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==Introduction==
 
==Introduction==
Biodiesel can be used in nearly any diesel engine, with little or no engine conversion. However, biodiesel is a stronger solvent than regular diesel ([[petrodiesel]]) - so much so that it will not only "clean out" the fuel tank, sending debris into the fuel filter, but it will also soften and dissolve many rubber and plastic products, including those used in fuel lines, filters and pumps. This deterioration can take years, however, and the replacement of rubber components does not have to happen immediately. Thus for long life, a different grade of components is needed in an engine designed for biodiesel.  
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Biodiesel can be made from any{{fact}} fat or oil. It can be used in nearly any diesel engine, with little or no engine conversion. However, biodiesel is a stronger solvent than regular diesel ({{WP|petrodiesel}}) - so much so that it will not only "clean out" the fuel tank, sending debris into the fuel filter, but it will also soften and dissolve many rubber and plastic products, including those used in fuel lines, filters and pumps. This deterioration can take years, however, and the replacement of rubber components does not have to happen immediately. Thus for long life, a different grade of components is needed in an engine designed for biodiesel.  
    
Biodiesel produces less particulates than petrodiesel and is thus much better for the health of the population, particularly those living in urban areas exposed to significant levels of pollution.{{fact}}  
 
Biodiesel produces less particulates than petrodiesel and is thus much better for the health of the population, particularly those living in urban areas exposed to significant levels of pollution.{{fact}}  
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While {{WP|straight vegetable oil}} can be used as fuel, it has a negative effect on the engine after prolonged use. Thus it is better to process the oil into biodiesel, especially for vehicles which get heavy use.
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==Vegetable oil extraction and conversion==
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The process of oil extraction is carried out the same way as for extraction of edible oil from plants. There are many crops grown in rural areas of the developing world which are suitable for oil production – sunflower, coconut, cotton seed, palm, rapeseed, soy bean, peanut, hemp and more. Sunflower oil, for example, has an energy content about 85% that of diesel fuel.
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There are two well-established technologies for oil extraction:
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*The simple screw press, which is a device for physically extracting the oil from the plant - this technology is well suited to small-scale production of oil as fuel or as foodstuff in rural areas. The press can be motorised or hand-operated.
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*Solvent extraction is a chemical process which requires large, sophisticated equipment. This method is more efficient - that is, it extracts a greater percentage of the oil from the plant - but is less suited to rural applications.
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The oil, as well as being used for lighting and heating, can be used as a fuel in internal combustion engines.
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Biodiesel production is not complex and can be done on a small scale. The vegetable oil is converted to a useable fuel by adding ethanol or methanol alcohol along with a catalyst to improve the reaction. Small amounts of potassium hydroxide or sodium hydroxide (commonly called lye or caustic soda, which is used in soapmaking) are used as the catalyst material. Glycerine separates out as the reaction takes place and sinks to the bottom of the container. This removes the component that gums up the engine so that a standard diesel engine can be used. The glycerine can be used as a degreasing soap or refined to make other products.
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{{content from|Original:Biogas and liquid biofuels|Practical Action}}
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==Straight vegetable oil==
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While {{WP|straight vegetable oil}} can be used as fuel, it has a negative effect on the engine after prolonged use. Thus it is usually better to process the oil into biodiesel, especially for engines which get heavy use.
    
==Sources==
 
==Sources==

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