Alternative Energy, Ethanol

Sources and Production Processes

Ethanol is derived from several sources. Food products such as corn, wheat, sugar cane, and rice are all viable candidates for ethanol production. Ethanol is produced through the fermentation of the sugars supplied from these foods. Materials used in ethanol production are wood chips, yard waste, crop residues, and solid animal waste. It can be made from just about any feedstock that has ample amounts of sugar, or materials that can be converted to sugar, such as sugar beets, sugar cane, or organic materials containing high levels of sugar such as starch and cellulose. Corn is widely used to produce ethanol. There are certain elements that are not as easily converted to sugar, such as trees and grasses, which are made of cellulose. Ethanol is also made from a wet-milling process. Many larger ethanol producers use this process, which also yields products such as high-fructose corn sweetener. These other materials are viewed as potential sources of low-cost ethanol production, because corn may not always be practical for ethanol because land needed to grow corn is needed for food and feed corn.

There are several ways to produce ethanol. One method is to convert lignocellulosic materials to ethanol. This method involves two processes. The first step is the hydrolysis of cellulose in the lignocellulosic materials to fermentable reducing sugars. After hydrolysis comes the fermentation of the sugars to ethanol. Another mode of production involves cereal grains. The grains are milled, which produces amylase and heat. The results go through a gelatinization process, resulting in amyloglucosidase and yeast. Next, saccharification and fermentation are conducted, and the product is heated, and then distilled. This produces ethanol, as well as stillage. When heat is added to the stillage, dry grain is produced.

Ethanol can be manufactured from a variety of different naturally-growing carbon-based organisms. For instance, in India, sugar cane molasses, a byproduct of the sugar industry, contains 45–50 percent fermentable sugars, allowing India to efficiently produce a significant amount of ethanol. Fermentation represents an ideal way to produce ethanol, as it is easy to ferment these sugars, and quite cost effective.

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