Thursday, May 17, 2007

Does it take more energy ...?

Does it take more energy to make ethanol than is contained in ethanol?

That seems to be the question asked by consumers and industry "experts" each day.

Separating fact from fiction can often be a challenge. Some answers appear to be more right than others. And all have varying assumptions that can be confusing and contradictory. But the overwhelming evidence suggests that ethanol has been, is, and will be a positive net energy producer.

David Morris offers a wide discussion of the issue HERE. But it seems to boil down to a few key points that he lists:

The United States Department of Agriculture has done the best job of showing comparative data of all the major studies on the energetics of ethanol. This is an excellent place to understand why there are differences. The initial USDA report was done in 1995. Click here for the 1995 USDA study. An update was published in 2002. Click here for the 2002 USDA study.

David Pimentel, a Cornell University professor, has been ethanol’s most consistent critic. He has done several studies over the last few years. His latest was published in 2003. Click here for Pimentel's study. For a more recent critical analysis, see University of California Berkeley professor Tad Patzek's study, Thermodynamics of the Corn-Ethanol Biofuel Cycle (2004).

There have been several critiques of Pimentel’s methodology and numbers. Here is a brief one - Click here for the study and critique of Pimentel's work . Another much more extensive, indeed exhaustive, analysis is available here. Click here for study. To my knowledge, Pimentel has not responded to his critics nor done a detailed critique of studies that come to different conclusions.

It's worth reading mr. Morris' complete site reference. Don;t say that we didn't warn you that your head will hurt!


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