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The Great Ethanol Energy Balance Debate, Round n+1

The National Corn Growers Association (NCGA) is hosting an Ethanol Energy Open Forum next week in which Bruce Dale, a Michigan State University professor, and John Sheehan, a senior engineer at the National Renewable Energy Laboratory, will debate David Pimentel, a Cornell University professor, and Tad Patzek, a professor from University of California–Berkeley, on the merits of the latter two’s recent energy balance study.

That study slammed both ethanol and biodiesel as “not sustainable”(earlier post).

NCGA organized the event on 23 Aug at the National Press Club in an effort to refute the study...or at least to provide a counterbalance to the publicity the study generated. (The event, from the National Press Club’s point of view, is a third-party news conference.)

The debate portion of the program will be followed by a session on the promise of renewable fuels. The second session, called “Renewable Energy: Dynamic Possibilities,” will feature presentations by representatives from the US Department of Agriculture, Argonne National Laboratory and several other ethanol experts.

This forum is all about solutions. On one hand, we have critics of renewable energy who manipulate numbers to create worst-case scenarios and criticize the potential impact of renewable energy and biofuels. On the other hand, the public will finally get to hear about solutions and what biofuels can and are doing to help with our energy problems.

We are very confident in our facts and science, and that is why we want our opportunity in front of the public microphone to tell the true and accurate story about biofuels and renewable energy.

—Rick Tolman, CEO, National Corn Growers Association

It’s not clear at this point if there will be a webcast or a public transcript.



Outstanding. Bona-fide scientists on both sides, presenting information that has a huge impact on public policy.

Why don't we have more of these?!


In the short run economics may be more important than chemistry, bearing in mind the corn crops and harvesting machinery are already there. The question should be what should we be doing about alternative fuels in 10 years time, assuming no subsidies or tax breaks. If the answer is forget ethanol then a case must be made for a better alternative.


If ethanol is energy-negative, why does someone who says so have to make a case for any alternative at all?

There's also the issue of energy production.  Corn ethanol, assuming 200 bushels/acre/year, 2.66 gallons/bushel and 12780 BTU/gallon yields an average power of 227 watts/acre; you might get 20% of that out at the wheels, or ~45 watts/acre delivered to the road.  In contrast, a modern 2 megawatt wind turbine with a capacity factor of 30% and situated on a square kilometer by itself averages 2430 watts/acre.  Allowing 15% losses for long-distance transmission, 10% in the charger, 10% in a battery and 20% in a motor you get 1020 W/acre at the wheels.

If we're going to spend a billion a year on alternative energy subsidies for cars, 80% of that should go for batteries.


I made a mistake above; ethanol is 12780 BTU/lb, not per gallon.  At a density of .7893 it would have 6.59 lb/gallon, so make it 296 watts/acre average.

Wind still yields more than 3 times as much energy per acre as ethanol, and you can grow food on the land.


What about cellulose to ethanol conversion systems? Energy is already invested in growing an entire plant for food. The grain is a minor fraction of the plant's mass. Put corn in your pie hole and the stover in the processor. Use juice from that MW turbine to power the processor.


I did a quick check and found a claim that #2 yellow corn weighs about 56 pounds/bushel; at 200 bu/ac the yield would be 1120 lb of maize.  At that same yield, the excess corn stover would amount to 3.8 tons, or about 3.5 times as much as the grain.  Assuming the same conversion efficiency for both, that would put the yield of wind and cellulosic ethanol at about par.

On the other hand I seriously overestimated the area required for such a small wind turbine, and the EROEI of the wind system is far greater.


Why not do it all? Put up your wind turbine, grow corn under it, eat the grain, convert the stover to ethanol, if there's anything left over, consider using it for animal feed. Live life. Be happy.


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