Welcome to Biodiesel Booklet
Biodiesel is a clean-burning renewable source of fuel made from straight or waste vegetable oil. Straight vegetable oil (SVO) is generally new, unused cooking oil, whereas waste vegetable oil (WVO) is that which has already been used and is traditionally dumped into landfill sites once finished with. Far from being an inferior homemade biofuel, biodiesel is better both for your car engine and the environment than fossil-based fuels such as petrol or petro-diesel (regular diesel). And with unpredictable prices at the pumps, many people are turning to either making biodiesel or purchasing it already made from a supplier. With the former option, making biodiesel safely should be a priority. With the latter, finding a Biodiesel supplier near enough to become economical can often prove difficult, however, a list of suppliers can usually be found by searching online.
Making biodiesel is nothing new. One Rudolf Diesel, the inventor of the diesel engine, showed interest in using vegetable oil (peanut oil) to run his engine. Even then the advantages for the environment and agriculture were clear to this genius. It was only after his controversial death that the petroleum industry capitalised on his invention by naming one of their by-products of petroleum-distillation diesel fuel (petro-diesel). This is how the polluting diesel fuel we know today became the common fuel for the diesel engine, and the more environmentally friendly vegetable oil fuel was mostly forgotten - until now. And these days, environmentally fuels are more important than ever.
There are basically three ways to run a diesel engine on vegetable oil:
- Use the vegetable oil (usually SVO) just as it is (don't - please read below first!)
- Mix it with paraffin or petro-diesel or solvents
- Convert the oil to biodiesel (transesterification)
Vegetable oil is roughly five times more viscous than diesel. As a result a diesel engine would need to be modified to cope with this, either to pre-heat and therefore thin the oil before it enters the injectors, or by installing a double tank system whereby the car is run on normal diesel until warm and then switched over to biodiesel. The purpose of mixing the oil with other fuels and solvents is again to lower the viscosity to make it thinner, so that it flows more freely through the fuel system into the combustion chamber. However, this method still involves using fossil based fuels for the mixing so isn't ideal.
For many people, making biodiesel themselves is becoming the preferred option because biodiesel will work in any diesel engine, neaning that no modifications are required whatsoever. Biodiesel has better cold weather properties than SVO too (but less than petro-diesel) and it is clean, safe, and has good lubrication properties for the engine. Production costs tend to vary but depend mostly upon whether using new or used oil. Used oil is the cheaper option (and is often available for free). The only downside is that used oil has to be processed first, which is relatively straightforward, or it can even be bought that way (which, however, would be subject to tax).
Making Biodiesel (transesterification)
Turning vegetable oil into biodiesel is carried out by a process called transesterification. Despite the long name, this simply requires adding a commonly found catalyst to alcohol (collectively called the reactants), which is then added to the oil. The end result is transesterified vegetable oil, or biodiesel. There are two choices for the catalyst:
- Sodium hydroxide (otherwise known as caustic soda or lye)
- Potassium hydroxide (otherwise known as potash)
And in addition, there are also two choices for the alcohol:
- Methanol
- Ethanol
Out of the first two, sodium hydroxide is cheaper, but potassium hydroxide is easier to use and mixes better with methanol (if using methanol that is). The process is much the same using either catalyst but more potassium hydroxide will be needed than when using sodium hydroxide (about 1.4 times more). As for the alcohol, making biodiesel using ethanol is much more difficult (and certainly not for beginners), and so most people tend to use methanol. As a result, the biodiesel recipies in this booklet will focus on using methanol and sodium hydroxide. In either case, making biodiesel safely should always be your first priority so please make sure you read the section on health and safety.
Is it Legal?
The goalposts have moved somewhat over the years, but currently making biodiesel for personal use is perfectly legal; the government permits the production of 2,500 litres of biodiesel a year TAX FREE. Visit HM Revenue & Customs website for more information (4.2.1. Exempt producers/users). Also, The Environment Agency provides details about the regulations surrounding biodiesel production.
A note on Home Insurance
As well as noting the safety implications of making biodiesel, consideration must be given as to whether your home insurance policy will cover any damage caused if an explosion occured. Most insurers policy wordings state that policyholders are required to ensure that 'reasonable precautions' are adhered to. If you intend to make biodiesel, check first with your insurance company to confirm that cover will be provided against any damage caused to your home. It is advisable for the manufacturing process to be carried out as far from your house as possible and in an area, should the worst happen, that the impact of any damage would hopefully be reduced.
