Sunday, May 13, 2007

New Technologies in Ethanol Production

New Technologies in Ethanol Production
C. Matthew Rendleman and Hosein Shapouri
February 2007
Office of the Chief Economist, Office of Energy Policy and New Uses
(Agricultural Economic Report Number 842)

Abstract
Fuel ethanol production has increased steadily in the United States since the 1980s, when it was given impetus by the need to reduce energy dependence on foreign supplies. The momentum has continued as production costs have fallen, and as the U.S. Clean Air Act has specified a percentage of renewable fuels to be mixed with gasoline. The fraction of annual U.S. corn production used to make ethanol rose from around 1 percent in 1980 to around 20 percent in 2006, and ethanol output rose from 175 million gallons to about 5.0 billion gallons over the same period. New technologies that may further increase cost savings include coproduct development, such as recovery of high-value food supplements, and cellulosic conversion. High oil prices may spur the risk-taking needed to develop cellulose-to-ethanol production. Developments such as dry fractionation technology, now commercially viable, may alter the structure of the industry by giving the cheaper dry-grind method an edge over wet milling. Dry milling requires smaller plants, and local farmer cooperatives could flourish as a result. Though improvements in processing and technology are important, however, the fluctuating price of inputs such as corn, the cost of energy alternatives, and environmental developments play larger roles in the fortunes of the
industry.

Table of Contents
Introduction . . . . . 1
Changes Since the 1993 ERS Analysis of Ethanol Production . . . . . 3
Ethanol’s Energy Efficiency . . . . . 5
Ethanol Production Processes . . . . . 6
Input Improvements: Higher-Ethanol-Yielding Corn . . . . . 8
Process Improvements . . . . . 10
Advances in Separation Technologies . . . . . 10
New Ways of Fermentation . . . . . 12
New Enzymes . . . . . 13
Distillation Technology . . . . . 14
Control Systems . . . . . 14
Environmental Technologies . . . . . 15
Technologies Involving Coproducts . . . . . 16
The Growing Supply of Feed Coproducts . . . . . 16
Sequential Extraction . . . . . 17
Corn Germ Recovery for the Dry-Mill Process . . . . .17
Centrifugal Corn Oil Separation from the Distiller’s Grain Stream . . . . . 17
CO2 Recovery . . . . . 17
Stillage Clarification and Other Uses of Membranes . . . . . 18
Biorefinery . . . . . 18
Extraction of Compounds from DDGS . . . . . 19
Corn Fiber Oil Recovery . . . . . 19
Regional Impacts of Ethanol Plants . . . . . 20
National Benefits from Ethanol . . . . . 21
Biomass: Ethanol’s Future? . . . . . 22
Cellulose to Ethanol: The Process . . . . . 22
Supplying Biomass . . . . . 23
Biomass Byproducts: Problems with Acid and High Temperatures . . . . . 23
Other Biomass-to-Ethanol Improvements . . . . . 25
Conclusions: Ethanol’s Potential . . . . . 26
References . . . . . 27

Full Text Available
[http://www.usda.gov/oce/energy/aer842_ethanol.pdf]

About the Authors
C. Matthew Rendleman is with the Dept. of Agribusiness Economics, Southern Illinois University, and Hosein Shapouri is with the Office of Energy Policy and New Uses, USDA.

Acknowledgments
The authors wish to thank a number of people who made valuable suggestions and corrections to the paper. They include Don Erbach and Andrew McAloon of the Agricultural Research Service, USDA, Jack Huggins of the Nature Conservancy, and Vijay Singh of the Dept. of Engineering at the University of Illinois at Urbana-Champaign.

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