Tue 14 Oct 2008
Biodiesel is the common name for a variety of ester-based oxygenated fuels made from vegetable oils or animal fats. Dr. Rudolf Diesel developed the first diesel engine to run on vegetable oil and demonstrated his engine at the 1900 World Exhibition in Paris using peanut oil as fuel. One of the first wide uses of biodiesel (transesterified vegetable oil) was powering heavy vehicles in South Africa before World War II. biodiesel can be used in a typical diesel generator without any need for modification, and can be blended with petroleum diesel fuel, the most common of which is a mix of 20% biodiesel and 80% petroleum diesel known as “B20”. Pure biodiesel is also known as “B100”.
The primary benefits of using biodiesel include:
- Biodiesel is biodegradable and non-toxic.
- Biodiesel produces approximately 80% fewer carbon dioxide emissions than standard diesel fuel and almost 100% less sulphur dioxide.
- Biodiesel is safer to store and transport as its flash point is about 125°C compared to petroleum diesel fuel, which has a flash point of 55°C.
- Biodiesel is more lubricating than diesel fuel, increasing the life cycle of the engine or generator, while fuel consumption and power output are relatively unaffected.
- Biodiesel can be made from domestically produced, renewable oilseed crops such as soybeans, canola, cotton seed and mustard seed.
- Biodiesel can be stored anywhere that petroleum diesel fuel is stored without modifications.
- Reduced fuel costs. Biodiesel is cheaper to produce than petroleum diesel. If biodiesel is produced locally, transport costs are also reduced or eliminated.
- Biodiesel is a renewable resource.
- Production levels and rates can be established to meet demand.
- Energy security as fuel can be supplied locally.
- Horrible exhaust fumes replaced with the pleasant smell of popcorn.
The primary disadvantages of using biodiesel include:
- Limited availability. Biodiesel not readily available in most places. Local production of biodiesel could alleviate this concern, and petroleum diesel could serve as a backup.
- Nitrous oxide emissions are increased by up to 15% over petroleum diesel fuel, which can contribute to smog production. Retarding the injection timing can reduce these emissions.
- Cold weather gelling. As with petroleum diesel fuel, biodiesel can gel in cold weather. There are simple preventative measures that can be taken to lower the risk of cold weather gelling.
- For older vehicles or generators, can require upgrading the fuel lines, as biodiesel can eat through certain kinds of rubber.
Before using biodiesel the following minor adjustments should be made to the diesel engine or generator:
1. Retard the injection timing by 2-3 degrees to overcome the effect of biodiesel’s higher cetane level. This will also causes the fuel to burn cooler, thus reducing nitrous oxide emissions.
2. Biodiesel is a good solvent and is likely to free up a lot of dirt and residue that might be left in the tank and the fuel system after using petroleum diesel. Be sure to start off with a new fuel filter and perform regular checks of the fuel filters when first switching to biodiesel.
3. Replace any natural rubber parts in the fuel system with Viton or other suitable non-rubber material.
Some further considerations for biodiesel usage include:
- Biodiesel is a solvent. Painted surfaces must be wiped immediately when using biodiesel. If left on a painted surface long enough, biodiesel can dissolve certain types of paints.
- Rags which have been soaked in biodiesel or biodiesel blends should be stored in a safety can to avoid spontaneous combustion.
- Biodiesel should be used within one year to ensure that the quality of the fuel is maintained.
The governments of most countries are actively promoting the use of biodiesel. The US and Europe have over 2 decades of experience with millions of miles logged using biodiesel. The Chinese government has banned the use of grain for ethanol production to ensure that it will be available for food use, and therefore have very ambitious plans for biodiesel. Current plans are to increase biodiesel output to 200,000 tons by 2010 and 2 million tons by 2020. The government plans to cultivate 13 million hectares of high-grade bio-energy forest by 2020, which will yield 6 million tons of biodiesel. That would be enough to fuel an 11 million kilowatt power plant. According to a forestation plan compiled by the SFA, raising biofuel forests in mountain areas will save farmland, make full use of the uninhabited mountains, and increase local people’s family income if they are employed to take care of the trees.
A final note - if you are planning on producing your own biodiesel, most countries will require you to pay tax! Although you dramatically cut your fuel costs and reduce greenhouse gas emmissions, if you are powering your vehicle with biodiesel you are required to pay the same road and fuel taxes that are applied to gasoline or petroleum diesel, although some of these costs may offset by tax credits designed to encourage the use of alternate fuels.
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