Factsheet: Biodiesel
What is biodiesel?
Biodiesel is a renewable fuel that is produced from domestic renewable resources such as virgin vegetable oils (e.g. grapeseed, soybeans, oilseed, sunflowers) as well as from waste cooking oils.
The process of changing waste vegetable oil into biodiesel is called transesterification. It is reacted with methanol to produce methyl esters, such as rape methyl ester (RME). This process brings the specification closer to that of mineral, oil-based diesel.
Biodiesel contains no petroleum, but it can be blended at any level with petroleum diesel to create a biodiesel blend. It can be used in compression-ignition (diesel) engines with little or no modifications.
European specification EN14214 relates to transesterified biodiesel. In the UK, it is most commonly blended at 5% by volume into existing diesel to produce EN590. Motor manufacturers warrant their vehicles to run on EN590, although some manufacturers are happy at 10-30%, provided it is sourced from a respected supplier (please check with the vehicle manufacturer before using).
Is Biodiesel the same as raw vegetable oil?
No! Biodiesel must be produced to strict industry specifications (ASTM D6751) in order to insure proper performance. Biodiesel that meets this specification has to be legally registered with the Environmental Agency in order for it to be a legal motor fuel for sale and distribution. Raw vegetable oil does not meet these specifications and so is not a legal motor fuel.
Environmental benefits of using biodiesel?
· The crops from which the vegetable oil is derived to make biodiesel take up CO2 when they grow; therefore biodiesel is considered a renewable fuel. It gives a 60% reduction in CO2 well to wheel, which means a 3% reduction in a 5% blend.
· It is highly biodegradable, biodiesel does not accumulate and seriously pollute soil and waterways if it is spilt.
Environmental negatives of using Biodiesel?
· Oxides of nitrogen, (smog-forming gas) are slightly higher in biodiesel than with ultra-low sulphur diesel.
· Biodiesel can be manufactured from palm oil. Although Palm oil is a renewable resource, it is often grown after clearance of rain forest.
How much does it cost to run a vehicle on biodiesel?
Biodiesel pump prices are now roughly the same as standard diesel. In July 2002, the Government reduced the tax on biodiesel by 20 p per litre to encourage the production/ use of this fuel. Up until then biodiesel (EN 14214) was not an economically viable alternative as it tends to cost more than regular diesel to produce.
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