Run a Diesel Vehicle on Vegetable Oil

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by John Hardesty

You can run a diesel vehicle on vegetable oil. Vegetable oil can power your vehicle, but the effects on the environment are still unclear.

This may sound strange, but you can run a diesel vehicle on vegetable oil and nearly eliminate your use of traditional gas or diesel. For certain people, veggie oil could lead to major savings. Called “veggie cars” or “grease cars,” these vehicles have fuel systems modified to burn both diesel fuel and straight vegetable oil. The idea is actually a modern twist on the original intention for the diesel engine.

But even proponents say veggie oil is not for everyone because of the extra work it requires. Nevertheless, there is a small, but growing, part of the population that’s passionate about using grease to make their cars go. These people are drawn to this alternative fuel because it saves them money, gives them more control of their transportation fuel needs, and makes a difference for the environment.

All this may sound too good to be true, and in some ways it is. Is it the most environmentally friendly alternative fuel? Should new vegetable oil or used grease be used? And here’s the real kicker: It’s technically illegal (see “Veggie Oil Vehicles and the Law,” below). So, before you start hoarding Wesson Oil, there are a few things you should consider.

Want Fries with That?

To get a sense of how this works, consider the example of Ty Martin. On Thursdays and Sundays the Lawrence, Kan., auto mechanic parks behind his favorite restaurant and heads inside for a hamburger and fries. As he eats with friends at the bar, kitchen staff fill a tank in the back of his truck with grease that was used to cook food just the day before. An hour later, truck and driver head home, both smelling faintly of burnt peanut oil. The used grease then propels Martin’s pickup all over town, all for free (except the food).

For Martin, burning vegetable oil means more than maintaining a dual fuel system. It’s a lifestyle, attracting the bohemian in a growing number of Americans who, for environmental, financial and/or political reasons, bristle over using fossil fuels for transportation. Whatever your motivation might be, if you have a diesel engine, it could run on cooking oil.

In fact, in the 1890s German inventor Rudolf Diesel originally designed his engine to run on vegetable oil.

A New Kind of Kit Car

The big challenge with using vegetable oil in Diesel’s engine was, and is, cold weather. Vegetable oil works best when it is hot — ideally 160 degrees — and it thickens like butter when it is cold. That means the engine has to be warmed up before it can run on vegetable oil, and the veggie oil must be flushed out before the engine cools down. Otherwise, you will have clogged fuel lines when you next try to start the car. To convert a diesel engine to run on veggie oil, you have several options.

The conversion hardware can be bought in kit form from a variety of manufacturers. Greasecar Vegetable Fuel Systems of Easthampton, Mass., estimates they’ve sold about 4,000 of their conversion kits over the past few years at prices ranging from $995 to $2,000. Lovecraft Bio-Fuels of Los Angeles, Calif., and Portland, Ore., which sells kits and installs them, estimates it has sold about 1,800 units, starting at $425 for the kit alone and $870 installed. (Lovecraft also sells a one-tank system.)

Some people custom build veggie cars. Martin saw his friend Marcos Markoulatos’ Greasecar kit in operation and decided he could do the conversion himself. He ended up with a used gas tank behind his truck seat and rubber heating hoses running from his truck radiator through the tank — all for $250.

Veggie-Capable Vehicles

Finding just the right car to burn vegetable oil can be more challenging. First and foremost, it has to have a diesel engine. The best cars to convert tend to be older models, according to Lovecraft. The exception appears to be the Volkswagen Jetta TDI — even more recent editions can be converted easily. Among the better older models for veggie conversions is the Mercedes 300 SD, particularly model years 1981 to 1985. Greasecar, on the other hand, says the majority of its kits go in newer domestic trucks or Volkswagen cars.

Diesel trucks get plenty of power out of vegetable oil. Martin said his 1990 Dodge Ram pickup made the switch without slowing down. Lovecraft and Greasecar both said the Ford F250 diesel models from 1995 to 2000 are well-suited for conversions. These trucks easily accommodate the necessary plumbing changes for burning vegetable oil.

New or Used Cooking Oil?

Vegetable oil enthusiasts love the idea of free fuel, so they take used cooking oil restaurants would otherwise throw away. Learn about collecting used vegetable oil by reading this article, “Negotiating For Waste Vegetable Oil.”

