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Ethanol
 Anhydrous ethanol (alcohol containing less than 1% water), has been found be a useful transportation fuel. Alcohol can be blended with varying quantities of gasoline and may be used in standard gasoline style engines. Ethanol is commercially produced by large scale fermentation of biological substrates rich in sugars such as sugar cane, bagasse, sorghum, switchgrass, barley, hemp, potatoes, sweet potatoes, cassava, sunflower, molasses, corn, grain, wheat, cotton and the like. Currently this method of producing ethanol is drawing a lot of criticism as this encroaches into the food resources of the world in the form of actual produce and the land required for producing them. Other types of carbon substrates like cellulose /lignin are currently explored for large-scale ethanol production that would meet energy needs. Cellulose based substrates are numerous, can be procured from any types of bio-waste and are sustainable without having the undesirable sociopolitical implications associated with the use of starch. Nevertheless, they are a form of sugar that are very resistant to chemical attack and are therefore more difficult for conversion into alcohol.
The principle process in the production of alcohol from biomaterials is called fermentation and is mediated by microbes. In the case of simple sugars this is a one step process, while in the case of cellulose, it is a two-step process where the cellulose is first converted into a simple sugar before being broken down to form alcohol. The alcohol formed is found along with water, which is also a by-product of the chemical reaction. Water and alcohol are separated through a process called distillation, where the difference in the boiling points of the two liquids is utilized to separate them. This method of separation only results in alcohol purity of 95%-96%, that is insufficient for fuel needs. The distilled alcohol is therefore further treated through a dehydration process to remove the remaining water molecules from the distillate. There are five types of dehydration processes known to bring about this change. Of these the most common ones are:
 In azeotropic distillation, benzene and cyclohexane are added to the mixture and redistilled. The process results in production of pure anhydrous ethanol.- Extractive distillation is a process that consists of adding a ternary compound to the distillate. This would increase volatility of ethanol leading to removal of water.
- Currently, the predominant method of dehydration of ethanol is by the use of molecular sieves. Pressurized ethanol vapours are passed through porous molecular sieves that adsorb water molecules leaving the alcohol to pass into another chamber. The technique is said to save nearly 3,000 btus/gallon.
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Another method of producing ethanol from cellulose-based materials is to subject them to pylorysis ( to very high temperatures), which converts the entire plant into either a liquid or a gas (Syngas). Methods utilizing plant grasses, wood or agricultural wastes such as straw are considered as secondary methods for producing bioethanol. Bioethanol is also produce synthetically by using petroleum, coal, gas, and through chemicals such as ethylene, acetylene and so on. In 2003 5% of ethylene produced was through the synthetic process.
A total of 13.5 billion US gallons of ethanol was produced in 2006, where the top five-ethanol countries were US, Brazil, Chine, India and France.
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The energy output for per unit volume of ethanol is found to be 34% less than that of gasoline. However, experts argue that this large gap is because ethanol requires engines with technologies that are slightly different from the ones used for gasoline. Presently, the engines used for gasoline double up to use ethanol in hybrid vehicles. It is said that if ethanol E100 (100% ethanol) is to be used efficiently, the engine should have greater compression ratios that will give slightly higher power and torque. This would make the efficiencies of the two fuels almost equal, but this kind of an experiment is not possible with hybrid vehicles, as turning up compression would render it useless for gasoline operation. However, ethanol volumes of usage will still have to be slightly higher (15%) to equate with gasoline. Several other engine models that promise better out put from ethanol when compared to gasoline are emerging from some of the premier schools in the USA.
As far as fuel economy ethanol fuel engines will give 34% less mile per gallon than gasoline engines. With lower levels of Ethanol like E10, the difference is not so marked, but as ethanol amounts increase (E85) there is a significant difference that can be discerned. The EPA has estimated E85 to have 25.56% less fuel economy when compared to unleaded gasoline. When compared this way dollar to dollar it has been found (2006 data) that E85 would actually cost $ 3.71, when gasoline costs $ 3.03.
