Tuesday, October 10, 2006

Ethanol primer

A lot of people are singing the praises of ethanol these days -- from George W. Bush to Willie Nelson. Its promise for being the environmental alternative to oil seems almost to good to be true. In fact, some prominent agricultural economists are convinced that the claims are exaggerated. It can get awfully confusing. So what's the scoop?

M. J. Bradley Associates, a strategic information service, produces an incredibly informative bi-monthly newsletter called "Environmental Energy Insights". The July/August 2006 issue has a lead story entitled "Biofuels: The Real Deal -- or Not?" It does a very good job at framing the ethanol issue. Excerpts from that article follow. (GW)

Biofuels: The Real Deal -- or Not?
Corn ethanol is a mixed bag, and the contentious debate about its virtues and disadvantages has only obscured the reality. It could promote rural economic growth, and likely provides some energy and greenhouse gas benefits, even when produced with the usual mix of fossil fuels. On the other hand, it may be disadvantageous from the point of view of other environmental considerations. In theory, corn ethanol could very substantially reduce our dependence on foreign oil supplies—but only if it offsets a large portion of our gasoline consumption, which it appears unlikely to do.

Cellulosic ethanol is an entirely different story, but appears not to be close to large-scale commercial production. Corn ethanol may be useful in providing a transition to cellulosic ethanol, but until cellulosic ethanol is widely available other strategies for achieving some of the same goals—such as increasing vehicle fuel efficiency and promoting hybrid technology and public transportation—are likely to deliver bigger benefits.

The core debate around ethanol has centered on whether more energy goes into its production than it actually supplies, with the highly publicized work of two scientists concluding that the energy balance is substantially negative (which is almost certainly incorrect). Unfortunately, the extreme position of the energy balance contrarians, juxtaposed with the enthusiasm of the corn lobby, has obscured a much more nuanced story: corn ethanol can provide both a small to moderate energy and greenhouse gas benefit depending on the conditions of its production (e.g., whether the land on which the corn is grown is already farmed, how much fossil fuel is used to make it).

Corn ethanol may be good news for the economy of rural America, although this will depend in part on the sustainability of ethanol-related land use practices. Moreover, although in theory corn ethanol could substantially reduce our dependence on foreign oil supplies, it is unlikely to be produced in sufficient quantities to do so. In fact, converting the country’s entire corn crop to ethanol—a clearly untenable idea—would supply only 12 percent of U.S. demand for gasoline.

But if corn ethanol presents an ambiguous picture, cellulosic ethanol does not—except that it is nowhere in the world produced commercially, and probably will not be, at least in substantial quantities, for many years. Cellulosic ethanol is ethanol made from nonfood feedstocks like corn stalks, rice husks, switchgrass, woody plants, and prairie grasses. It may well be the transportation fuel of the future. In the meantime, we should keep in mind that increasing the fuel efficiency of vehicles, promoting hybrid technology, and supporting public transportation will be important companion strategies to the development of biofuels.

We focus on E85 (fuel with 85 percent ethanol and 15 percent gasoline) rather than E5 or E10, which are used as oxygenates to help areas meet air quality standards.

Frequently Asked Questions:

Does It Take more Fossil Fuel Energy To Make Corn Ethanol than the Ethanol Provides as a Fuel?

Answer: No.

The public debate around corn ethanol has focused almost to the exclusion of other issues, on whether it takes more fossil fuel energy to make than it actually provides as a fuel. One way to think about the net energy balance for corn ethanol—which is almost certainly positive—is to think about the fossil fuel inputs as liberators of the corn’s solar and chemical energy.

In order to calculate the net energy value of corn ethanol, researchers measure the energy value of the outputs—the ethanol and its coproducts—as compared to the energy of all of the fossil fuel energy inputs. On the inputs side of the equation, corn uses large amounts of synthetic fertilizer (made mostly from natural gas) and pesticides (made primarily from petroleum).

Plowing, planting, spraying, and harvesting use diesel fuel; drying the corn after it is harvested requires natural gas. And all of that comes before the corn is distilled into ethanol, an energy-intensive process that also requires fossil fuel. However, on the outputs side there are coproducts like “distillers’ dry grain with solubles” (an animal feed), corn gluten feed, and corn oil, in addition to the ethanol itself.

