MIT develops way to bank solar energy at home

Tag : metal glasses
Scott Malone

CAMBRIDGE, Massachusetts, Aug 2 (bdnews24.com/Reuters) - A USscientist has developed a new way of powering fuel cells that couldmake it practical for home owners to store solar energy and produceelectricity to run lights and appliances at night.

A new catalyst produces the oxygen and hydrogen that fuel cells useto generate electricity, while using far less energy than currentmethods.

With this catalyst, users could rely on electricity produced byphotovoltaic solar cells to power the process that produces thefuel, said the Massachusetts Institute of Technology professor whodeveloped the new material.

"If you can only have energy when the sun is shining, you're indeep trouble. And that's why, in my opinion, photovoltaics haven'tpenetrated the market," Daniel Nocera, an MIT professor of energy,said in an interview at his Cambridge, Massachusetts, office. "If Icould provide a storage mechanism, then I make energy 24/7 and thenwe 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 750megawatts. But it is still a tiny power source, producing enoughenergy to meet the needs of about 600,000 typical homes, and onlywhile the sun is shining, according to data from the Solar EnergyIndustries Association.

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

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

Companies including United Technologies Corp produce fuel cells foruse in industrial sites and on buses. Automakers including GeneralMotors Corp and Honda Motor Co are testing small fleets offuel-cell powered vehicles.

POTENTIAL FOR CLEAN ENERGY

Fuel cells are appealing because they produce electricity withoutgenerating the greenhouse gases associated with global climatechange. But producing the hydrogen and oxygen they run on typicallyrequires burning fossil fuels.

That has prompted researchers to look into cleaner ways of poweringfuel cells. Another researcher working at Princeton University lastyear developed a way of using bacteria that feed on vinegar andwaste water to generate hydrogen, with minimal electrical input.

James Barber, a biochemistry professor at London's ImperialCollege, said in a statement Nocera's work "opens up the door fordeveloping new technologies for energy production, thus reducingour dependence on fossil fuels and addressing the global climatechange problem."

Nocera's catalyst is made from cobalt, phosphate and an electrodethat produces oxygen from water by using 90 percent lesselectricity than current methods, which use the costly metalplatinum.

The system still relies on platinum to produce hydrogen -- theother element that makes up water.

"On the hydrogen side, platinum works well," Nocera said. "On theoxygen side ... it doesn't work well and you have to put way moreenergy in than needed to get the (oxygen) out."

Current methods of producing hydrogen and oxygen for fuel cellsoperate in a highly corrosive environment, Nocera said, meaning theentire reaction must be carried out in an expensivehighly-engineered container.

But at MIT this week, the reaction was going on in an open glasscontainer about the size of two shot glasses that researchersmanipulated with their bare hands, with no heavy safety gloves orgoggles.

"It's cheap, it's efficient, it's highly manufacturable, it'sincredibly tolerant of impurity and it's from earth-abundantstuff," Nocera explained.

Nocera has not tried to construct a full-sized version of thesystem, but suggested that the technologies to bring this into atypical home could be ready in less than a decade.

The idea, which he has been working on for 25 years, came fromreflecting on the way plants store the sun's energy.

"For the last six months, driving home, I've been looking atleaves, and saying, 'I own you guys now,'" Nocera said.

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