Economics ethanol feedstock costs

The process economics is dominated by the feedstock cost. Because fuel ethanol is widely used as gasoline additive, the cost of ethanol is dependent on the prevailing oil (gasoline) price. At present the... 

Whey is a coproduct of cheese manufacturing. In 2000, California produced an estimated 1.5 billion lb of cheese, yielding 747,000 t of dried whey. It is costly to dispose whey in municipal water systems. Hence, an alternative use for whey would enhance the economics of cheese production. Currently, whey protein is used as a food additive, a protein supplement, and an animal feed. In addition, there are a few ethanol plants in California and the Midwest that use whey as a feedstock. The current California whey production would yield approx 4.7 million gal of ethanol. 

As many as 70 products were at one time produced commercially from ethanol. Some of these downstream products are butanol, 2-ethyl hexanol, crotonaldehyde, butyraldehyde, acetaldehyde, acetic acid, butadiene, sorbic acid, 2-ethylbutanol, ethyl ether, many esters, ethanol-glycol ethers, acetic anhydride, vinyl acetate, ethyl vinyl ether, even ethylene gas. Many of these products are now more economically made from other feedstocks such as ethylene for acetaldehyde and methanol-carbon monoxide for acetic acid. Time will tell when a revival of biologically-oriented processes will offer lower-cost routes to at least the simpler products. 

There are continuing efforts to develop cost-effective processes for fuel alcohol production, although the economics are often dependent on the availability of subsidized feedstocks to compete with traditional fuels derived from oil. The pretreatment and fermentation of such feedstocks, derived from corn, sugar cane, and even municipal waste, yields a dilute aqueous solution of ethanol which must be separated from a complex mixture of waste materials and then concentrated by distillation to remove water. Both batch and continuous production processes have been developed, with the requirement for effective bioseparations during both the pretreatment and ethanol recovery parts of the process. 

In the mid-1990s, few virgin biomass species were grown and harvested in the United States specifically for energy or conversion to biofuels, with the possible exceptions of feedstocks for fuel ethanol and a few tree plantations. This is not difficult to understand from an economic standpoint, especially if conversion costs are included. The nominal price of natural gas in the United... 

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