First, the post to which I was responding:
By TomZ on 2/11/2009
It has so many disadvantages:
- lower energy per volume (MPG)
- not lower cost, likely higher cost
- cross-impact on food costs- no CO2 reduction, or maybe an increase
Let's stop the handout madness! Stop Ethanol use today!
And my response on 2/11/2009:
Corn based ethanol is good for drinking (e.g. Bourbon), but it's a terrible fuel. In addition to the above reasons, corn requires huge amounts of water to grow and the increase in corn production for ethanol has accelerated the lowering of the ground water table in the massive Ogallala aquifer.
Corn based ethanol uses up precious farm land, uses huge amounts of water, and only produces about 30% more energy that it takes to produce (and that's considered a generous estimate, it may be closer to break even).
Stop the insanity! No subsidies for corn, corn based ethanol, or cornstarch/HFCS. Tell your congresspersons to end the subsidies on corn, end the taxes on sugar cane, and end or delay the ethanol blend requirements. That will affect the ethanol and alternative fuel markets as well as the sugar and sweetener market and food prices.
The corn growers and corn based ethanol distillers may not like it, but until they can demonstrate a viable way to make cellulosic ethanol, the only ethanol made from corn should be in liquor stores.
Additional notes added 2010-11-05:
The current 10% ethanol blend actually increases our oil consumption. Prior the ethanol blend requirements, a gallon of gas was 85% gasoline and up to 15% MTBE (or ETBE). Now it's 90% gasoline + 10% ethanol, an increase of 5.8%. Because ethanol has a lower energy density than MTBE/ETBE and because current engines do not run optimally on ethanol or ethanol blends, fuel economy has also decreased by 5%-10%, for a net increase in gasoline consumption of about 10%-15%.
Ethanol produced from sugar cane (as is common in Brazil) produces about 5x as much ethanol as the energy spent to produce it, vs the most efficient corn based ethanol production @2.2x, with 1.3x-1.5x typical.
The US government places maximum quotas on sugar from sugar cane & sugar beets on each state that produces those products, with a high tariff on any they sell in the US above that amount (so any excess is sold internationally). At the same time, they pay subsidies to corn growers AND to corn based ethanol refiners.
Growing corn requires a lot of nutrients from the soil, and enormous amounts of water (up to 4000 gallons per acre per day). This is depleting our farm land AND extracting water from our aquifers faster than nature can replenish it.
It's bad policy, it's not "green", and it's certainly not sustainable.
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I agree it's bad policy. In my thermodynamics class at WPI back in 1977, we discussed exactly those issues you've described and those pointed out by TomZ. Nothing in the analysis of the situation has changed from an engineering thermodynamics point of view. The laws of thermodynamics don't change. Sadly, the politicians were sold a bill of goods by the Iowa corn growers and now we are all stuck with it.
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