The highly publicized work of only two scientists, David Pimentel and Tad Patzek, take the view that the energy balance for corn ethanol is substantially negative. All of the studies cited above conclude that the work of Pimentel and Patzek is fundamentally flawed. Among other things, it fails to assign energy inputs to coproduct outputs correctly; uses unrepresentative and poorly documented data (e.g., energy values for farm machinery that are more than an order of magnitude greater than values reported elsewhere); and includes energy inputs that other studies do not include, such as the energy costs of manufacturing farm equipment.

Can Corn Ethanol Help Us Reduce our Reliance on Petroleum Products?

Answer: Yes.

Gasoline is refined from crude oil, or petroleum, about 60 percent of which comes from foreign sources, while corn and other ethanol feedstocks are home grown commodities. Moreover, many people believe that the world is soon to run low on oil Although it takes energy to make ethanol, most of that energy typically comes from coal and natural gas, of which there are abundant domestic supplies.

A 2002 U.S. Department of Agriculture study evaluates the net energy gain for corn ethanol from the perspective of petroleum product (i.e., gasoline, diesel, and fuel oil) use, which gives an estimate of the petroleum displacement value of ethanol. According to the study, only a small amount—about 17 percent—of the energy used to make corn ethanol comes from petroleum products, with the rest primarily from coal and natural gas. The researchers conclude that one British thermal unit (Btu) of liquid fuel, used with other forms of energy (e.g., coal, natural gas), will produce 6.34 Btu of corn ethanol. In other words, to the extent that we substitute corn ethanol for gasoline, we greatly decrease our reliance on petroleum products

How Does Corn Ethanol Compare to Gasoline inTerms of Greenhouse Gas Emissions?

Answer: Corn ethanol is slightly better, assuming favorable production methods.

If making corn ethanol simply involved burning the same carbon that a plant just recently removed from the air, then corn ethanol would have a big greenhouse gas advantage over gasoline. But this is overly simplistic for a number of reasons. For one, agricultural practices like tilling (in the growing and harvesting of corn) result in greenhouse gas emissions. For another, as we have already discussed, fossil fuels are implicated in making corn ethanol—for example, in manufacturing fertilizer, plowing fields, and distilling corn into ethanol. Additionally, carbon dioxide is not the only greenhouse gas in this picture because nitrogen fertilization can cause the release of nitrous oxide, a powerful greenhouse gas.

Is Corn Ethanol Better than Gasoline in Terms of other Environmental Impacts?

Answer: Doubtful.

There is remarkably little information available on the other environmental impacts of corn ethanol from a lifecycle perspective. However, agrichemicals, especially nitrogen and phosphorus, and pesticides have significant environmental impacts, including the eutrophication of coastal waters, loss of biodiversity, and contamination of coastal waters, loss of biodiversity, and contamination of drinking water.

One study, the “Well-to-Wheels Analysis” referenced above, does quantify the life-cycle air pollution impacts of corn-based E85 as compared to gasoline, showing a small total increase in emissions of volatile organic compounds and carbon monoxide, and a sizable increase in emissions of total nitrogen oxides, particulate and sulfur oxides on a Btu or grams per mile basis.

Is Corn Ethanol more Expensive than Gasoline?

Answer: Yes.

E85 has 72 percent of the energy of gasoline. To be truly cost-competitive, the price at the pump must reflect that differential; for example, when regular gasoline is priced at $3.00 per gallon, E85 should cost $2.13 per gallon for the prices to be the same on an energy equivalent basis. Although the prices of both gasoline and ethanol vary over time and from region to region, ethanol has generally been more expensive than gasoline.

How Much of our Gasoline Use Can Corn Ethanol Replace?

Answer: Currently, we’re at about two percent. Going a lot higher would require the production of large amounts of cellulosic ethanol.

At the moment, there is a large gap between facts and aspirations. The Ethanol Promotion and Information Council, the Department of Energy, and the Natural Resources Defense Council (organizations that do not always find themselves on the same page) have high hopes for the future of ethanol, but those hopes appear to reside mainly with cellulosic rather than corn ethanol.


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