Just Asking...David Tilman

After years of prize-winning breakthroughs in the scientific major leagues of physics and chemistry, the field of ecology might finally be ready for the big time. Well, at least it’s big in Japan.

On December 8, in Tokyo, Emperor Akihito will present University of Minnesota Regents’ Professor David Tilman with $100,000 and the International Prize for Biology, an award just behind the Nobel in terms of prestige. Tilman has been at the university since 1976, teaching in the department of ecology, evolution, and behavior on the St. Paul campus, but he spends much of his time at the Cedar Creek Ecosystem Science Reserve researching prairie grass as a potential biofuel. Japan is recognizing Tilman for his work proving that biodiversity makes ecosystems more productive and resistant to drought, disease, and pests. “I’m not sure what prestige is,” Tilman says. “But if I look ahead to the next fifty years, some of the biggest problems that the world faces are related to humans and the environment. The ecological sciences are going to be a big part of finding solutions.”

Making fuel from prairie grass sounds so impressive on paper: it grows in terrible soil, it yields 51 percent more energy than corn, it doesn’t require pesticides or fertilizer, it enriches the soil in which it grows. It practically comes with a box of steaks. Why isn’t it in production already?
Our idea just shows how to get the raw material—the hay, if you will, that can be used to make the fuel. You can turn this biomass into alcohol or synthetic gasoline; we know the technologies to do both of those, but neither one is a commercial technology yet. It’ll be probably eight or ten years before an idea like this provides fuel to go in the gas tank.

When did you start concentrating on alternative energy?
About four years ago. When we started looking at corn being turned into ethanol and soybeans being turned into biodiesel, we didn’t know what we would find. We wanted to find out what the net benefits and the net costs to society were. So we spent a lot of time finding how much energy it takes to make steel, how much steel it takes to make a tractor, how much energy it takes for a factory to turn raw steel into a tractor, how long the tractor lasts on a farm, and how much energy it costs per acre of land farmed by that tractor. We did the same analysis for the energy to make fertilizer—we went through everything.

Is there anything you could do to provoke more dramatic change? Maybe sex up your data in a documentary or a reality TV show for farmers?
I wouldn’t want to convince farmers to do it more quickly than what is happening right now. We have to have a system where the farmer who does this actually can earn a living doing it and keep doing it year after year.

But I’m sure you’ve heard the conspiracy theories: John Rockefeller made sure Prohibition passed so oil would become the standard fuel for the automobile; Detroit is in cahoots with Big Oil to make sure alternative fuels remain undeveloped. At this point, isn’t the economic sustainability argument just handing these companies an excuse for maintaining the status quo?
Any company that’s comfortable doing what it’s doing now is going to be most comfortable doing that same thing in the future. It’s the quickest way to maintain profits. But in the long term, good ideas win out. I don’t think there’s a conspiracy in the sense that there’s something illegal or villainous. I just think that right now there are people who know how to make fuels from oil quite well. The United States uses about 200 billion gallons of gasoline a year. In the Energy Independence and Security Act of 2007, Congress has set a goal of making 30-some billion gallons of renewable energy. Not bad, but that’s a lofty goal, and it’s only 15 percent.

If you believe that good ideas win out, let’s talk about the “cornspiracy.” Your research shows that producing ethanol from corn is inefficient compared to creating biodiesel from soybeans or, better yet, biomass obtained from prairie grasses. If that’s the case, why have ethanol subsidies won out?
One of the oldest technologies is turning grain into alcohol. It’s been going on for 3,000 years or more. So it was pretty natural to say, “Let’s turn our extra grain into alcohol and use the alcohol as a fuel.” It wasn’t a bad idea. It was proposed by people in agriculture. People in government thought it was a good idea. No one had done the kind of analysis that we have done now. You can criticize them in retrospect, but they made what seems like reasonable guesses. They didn’t think about how much energy it takes to grow corn or to convert corn into ethanol. If they did, they probably wouldn’t have gone that way.

