Ethanol, an alternative Fuel
What is ethanol? Ethanol is an alcohol often produced from corn or sugar cane, and has a higher octane rating than gasoline. Ethanol can be mass-produced by fermentation of sugar or by hydration of ethylene from petroleum and other sources. The ethanol, produced from the fermentation process, contains a significant quantity of water, which must be removed. This is accomplished by fractional distillation. The distillation process works by boiling the water and ethanol mixture. Since ethanol (lighter) has a lower boiling point compared to that of water (heavier), the ethanol vaporizes from the water and is separated.
Ethanol is considered a renewable source because it is the result of converting the sun's energy into usable energy. Producing ethanol starts with photosynthesis causing the necessary crops, produced domestically, for ethanol production to grow. These crops are then processed into ethanol. Current interest in ethanol lies in production derived from farming of crops. It is readily obtained from the starch or sugar found in a wide variety of crops. Ethanol fuel production depends on availability of land area, soil, water, and sunlight. An estimated 5% of the ethanol produced in the world is actually a petroleum product. Petroleum derived ethanol is made by catalytic hydration of ethylene. It can also be obtained by ethylene or acetylene from calcium carbide, coal, oil gas, and other sources. Two million tons of petroleum derived ethanol is produced annually. The principal suppliers are plants in the United States, Europe, and South Africa. Petroleum derived ethanol is chemically identical to bio-ethanol. Bio-ethanol (ethanol produced from crops) can be produced in different ways, using a variety of feedstock. Crops with higher yields of energy, such as switch-grass and sugar cane, are more effective in producing ethanol than corn. Ethanol can also be produced from sweet sorghum, a dry land crop that use much less water than sugarcane, does not require a tropical climate, and produces food and fodder in addition to fuel. One of the added benefits of producing ethanol from crops is the uptake of carbon dioxide by the plants as they grow to produce the biomass; this helps to lower the overall carbon dioxide produced when burning this alternative fuel. Producing ethanol could get more efficient soon, as new technologies help farmers get more corn per acre of land, and use of genetically modified seeds, as well as chemicals for protecting crops; this will allow ethanol producers to get more of the alcohol fuel from the same amount of corn which was used before.
Like other alcohols, ethanol can be used as a fuel in gasoline engines. Ethanol is blended with gasoline and used in cars with no modification of the engine. E85 is 85 percent ethanol and 15 percent gasoline and can used as a flex fuel on a vehicle with a motor set up to run on gasoline or blends of gasoline and ethanol. E85 will produce lower mileage than gasoline, and will require more frequent refueling. Ethanol can be mixed with gasoline up to a concentration of 100 percent ethanol.
Ethanol is increasingly replacing Methyl T-Butyl Ether (MTBE), a chemical difficult to recover from groundwater and soil, as an oxygenate additive for standard gasoline. A 10% ethanol gasoline mixture reduces the possibility of engine knock by increasing the octane rating of the fuel while reducing our gasoline usage. Ethanol at larger concentrations can greatly reduce our dependency on petroleum refined gasoline. Currently the United States are dependent on gasoline. With the increasing cost of gasoline, alternatives fuels must be considered. Not only cost is a factor, our environment is also a great concern with the reduction of air pollution greatly needed to reduce smog-forming emissions and greenhouse gases. In addition, ethanol is highly biodegradable, making it safer for the environment in the event of spills or leaks into the soil. Compared with gasoline, ethanol is a particulate-free burning fuel which burns cleanly with oxygen to form carbon dioxide and water. Use of ethanol emits a similar amount of carbon dioxide but less carbon monoxide than gasoline. If all production energy came from non-fossil sources, the use of ethanol as a fuel would add no greenhouse gas; when the plant-derived bio-fuel is burned in an engine, the carbon dioxide released is offset by the amount of carbon dioxide gas absorbed by the plants for photosynthesis when they are grown; this process will create a balance of carbon dioxide burned to carbon dioxide used in plants and is basically carbon neutral. The contribution of biomass to the greenhouse effect is therefore far less than for traditional fossil fuels.
One of the more exciting ethanol prospects on the horizon is cellulosic ethanol, which can be made from a number of plant by-products, including cornstalks. Although it's unlikely to be commercially available for at least a few years, cellulosic ethanol eventually could help substantially reduce costs. In other words, your car in the future could run on the refuse of farms across the U.S.
