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Berkeley Lab’s Steven Chu assesses the pitfalls on the way to clean energy Co-recipient of the 1997 Nobel Prize in physics, Professor Steven Chu is an international expert in atomic physics, laser spectroscopy, biophysics, and polymer physics. As director of the Lawrence Berkeley National Laboratory, Chu oversees the Department of Energy’s oldest and most scientifically diverse research laboratory, which has an annual budget of $520 million and nearly 4,000 employees. He is currently working on a theoretical process to produce ethanol from wood by mimicking the digestive tract of termites. Interview by Steven Boyd Saum. Tell us about your theory for creating biofuels, particularly turning cellulose into methane and taming bacteria. One approach is to sequence the bacterial One approach is to sequence the bacterial colonies that convert cellulose into chemical fuel—colonies found at the bottom of a swamp(where natural gas was first discovered), to colonies in the stomach of a termite or a cow. We look at how these microorganisms break down biomass—whether it’s cow dung; or biowaste from a lumberyard, factory, or a city sewer; or biomass that you grow for efficient breakdown, such as switch grass or maybe a super switch grass. We don’t want to eat this plant, we want to produce energy from it. We are currently using plants we use for food, like sugar and corn. But let’s think big here. About $20 billion of agricultural subsidies are going to grow certain crops. It’s going to get harder and harder to put those crops on the international market because of the World Trade Agreement. How economically feasible is carbon sequestration, and how far off is it from being widely implemented? I’m cochair of a collection of national academies of science around the world that have formed what is called the InterAcademy Council. They are sponsoring a worldwide study of transitions to sustainable energy. One of the workshops will be held in China in a couple of months. The committee hopefully will have some impact on governments around the world; there’s a lot of science and technology on the horizon. The Chinese workshop will be on carbon and coal—and a new generation of coal and carbon sequestration. What’s the promise of methane hydrates? Is it short term, or something 50 years out? There is a tremendous potential energy resource from clathrates (methane hydrates). This is essentially methane frozen into icelike rock. With a very small change in temperature or pressure, methane quickly becomes mobile. It’s now thought that it shoots out of these formations. It’s conjectured that the periods of very rapid increases in temperature over the past 420,000 years didn’t occur over a hundred years; these were changes that occurred over just decades. And it’s been conjectured that a sudden warming trips the balance, and then this methane gets released. Methane’s about 20 times worse as a greenhouse gas when it gets released. How do you recover it? You heat it up, and it begins to flow. But the question is, what fraction will you recover versus what you will release? What’s the most promising work with solar? With single-crystal silicon, you can drive to higher efficiency to make multiple band gaps(so that the solar cell makes use of different frequencies of light), and we’ve done that. There’s the dream that you can use a wet chemical process (working with the nanoparticles that you can then embed in anothermaterial) that may not be silicon-based—and solar can become much cheaper. But the trouble with the wet chemistry process is there is photodegradation: Efficiency starts at about 12 percent and degrades to 8 or 9 percent over a year or two. So there is a research problem: How do you get wet chemistry—especially organic wet chemistry—so it doesn’t photodegrade in a couple of years? It’s a tough nut to crack. What should the right mix of energy sources be? I’d like to have a mix of economically viable crops for biofuels, with it’s conversion—efficiently—either directly into electricity on demand or conversion into chemical fuel where you can convert to electricity on demand. Also, the biofuels should replace gasoline for transportation fuels, which is a quarter of our energy budget. If it can’t replace it all, then work with hybrids, where you can go to other means of using electricity. Some new-generation nuclear energy will probably have to play a role, at least in the transition, before we get to sustainable solar. And there are too many unanswered questions bout coal. Regarding nuclear energy, there are two major issues that people should be concerned about: waste and weapons proliferation. With new-generation nuclear, you recycle and burn down the waste. I’m more concerned about carbon and coal than I am about nuclear. We have to solve the problem before oil runs out. |
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