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Observations

Opinion, arguments & analyses from the editors of Scientific American

What happens when coal is gone?

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LINDAU, Germany--What’s the best way to address a politically charged topic such as the future of energy? Remove the politics. “We’re going to skip over the politics,” Robert P. Laughlin, who won a Nobel Prize for physics in 1998, told a rapt audience of young scientists and others here at the 60th annual Nobel Laureate Lectures at Lindau. “I’m not interested in now but in the time of your children’s children’s children, six generations into the future and 200 years from now,” when all carbon burning has stopped because it’s been banned or none is left, he said. “Thinking about a problem this way is so simple. Instead of arguing about what to do now, I want to talk about what will happen when there’s no coal."

In two centuries, people will still want to drive cars, fly in airplanes and have lighting in their houses. “Everybody I know thinks there will be big price increases with the end of easy oil and there’ll be a struggle over the resources,” he said Monday. The young scientists in the audience “need to figure out how to keep that struggle from turning into a hot war.”

Toward that end, Laughlin established some principles about hydrocarbons such as gas, oil and coal: everyone wants the cheapest gas possible; when oil runs out, prices will fluctuate but can be managed with technologies in development; and when coal ultimately runs out, further innovation will have to happen to keep society stable.

“Why not just use less coal?” he asked. He showed a graph that linked burning carbon with an increase in gross domestic product, or GDP, for several countries. “This is why nobody wants to go first” when it comes to cutting nationwide carbon use, he added. “We will never have a no-carbon economy.”

Another reason we’ll never fully escape carbon: existing and developing technologies can ease some aspects of the energy-source problem, but the laws of physics create a barrier for others. For instance, nuclear power, solar and wind can keep the lights on when hydrocarbons are no longer widely available. “Right now nobody likes nuclear power, but who do you think would vote against nuclear power if you gave them a choice between nuclear and the lights won’t go on?” asked Laughlin. Coal can be converted to gasoline, if necessary, as the Germans did during World War II using a process developed by Franz Fischer and Hans Tropsch in the 1920s. But no other fuel currently offers the energy density—the energy per unit weight—that jet fuel provides for airplane flight. “It’s fundamentally impossible to improve on jet fuel because it would break the laws of physics,” pronounced Laughlin. “You can’t have airplanes unless you make hydrocarbon fuel.”

Laughlin said the Fischer-Trophsch process, which produces liquid hydrocarbons by passing carbon monoxide and hydrogen over iron or other catalysts, can use different feedstocks. In the 1940s, the Germans used coal. Today, several plants are coming online that start with natural gas instead of coal for a better carbon footprint. A couple of the largest are a Shell facility in Malasia and one in Qatar. In the future, there will be other feeds, such as plant materials.

Agriculture alone won’t be sufficient as a source—for the U.S., the required area would be slightly bigger than the state of Texas. But a combination of sources, perhaps including saltwater-grown plants, could get us there in the relatively near term. “Oil will disappear and there’ll be no change at the gas pump because there’ll already be technologies in place,” predicts Laughlin. “The good news is once you build these [Fischer-Tropsch] plants, you can use anything, including garbage, for the biofuel conversion. The big problem is the initial capital cost.” We can adapt the facilities over time.

Eventually, said Laughlin, today’s situation, where energy is relatively costly and carbon is cheap, will be reversed: “200 years from now there will be a new industry that doesn’t exist now. 200 years from now, energy scarcity is not the problem; carbon scarcity is the problem.” What then?

Ultimately, predicts Laughlin, we will learn how to reclaim carbon from air. That carbon could feed into a modified Fischer-Trophsch process. “This development is good news if it happens, and I think it will happen,” he concluded.

Learn more at Scientific American's sister publication Nature, and a special web site featuring Lindau blogs, organized by Nature and Spectrum der Wissenshaft, Scientific American ’s German language edition. A slide show, Discoveries 2010: Energy, covers another Lindau initiative, a museum exhibit on energy sources.

The views expressed are those of the author and are not necessarily those of Scientific American.

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