Some people still don’t believe in global warming. Is there any credible scientist left on the other side of this debate?
Do I believe in global warming? As a scientist I don’t believe in anything. But I can tell you this: The way you get to be famous in science is by showing that some big idea is wrong. If you can knock down a big idea, you’re at the top of the heap. And this idea has been very hard to get rid of.

What does President Obama have to do in, say, his first year, to show you, as an ecologist, that he’s committed to dealing with this challenge?
Conserving energy often saves money, but it often takes capital. So I would like to see the administration outline the major ways that are cost-effective for us to reduce greenhouse gases. And that has to do with energy efficiency in vehicles and buildings. In this country, we use twice as much energy in buildings as we do in cars. Our buildings are massively energy inefficient. The heating systems most of us have in our homes are old and outdated. Windows aren’t very good. Insulation isn’t good. Refrigerators are very inefficient. We now have technology that can cut that energy way down.

Nothing crazy, like a ban on front lawns or something.
Nothing crazy.

The situation is playing to Obama’s strengths in some ways—just communicating.
There are many times when politicians, because they’ve interacted with scientists and others, know more about a situation than most citizens do. But it’s very hard for them to do something about it because the public doesn’t understand the issue. Someone like Barack Obama, who is so good at communicating, has a chance to exert significant leadership on climate change and other environmental issues.

Will he be able to explain what negative carbon-dioxide sequestration means?
Well, I hope he can. When you burn something like alcohol or synthetic gasoline made from switchgrass or prairie grass, it’s recycled carbon dioxide. No increase in the air.

So the plant actually consumes the carbon dioxide. How is that different from burning fossil fuels?
Well, you’re burning carbon that was stored in the earth and you’re now putting it into the atmosphere. Fossil fuels cause greenhouse gases in the air to go up and up and up. If you have renewable fuels, it doesn’t go up at all anymore. We discovered that when you have these worn-out agricultural soils and you plant a mixture of prairie plants on them, not only will these plants remove carbon dioxide that is above ground, they’ll also put some of that into their roots below ground, and those roots get shed every year rebuilding carbon back up in the soil. [At Cedar Creek] we had more than a ton of carbon dioxide taken out of the atmosphere and stored in an acre of soil as dead organic matter every year. It went up by about a ton per acre, year after year after year. When you make a fuel with that biomass, the above-ground biomass becomes the fuel. The stuff building up in the soil restores it back to what it was before farming, and over the whole life cycle, carbon dioxide is removed from the air. It goes into the field, into the soil, and is stored and stays there as organic matter year after year. That means that these fields are carbon negative. At the end of making and burning this fuel, you have less greenhouse gas at the end than you did in the beginning because it’s being stored in that soil.

Whether it’s our electorate or what’s put on our table, diversity has a lot of cachet right now.
It’s interesting—as best we understand it, three and a half billion years ago there was no life on earth. Then there were some very primitive single-cell organisms, and those things have diversified through time. Now we have 3 million or maybe 10 million—we’re not sure—plants and animals and microbes living here. We now understand what those reasons are. Species on earth exist with each other basically because they do different jobs. When you have many species living together, that system as a whole actually functions better. It’s like having an economy—you want to diversify your portfolio. You actually get better long-term returns with diversification than you would if you bought any single stock on its own and just sold it.

We were addicted to monocultures for so long: White people are awesome. Corn is awesome. Ford and Chevy are awesome. How did this shift to diversity happen?
I’m not a social scientist, but it’s one of my untested hypotheses that some of our greatness as a nation is a result of accepting many, many different people with different backgrounds who have different ways of thinking. And we’ve let those with new ideas sort of invade our society and let those ideas grow and spread. So in many ways our long-term culture has been one of embracing diversity and using it—using intellectual diversity, using cultural diversity, taking the best part of one culture and the best part of another, and making a new culture. That’s really how diversity works in nature. There’s this competitive interaction. Things that do better when it’s hot take over when it’s hot, and when it’s cold, something else takes over. And in total, that system functions better.