Most people would agree that the United States needs a new source of fuel: something reMnewable and nonpolluting with which to replace gasoline … something that could be produced right here at home. Deep in America’s heartland, a lot of people think they know the answer: ethanol, a fuel made from fermented corn.
According to U.S. Department of Agriculture estimates, you can get about 21/2 gallons of it from a bushel of corn. And an increasing number of states are working to make an 85 percent ethanol fuel called E85 available at gas stations at prices significantly below that of regular gasoline … even when you account for the fact that ethanol provides only 62 percent of the mileage of gasoline.
It sounds like a perfect, win-win solution for both the nation’s farm economy and its energy needs. According to the National Corn Growers Association, ethanol production could make 1.4 billion bushels of corn “disappear” in 2004 … enough to replace more than 2 billion gallons of gasoline and provide a much-needed market for farmers stricken with chronically low corn prices.
There’s just one catch: According to scientists in New York and California, it takes more energy to make ethanol than you get back in fuel savings. More precisely, says David Pimentel of Cornell University, it takes the equivalent of 1.29 gallons of gasoline to produce enough ethanol to replace one gallon of gasoline at the pump. Instead of making the nation more energy self-sufficient, ethanol production actually increases our need for oil and gas imports, Pimentel says.
Pimentel is an ecology professor who had been examining energy usage in corn production since 1970. It may sound odd for an ecologist to study agriculture, but it’s not actually a big jump, because ecologists have long been interested in energy flows in natural systems. Pimentel sees his work merely as applying a traditional way of thinking to a new arena.
In a recent paper in the journal Natural Resources Research, he calculates that it takes the energy equivalent of 271 gallons of gasoline to grow a hectare (about 2.47 acres) of corn. Part of that energy is for tractor fuel, but the biggest use is for manufacturing nitrogen fertilizers, which are mandatory for high-yield corn-growing.
These fertilizers are made by heating natural gas under controlled circumstances so that it reacts with nitrogen in the air. Not only does it take heat to do this, but it uses up natural gas that could have been burned as fuel. Pimentel estimates that in corn-growing, nitrogen fertilizers alone use the equivalent of 80 gallons of gasoline per hectare.
More energy is needed to turn the corn into fuel. Ethanol is produced by grinding corn, mixing it with water, and fermenting it in a process similar to that used to make beer or wine. The unprocessed product, in fact, is a lot like beer: 8 percent alcohol and 92 percent water. Not something that’s going to burn in a car engine.
To make a usable fuel, all but 0.5 percent of the water must be removed. This is done by a series of distillation and chemical extractions that, according to Pimentel’s calculations, use even more energy than was used to grow the corn. And that doesn’t count the diesel fuel needed to ship corn to the ethanol plant or ethanol to the pump. In theory, all of these energy costs should make ethanol uneconomical to produce.
But it can be produced affordably, Pimentel says, because the government is subsidizing its production to the tune of $3 billion per year.
Tad Patzek, a chemical engineer at the University of California Berkeley, who collaborated with Pimentel, calls the whole thing a “politically driven initiative” by “confused people” who think it’s good for the country. But really, he says, it’s equivalent to the medieval alchemist’s quest for the mythical Philosopher’s Stone, which could turn anything into gold. The only difference is that in this case, the reward isn’t gold, it’s “pure, environmentally benign energy” that could satisfy the greenest of environmentalists.
“We need a new liquid fuel,” Pimentel adds, “but this isn’t the one.”
Outside the gates
Hosein Shapouri disagrees. An economist with the U.S. Department of Agriculture, he too has spent years studying the amount of energy needed to produce ethanol. His latest calculations, published in 2004, conclude that for each gallon of gasoline invested (or its equivalent in coal, electrical power, etc.), you get back the equivalent of 1.67 gallons of gasoline. That’s up, he adds, from 1.36 gallons in 1996 and 1.24 gallons in 1991.
Shapouri charges that Pimentel’s work is based on an outdated understanding of how the industry works. “He doesn’t see technology,” Shapouri says. “Corn production is becoming more efficient, and ethanol is, too.”
Pimentel, on the other hand, charges Shapouri with overlooking important steps in the farm-to-ethanol process. “The reason the USDA comes up with positive returns and we do not,” he says, “is that they omit about half of the inputs.”
One “input” that Shapouri has overlooked, Pimentel says, is the energy used to make and maintain farm equipment. “Have you seen many farmers raising corn by hand?” he asks. Shapouri “draws the boundary too close to the gates of the ethanol plant,” Patzek says. “His whole analysis accentuates the last element of the chain, which is ethanol production.”
