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This video was recorded at MIT Energy Short Course. Mildred Dresselhaus jumped on the hydrogen bandwagon following President Bush's call for scientists to pursue a "Hydrogen Economy." She led the Department of Energy study laying out essential research avenues in hydrogen production, storage and use. She describes hydrogen as "an interesting medium" that will provide one part of the renewable energy mix. But Dresselhaus also acknowledges "it is a really hard problem." The premise behind the hydrogen initiative is deceptively simple: hydrogen, as part of water, is pretty much everywhere, so it presents a nearly endless energy supply, unlike fossil fuels. Hydrogen-based fuel cells could be more than twice as efficient as the internal combustion engine, and the byproducts of using hydrogen for energy are benign. But there are major problems. For one thing, we can't mine for hydrogen, we have to make it, and production today averages a measly 9 million tons per year. Scaling up can't yet be done cheaply in large quantities. Any practical application for vehicles must include a storage solution competitive with current gas technology -- approximately 300 miles per "fill up." Dresselhaus sees solutions, albeit long-term, to these problems. "Every aspect of the hydrogen picture involves catalyses, whether in production, storage or end use," she says. Her research specialty of nanotechnology seems to be particularly relevant. Because nano-sized particles present completely new parameters to work with, such as greater surface area, they function extremely well as catalysts, especially when it comes to hydrogen reactions. Nanostructures could permit these processes to take place at room temperature, and could help bind hydrogen atoms more tightly, so that hydrogen fuel could be stored in smaller and more manageable volumes. A carbon nanotube foam might be used to help load hydrogen into a vehicle, so drivers don't have to wait two hours to fill up with this otherwise highly volatile element. The ideal of a mature hydrogen economy, where "water and sunlight are somehow making hydrogen to power fuel cells to supply energy for the world" is not impossible, says Dresselhaus. To get there, research must proceed at full steam to solve issues of thermal management and hydrogen kinetics. "We concluded only that it's very difficult," she says, with "time horizons 30 to 50 years out."

Disciplines:

• Science and Technology