By Harriet Blake

Mainstream, affordable solar power is not just pie (or energy) in the sky. So say MIT researchers who have devised a process to store solar energy for use when the sun doesn’t shine.

Photo: Donna Coveney
 
MIT professor Dan Nocera

Massachusetts Institute of Technology energy professor Dan Nocera and post-doctoral fellow Matthew Kanan have found a way to harness the sun’s energy to split water into hydrogen and oxygen gases, according to an effusive announcement today by the university. The oxygen and hydrogen then can be recombined inside a fuel cell that can produce carbon-free electricity for homes and electric cars – regardless of whether it’s day or night.

The researchers say the process is so simple it could be powering our lives within a decade, triggering nothing less than a “solar revolution”, according to the MIT news office.

Nocera and Kanan were inspired by photosynthesis – the energy storage system of plants. In their work, the scientists came up with a system that duplicates the water-splitting reaction that occurs during photosynthesis and then used the fuel cell to store that energy.

A fuel cell is similar to a battery in that it produces electricity by converting the energy released from a chemical reaction into electric power. The two differ in how they are fueled – batteries have an internal fuel source that keeps them charged; fuel cells have an external fuel source – usually hydrogen gas. Fuel cells produce electricity as long as fuel is supplied. As a result fuel cells never need electrical recharging.

The MIT process requires a special catalyst made of cobalt metal, phosphate and an electrode, placed in water. But it is relatively simple to set up and works at room temperature, according to the MIT release. “That’s why I know this is going to work. It’s so easy to implement,” Nocera said in the MIT statement. (For more from Nocera see the MIT Tech TV video.)

The operation of the fuel cell is relatively simple, but until now, they have been expensive to make, according to the Rocky Mountain Institute, an entrepreneurial nonprofit organization that advocates for the efficient use of resources for a sustainable world. At the moment, fuel cells cost more than traditional power sources, but that may be a thing of the past, thanks to MIT’s latest discovery.

“This is the nirvana of what we’ve been talking about for years,” said Nocera, the Henry Dreyfus Professor of Energy, in the July 31 issue of Science. “Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon.”

Nocera believes that within a decade, homeowners will be able to power their homes in daylight through photovoltaic cells. The excess solar energy will then produce hydrogen and oxygen that in turn will generate household fuel cells. He says that electricity-by-wire from a central source — the “grid” power system — will be history.

Department of Energy spokesperson Jennifer Scoggins says that the DOE will be reviewing the MIT discovery, but couldn’t comment on it at this time. The MIT news, she says, coincides with what the DOE is doing in terms of researching ways to make solar cost competitive.

“And not just solar,” she adds, “but wind and geo-thermal – all clean energy sources. We’re already seeing breakthroughs.”

Brian Palmintier, a fellow with the Rocky Mountain Institute’s Resource and Energy team says the findings are potentially exciting because “the concept of storing solar energy is huge” But he had not reviewed the MIT results yet and had reservations about how practical the process would be.

For the immediate future, he said, researchers should be looking at not just solar, but wind and geo-thermal energy solutions, and “at balancing clean energy with the existing grid system.”

The MIT project was funded by the National Science Foundation and by the Chesonis Family Foundation, which gave MIT $10 million to launch the Solar Revolution Project.

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