Read Present at the Future Online
Authors: Ira Flatow
Turning waste cellulose into clean-burning energy offers an added bonus of cleaning up the air. Kammen says lots of that waste cellulose in the form of husks and shells that might otherwise be burned can be turned into ethanol, “and so in California’s central valley, where there are real air-pollution problems from burning rice shells and the shells from walnuts,” there is the potential to eliminate all that air pollution.
And if you wanted to grow crops specifically to turn them into ethanol, other plants yield a whole lot more energy than corn does.
FORESTS OF ALCOHOL
Even with all the waste cellulose available to us, we could increase the amount of biofuels by growing it. “Like switchgrass, which can grow in prairies, says Kammen, “as well as some of the fast-growing trees.”
Trees? Absolutely. Try poplar and willow trees. The state of New York, for example, is experimenting with turning northern hardwoods, willows, into alcohol. “In New York State, we’ve got 18.5 million forested acres. And much of that acreage is made up by our northern hardwoods,” says Dr. Carol Murphy, executive director of the Alliance for Clean Energy New York. “There’s a series of compounds in those hardwoods called hemicellulose. We’re looking at how we can extract the hemicellulose from the northern hardwood chips, convert the hemicellulose into five-carbon sugars, and ferment the five-carbon sugars into ethanol.”
And what makes those trees so enticing? Remember our energy numbers? Remember that corn ethanol gives you a return of 1.25
energy units for each energy unit you put into growing, harvesting, and turning the corn into ethanol? Well, how about these numbers? “In the case of our northern hardwoods, for every unit of energy in, you get fourteen units, to maybe sixteen or eighteen units” out. That’s more than ten times what you get from corn. What a difference!
New York State has 600,000 acres of land not currently engaged in agriculture. There are another 600,000 acres of land that are probably a little too wet to be used for crops but that all would be just great for growing willows. “We can literally grow our biomass on that 1.2 million acres of land, give a return to our agricultural community, and help wean us off the petroleum base, particularly for transportation fuels.”
Just as forests are grown and harvested for plywood pulp, forests could be grown and harvested for fuel. And willows are an ideal crop, says Murphy. “We can start with a six-inch sprig and literally in three years it’s thirty feet tall.” So while a plywood forest may take 10 to 15 years to mature and harvest, a willow forest takes just three years. And Murphy thinks that New York can get this project underway in as little as two or three years.
But while growing energy forests may be part of an overall energy future, it won’t serve as the sole solution. “Some estimates have been made that to offset a million barrels of oil, you need basically a billion tons of biomass. There’s no question that we need to look very carefully at some of those things. But equally there needs to be balance in our approach to renewable energy. There is not going to be any single solution. It’s going to require a number of different sources of renewable energy using biomass as a source, indigenous sources of biomass. We need to take a balanced approach. The total solution to our problem certainly isn’t willow and certainly isn’t ethanol from willow.”
SWITCHGRASS: BACK TO THE FUTURE
A key answer to biofuels might be turning to a plant once so abundant in the Great Plains that it stretched as far as the eye could see, and even then, for hundreds of miles more. It’s called switchgrass. And it is one of the few plants singled out for mention by President George W. Bush when he talks about renewable biofuels. This perennial’s potential for becoming a major source of alternative energy has even made the federal government’s Oak Ridge National Laboratory (ORNL) wax poetic about the endless acres of switchgrass that used to grow wild on the American frontier:
The grass stretched as far as the eye could see, and hundreds more miles beyond that. An ocean of grass—deep enough to swallow a horse and rider—swaying and singing in the steady wind of the Great Plains. The American prairie—tens of millions of acres—once looked like this. But that was centuries ago, before the coming of the white man, the railroad, and the steel plow. Today, corn and beans hold sway, and the remnants of America’s tallgrass prairie are confined mostly to parks and preserves. Now, though, in research plots and laboratories in the Plains states and even in the Deep South the seeds of change are germinating. The tall, native grasses of the prairie, so vital to our land’s ecological past, may prove equally vital to its economic future. Such grasses once fed millions of bison. Soon, grown as energy crops, they may help fuel millions of cars and trucks, spin power turbines, and supply chemicals to American industries.
