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April 24, 2014  |  Login
Vegetable Oil as Fuel?

By Dan Chiras

Biodiesel isn't the only renewable liquid fuel available to us. Some car owners are currently burning vegetable oil directly in their diesel vehicles.

That's right, your eyes aren't deceiving you, they're burning vegetable oil in cars and trucks and buses equipped with diesel engines. Some individuals acquire their fuel from vegetable oil they purchase in bulk. Others salvage vegetable oil from fast-food chains and other restaurants.

How to burn vegetable oil in a diesel car

To run a vehicle on straight vegetable oil, which is thicker (more viscous) than biodiesel or conventional diesel fuel, car and truck owners must make some modifications to their vehicles. To make these vegetable oil conversions simpler, several companies now manufacture conversion kits costing $300 to $800, depending on the quality of the kit. Individuals can install the kits themselves, if they're mechanically inclined, or can hire a professional to do the job.

Before we examine the contents of a conversion kit, it's helpful to understand the main purpose of these kits. That way the parts will make sense to you.

First, most conversion kits are designed to store vegetable oil apart from the diesel or biodiesel fuel. In the majority of cars, you can't simply fill a diesel tank with vegetable oil because veggie-oil cars and trucks can't run on 100 percent vegetable oil all of the time. The main reason for this, which will make sense soon, is that you can't start a car or truck using straight vegetable oil. (There is a new conversion kit from a German company that allows 100 percent veggie-oil operation, discussed shortly.)

Second, because vegetable oil is much thicker than diesel, it needs to be heated to around 165°F or 74°C before it can be burned in a diesel engine. Heating makes the oil thinner.

All kits provide simple yet ingenious devices that heat vegetable oil so that it flows freely into the engine. If they didn't, the oils would clog up the works!

With this in mind, let's take a look at a typical conversion kit. As just noted, all conversion kits (except for one) include a separate tank for storing vegetable oil. They're made from steel or plastic and are placed in the trunks of cars or the beds of pickup trucks.

Conversion kits also come with tubing to connect the vegetable oil tank to the combustion chambers in the diesel engine and a filter to remove impurities, if any, from the oil before it reaches the engine.

Conversion kits also include valves to control the flow of biodiesel, described momentarily. Switches that allow the operator to control the valves are typically mounted on or near the dashboard to permit ease of use. A fuel gauge is included to monitor vegetable oil in the ancillary tank.

One of the most important components of the conversion kit, however, is a device to heat the vegetable oil. Some systems rely on electric (resistance) heaters. Others use heat exchangers that transfer engine heat to the vegetable oil. Both systems warm the vegetable oil to make it thin enough to flow freely to the engine.

How vegetable oil heating systems work

To understand how a heating system works, let's take a look at the Greasecar Vegetable Fuel Systems conversion kits These kits rely on a heat exchanger that, like others of similar design, transfers heat from the engine's cooling system to warm the veggie fuel. more




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