What is biodiesel?
Pure vegetable oil or a combination of diesel and vegetable oil is called biodiesel. In scientific terms, biodiesel consists of short chain alkyl esters. While vegetable oil is preferred, animal fats may also be used as a source of biodiesel. Vegetable oil undergoes transesterification to yield biodiesel. The commonly used biodiesel crops are soybean, canola, mustard seeds and cotton seeds.
What are the different blends available?
Although 100% vegetable oil is most effective as biodiesel, this is very rarely available in the retail world. Most commercially available biodiesel is a blend of vegetable oil and petrodiesel. The primary reason for blending is to allow biodiesel to be used in conventional diesel engines without modifying the engine. Another reason is to prevent growth of mold in the vegetable oil by adding petrodiesel and making it slightly toxic.
Throughout the world, the purity of biodiesel is determined by the 'B' factor, which identifies the amount of biodiesel in a fuel mixture. Pure biodiesel is known by B100 while biodiesel blended with 1% petrodiesel is B99. For unmodified diesel engines, B20 is used.
What are the benefits of using biodiesel?
Biodiesel is an extremely clean burning fuel. Using biodiesel produces zero sulfur dioxide and 80% less carbon dioxide emissions compared to burning conventional fuels. Using biodiesel sees a significant reduction in unburned and aromatic hydrocarbons as well as carbon monoxide and particulate matter. At present biodiesel is the only alternate energy fuel to successfully complete the EPA Tier I Health Effects Testing regulations. These tests are carried out under section 211(b) of the Clean Air Act.
Biodiesel also makes for better diesel engine maintenance. Since biodiesel does not contain sulfur, it provides better lubrication compared to regular diesel. In addition, the increased oxygen content of the fuel (11%) is beneficial for the ignition, engine torque, and power output. Its non-toxic nature and high flashpoint of 125 ˚C makes biodiesel safe to transport. An additional bonus is that the fuel burns with a pleasant smell.
What are the disadvantages of biodiesel?
At present, biodiesel has a shelf life of about one year. Its biological origin makes this fuel degradable in nature and hence must be utilized before its quality is compromised. Biodiesel is also highly solvent. Over time, it can dissolve rubber and elastomeric-based components in an engine. To overcome this, engines need to be suitably modified so that these components do not come in contact with the fuel.
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