Opinion, arguments & analyses from the editors of Scientific American

Shift happens: Will artificial photosynthesis power the world?


One drinking-water bottle could provide enough energy for an entire household in the developing world if Dan Nocera has his way. A chemist from M.I.T. and founder of the company Sun Catalytix, Nocera has developed a cobalt-based catalyst that allows him to store energy the same way plants do: by splitting water.

"Almost all the solar energy is stored in water splitting," Nocera told the inaugural ARPA-E conference on March 2. Solar Catalytix is among five companies awarded government funding to develop "direct solar fuels," dubbed "electrofuels" by ARPA-E, the new Advanced Research Projects Agency for transformational energy technologies. "We emulated photosynthesis for large-scale storage of solar energy."

According to Nocera, his new system can work at ambient temperatures and pressures, without corrosion in a simple glass of water, even polluted water. "If you need pure water for energy storage, they'll drink it," Nocera said. "Use puddle water instead." In fact, Nocera has been running his prototype on untreated water from the Charles River in Boston. And it's cheap, not $12,000 per kilowatt like commercial electrolyzers that do the same thing. "That's not going to help the energy situation for the U.S. or poor people of the world."

Using the electricity generated by a photovoltaic array five meters by six meters, Nocera claims he can split enough water in less than four hours "to store enough energy for the average American home" for a day, a little more than 30 kilowatt-hours. "We need to stop making big energy systems one a time to service lots of people. We need to do it the old American way of making one small one and then manufacturing that system to give it to the masses."

His example? The automobile. After all, in 1898, concerned civic leaders from around the world gathered because estimates predicted that London would be buried under three meters  of manure at then current rates of growth; New York City would have piles reaching to the third story of buildings. Within two decades, that problem was entirely gone. "They didn't see the automobile industry coming," Nocera said. "Shift happens."

The views expressed are those of the author and are not necessarily those of Scientific American.

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