Converting to Biodiesel

Compared with the mental and mechanical gymnastics involved in converting your car or truck to propane or Flex Fuel, converting your diesel-powered car or truck to biodiesel is a breeze—just fill the tank with a biodiesel fuel. According to the DOE, the various biodiesel blends available can be used in any light- or heavy-duty diesel engine.

That being said, some auto manufacturers are a little antsy about biodiesel fuel being used in their engines, so check with your owner's manual so you don't inadvertently void your warranty. In older vehicles, high-percentage blends of biodiesel (greater than 20 percent) can adversely affect fuel hoses and pump seals. And for the use of 100 percent biodiesel, hoses and gaskets should be made of materials that are compatible to the fuel. Your vehicle manufacturer is the best source of information on this.

Biodiesel fuels are available in several "flavors" in the United States. The most common blend of biodiesel is B20 (20 percent biodiesel/ 80 percent petroleum-based diesel), which is the same kind of hedge-your-bets mix as E10 gasoline. But B100 (100 percent bio-derived diesel fuel also called "neat biodiesel") and blends of less than 20 percent biologically derived diesel are available as well.

Though it is gaining popularity, biodiesel is not widely available in the United States. Using the DOE's or your state's Alternative Fuel Station Locator could help you find locations offering the fuel near your home, but it is more likely that you'll have to drive a considerable distance to purchase biodiesel. When you get there, refueling with biodiesel is safer than refueling with gasoline or petro-based diesel fuel. The flashpoint of biodiesel is significantly higher than that of conventional diesel fuel, which makes the fuel safer in general. And "neat biodiesel" is nontoxic, biodegradable, and emits fewer carcinogens in the exhaust than conventional diesel fuel. In fact, if you want to, you can drink it, but that's not advised.

Although we jest about imbibing it, biodiesel is very nearly a food. Although there are various blends, typical biodiesel is predominantly soybean oil combined with an alcohol such as methanol and a catalyst. Because it is based on something pretty pure to begin with, you might expect it to turn in good exhaust emissions performance, and you'd be right. According to the National Biodiesel Board, which is, of course, pushing the stuff, using a B20 biodiesel fuel blend will provide a 20 percent reduction in unburned hydrocarbons, a 12 percent reduction in carbon monoxide, and a 12 percent reduction in particulates such as soot. As the percentage of bio-derived stock to petrol-derived stock goes up in the fuel, the emission performance gets commensurately better.


GreenPlan is a carbon neutralization program that allows companies to counterattack carbon emissions from their corporate fleet vehicles through tree planting. The idea is to replace the carbon dioxide emitted by company vehicles with oxygen using trees as the conversion medium. Trees pull carbon dioxide from the air into their growth process, separating the carbon and emitting oxygen as a byproduct.

Okay, except for availability, it's all good. What about price? Well, not so good. So far, perhaps because of limited availability (and limited competition between retail suppliers), biodiesel fuel is more expensive than petro-diesel. In general, B20 has been tracking at $0.20- to $0.40-per-gallon more than conventional diesel, while B100 has recently been selling for about 25 percent more than conventional diesel fuel. Not only that but the energy content of B100 is 10 to 12 percent lower than conventional diesel. If you fill up with B20 you basically will not be able to tell the difference, but with B100, your fuel economy will suffer perhaps 10 percent.

Because it is derived from domestic crops such as soybeans and mustard seeds, biodiesel is both renewable (we can grow more) and a buffer against foreign oil. It can also be derived from organic garbage and discarded cooking grease.

Speaking of discarded cooking grease, a company calling itself, amusingly, Greasecar Vegetable Fuel Systems, offers a conversion system that allows diesel vehicles to use vegetable oil as fuel. It is not technically a biodiesel system because it is designed for use with straight, unprocessed, new or used vegetable oil, while biodiesel is adulterated vegetable oil. Many Greasecar customers obtain used fry grease from local restaurants, often for free, and use it as fuel. In fact, Greasecar even gives tips on where to find the best sources of used frying oils.

Rather than simply using biodiesel in the vehicle's fuel tank, the Greasecar system is a dual-fuel, two-tank arrangement that utilizes the existing diesel tank and filters to supply diesel fuel to the engine at start-up and shutdown. After start-up, radiator coolant is used to transfer heat from the engine to the heat exchangers in the Greasecar fuel system to heat the vegetable oil in the fuel filter, lines, and fuel tank.


According to Greasecar, fast food is as bad for your car as it could be for you, because many fast food restaurants use hydrogenated oils, which, while they will work in the Greasecar system, are not optimum. The key reason is that they "gel" or firm up at lower temperatures than higher-quality oils.

This is a key part of the process, because the heat reduces the viscosity of vegetable oil to a level approximating that of diesel fuel, so it can be injected into the engine properly. Equally important, when the vehicle is being shut down for a period long enough for the fuel to cool, the vegetable oil must be purged from the fuel system and replaced with diesel for the next start-up. Otherwise a nasty clog results, and you won't go anywhere.

The Greasecar conversion kit, which costs around $900, is designed for a do-it-yourself installation. Key components are the aluminum, heated fuel tank, quick-flush switching mechanism to switch between conventional diesel and vegetable oil fuels, and a 10-micron fuel filter (to take out french fries). Though designed as a do-it-yourself project, some installations are more complicated than others, so a professional installation by a Greasecar-approved installer might be a wise choice.

Given the price of conventional diesel fuel and biodiesel these days, you can see that a quick payback is possible with the Greasecar system if you get used cooking oil free from restaurants wanting you to haul it away. But suffice it to say this method of obtaining fuel is not for everybody, nor are their enough vats of onion ring and codfish grease in the country to keep us all in veggie-fuel very long. But for those who want to give the ultimate nose-thumb to "the system," Greasecar is the way.

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