For converts less concerned about saving money, or perhaps skeptical about using waste oil, brand-new vegetable oil is another option. But you’ll pay a premium. At your local supermarket it can cost $6 a gallon or more. The cheapest oil right now is soybean oil, which can be bought in 250 gallon containers for about $3.40 a gallon. A company called Smarter Fuel, based in Bethlehem, Pa., refines used vegetable oil from restaurants across the mid-Atlantic states and resells it for $1.95 per gallon.

The cost of the new and refined oils does translate into fewer headaches than burning free used vegetable oil, which can have bread crumbs, water, even the occasional chunk of catfish in it. But there are different schools of thought on how clean used vegetable oil needs to be before you burn it in an engine.

One restaurant prefilters the oil for Martin and Markoulatos to clean it up a bit, and then the two tinkerers pour the oil into a 55-gallon plastic drum with a spigot 6 inches from the bottom. They let the oil sit for a week before drawing off everything above the dregs. Before they pour that into their trucks, they filter it again.

Pollution-wise, the differences between burning new and used vegetable oil are less stark. William Kemp, in his book Biodiesel Basics and Beyond says that new and used oil just about tie on soot and nitrogen oxide emissions, while waste oil puts out more carbon monoxide, and new oil puts out more carbon dioxide.

When comparing vegetable oil emissions to petrodiesel, the results are more mixed. Diesel exhaust puts out more soot than veggie oil, while putting out about 10 percent fewer hydrocarbons. But these measurements, Kemp says, don’t account for the biggest environmental argument in favor of vegetable oil to fuel cars: global warming. You have to grow plants to produce vegetable oil so the carbon dioxide emitted by burning it is captured as a new crop of oil plants grows.

Then there is veggie oil’s close cousin (some would say rival) — biodiesel — which is vegetable oil chemically processed to work like petrodiesel in standard diesel engines without modifications. It is available, usually blended with petrodiesel, at hundreds of filling stations across the country. Biodiesel proponents say veggie oil fuel, particularly waste oil, will always be a low-volume, backyard enterprise.

“People think vegetable oil and biodiesel are the same; they are not,” says Joshua Tickell, author of Biodiesel America. “Modern diesels are not made to run on straight vegetable oil (SVO). The SVO concept distracts from the huge potential of the biodiesel industry. There is no prospect for straight vegetable oil being a reliable fuel,” Tickell says.

There are numerous fans of veggie oil fuel, though, who have come to the opposite conclusion and feel just as strongly.

“Our conversion kits are developed and tested by our engineers for each specific application to ensure compatibility, and we have many customers who have been running successfully for almost 10 years,” says Justin Carven, founder of Greasecar.

(These contrasting perspectives are but one example of the contentious and evolving debate about the short- and long-term feasibility of biofuels. For more on their potential compared to other energy options, see “Harnessing Solar Energy Power.” — MOTHER)

With all this in mind, the decision to use vegetable oil for fuel is one to consider carefully. Concerns about taxes and EPA regulations are significant. And for many people, filtering the veggie oil and the potential for mechanical problems would be inconvenient. But for those who can embrace these challenges, veggie oil is a fun and empowering solution.

Veggie Oil Vehicles and the Law

Excited about the idea of running your car on veggie oil? Maybe even free waste oil? Before you get too excited, carefully consider this problem: It’s technically illegal, although that may be changing soon.

How could something so simple and well-intentioned cause legal problems? Here’s the skinny:

  • Fuel taxes on “traditional” fuels (gasoline, petroleum diesel) help fund the building and maintenance of roads used by veggie oil cars. Using vegetable oil as a fuel without paying fuel tax on it is considered tax evasion.
  • The U.S. Environmental Protection Agency (EPA) frowns on using vegetable oil in engines designed to burn diesel fuel because the emissions are not the same. If, for example, someone were to develop an unusual chemical concoction to burn in gas or diesel engines, it could cause toxic air pollution if it weren’t tested and approved prior to use.

All states have a fuel tax of some kind and the federal government also taxes fuel, but enforcement of tax laws regarding vegetable oil as a fuel are inconsistent. When it comes to biodiesel, which is basically chemically processed vegetable oil that mimics petroleum diesel fuel, federal tax laws are straightforward: You’ve got to pay taxes on it no matter where it comes from.

While enforcement of these laws has traditionally been lax, a few recent cases have received attention and may signal a new level of concern:

  • In May 2007 in Charlotte, N.C., Robert Teixeira was fined $1,000 for failing to pay taxes on the vegetable oil he burns in his 1981 Mercedes.
  • Two months before that David and Eileen Wetzel, of Decatur, Ill., were told they needed to be licensed as a special fuel supplier if they wanted to keep driving their veggie car or face possible felony fines for not paying fuel taxes.

