Vegetable oil as fuel

This page is Work In Progress and therefore may not be complete.

Introduction to Vegetable Oil as Fuel

It is possible for any diesel engine to run with vegetable oil as a replacement to diesel fuel but the ancillary fuel system components and the design of the engine itself may make long term use of vegetable oil as a fuel impractical or impossible.

Before you embark on using vegetable oil as a fuel there are many factors to be considered and they fall loosely into two categories, the suitability of the vegetable oil and the suitability of the engine and ancillaries.

The Suitability of the Vegetable Oil

Vegetable oil to be used as fuel can be either new and bought from the cash and carry or supermarket (this is commonly called Straight Vegetable Oil and is abbreviated to SVO) or oil that has been previously used for cooking (this is commonly called Waste Vegetable Oil and is abbreviated to WVO or Used Cooking Oil which is abbreviated to UCO)

SVO is probably the easiest biofuel to use in a suitable diesel engine but is also the most expensive. WVO is a much cheaper and more environmentally friendly alternative as once it has been used for cooking, it becomes a waste product. The downside to this is that it requires processing before use as a fuel.

There are a number of problems associated with using vegetable oil as a fuel in a suitable engine but most of these issues can generally be overcome to an acceptable degree by exercising care when processing your fuel. The main issues with using vegetable oil as fuel are:

1] Vegetable oil is much more viscous that diesel and will put a greater strain on the fuel system components. It is also harder to obtain a complete burn, especially in a cold engine. You can lower the viscosity of your oil by either heating it before it enters the main fuel system components or by thinning it with a thinning agent such as petrol before you put it in your fuel tank.

2] Used oil will contain food particles and fats which can block the various filters in your fuel system. Filtering liquid, well settled oil to a level below that of your main fuel filter (generally 10 micron) should be done at a similar ambient temperature to when you are intending to use your fuel and should remove food particles and fats.

3] Used oil may contain suspended water which will cause long term damage to the fuel system and enable the free fatty acids within the oil to become corrosive. Dewatering can be achieved using either the heat and settle method or by boiling the water off.

4] Vegetable oils typically contain less energy than diesel so a slight reduction in power and/or fuel economy is common. If this proves to be a problem, some people have had success using products designed to boost the cetane value of your fuel.

The Suitability of the Engine & Fuel System

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