Bright Days for Solar

New investment fuels promising energy research at MIT.

When Tonio Buonassisi finished his PhD at the University of California, Berkeley, in 2006, he wanted out of academia. He had a mission: to cover the world's roofs with solar panels that would provide clean, ­carbon-­free electricity. A cash-strapped university research program wasn't the place to make that happen. But research dollars were ­plentiful in the solar industry, which was doubling in size every couple of years. Having "lived through times of famine" as a grad student, Buonassisi says, he decided against taking a postdoc appointment and went to work at a manufacturer of solar panels based in Marlborough, MA.

Sunny Side of the Street: Tonio Buonassisi is optimistic that innovation in the lab can make solar energy affordable. Credit: Asia Kepka

Less than three years later, Buonassisi is back in academia as an assistant professor of mechanical engineering at MIT, which has seen a new surge in solar research propelled by the MIT Energy Initiative and a growing student energy club. For decades, the only solar research at MIT had been carried out intermittently by a small cadre that Buonassisi describes as "a few lonely torch-­bearers wandering around in the caves." A "dead period" descended on the worldwide solar-research community after both oil prices and interest in alternative energy plummeted in the mid-1980s, he says. But now the world is clamoring for affordable clean energy. And thanks in large part to the establishment of the MIT-­Fraunhofer Center for Sustainable Energy Systems (where Buonassisi is scientific director) and the Solar Revolution Project, tens of millions of dollars earmarked for solar research have started to pour into the Institute from both government and private sources. About 20 MIT researchers have turned their attention to solar energy so far.

The potential of solar power is enormous. In just over one hour, enough energy from the sun reaches the earth to meet the world's needs for an entire year. But as of yet, that potential is far from being realized. Solar panels, which convert the energy in sunlight into electricity, are so expensive and inefficient that they now produce just a fraction of 1 percent of the world's power.

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That has to change if the world is to hit widely accepted targets for cutting carbon dioxide emissions while meeting growing energy demand. The targets call for at least 10 million megawatts of ­carbon-­free generating capacity by 2050, most of which will probably need to come from solar, given the limits of other clean energy technologies. Solar power now provides only about 10,000 megawatts worldwide. To reach 10 million megawatts, the solar industry will need to continue its rapid growth for the next 20 to 30 years.

Some of the research at MIT could have an almost immediate impact on the industry. One example is Buonassisi's effort to improve the price and efficiency of solar cells, the ­semiconductor-based components--most often made of silicon--that convert light into electricity in a solar panel. (Each panel is made of many cells packaged together with electronics and a frame.) Other projects may take longer to complete but could yield big results. One group of researchers is pursuing a way to concentrate sunlight using luminescent dyes developed for next-generation flat-screen displays; such technology could greatly reduce the amount of expensive silicon needed to generate electricity from the sun. Another professor is creating catalysts that imitate photosynthesis, using sunlight to make chemical fuels. That could solve one of the basic problems with solar energy today: there's no good way to store it.