Heat Your Home with Biodiesel

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Although it has been promoted mostly as a fuel for diesel-powered vehicles, biodiesel is perfectly suited as an additive or replacement fuel in a standard oil-fired furnace or boiler.

When used as a heating fuel, biodiesel is sometimes referred to as " biofuel" or "bioheat." Made from new and used vegetable oils or animal fats, this fuel also has the advantage of being biodegradable, nontoxic and renewable: While fossil fuels took millions of years to produce, fuel stocks for biodiesel can be created in just a few months, and the plants grown to make biodiesel naturally balance the carbon dioxide emissions created when the fuel is combusted. What's more, the resulting fuel is far less polluting than its petroleum-based alternative.

A HOT IDEA

The idea of using vegetable oil as a fuel source isn't a new one: In 1900, Rudolph Diesel, a German engineer for whom the diesel engine is named, used peanut oil to power one of his engines at the World Exposition.

Today, Rudolph Diesel's original idea of using vegetable oils as a fuel source has been revived with the development of biodiesel.

Technically a fatty acid, methyl ester, biodiesel is made by reacting a wood or grain alcohol, such as methanol or ethanol, with vegetable oil or animal fats. With the help of a sodium hydroxide (lye) catalyst, the reaction produces two products: biodiesel and glycerine. The process is relatively simple, although the chemicals required are caustic and need to be handled carefully.

After I first heard about this idea at a renewable energy fair in 2001, I decided to try biodiesel in my old oil furnace. That November, shortly after our fuel tank in the basement had been filled with No. 2 fuel oil, I carefully added about 5 gallons of biodiesel to the tank, which resulted in a B2 blend (2 percent biodiesel; 98 percent fuel-oil).

I started the experiment with such a modest amount because, among its many properties, biodiesel also is a solvent. This potent property tends to dissolve the sludge that often coats the insides of old fuel tanks and fuel lines, which can cause a clogged fuel filter or burner head. As the 2001-2002 heating season progressed, I gradually increased the percentage of biodiesel until the furnace was burning a B10 blend.

Despite my initial concerns, the old oil-fired boiler in the basement continued to operate without any problems. Last year, I increased to a B20 blend, which burned with similar results.

SPECIAL CONSIDERATIONS

The beauty of heating with biodiesel is that no new heating appliance and no retrofitting is required. Although fueling your furnace with biodiesel is as simple as pumping gas into your car, you should take these few precautions:

Storage. Because biodiesel, like No. 2 heating oil, will gel if stored outside in extremely cold weather, it should be stored in an indoor (or underground) storage tank. If you use biodiesel, keel in mind the characteristic of fuel Oil known as the "pour point" (the temperature below which it will not pour). The pour point for No. 2 fuel oil is 11 degrees below zero. Although the actual pour point temperature for biodiesel varies, depending on its concentration and original feedstock, it is consistently higher than No. 2 fuel oil. You'll need to store biodiesel fuel at temperatures; shove its pour point.