Wednesday, October 26, 2011

MIT touts recent clean energy breakthroughs

By James M. Connolly

While MIT puts out its share of news on biotech, computers, advanced materials and other topics, this week, it’s all about clean energy.

The MIT News Office is highlighting some of the breakthroughs that the school’s researchers have published. The five-part series continues throughout the week.

The research so far:

Power from the earth. MIT says that the earth can provide carbon-free sources of energy, such as biofuels, geothermal energy and advanced nuclear power, but that scalability remains an issue.

The college cites a 2009 study by the MIT Joint Program on the Science and Policy of Global Change that found that, done wrong, biofuels could increase the level of greenhouse gases entering the atmosphere. For example, clearing forests to grow crops for biofuels would remove the trees that absorb carbon from the air.

In addition, a study by researcher James Hileman of MIT’s Department of Aeronautics and Astronautics, found that replacing fossil fuels with biofuels for aviation could have either positive or negative effects — depending on which crops are used as feedstock, where the crops are located, and how the fuels are processed and transported.

When it comes to geothermal energy, drilling deep into the earth could access temperatures sufficient to drive generating turbines. “There are thousands of years’ worth of energy available,” says Taylor. “But you have to drill deeply,” which can be expensive using present-day drilling methods, he says.

Zero-carbon options. At any given time, 14 terawatts of energy is being used around the globe for transportation, cooking, electricity, heating, cooling and other uses, and that figure could double by 2050, according to MIT, which says that 85 percent of the 14 terawatts comes from fossil fuels. Researchers say that even maintaining the present rate of carbon emissions would require coming up with another 14 terawatts of non-carbon sources to meet that 2050 demand, and that actually reducing emissions “is essential to averting catastrophic changes.”

According to MIT’s Joint Program on the Science and Policy of Global Change, even maintaining current emissions levels could trigger a rise in global temperatures of at least 2.3 degrees Celsius by 2100.

MIT professor Ernest J. Moniz, director of the MIT Energy Initiative, suggests that a non-carbon energy future will likely consist largely of some combination of nuclear power, renewable energy sources and carbon-capture systems that allow fossil fuels to be used with little or no emissions of greenhouse gases.

Wind power. Of the various zero-carbon energy sources available today, only wind power currently is truly cost-competitive. Paul Sclavounos, an MIT professor of mechanical engineering and naval architecture, is working on the design of wind turbines for installation far offshore. Those installations would be based on floating platforms along the lines of offshore oilrigs. He says that such installations along the East Coast could provide most of the electricity needed for the eastern half of the country, while platforms off California could supply more than two-thirds of the state’s electricity.

Solar energy. MIT says that solar energy is still too expensive to address global energy needs, but that it could become more competitive “if new technologies can tip the balance of solar economics.”

The potential is enormous, according to MIT physics professor Washington Taylor, who says that a total of 173,000 terawatts of solar energy strikes the Earth continuously. He says that’s more than 10,000 times the world’s total energy use. And that energy is completely renewable — at least, for the lifetime of the sun. “It’s finite, but we’re talking billions of years,” Taylor says in an MIT News Office article.

Professor Daniel Nocera describes a time when every home could have a self-contained system. He says that one example could be the use of photovoltaic panels that would run an electrolyzer, producing hydrogen to feed a fuel cell that generates power. Nocera has invented a system for producing hydrogen from water, which could help to make such systems cost-competitive.