Researchers at the Massachusetts Institute of Technology have announced a breakthrough in storing solar energy that could have much broader applications for all forms of renewable energy. Two scientists say they have found a way to mimic photosynthesis to store electricity cheaply. They tout the advantages for solar power, but others say it might also be useful to store electricity from other sources.
The process, developed by Daniel G. Nocera, professor of energy, and Matthew W. Kanan, postdoctoral fellow, runs electricity through an electrode placed in room-temperature, pH-neutral water. A cobalt and phosphate catalyst forms a thin film on the electrode and oxygen is produced. Another catalyst, such as platinum, is used to produce hydrogen from the water. The gases are stored in fuel cells for later use.
Nocera says the process can be used for other forms of power storage, but stresses the benefits of storing solar. “Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon,” he says. Wind power also is a candidate, because much of it is generated at night when it is not as useful.
“This is a pretty big breakthrough if they can use room temperature,” says Cara Libby, a project manager with the Electric Power Research Institute, Palo Alto, Calif. The process would make the creation of hydrogen and oxygen more affordable and user-friendly because cobalt and phosphate are cheap and abundant. Current electrolyzing processes require expensive materials in alkaline solutions.
There are some skeptics. “It’s more an issue of an alternative way of creating hydrogen,” says Paul Wormser, senior director of product development for Sharp Solar, the world’s largest manufacturer of photovoltaic cells. “If I’m generating solar electricity, I’m using it the moment it’s created,” he says. “There’s not a whole lot of benefit to generating it and holding onto it.”
Nocera and Kanan’s work is not the first attempt to mimic photosynthesis or to create in-home hydrogen systems, says Rick Farmer, team leader of the Dept. of Energy’s hydrogen program. DOE is funding research to mimic photosynthesis at Arizona State University, and Honda Motor Co. has been working on in-home hydrogen fueling stations.
“I think it is an interesting new technology,” Farmer says of the MIT development. “What we want to try to do is have a portfolio of technologies. We don’t want to just limit it to one.”
While the research may have application for alternative-energy power stations, Nocera says in-home systems using the MIT discovery will be common in about 10 years. Storage of solar power in homes is possible, but it is very expensive, Libby says. Solar power can be collected and stored thermally, but that is only cost effective in large collecting stations.
Wormser says lack of energy storage is not holding solar back. “Solar is growing incredibly well,” he says. “For the foreseeable future, solar does not need storage to have absolutely spectacular growth.”
Libby, Wormser and Farmer say the discovery has several cost hurdles ahead. Photovoltaic systems are several thousand dollars for home systems, and fuel cells also are expensive. “Making this cost-competitive will be the biggest challenge to making it practical for people’s homes,” Libby says.
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