What is biodiesel?
Biodiesel is the name of a clean burning alternative fuel, produced from renewable resources such as straight vegetable oils, rape seed, soya, animal oil/fats, tallow and waste cooking oil. Biodiesel is an alternative fuel similar to conventional or ‘fossil’ diesel.
Biodiesel contains no petroleum, but it can be blended at any level with petroleum (fossil) diesel to create a biodiesel blend in any percentage, and can be used as a pure fuel as well. In Sweden, Norway, France and UK, 5% biodiesel is common in the normal diesel, and is already used as pure 100% biodiesel in many countries such as Sweden, Norway, Austria and USA. All vehicle manufacturers’ warranties cover use with 5% biodiesel blends, and many also approve up to 100%. 100% biodiesel must meet EU quality standard EN 14214 in order to comply with most vehicle manufactures. Biodiesel is simple to use, biodegradable, non-toxic, and essentially free of sulphur and aromatics.
The process used to convert these oils to biodiesel is called transesterification, whereby the glycerine is separated from the fat or vegetable oil. The process leaves behind two products – methyl esters (the chemical name for biodiesel) and glycerine (a valuable by product usually sold to be used in soaps and other products). This process is described in more detail under “biodiesel production overview”.
The largest possible source of suitable oil comes from oil crops such as rapeseed, palm or soybean. In the UK rapeseed represents the greatest potential for biodiesel production. Most biodiesel produced at present is produced from waste vegetable oil sourced from restaurants, chip shops, industrial food producers such as Birdseye etc. Though oil straight from the agricultural industry represents the greatest potential source it is not being produced commercially simply because the raw oil is too expensive. After the cost of converting it to biodiesel has been added on it is simply too expensive to compete with fossil diesel. Waste vegetable oil can often be sourced for free or sourced already treated for a small price. (The waste oil must be treated before conversion to biodiesel to remove impurities). The result is biodiesel produced from waste vegetable oil can compete with fossil diesel. More about the cost of biodiesel and how factors such as duty play an important role can be found here.
What are the benefits of biodiesel?
Biodiesel has many environmentally beneficial properties. The main benefit of biodiesel is that it can be described as ‘carbon neutral’. This means that the fuel produces no net output of carbon in the form of carbon dioxide (CO2). This effect occurs because when the oil crop grows it absorbs the same amount of CO2 as is released when the fuel is combusted. In fact this is not completely accurate as CO2 is released during the production of the fertilizer required to fertilize the fields in which the oil crops are grown. Fertilizer production is not the only source of pollution associated with the production of biodiesel, other sources include the esterification process, the solvent extraction of the oil, refining, drying and transporting. All these processes require an energy input either in the form of electricity or from a fuel, both of which will generally result in the release of green house gases. To properly assess the impact of all these sources requires use of a technique called life cycle analysis.
Biodiesel is rapidly biodegradable and completely non-toxic, meaning spillages represent far less of a risk than fossil diesel spillages. Biodiesel has a higher flash point than fossil diesel and so is safer in the event of a crash.
The European Union has set the goal of 2% use of biodiesel in 2005 with an increase of 0.75% per annum to 5.75% in 2010. Production is expected to triple due to EU requirements, with some member states adopting mandates earlier. The country with the highest capacity is Germany, followed by France, Italy and Austria.
Asian biodiesel is made mostly from palm oil and is called Palm Methyl Ester (PME). Palm oil producing countries like Malaysia and Indonesia are the main Asian biodiesel producers.
The use of biodiesel has various environmental benefits. Tests have shown that the toxicity of biodiesel is lower than that of petroleum-based diesel, and that in the environment it degrades more readily.
In terms of storage, handling and distribution, biodiesel is as safe as diesel, and it has a much higher ignition point. Biodiesel can be safely stored without degrading for up to six months, to keep for longer than that stabilising additives are needed.