Plants like switchgrass don’t need to grow on high-priced farmland but can thrive on marginal lands. They don’t need expensive,
energy-intensive fertilizer or pesticides. They thrive in dry soil and their roots can reach deep down for a drink. Like willows, switchgrass grows quickly; it can stand 10 feet tall after one season. It processes sunlight efficiently, and turns photons and CO
2
into rugged cellulose.
And because it’s been around for millions of years, switchgrass has learned how to live in just about any soil and in harsh climates. It can be grown in fields and harvested and baled like cotton, needing to be replanted only once every 10 years or so. Many plants deplete the soil as they grow, but not switchgrass. It adds organic material to the soil as it grows, and its extensive root system fights winter erosion.
And “buffer strips of switchgrass, planted along stream banks and around wetlands,” says ORNL, “could remove soil particles, pesticides, and fertilizer residues from surface water before it reaches groundwater or streams—and could also provide energy.”
Test plots of switchgrass at Auburn University, says ORNL, have produced up to 15 tons per acre, equivalent to 1,150 gallons of ethanol per acre per year. And researchers are genetically engineering the plant to become even better, making it even more adaptable to a wider range of growing conditions. So not only is the yield better per acre but also the plant will be able to grow under more adverse conditions. I could go on singing the praises of switchgrass, but you can read about it yourself at http://bioenergy.ornl.gov/papers/misc/switgrs.html.
Why not have farmers change crops, from, let’s say, tobacco—the crop of yesterday—to switchgrass, the crop of tomorrow? “I’ll grow anything,” a farmer once told me, “as long as I can make a profit.”
“The reason corn has become so popular is because it’s there and we’re producing it in huge quantities,” says Brown, “and there’s strong support from farmers to convert part of that crop into ethanol. But the willow trees and the fast-growing hybrid poplars are two of the strongest candidates for cellulosic ethanol production, along with switchgrass.”
Here’s my vision of our energy future: fields of switchgrass, forests of willows and poplars, and planted among them, rows and rows of wind turbines, all creating a future of clean energy independence. But that vision may have to wait a bit because the technology for turning cellulose into fuel is not quite ready for prime time, says Brown. “We’re probably at least five years away from technologies to convert either willow trees or switchgrass into ethanol on an economically competitive basis.”
In addition, other alternatives to ethanol may be more productive, says Brown, such as a move toward plug-in electric cars powered by electricity produced by wind turbines. “If you take a car like a Toyota Prius, which is the most widely sold gas–electric hybrid, and if you add a second storage battery and a plug-in capacity, then we can do most of our short-distance driving—commuting, grocery shopping, and so forth—almost entirely with electricity. And the idea that we now have the technologies and an abundance of wind resources that would permit us to run our cars largely on wind energy is, I think, very exciting. Especially when you realize that the costs of the wind-electricity equivalent of a gallon of gasoline is less than a dollar a gallon. There will be no source of ethanol, even cellulosic ethanol, that’ll be able to compete with the equivalent of a dollar-a-gallon wind energy.” Wind turbines can produce electricity at under five cents per kilowatt-hour, making your plug-in auto cheaper to run than a gas-powered model. And as turbine technology progresses and the number of installed wind turbines grow, the costs can come down even more.
ALCOHOL VERSUS DIESEL: A COMPARISON
Given the headlong rush to build ethanol plants, some of the world’s top economists and agriculture experts are wondering if it makes any sense to grow crops just to turn them into alcohol. For example, one study shows that when you take into account the economic, environmental, and energy costs and benefits, biodiesel is a better choice than corn ethanol as a fuel.
Research teams at the University of Minnesota and St. Olaf College studied alternative biofuels—that is, fuels made from plants as opposed to oil, coal, and natural gas. To be a viable alternative energy source, they wrote in the Proceedings of the National Academy of Sciences, a biofuel should produce more energy than it takes to grow and process, it should have “environmental benefits,” be able to compete economically with other fuels, and “be producible in large quantities without reducing food supplies.” Using those criteria, they compared the life cycle of corn used to make ethanol with the life cycle of soybeans used to make biodiesel.
