MIT develops way to bank solar energy at home

By Scott Malone

CAMBRIDGE, Massachusetts (Reuters) - A U.S. scientist has developed a new way of powering fuel cells that could make it practical for home owners to store solar energy and produce electricity to run lights and appliances at night.

A new catalyst produces the oxygen and hydrogen that fuel cells use to generate electricity, while using far less energy than current methods.

With this catalyst, users could rely on electricity produced by photovoltaic solar cells to power the process that produces the fuel, said the Massachusetts Institute of Technology professor who developed the new material.

"If you can only have energy when the sun is shining, you're in deep trouble. And that's why, in my opinion, photovoltaics haven't penetrated the market," Daniel Nocera, an MIT professor of energy, said in an interview at his Cambridge, Massachusetts, office. "If I could provide a storage mechanism, then I make energy 24/7 and then we can start talking about solar."

Solar has been growing as a power source in the United States -- last year the nation's solar capacity rose 45 percent to 750 megawatts. But it is still a tiny power source, producing enough energy to meet the needs of about 600,000 typical homes, and only while the sun is shining, according to data from the Solar Energy Industries Association.

Most U.S. homes with solar panels feed electricity into the power grid during the day, but have to draw back from the grid at night. Nocera said his development would allow homeowners to bank solar energy as hydrogen and oxygen, which a fuel cell could use to produce electricity when the sun was not shining.

"I can turn sunlight into a chemical fuel, now I can use photovoltaics at night," said Nocera, who explained the discovery in a paper written with Matthew Kanan published on Thursday in the journal Science.

Companies including United Technologies Corp produce fuel cells for use in industrial sites and on buses. Automakers including General Motors Corp and Honda Motor Co are testing small fleets of fuel-cell powered vehicles.