Recent advancements in distillation and blending technologies are being widely recognized as influencing the global proliferation of biofuels. The idea of biofuels is not new; in fact, Rudolf Diesel envisaged the significance of biofuels back in the 19th century, stating, "The use of vegetable oils for engine fuels may seem insignificant today. But such oils may become in the course of time, as important as petroleum and the coal tar products of the present time" (Cowman, 2007).
Rudolf Diesel's first compression ignition engines ran on peanut oil at the World Exposition in Paris. The current drive toward greater use of biofuels is being pushed by the diversification of energy sources using renewable products, as reliance on carbon-based fuels becomes an issue, and the need to replace the methyl tertiary butyl ether (MTBE) component used in many of the world's petroleum products. The change from fuels with an MTBE component started as an environmental issue in various parts of the world.
Ethanol has been recognized as the natural choice for replacing MTBE, and the need for blending ethanol into petroleum products is now a global requirement. Brazil has long been the world's leader when it comes to fuel ethanol capacity, but the United States is trying to exceed this and other countries in the Western Hemisphere by rapidly growing its production. European legislation has set substantial targets for the coming years, and EU Directive 2003/30/EC promoting the use of biofuels in transport sets a target of 5.75% use by 2010. Standards for biofuels have already been established, with the undiluted base products being defined as B100 (100% biodiesel) and El00 (100% ethanol). Subsequent blending will modify this number, such as a blend of 80% petrol and 20% ethanol, defined as E20, or a blend of 95% diesel and 5% biodiesel, defined as B5 (Cowman, 2007).
Biodiesel can be used in any concentration with petroleum-based diesel fuel, and little or no modification is required for existing diesel engines. Biodiesel is a domestic renewable fuel for diesel engines and is derived from vegetable oils and animal fats, including used oils and fats. Soybean oil is the leading vegetable oil produced in the United States and the leading feedstock for biodiesel production. Biodiesel is not the same as a raw vegetable oil; rather, it is produced by a chemical process that removes the glycerin and converts the oil into methyl esters.
Utilizing the current petroleum distribution infrastructure, blending is typically carried out at the storage or loading terminal. The most common locations for blending are the storage tank, the load rack headers, or most effectively, at the load arm. The most important requirement for this process is the accurate volume measurement of each product. This can be done through sequential blending or ratio blending but most beneficially utilizing the side-stream blending technique.
Although petroleum products containing MTBE could be blended at the refinery and transported to the truck or tanker loading terminals via a pipeline or railcar, ethanol blended fuel contains properties that make this difficult. Ethanol, by nature, attracts any H2O encountered on route or found in storage tanks. If this happens in a 10% blend and the concentration of H2O in the blended fuel reaches 0.4%, the combined ethanol and H2O drops out of the blend. The exact point of dropout depends on the ethanol percentage, make-up quantity, and temperature. If this dropout occurs, the ethanol combines with the H2O and separates from the fuel, dropping to the bottom of the storage tank. The resulting blend goes out of specification, and getting back to the correct specification requires sending the contaminated ethanol back to the production plant.
The solution to this problem is to keep the ethanol in a clean, dry environment and blend the ethanol with the petroleum products when loading the transport trucks and tankers. Moving the blend point to the loading point minimizes the risk of fuels being contaminated by H2O.
In general biodiesel processing, the fat or oil is degummed, then reacted with alcohol, such as methanol, in the presence of a catalyst to produce glycerin and methyl esters (biodiesel). Methanol is supplied in excess to assist in quick conversion, and the unused portion is recovered and reused. The catalyst employed is typically sodium or potassium hydroxide, which has already been mixed with the methanol (Cowman, 2007).
Whereas fuel produced from agriculture has had only marginal use in today's climate, there are political, environmental, legislative, and financial benefits for using biofuels. With oil prices remaining high and very unlikely to reduce, demand for biofuel will continue to rise and provide exciting growth prospects for both investors and equipment manufacturers.
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