Using Biofuels and Biodiesel in Diesel Cars and Trucks

There are three ways to run a diesel engine on bio-fuel using vegetable oils, animal fats or both. All three can use both fresh and used oils.

1. Mix it with kerosene (paraffin) or petroleum diesel fuel, or with biodiesel, or blend it with a solvent, or with gasoline;

2. Use the vegetable oil just as it is -- usually called SVO fuel (straight vegetable oil) or PPO fuel (pure plant oil);

3. Convert it to biodiesel.

1. Mixing it

Vegetable oil is much more viscous (thicker) than either petroleum diesel or biodiesel. The purpose of mixing it or blending it with other fuels is to lower the viscosity to make it thinner, so that it flows more freely through the fuel system into the combustion chamber.

Mixing vegetable oil with petroleum diesel or kerosene uses some fossil-fuel. However, for every gallon of vegetable oil that is used, that is one gallon of fossil-fuel saved. Various mixes can be used, ranging from 10% vegetable oil and 90% petroleum diesel to 90% vegetable oil and 10% petroleum diesel.

Blends with various solvents and/or with unleaded gasoline are "experimental at best"; little or nothing is known about their effects on the combustion characteristics of the fuel or their long-term effects on the engine.

Higher viscosity is not the only issue with using vegetable oil as a fuel. Vegetable oil has different chemical properties and combustion characteristics from the petroleum diesel fuel for which diesel engines and their fuel systems are designed.

Using a blend of up to 20% vegetable oil of good quality with 80% petroleum diesel is said to be safe enough for older diesels, especially in summer. Otherwise using vegetable oil fuel needs either a professional SVO solution or biodiesel.

2. Straight Vegetable Oil

Straight vegetable oil fuel (SVO) systems can be a clean, effective and economical option.

Unlike biodiesel, with SVO you have to modify the engine. The best way is to fit a professional single-tank SVO system with replacement injectors and glow plugs, optimized for vegetable oil, as well as fuel heating. With the German Elsbett single-tank SVO system for instance, you can use petroleum diesel, biodiesel or SVO, in any combination. Just start up and go, stop and switch off, like any other car.

There are also two-tank SVO systems which pre-heat the oil to make it thinner. You have to start the engine on ordinary petroleum diesel or biodiesel in one tank and then switch to SVO in the other tank when the vegetable oil is hot enough, and switch back to petroleum or biodiesel before you stop the engine, or you'll coke up the injectors.

3. Biodiesel

Biodiesel has some clear advantages over SVO: it works in any diesel, without any conversion or modifications to the engine or the fuel system -- just put it in and go. It also has better cold-weather properties than SVO. Unlike SVO, it is backed by many long-term tests in many countries, including millions of miles on the road.

Biodiesel is a clean, safe, ready-to-use, alternative fuel, whereas it's fair to say that many SVO systems are still experimental and need further development.

On the other hand, biodiesel can be more expensive, depending how much you make, what you make it from and whether you're comparing it with new oil or used oil. And unlike SVO, it has to be processed first.

When using used oils, you have to process SVO, especially WVO (waste vegetable oil, used, cooked oil, also called UCO, used cooking oil), which many people with SVO systems often use because it's cheap or free for the taking. With WVO, food particles and impurities and water must be removed, and de-acidified.

Costs and prices:

Bio-diesel users who use waste oil feedstock make biodiesel for about 50 cents to $1 per gallon. Most people in the United States use about 600 gallons of fuel a year (about 10 gallons a week), costing about $1,800 a year (mid-'07 prices).

Bio-diesel users pay approximately $300-360 for their fuel, while a good processor can be set up for around $100 up. An SVO system costs from about $500 to $1,200 or more. So with an SVO system you'll be ahead of fossil-fuel prices within a year.

For a cost perspective biodiesel is the most affordable option and best for the environment.

How to make your own Biodiesel:

Mike Pelly's biodiesel recipe -- the most popular biodiesel how-to.

Aleks Kac's two-stage process -- high quality fuel and no titration (not for novices).

FOOLPROOF biodiesel method -- method for advanced biodiesel users

Source: journeytoforever.org