Vegetable Oil Fuel

Turn used vegetable oil into a valuable fuel source for your vehicle.

| August/September 2004

We sometimes drive 100 miles in our truck on 1 gallon of petrodiesel from the fuel pump because most of the fuel we are burning is used vegetable oil — and that’s even while dragging our homestead along behind us: a shiny 3,000-pound Airstream camper.

Shawn and I can stretch our petro-dollars far because of the ingenuous yet simple auxiliary fuel system we installed — one that enables us to burn a cleaner, greener and cheaper fuel that we regularly harvest from greasy spoons and fine eateries alike.

The Squeaky Wheel

Our diesel truck burns used vegetable oil, almost straight from the restaurant where we collect it to our fuel tank. Pyrotechnically speaking, vegetable oil and petrodiesel fuel aren’t so very different. If you thin vegetable oil (either with chemicals, as in biodiesel, or with heat, as with straight vegetable oil), it combusts very similarly to petrodiesel.

In fact, Rudolf Diesel, the German engineer who pioneered diesel engines in the early 1900s, originally designed diesel engines to burn vegetable oil. Today’s modern diesel engines will burn vegetable oil as easily as petrodiesel, too, as long as the oil is warmed (and therefore thinned) before combustion. Using used vegetable oil for fuel produces less pollution and decreases particulate emissions, helps keep grease out of landfills and sewers, and reduces our reliance on foreign oil. And it’s nontoxic and biodegradable, too.

Pieces and Parts

The two heat exchangers, which rest in the bottom of the tank, are plumbed to the engine’s coolant line. We fire up the engine on petrodiesel or biodiesel, and drive a few miles until the engine is warm. After the engine begins to generate heat, the warmed coolant (routed to the heat exchangers) transfers the waste engine heat to the veggie oil tank, warming and thinning the oil, and readying it for combustion. Six or eight miles down the road, a solenoid connected to a manual switch in the truck’s cab opens the gate to the veggie oil fuel line, which is nestled between the two plumbed — and warm — coolant lines. The fuel pump pulls the thinned veggie oil through the heated filter, through the standard diesel filter and to the injectors. And, without a hiccup, we’re off.

Before we shut down for an extended period (usually overnight), we make sure we flush the vegetable oil out of the fuel filter and lines by switching back to petrodiesel for our fuel for the final six to 10 minutes of actual drive time (not idling time).

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