If you buy veggie oil that is intended to be used as fuel, the taxes have already been paid by your supplier. Dave Dunham, owner of Smarter Fuel in Bethlehem, Pa., is paying a lot of taxes on the used vegetable oil he gathers for free. He collects hundreds of thousands of gallons of oil from about 1,000 restaurants stretched across five states. Then he cleans it up and resells it for about $1.95 per gallon, depending on state taxes. Since the taxes are already accounted for, consumers don’t need to report and pay the fuel tax individually.

The federal government does require you to fill out the necessary registration forms to make biodiesel for your car but it does not charge a fee for doing so, according to Enesta Jones, a spokesperson for the EPA.

There is also a concern that vegetable oil cars might violate the federal Clean Air Act. The Act bans tinkering with auto emissions by anyone who doesn’t have EPA certification to do so, according to spokesperson John Millett. Using vegetable oil instead of diesel fuel could quite likely affect the emissions from your car, Millett says.

“Also, a vehicle has to be modified to run on vegetable oil.” Jones says. “Such a modification is not legal unless it has been through an emissions certification procedure — this is different than just registering the fuel — to ensure that the modified vehicle itself meets emission standards.”

With some state laws still very much up in the air, there are ways to play it safe if you’re not sure if you should be paying taxes or not. On his website, Graydon Blair, owner of Utah Biodiesel Supply, a parts distributor for home biodiesel brewers, suggests you keep a log of the gallons of biodiesel or veggie oil you burn. Then if you do get into trouble with the state tax authorities you can produce the log and tell them you plan on paying at tax time. State and federal income tax forms have provisions for paying fuel taxes, Blair says. (Consult your tax advisor for details on how to best handle taxes in your state. — MOTHER)

Straight Talk on Biodiesel, Veggie Oil

William Kemp is the author of Biodiesel Basics and Beyond, a how-to on making fuel from all manner of oil-producing plants. While he is an advocate of the technology, he offers a sobering assessment of its limitations in his answers here:

Mechanically, what is the difference between grease cars and biodiesel cars?
What it boils down to is biodiesel can be used with the existing fuel infrastructure of any diesel vehicle, while straight vegetable oil can’t be combusted in a modern diesel engine without modifications. Also, in grease cars you need a system to preheat the oil and filter it before the fuel can be combusted.

And what about the costs?
Straight vegetable oil has the advantage in that the cost and complexity of the fuel drops dramatically, compared to biodiesel. If you look at the costs of making biodiesel, 70 percent of the cost of the fuel is the feedstock — that’s the canola, soy or peanuts that are used to eventually produce the fuel. The rest of the cost is processing that feedstock. You don’t have those costs with straight-oil fuel, although capital costs must be amortized.

Which is easier to use?
Biodiesel. You still need some petrodiesel or biodiesel fuel to run a vegetable oil car. The car has to start on diesel and it has to be shut down on diesel. So owning a vegetable oil car becomes more of a tinker’s game.

Once the oil is hot, what’s the difference between the two fuels?
Once the temperature of the vegetable oil gets to 176 degrees, viscosity of the oil comes down to the level of diesel fuel and it becomes much like straight diesel fuel.

Will vegetable oil cars ever be a mainstream mode of transportation?
In a word, no. I think using virgin vegetable oil or waste vegetable oil is always going to be a fringe sector of the transportation industry. Automakers will never get behind it.

Which is better for the environment?
With biodiesel you have the farming and harvesting for the feedstock that’s eventually processed to make the biodiesel. That has to be taken into consideration in the overall formula for the carbon released when you burn it. Then there’s also the toxicity of the chemicals used to make biodiesel — those can endanger the environment. The beauty of using waste oil is it’s something that’s already been used and you’re giving it a second life, providing low carbon and air pollution emissions.

Do you support one fuel over another?
I’m not a big advocate of using food crops for fuel. Even if we exploited all the biofuel potential in North America it would be no better than enforcing higher fuel efficiency standards for all vehicles. And does anyone really need a 300 horsepower car to get to work? Energy efficiency first, energy generation second; that is the sustainable path.

Originally published as “Would You Use Veggie Oil to Fuel Your Vehicle?” December 2007/January 2008 MOTHER EARTH NEWS.