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A Probabilistic Analysis of the Switchgrass Ethanol Cycle
Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, TX 78712, USA
Received: 24 August 2010; in revised form: 26 September 2010 / Accepted: 29 September 2010 / Published: 30 September 2010
Abstract: The switchgrass-driven process for producing ethanol has received much popular attention. However, a realistic analysis of this process indicates three serious limitations: (a) If switchgrass planted on 140 million hectares (the entire area of active U.S. cropland) were used as feedstock and energy source for ethanol production, the net ethanol yield would replace on average about 20% of today’s gasoline consumption in the U.S. (b) Because nonrenewable resources are required to produce ethanol from switchgrass, the incremental gas emissions would be on average 55 million tons of equivalent carbon dioxide per year to replace just 10% of U.S. automotive gasoline. (c) In terms of delivering electrical or mechanical power, ethanol from 1 hectare (10,000 m2) of switchgrass is equivalent, on average, to 30 m2 of low-efficiency photovoltaic cells. This analysis suggests that investing toward more efficient and durable solar cells, and batteries, may be more promising than investing in a process to convert switchgrass to ethanol.
Keywords: cellulose; yield; conservation law; GHG emissions; monte carlo
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MDPI and ACS Style
Patzek, T.W. A Probabilistic Analysis of the Switchgrass Ethanol Cycle. Sustainability 2010, 2, 3158-3194.
Patzek TW. A Probabilistic Analysis of the Switchgrass Ethanol Cycle. Sustainability. 2010; 2(10):3158-3194.
Patzek, Tadeusz W. 2010. "A Probabilistic Analysis of the Switchgrass Ethanol Cycle." Sustainability 2, no. 10: 3158-3194.