Renewable energies are good sources for global final energy consumption. Renewable energy comes from natural sources that can be replenished. They are found under various forms. They can be derived directly from the sun; obtained deep within the earth, or they can be plant sources from nature. A good source of renewable energy is biodiesel. What is biodiesel?
Biodiesel is an organic fuel which is very similar in properties to normal diesel. It consists of methyl or ethyl esters, depending on whether methanol or ethanol is used in the production process. Biodiesel can be made from plant oils including straight vegetable oil or used/waste vegetable oil (UVO/WVO) and even animal fats or tallow. Biodiesels are helpful in the reduction of emissions from diesel-fed engines.
Generally, Biodiesels are used in standard diesel engines. Although they come from natural sources, they are distinct from vegetable oils or waste oils, which are commonly used in fuel converted engines. Biodiesels are pure; however, they can be used alone, or they can be blended with a petrodiesel.
Biodiesels have a great lubricating property. It has also higher cetane rating than most low-sulfur diesel fuels. The calorific values of biodiesels are lower than regular petodiesels. The calorific value of Biodiesel range at about 37.27 Mj/kg. Biodiesels also have varying color. They can be found between golden brown and dark-brown color, depending on feedstock production. Biodisels are also immiscible in normal water and has a high boiling point with a lower vapor pressure. Biodiesels also have low or almost zero sulfur content.
Earlier, it was mentioned that biodiesels are produced by the reaction of lipids with fatty esters. Biodiesels generally are produced by transesterification of natural oil. Several methods can be used to carry out the transesterification of natural oils. These methods include batch process, ultrasonic methods, supercritical processes, and microwave methods.
Another by-product of transesterificaion process is glycerol. Glycerol was once valuable in the global market, however, the massive production of biodiesel lead to the crash of this by-product on the global market.
References:
http://en.wikipedia.org/wiki/Portal:Renewable_energy/Selected_picture