Patzek also says that Shapouri accidentally mixed up ethanol-production statistics for corn with different amount of moisture in it, so-called “wet” and “dry” corn. “That overestimates the yield by 15 percent,” he says.
Shapouri, on the other hand, charges that Patzek and Pimentel should be basing their study on USDA’s corn-growing data, rather than attempting to supplement the government statistics with figures from other sources. “We used a USDA corn survey and also a survey of ethanol plants,” Shapouri told the National Corn Growers Association in 2004. “Our data are crystal clear.”
Patzek, on the other hand, sees no reason not to try to improve on the USDA data. “They’re not God,” he says.
Rating the leftovers
But the most important dispute involves how to account for the fact that fuel isn’t the only product to come from an ethanol plant. The leftovers from the fermentation process form dry distillers grain, which can be used in food production. Because dry distillers grain represents nearly 34 percent of the plant’s output, Shapouri says that 34 percent of the total energy cost should be credited to it. That leaves only 66 percent to be charged against the ethanol.
Pimentel agrees that a credit is appropriate but argues that because soybean meal can be used for many of the same purposes, the appropriate adjustment is for the amount of energy needed to grow and produce soybean meal – vastly smaller than the amount needed for growing corn and making dry distillers grain.
An additional problem is that corn is an environmentally unfriendly crop. It contributes more to soil erosion than do other crops, says Pimentel, and pesticides and the nitrates from nitrogen fertilizer contaminate creeks, rivers and even the Gulf of Mexico.
These problems can be reduced by using other crops for ethanol, such as grass or wood, or by making biodiesel from soybean oil or sunflower oil. But grass and wood are difficult to process, and oilseed crops have relatively low yields compared with corn. Pimentel did his energy calculations with all four and found that only soybeans fare better than corn (because they don’t need nitrogen fertilizer to grow). But even they require 1.27 times as much energy to produce as they give back in biodiesel, he says.
A fifth alternative, sugar cane, might be slightly better, he adds, but it too depletes soils and increases erosion.
In his 1966 novel “The Moon Is a Harsh Mistress,” science fiction writer Robert A. Heinlein coined the slogan TANSTAAFL – short for There Ain’t No Such Thing as a Free Lunch. If there is any single thing that the ethanol dispute reveals, it’s that in the search for alternative fuels, Heinlein’s motto is depressingly correct.
Even Shapouri’s figures show only a 67 percent return on the energy investment needed for ethanol production. But many other forms of energy suffer from the same problem, including drilling for oil and mining coal, which require a lot of energy for drilling, transportation and digging.
“That’s the thing,” he says in an echo of Heinlein. “If you want to produce energy, you have to spend energy.”
Pimentel thinks we’d get more return on our energy investment by growing trees for woodstoves or other such uses. “Wood is an extremely valuable resource,” he says. “We already get 3 percent of our energy from biomass – the same as we get from hydropower. But that’s thermal energy, not liquid fuel.”
Patzek thinks the U.S. needs a two-pronged approach, neither of which involves ethanol. First, he says, we need more efficient cars. Doubling the average car’s fuel efficiency would cut gasoline needs in half, while converting all of the nation’s corn production into ethanol would only satisfy 12 percent of current needs, he says.
Similarly, he says, we could reduce fuel needs by redesigning cities to be livable, rather than “drive-in deserts.”
Secondly, he says, we need to remember that corn is merely a natural means of converting solar energy into chemical energy, and that it’s not really all that efficient at doing so. Solar cells are much more efficient, and could be harnessed to make hydrogen fuel.
Rather than subsidizing ethanol production, Patzek says, we should invest in research designed to make it possible to produce these cells more efficiently. In the U.S., he predicts that people will eventually realize that corn ethanol isn’t efficient and will switch to a succession of other crops, none of which will be much better. A much bigger problem, he says, will come with efforts to supply the developed world’s fuel needs with “green” imports from developing countries.
“All this hoopla about corn ethanol is child’s play compared with the issue of biomass production in the tropics,” he says. “The issues with converting pristine, important ecosystems into plantations will dwarf the problems we have with corn ethanol in the U.S. We’re encroaching on the basic environmental services of the planet, and that’s a lot more scary than polluting the Mississippi Basin and Gulf of Mexico with nitrates.”
Patzek would most likely agree with Heinlein’s TANSTAAFL principle. As he sees it, there’s no such thing as a totally benign, farm-grown energy source. “It’s not that simple,” he says sadly. “It’s anything but simple.”
Richard A. Lovett , a freelance writer in Portland, Ore., has a Ph.D. in natural resource economics.