 One real issue related to the use of ethanol blends as an auto fuel is that the engines have trouble starting in cold climates. This is because sufficient vapor pressure cannot be achieved as the fuel evaporates. This is the reason for the use of E85 blends in engines in the US and EU in temperatures below 11 degrees Celsius. In winter, some parts of the US also mandate the use of lesser amounts of ethanol in the fuel blend (E70) an in Sweden the reduction is lesser E75. Engine heaters have also been recommended for use for both gasoline and ethanol engines during winter. In the hotter climates of Brazil E100 is used with less problems. However, in most cold places in Venezuela and Brazil, gasoline reserve tank complements ethanol engines. Gasoline power is utilized for starting the vehicle during cold winters.
The other problem associated with ethanol fuels usage in automobiles is, water accumulation in the fuel pipeline. While in the case of gasoline, water remains as a separate phase, the miscibility of water and ethanol makes water exist in a single phase. It has been found that E30, for instance has 2% water content. As the amount of alcohol in the fuel increases, the phase separation between fuel and water decreases. This phenomenon results in declining mileage with increased water content.
Despite technical drawbacks, many countries have regulated toward greater use of ethanol as fuel because of sustainability and environmental reasons. Geographic magazine estimates roughly 22% less carbob-di-oxide emissions are seen with the production and use of corn ethanol and 56% with cane ethanol, compared to gasoline.
Brazil calls for use of hybrid vehicles that would use a minimum of 25% ethanol (2007), while the US allows E10.Several designs of cars and light trucks today have been designed to be, “flexible fuel vehicles.” Modern vehicles are computerized to adjust the engine to varying flows different types of fuels using chips as oxygen sensors. In fact from 1999 there have been engine designs that allow for utilization of any blend of fluid in different proportions.
The biggest success with the use of ethanol in vehicles has been found in Brazil where only 1% of arable land has been diverted to till sugarcane for ethanol production. Approximately 3.6 million hectors of land has been used for the purpose with production of 7,500 liters of ethanol per hector resulting in a total of 4.3 Billion US Gallons of ethanol production in 2006. Brazil’s Ethanol industry is 30 years old. Through regular subsidies and government support, the industry has grown to such as extent that it provides 18% of the country’s transport fuel needs. Ethanol together with domestic oil resources has served to make Brazil self –sufficient in the oil sector.
The country that produces and consumes the largest quantity of Ethanol fuel is the USA, producing 4,855 million US gallons in 2006. Most of the ethanol in the US is produced from Corn, which 6-5 times less efficient than sugar can; yielding only 3000 liters per hector. The US has 1, 587 gas stations that supply ethanol fuel, with most of it near the place of production-the Corn Belt. Transport of ethanol through pipeline and tankers is a challenge as Ethanol is corrosive and produces structural damage to pipelines. Stainless steel pipelines and tankers may on the other hand be too expensive for viability. While ethanol powered cars have been in existence in the US since 1896(Ford), today almost all major car companies offer flexible-fuel vehicles that has swelled the number of Ethanol powered vehicles to 6 Million in 2006.
The EU has passed a legislation that states that by 2010, there should be a minimal use (5.75%) of non-mineral fuel to the proportion of total fuel consumed in every country. Accordingly many European countries are changing to include ethanol as an auto fuel option. Sweden leads the pack in the use of Ethanol fuel with 1,200 ethanol pumps and (as of 2008, July), nearly 116 thousand flexible-fuel vehicles on the roads. Germany (193 stations) and France (211 stations), follow Sweden in the EU endeavor, and are making large-scale efforts to switch to ethanol fuel for vehicles. Governments are extending incentive packages and tax breaks to promote lower carbon emission fuels like ethanol.
Australia prefers use of E10 in their pumps, while a few Asian countries like China and Thailand have taken the lead to Ethanol switch. The Caribbean nations, Central America and Andean nations have started investing heavily on ethanol production as a tariff-free trade environment prevails here. Trade in Ethanol was encouraged here to boost exports of ethanol fuel to the USA that has steadily grown to over 4 million US gallons.
There are many criticisms and controversies linked with bioethanol. Diverting food products away from the food chain and into ethanol production has created an acute food crisis. Tilling all land for incessantly is not compliable with soil conservation norms. Besides, bio-diversity in the earth with respect to plants would be seriously affected leading to limiting in biodiversity of animals living in the area that would threaten the world’s bio-balance. Costs can be calculated in many ways and when different types of financial instruments are used, bioethanol does not necessarily prove to be a financially laudable switch. Nevertheless, the whole concept is at its infancy and technologists will soon find a way to balance the act.
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