Renewable Energy Technology Assessments - Kauai Island Utility ...
Renewable Energy Technology Assessments - Kauai Island Utility ...
Renewable Energy Technology Assessments - Kauai Island Utility ...
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Kaua’i <strong>Island</strong> <strong>Utility</strong> Cooperative<br />
<strong>Renewable</strong> <strong>Energy</strong> <strong>Technology</strong> <strong>Assessments</strong><br />
3.0 <strong>Renewable</strong> <strong>Energy</strong> <strong>Technology</strong><br />
Options<br />
Resource Availability<br />
While most of the ethanol produced in the United States today is derived from<br />
corn, ethanol is also produced from agricultural feedstocks that are high in simple sugars<br />
such as sugarcane and sugar beets. Currently, the sugar or starch components of plants<br />
are primarily used for ethanol production. It is also possible to utilize the more fibrous<br />
parts of biomass, such as the cellulose, hemicellulose polymers, and lignin to produce<br />
ethanol. While the sugar polymers in hemicellulose and cellulose are more resistant and<br />
difficult to break down using conventional dry milling processes, other production<br />
processes are being developed that allow these components to be fully utilized.<br />
Researchers have focused their efforts on acid hydrolysis and enzymatic hydrolysis<br />
technologies that are capable of breaking down or hydrolyzing the sugar polymers in<br />
lignocellulosic biomass such as trees, grasses, and waste biomass. Processes are also<br />
under development that gasify organic feedstock (including municipal waste) and<br />
synthesize ethanol from the product gas. These alternative processes hope to expand the<br />
biomass resource base and lower feedstock cost in ethanol production.<br />
Cost and Performance Characteristics<br />
As a fuel, ethanol has a lower energy density than gasoline, which means that it<br />
contains less energy per gallon than gasoline does. The energy content of ethanol is<br />
84,000 Btu/gallon which, when compared to a gallon of gasoline, translates into only 70<br />
percent of the energy per gallon. The price of ethanol is dictated by a complex<br />
interaction of the cost of the raw feedstock, the processing technology, state and national<br />
subsidies, and the supply and demand for the product. Because of all of these factors, it<br />
is not necessarily true that a rise in gasoline prices will make ethanol comparatively<br />
cheaper. Nationally, ethanol has recently cost anywhere from $18/MBtu to $25/MBtu,<br />
which is $6-$8/MBtu more than gasoline.<br />
Currently the costs of ethanol production using the advanced lignocellulosic<br />
technologies are not competitive compared to conventional dry milling and wet milling<br />
processes. The high costs are attributed to the high-volume acid requirements.<br />
Advancements in acid recovery and recycle will significantly reduce the cost of ethanol<br />
production using the lignocellulosic technologies. It has been estimated that such<br />
advancements can reduce the cost of ethanol production by up to 40 cents per gallon.<br />
Gasoline and diesel production far outweigh their biofuel counterparts. The<br />
market potential for ethanol is greatest in the Midwest, close to the corn feedstock. The<br />
difference in price between the Midwest and the West Coast, which has little corn<br />
production, can be 20 cents per gallon or more. However, proposed legislation to ban<br />
MBTE as a fuel additive and implement new renewable fuel standards, may drastically<br />
21 March 2005 3-24 Black & Veatch
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