Ethanol Energy Debate Continues

The major parties in the continuing debate as to whether ethanol's energy efficiency is better than that of other fuels has completed its most recent round of arguments with Michael Wang's presentation.  He concludes that ethanol is better because it uses less fossil fuel in its production than gasoline does.  My conclusions after this round of studies are no different than in my previous analysis.  I agree with the Wang arguments. 

Wang of Argonne National laboratories argues that what really matters is that ethanol compares favorably to gasoline, the fuel it replaces.  His argument is that the fuel that uses the least fossil fuel in its production process, relative to its energy output, is the most desirable.  He defines the Fuel Energy Ratio (FER) as ratio of the energy in the fuel being considered to the fossil fuel input to the fuel during its life-cycle of production.  Ethanol comes out way ahead when compared to other fuels.  Cellulosic ethanol has an FER of 10.31, corn ethanol: 1.88, coal: 0.98, gasoline: 0.81 and electricity: 0.46. He also finds that ethanol produced from corn achieves moderate reductions in greenhouse gases.  Ethanol produced from grass and other "cellulosic" or woody biomass sources can achieve much greater energy and greenhouse gas benefits. He dismisses an ongoing academic argument about the amount of energy needed to produce ethanol.

A paper published in the March edition of "Natural Resources Research" by researchers at Cornell University and the University of California at Berkeley claims that ethanol production from corn requires 29 percent more energy than is provided by the resulting ethanol fuel. In contrast, a 2004 study by the U.S. Department of Agriculture (USDA) found that ethanol produces 67 percent more energy than is consumed in its production.  The chart below, from Wang, shows how the preponderance of studies show that corn ethanol has a positive energy value that has increased with time. 

Proponents of Shapouri argue that Pimentel continues to use outdated processes for the production of ethanol and includes energy from extraneous sources.  They also contend that he attributes to much energy to the production of fertilizer and to the growing of the corn.  Critics of Shapouri claim he omitted some energy inputs in the ethanol production system.  Wang presented data showing how the amount of fertilizer used in corn production has decreased with time.  Shapouri made the case for data that showed that the energy needed to grow corn is less than that used by Pimentel.

Resources:

"DOE National Laboratory Expert Notes Energy Benefits of Ethanol", EERE News, 8/31/05
"Energy and Greenhouse Gas Emissions Impacts of Fuel Ethanol", Michael Wang, Argonne National Laboratory, 8/23/05
"Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower" , David Pimentel and Tad W. Patzek, National Resources Research, March 2005
"The 2001 Net Energy Balance of Corn Ethanol", Hosein Shapouri et al., USDA, June 2005

Technocrati tags: ethanol, renewable energy, ethanol energy efficiency

Comments

[Engineer-Poet]

I find that these studies continue to beg important questions:

1. If we are trying to displace petroleum, is ethanol the preferred thing to use (other than over the short term)?
2. If we do intend to use (maize|switchgrass|paper mill byproducts) as an energy source, is ethanol the best thing we can make out of it?

Without answering those, the productivity of various crops is not terribly relevant.

[beev]

Thank-you, Jim, for this short and insightful analysis.

[Jim from The Energy Blog]

I believe that cellulosic ethanol is the best answer for replacing gasoline for at least the next 25 years. The combination of growing cellulosic crops plus waste product feedstocks provides the necessary feedstock to make significant quantities of ethanol.

Biodiesel from oil seed is not the answer because engine manufacturers do not like it and there is not enough land to grow it. It might be a good short term fuel until we have enough to make a 5% blend with petroleum diesel which the engine manufacturers accept. Some fleet operators seem to have no objection to biodiesel and if they are proved correct, the engine manufacturers should come along. An algae feedstock might change that picture if anyone can develop that system.

Fischer-Tropsch fuels are not well enough demonstrated or as energy efficient as ethanol at the present time. FT processes should be well explored on a large scale, as with the CHOREN gasifier/Shell FT process. The product from FT is very low sulfur and should be acceptable to engine manufactures. FT processes are likely to be the source for diesel fuel at some time.

I do not like hydrogen fuel cells at the present and don't think we can afford to wait until they are developed. My mind could be changed if a sensible plan could be developed for the hydrogen production, required infrastructure and cost and reliability of the cells. Biofuels make a much more sensible choice at the present time.

None of these alternatives will be implemented on a sufficient scale to be of any significant help in compensating for the decline of oil production and/or to reduce our dependence on forign oil in the next 5-10 years, but we must proceed with them. Hybrid vehicles, specifically plug-in hybrids are our best short term solution to reducing transportation fuel consumption.

[Engineer-Poet]

I have some preliminary answers regarding ethanol: production of ethanol from maize is not as good as burning the maize as home-heating fuel and using the natural gas or LPG that would otherwise be used for distillation or home heating as motor fuel.  Blog entries on this:

One: http://ergosphere.blogspot.com/2005/09/ethanol-mirage.html
Two: http://ergosphere.blogspot.com/2005/09/ethanol-mirage-ii.html

[Rich]

There is a new, patented distillation process available for ethanol, taking low content fermentation "beers" of 10-15% up to 99.5%, with no heat distillation process involved. This reduces the energy required to "refine" ethanol by 70%, thereby making it a truly viable fuel-stretching additive.

See January issue of "Chemical Engineering", page 15 for a brief article covering this new process, and the company owning it, Ultrasound Brewery Co. (Japanese).

[Engine Additive]

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