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October 05, 2006

Ethanol: Boon or Boondoggle?

Reducing America’s dependence on oil is certainly necessary for strategic and economic reasons and probably necessary for environmental reasons.  Is ethanol a good substitute for oil?  Economically?  Environmentally?  Does it make sense to make ethanol out of corn?  Or is the heavily subsidized corn ethanol program a boondoggle to buy votes from midwestern grain farmers and further enrich lobbying and grain processing powerhouse Archer Daniels Midland.

“All of the above” is the correct answer.

The primary argument against making ethanol from corn is the claim that the process consumes more fossil energy than it displaces, that more gallons of oil (or the equivalent of coal or natural gas) go into turning corn into ethanol than are displaced from America’s gas tanks by the ethanol produced.  The foremost ethanol-skeptics on this basis are David Pimentel, professor of ecology and agriculture at Cornell, and Tad W. Patzek, professor of civil and environmental engineering at Berkeley.  A study by them claims that corn as an ethanol source requires 29 percent more fossil energy than the fuel produced, soybeans 27%, switch grass (an alternative not in the human food chain) 45% and wood biomass 57%.

On the other side, the most cited study was done in 1995 by Hosein Shapouri, James A. Duffield, and Michael S. Graboski.  At the time, Shapouri and Duffield were economists with USDA's Economic Research Service. Graboski was director of the Colorado Institute for Fuels and High Altitude Engine Research, and professor of chemical engineering at Colorado School of Mines, Golden, CO.  This study estimates that you get about 1.3 times as much energy out as you put energy in when you make ethanol from corn.  Later estimates by the USDA are even higher (better) since corn production now uses less energy-expensive fertilizer and conversion to ethanol uses less energy.

Whom to believe? Actually, it looks like the government-affiliated reports have the upper hand.

To mediate, I read “Ethanol Can Contribute To Energy and Environmental Goals”, A UC Berkeley paper by Alexander E. Farrell, Richard J. Plevin, Brian T. Turner,Andrew D. Jones, Michael O’Hare, and Daniel M. Kammen (credentials in the paper).  This isn’t light reading but it does a scrupulous analysis of assumptions and calculations in six competing papers on the energy efficiency of ethanol production from corn and comes to the conclusion in the  title.  Excel spreadsheets are provided for those who’d like to play with the model.

I’m convinced that Pimitel and Patzek disregarded byproduct energy and used outdated numbers on yield and the energy required to produce the yield. Looks like you ARE displacing oil when use an ethanol blend.

What about saving the environment from carbon dioxide emissions?

First you have to buy the strange-sounding argument that carbon dioxide produced by burning fuel made from corn doesn’t count.  Most environmentalists do accept this argument because the carbon in the corn got there when the corn took carbon dioxide out of the air during photosynthesis; you can’t put more carbon dioxide back into the air by burning biomass of any kind than the biomass took out of the air while growing. On the other hand, when you burn coal or oil, you’re releasing carbon which was taken out of the atmosphere millions of years ago and increasing the CURRENT level of atmospheric carbon dioxide.

OK, if you buy that (I do after some thought), you then have to go back to the first argument.  If it takes more fossil fuel to produce ethanol than the ethanol displaces, you still aren’t doing the environment any favor (unless of course, you sequester the carbon dioxide produced in the process).  But, assuming that you do net displace fossil fuel by making ethanol from corn and that you don’t count the carbon dioxide produced by burning the ethanol, ethanol from corn does reduce carbon dioxide emissions per mile driven.  Phew…

Further questions for further posts:  Even if ethanol from biomass is effective in reducing oil dependence, is corn the right source?  Is growing crops the best way to harness solar energy from a field?  Is the investment the US is making in ethanol well spent?

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