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Liquid Bio-fuels - Alcohol - Ethanol, Methanol and Butanol
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The discussion on this page is about ethanol, however other alcohol fuels are mentioned. Ethanol (or ethyl alcohol) is a flammable, colourless and slightly toxic liquid chemical compound consisting of oxygen, hydrogen and carbon. It is used widely as a constituent of alcoholic beverages, flavourings, colourings and medicines as well as constituent of body scents and body/hair creams. Lately and out of search for alternative energy sources, Ethanol has also found use as fuel in equipment and vehicle engines, because it is a clean burning fuel.
Ethanol is produced in two ways: Ethylene hydration; and Biological fermentation of sugar or converted starch
Commercial alcohol is produced from ethylene hydration while ethanol biofuel is made from the fermentation of sugar or converted starch contained in grains and other agricultural products. Ethanol biofuel has been made from corn, wheat and other food crops. This development has been initially thought of as good in that it increases demand for farmer's products and provides increased employment opportunities. However, it has been argued that fuel production from agricultural crops reduces the amount of such crops available for feeding with the ultimate possible effect of leading to food shortages.
Consequently, to avoid dependence on food-based feedstock, researches are continuously being conducted to identify new feedstock (input materials) for ethanol fuel production. Certain plants or grasses have been found very promising in replacing food crops as ethanol feedstock. Some of the plants that are planted specifically for the generation of ethanol and methanol, include: switchgrass, hemp, hybrid willow, hybrid poplar (cottonwoods) and sugarcane.
For use in vehicle engines, ethanol is blended with gasoline to produce a fuel called "gasohol". Gasohol can be used in gasoline-powered vehicles manufactured since the 1980's. Similar to Biodiesel blend, ethanol blend is represented as Exx, where xx is the percentage of the ethanol in the gasohol. For instance, a 10% ethanol to 90 % gasoline blend is represented as E10; 15% ethanol to 85% gasoline blend as E15 etc.
Some of the advantages of using ethanol as fuel are:
- ethanol burns more cleanly and completely than gasoline.
- ethanol is renewable
- ethanol is better for the environment; it reduces greenhouse gas (ghg) emissions on the long run. Though the conversion of biomass (feedstock) to ethanol and the actual use of ethanol to power engines produce ghgs, the ghgs are far less (in quantity) than when using gasoline. Furthermore, ghgs (particularly carbon dioxide) are sucked up during the growing season of the feedstock used to manufacture ethanol; the plants used to produce ethanol serve as carbon sink during their days of growing.
Some of the downsides of ethanol as fuel are as follows:
- Ethanol has slightly lower energy than gasoline. 1 gallon of pure ethanol contains about 66 percent as much energy as 1 gallon of gasoline. 1 gallon of E85 (85% ethanol to 15% gasoline blend) contains about 71 percent as much energy as 1 gallon of pure gasoline. It could cost you more to buy ethanol for the same distance you travel on gasoline.
- Currently, ethanol production is mainly from corn and other food crops. Could lead to food shortage. However, ethanol will be sourced from wood and other cellulosic materials over time
- Ethanol production requires subsidies from governments to make it competitive to gasoline.
Most gasoline-powered vehicles can run on a E10 blend. This blend is already available in several service stations in North America. Some vehicles are specially manufactured to operate on an E85 ethanol blend (i.e. 85% ethanol to 15% gasoline). The 15% gasoline is needed to assist in engine starting because pure ethanol is difficult to ignite in cold weather. In other words, E100 dependent cars may not be effective year round in very cold regions. The E85 blend cannot be used in standard gasoline vehicles, but only in vehicles designed to use high ethanol blend. However, vehicles designed to run with a high ethanol blend can also operate using gasoline when necessary.
E10 blend fuel can be used directly in gasoline engines to produce same level of service without modifications to the gasoline engine. For higher blends (e.g. E85), larger fuel tanks are designed and larger quantity of gasohol is required to produce similar service levels as the gasoline fuel. Besides the larger fuel tank required, other modifications required in migrating from a gasoline-powered car to a high ethanol blend powered cars are:
- Modifications to the engine's intake valves,
- Modifications to the fuel-injection system;
- Modifications to the ignition system; and
- Replacement of all vehicle materials that could be destroyed by alcohol with materials that are alcohol resistant materials. Materials such as zinc, lead, magnesium, aluminum, plastics and rubbers, that are commonly used in gasoline-powered vehicles are not alcohol proof and can be broken down by alcohol. These materials will have to be replaced with alcohol resistant materials such as stainless steel. The fuel tank and fuel lines of most Flex-Fuel Vehicles (FFV) that use E85 blend are made of stainless steel.
Ethanol is produced in large heated tanks called digesters. Plant materials and chemicals or yeasts are added to the digester. The process converts cellulose in the plant materials into sugars and then the sugars are converted into alcohol through fermentation.
Other alcohols that fall in the category of ethanol are methanol and butanol
For in-depth discussion on ethanol and other biomass energy sources, we recommend that you get a copy of Clean Energy Fuels a book written by Dr. Dele Morakinyo one of the contributors to EnvironBusiness.com.
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