Storing the Sun

Three cheers for MIT!! They have made a major breakthrough in the ability to store solar power -- which is a key need if it is going to emerge as a mainstream form of power. This is a very exciting development -- and shows what can happen when America's ingenuity is applied to problem-solving rather than blame spreading.
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ClimateWire

ENERGY: MIT scientists announce breakthrough

Christa Marshall, ClimateWire reporter - Aug. 1, 2008

Harvesting the sun's energy at night may no longer be an impossible dream.

In new research that some experts said could have sweeping implications for a major source of carbon-free electricity, two Massachusetts Institute of Technology scientists have found a cheap way to potentially store solar power.

By a process mirroring photosynthesis, they have discovered how to split oxygen and hydrogen from water at low cost and using little electricity. The mechanism creates the possibility that the gases could hold power generated by the sun -- and possibly wind -- in fuel cells for later use in homes and businesses.

"What this allows is for the large-scale deployment of a technology that has yet to take off," said Daniel Nocera, an MIT professor of energy who performed the research, featured today in the journal Science.

"Until now we hadn't really been able to find a practical way to duplicate what a leaf does," he said.

Nocera and postdoctoral fellow Matthew Kanan recreated photosynthesis in the lab by putting an electrode in water filled with phosphate and cobalt metal. When a small amount of electricity was applied to the electrode, the chemical mix formed a thin film and produced oxygen bubbles.

Using existing technology, the team then used a nearby platinum electrode to produce hydrogen from a leftover oxygen proton.

Technology currently exists to split water in a similar fashion, but it relies on large equipment requiring massive amounts of electrical juice and an alkaline environment. In addition to being abundant and cheap, the cobalt-phosphate duo has the advantage of working in a small amount of water at room temperature.

'Major discovery' but not a 'silver bullet'

Nocera predicted that within 10 years, his technology could allow homeowners to live almost free of the electrical grid -- with photovoltaic cells powering most daytime needs and solar-powered storage operating at night.

Indeed, Nocera said he already was using the "photosynthesis" technique with a solar power panel in an MIT lab, although he acknowledged it was a bit "flimsy." The technology also could potentially be used to power cars if plug-in models became available, he said.

"This is a major discovery with enormous implications for the future prosperity of humankind," said James Barber, a professor of biochemistry at Imperial College London who was an early researcher of photosynthesis. He was not involved with Nocera's research.

A spokeswoman for the Solar Energy Industries Association, Monique Hanis, said the group typically doesn't comment on peer-reviewed studies, but that the industry as a whole is searching for ways to improve efficiency.

Still, others cautioned that the study provides a potential solution for only one aspect of using solar power to produce hydrogen and oxygen.

"This is not a silver bullet," said John Turner, a research fellow at the National Renewable Energy Laboratory (NREL). "This is just one part of a three-legged stool."

According to Turner, one of the biggest challenges for storage involves figuring out how to mass produce a new type of photovoltaic panel specifically designed for working with a fuel cell. Science hasn't figured out how to design such a tool, much less mass-produce it in a commercial infrastructure that doesn't currently exist, he said.

Nocera agreed that engineering work needed to be done to integrate his research with technology that captures sunlight. He said scientists at MIT and elsewhere were tackling the problem. Companies including Polaris Venture Partners have already contacted the MIT office expressing interest in the research, he said.

Harnessing the fickle sun

"Photovoltaics are expensive because they're not making enough of them at scale," Nocera said. "And manufacturers are only going to start making a lot of them with a storage mechanism."

The fickle nature of sunlight is one of the biggest challenges for the industry, along with uncertainty about federal tax credits and a need for transmission lines ferrying solar electrons to population centers.

Another challenge is that the element typically used to derive hydrogen from oxygen on electrodes, platinum, is expensive and scarce, but Nocera said ongoing investigation is making progress on that front.

And every small advance is important, according to many solar industry watchers. Solar power has doubled in installed capacity since 2005, with an 83 percent jump last year outside California, but still constitutes a small percentage of U.S. electricity, according to figures from the Solar Energy Industries Association.

"If we could just have three hours a day of solar storage, the price of photovoltaic technology would not really have to come down much at all to be competitive," said Larry Kazmerski, director of the National Center for Photovoltaics at NREL.

That potential has prompted Nocera to stare at plants for years and ponder how to use their natural chemical processes to revolutionize power generation. Work on the study officially began in December, but the thought process had a much longer history.

"This research has been 25 years in the making," he said.