine. Modification kits cost about $1,000; mechanics, $1,000 to $1,500. (Here's another good thing about your grease car: You can use "dino" (petroleum) diesel if you run out of the veggie stuff.)

Although SVO has many fans, biodiesel has its boosters, too. You can brew biodiesel at home, but "most of the people who do it are tinkerers," observes Meghan Murphy, one of Ithaca Biodiesel's founders. The equipment needed to make the stuff starts at $1,400 and can run as much as $13,000. That's why the fuel is often produced by co-ops, whose members can share the cost of automated fuel-processing equipment. (Rudensey helped organize a 24-member group in Seattle.) WVO-based biodiesel is available at a growing number of fueling stations across the country, such as Berkeley, Calif.'s Biofuels Oasis. (Check out biodiesel.org for a national listing of stations and offerings.) If you do choose biodiesel, make sure to have a mechanic swap any rubber parts in your car's fuel system for metal ones; biodiesel has some solvent properties that can cause rubber parts to crack and leak.

After all the parts and labor, depending on which filtering process you choose and where you get your grease, the price of your new fuel should range from $3 to as low as 50 cents per gallon.

In most cases, grease cars are against the law because they use a fuel that hasn't had emissions testing approved by the Environmental Protection Agency. (Some fueling stations, including Ithaca Biodiesel and Biofuels Oasis, do offer EPA-approved biofuels.) The EPA has also yet to approve fuel system modification kits. None of the greasers I talked to, however, has heard of anyone being prosecuted under the federal Clean Air Act. But EPA spokeswoman Roxanne Smith says: "We have conducted some inspections regarding possible noncompliant biodiesel. Because these investigations are ongoing, we cannot discuss them."

Depending upon where you live, you may be subject to certain road and fuel taxes that are usually included in the cost of petroleum at the pump. So consult a tax expert. And Bob McCormick, a biofuels expert at the federal National Renewable Energy Laboratory, warns that using waste vegetable oil can cause "carbon deposits in the engine, which could lead to poor performance." None of the greasers reported engine trouble or knew of grease car users plagued by engine trouble.

Running your car on WVO isn't for the time strapped. Wyatt estimates that collecting and processing grease takes him two hours a week. "You've got to be willing to put in the work," he says. "It's a hobby." But a profitable one: Given his 70-mile round-trip commute, Wyatt says, "I'm saving about $200 a month on gas. I only need to fill up on diesel about once a month."

Sadly, WVO isn't the answer to the nation's transportation fuel problems -- there's simply not enough of the stuff. The United States produces about 200 million gallons of waste grease each year, compared with a combined total of 180 billion gallons of gasoline and petroleum diesel used annually.

Nevertheless, running a car on WVO is definitely worth doing, says Rich Kassel, director of the Natural Resources Defense Council's Clean Fuels and Vehicles Project. "We'll never solve global warming by relying on used grease from the corner diner. But every little bit helps."

By Liz Galst

Liz Galst is a regular contributor to Plenty. Her writing has appeared in the New York Times, Newsweek, and Better Homes & Gardens.


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