Is Ethanol (E100) comparable to gasoline? Ethanol (E100) consumption in an engine is about 34% higher than that of gasoline, producing energy 34% lower than that of gasoline. However, this observation applies only to currently designed flex-fuel engines. Ethanol has a much higher octane rating of 105 for E85 versus 87 for regular unleaded gasoline. Because currently marketed flex-fuel vehicles must be capable of efficiently burning both gasoline and E85, their engines must be designed to tolerate lower octane rated petroleum-based fuels. However, higher compression ratios in an ethanol-only engine allow for increased power output and better fuel economy than the lower compression ratio. In general, ethanol-powered engines are tuned to give similar power and torque output to that of gasoline-powered engines to make performance issues void. In flexible fuel vehicles, to maximize ethanol’s benefits, a substantial higher compression ratio should be used, which would not allow the engine to be used with gasoline. When ethanol fuel availability increases to the point where high-compression ethanol-only vehicles are practical, the fuel efficiency of such engines should be the same or greater than current gasoline engines. An engine that is capable of running on both E85 and gasoline by changing the compression ratios of the stroke cycle to make maximum use of either fuel is possible, but currently is not practical.
E85 prices will almost certainly fall as production rises. Large-scale farming, necessary to produce ethanol, requires substantial amounts of cultivated land. There is concern that, as demand for ethanol fuel increases, food crops may be replaced by fuel crops, driving food supply down and food prices up. The key to producing large quantities of ethanol lies in starting with materials that produce it more efficiently than corn does currently.
While producing ethanol from corn uses only the starch, leaving the protein, minerals and nutrients for use as food for humans or animals, most researchers agree that using non-food resources, like wood chips, willow trees, switch grass or corn stalks is a better long-term solution. The cellulose within these products would then be broken down and distilled into ethanol. Currently, however, this method of producing cellulosic ethanol is expensive. Cellulosic requires an extra processing step called cellulolysis, breaking cellulose down into sugars. This process does not generate toxic emissions when producing ethanol. The United States government has invested millions of dollars into assisting the commercialization of cellulosic ethanol. On 28th Feb 2007, the US Dept of Energy announced $385 million in grant funding to 6 cellulosic ethanol plants. This grant funding accounts for 40% of the investment costs. The remaining 60% comes from the promoters of those facilities. A total of $1 billion will be invested for approximately 140 million gallon capacity.
Many benefit from using ethanol as a fuel alternative. Ethanol replaces gasoline that would require the use of 600,000 barrels of oil a day. Today there are more than 110 ethanol plants across the country. The U.S. ethanol industry supported the creation of over 160,000 jobs in all sectors of the economy in 2005, boosting household income by $6.7 billion. E85 is the cleanest burning fuel available on the market today. The use of 10% ethanol-enriched fuel reduces greenhouse gas emissions by 12 – 19% compared with conventional gasoline.
Making the choice to use ethanol as an alternative fuel source may be cheaper and less damaging to the environment than using petroleum fuels in the near future. Currently our dependency on petroleum fuels has increased the cost of these products. As the process of switching to alternatives fuels begins the initial cost is higher; continued improvements in manufacturing and increased production of this alternative fuel will begin to decrease the overall cost of the product making it an environmentally and cost driven choice over gasoline.
References:
Oxygenate. (2007, June 1). In Wikipedia, The Free Encyclopedia. Retrieved 13:18, July 22, 2007, from http://en.wikipedia.org/w/index.php?title=Oxygenate&oldid=135086034
BioCycle Creating Cellulosic Ethanol; Diane Greer April, 2005; http://www.harvestcleanenergy.org/enews/enews_0505/enews_0505_Cellulosic_Ethanol.htm
2007 Environmental Protection Agency http://www.epa.gov/mtbe/gas.htm
2007 Answers.com http://www.answers.com/topic/ethanol?cat=health
2000 Archer Daniels Midland Company http://www.admworld.com/naen/
2007 VeraSun Energy Corporation http://www.verasun.com/
1998-2007 HowStuffWorks, Inc. http://www.howstuffworks.com/