Say Anything Blog

Troy, the problem with this observation is that the energy density isn’t a good measure of quality of the fuel.  A more honest evaluate includes the rate-of-burn of the fuelent, the maximum compression etc.  After factoring in the higher volatility of ethanol and so forth, the best number possible, including a completely reengineered engine, gives ethanol an efficiency of 90-95% of gasoline per unit weight or volume.  Given that the best numbers suggest producing ethanol using current means generates 20% more energy that is used to produce it, this is still a net gain over gasoline from a strict energy budget perspective.  Factoring in the non-polluting nature of the ethanol compared to the health, economic and social consequences of the pollutants from petroleum-based fuels, and you can see why there is some enthusiasm here.

In any case, Pimental’s work is massively and often embarrassingly flawed.

He claims for example, that complete utilization of corn would only provide us with our gasoline needs, but we are already at the 5+% level (5 billion gallons ethanol produced last years compared to 95 billion gallons of gasoline consumed) of with less 10% of the corn being produced used to produce the ethanol. Scaling this up suggests a number closer to 50%, which is the EPAs number. Clearly Pimental’s argument needs some work.

Pimental also claims that producing ethanol uses more energy than it produces.  He is singular in making this claim, and no other researcher, including him apparently, agrees with him.  I say “including him” because the research paper that makes this claim of no net energy yield in its conclusion, is contradicted by its own numbers in the body of the paper.  Pimental’s own numbers suggest a 5-10% net yield.  Other researches, who have no underlying agendas, suggest that producing ethanol generates about 20% more energy than is used to create it. 

The embarrassing contradiction in Pimental’s manuscript arose, by the way, because of changes that were forced on his manuscript by the reviewers, who pointed out numerous numerical errors in his calculations.  He made the changes to the body of the article, but even though the revised numbers contradicted them, he breathlessly left the abstract and conclusions unchanged!  Also, Pimental’s anti-ethanol jihad started as a short note to a research journal a number of years ago written by Patzek and Pimental.  The paper was also embarrassingly wrong, containing numerous numerical errors as well as using antiquated or erroneous data.  Rather than just withdraw the claim, Pimental continues to dig himself in deeper.

And that doesn’t factor in using corn stover (the waste product from corn) or other cellusoidal sources to make ethanol from.  About 50% of the total bio-energy available in harvested corn is in its stover. Brazil by the way is already doing this. 

There may be good arguments against ethanol, but those given above aren’t it.

Robert108 brings up undesirable characteristics such as it is a solvent whereas gasolilne is naturally lubricating for example.

Another argument is that corn kernel is of course a food source.  Since energy costs are only 5% of the typical American’s budget, whereas food is more like 20%, increasing the food costs through use of ethanol produced from corn kernels may not make short-term economic sense.

Keep in mind we have been using petroleum to run engines for a century, so the engineering is quite mature there.  The push for ethanol-burning engines is very recent, and it will take a while to learn the ultimate limitations of this technology.  Ultimately producing ethanol from corn kernels may be abandoned in favor of other technologies, such as those based on corn stover or switch grass.  The future is hard to predict on this one, but a reusable non-polluting energy source is clearly superior to a finite-resource that creates a plethora of social, economic and political problems.  IMHO.

Some references:

A recent non-partisan study on ethanol-vs-gasoline production

Replacing the conventional four-stroke with a “Miller Cycle” engine promises improved efficiency for ethanol burning engines

Corn stover as primary source of ethanol?

The Advanced Energy Initiative

The biggest problem with using all the corn crop for ethanol is the fact that it would cause another civl war, the south needs their grits.