Their results were startling. Ethanol returns 25 percent more energy than it takes to put into it. So if you put 100 units of energy into growing, harvesting, and turning corn into alcohol, you get a yield of 125 units of energy. But biodiesel yields 93 percent more. Put 100 units of energy into growing, harvesting, and turning soybeans into diesel and you get 193 percent of energy out of it. That’s a tremendous energy-saving advantage over corn.
What about the environmental impact of each one? If biofuels are used instead of fossil fuels, “greenhouse gas emissions are reduced twelve percent by the production and combustion of ethanol and forty-one percent by biodiesel,” according to the research teams. Wow. “And pollution-wise, biodiesel also releases less air pollutants per net energy gain than ethanol.”
Why the big difference? The advantage of biodiesel is that it takes less energy to grow soybeans than it does to grow corn. And it’s a lot more efficient to convert soybean feedstocks to create biodiesel than it is to convert corn to ethanol.
On the other hand (and there always is another hand), even if you were to dedicate all the corn and soybean production in the United States to making biofuels, they “would meet only eleven percent of gasoline demand and eight-point-seven percent of diesel demand,” the researchers wrote. Clearly energy conservation and alternative energies have to be part of the solution.
Switchgrass could be one of those energy alternatives. It compares much more favorably with soy. But soy is already an established crop, the second largest in the United States, right after wheat. On the other (third?) hand, growing soy for fuel raises the same problem that comes with growing corn for fuel: You drive up the price of food. Which might be politically unacceptable. By growing switchgrass, you do not face a choice between food or fuel.
It is not too much to expect that our children will enjoy in their homes electrical energy too cheap to meter…
—LEWIS STRAUSS, CHAIRMAN OF THE U.S. ATOMIC ENERGY COMMISSION, 1954, SPEAKING ABOUT THE FUTURE OF NUCLEAR ENERGY
It wasn’t too long ago, after World War II, that the U.S. government had such high hopes for nuclear energy that it thought nuclear power would be so plentiful and cheap that it would be given away. Of course, that never happened. Nuclear power did get a foothold in this country, but the meltdown of nuclear fuel at the Three Mile Island power plant in Middletown, Pennsylvania, in 1979 put the lid on nuclear power development in this country.
But not in Europe. France gets about 75 percent of its electricity from nuclear power. Here in the United States, nuclear power usage is less than a third of that. France has brought 58 nuclear plants online since the 1970s. The United States hasn’t ordered any new plants since the Three Mile Island accident.
But that may all be changing. President George W. Bush has said
that he wants to see an increased emphasis on nuclear power in the United States, including starting construction on new plants by 2010. But is this country ready for nuclear power? Has the technology improved to the point where concerns over issues such as safety and waste disposal can be addressed? In the land where the phrase “Not in my backyard” strikes fear in the heart of politicians, is there a political will to build new plants?
But ironically, we are seeing some environmentalists who once were rigidly opposed to nuclear power now saying that compared with global warming, nuclear energy poses a much smaller threat. Take the ultimate tree hugger, Dr. Patrick Moore, cofounder and former leader of Greenpeace. He has helped create CASEnergy Co
alition, a group devoted to helping promote nuclear power. “There is a great deal of scientific evidence showing nuclear power to be an environmentally sound and safe choice. A doubling of nuclear energy production would make it possible to significantly reduce greenhouse gas emissions while increasing our energy supply.”
Other environmentalists are not convinced. But interestingly enough, where they used to argue that nuclear power was risky because of the threat of a meltdown, as happened at the reactor at Three Mile Island or in the explosion and fire at Chernobyl, they no longer present those arguments. Rather, they argue three other points. The first is economics.
“The rub for nuclear power today, particularly in the United States, is that it’s uneconomical compared to alternative energy sources for producing electricity.” That’s Dr. Tom Cochran’s argument against nuclear power. He’s director of a nuclear program at the National Resources Defense Council.