A new, cheaper way to store electricity to run air conditioners or vehicles promises to make solar power competitive with traditional generation, Massachusetts Institute of Technology researchers said.

The discovery might shatter the biggest barrier to widespread use of solar power, namely that it's unavailable after dark, said Daniel Nocera, an MIT energy professor. The process uses nontoxic natural materials to convert sunlight into gases, as described Thursday in the online version of Science.

Electricity produced from sun rays by photovoltaic cells costs about four times as much as power from conventional coal-fired generators. The higher expense of storing solar power in batteries has undercut its acceptance as a dependable source of renewable energy.

Cheaply storing energy from sun rays would mean ''you've answered everything,'' said Kevin Book, senior energy analyst for Friedman, Billings, Ramsey & Co., before the study was published. For solar power, ''It's the difference between being on the sidelines and being the quarterback,'' he said.

The breakthrough uses a relatively simple way to use electricity to produce oxygen and hydrogen from water, said Nocera, senior author of the paper. When the two gases later are recombined in a fuel cell they cause a chemical reaction that spins off electrons that are forced through a circuit, reproducing the electricity.

MIT's process might be integrated directly into solar panels used today at homes and businesses, provided more improvements are made, Nocera said.

Fuel cells first need to be made more efficient, and engineering problems must be resolved, before the new process can be commercially combined with solar devices, Nocera said.

''The reason photovoltaics have never penetrated the market is you can't store any energy from them,'' Nocera said. ''This is a basic science discovery. People are going to run with this because anybody can do it.''

Within 10 years, homes could be powered in daylight using solar cells, and at night by using fuel cells running on hydrogen and oxygen produced from surplus solar energy, Nocera said. The energy source eventually could eliminate the need for electricity to be supplied by power plants and delivered to homes over transmission lines, he predicted.

''This is a major discovery with enormous implications for the future,'' James Barber, the Ernst Chain Professor of Biochemistry at Imperial College London, said in a statement from MIT. ''It opens up the door for developing new technologies for energy production.''

Gore-Tex could substitute for platinum in creating electricity

Gore-Tex, a waterproof fabric used in jackets and ski clothing, may allow fuel cells to generate electricity as efficiently as platinum at a lower cost, researchers found.

Bjorn Winther-Jensen and colleagues at Monash University in Australia created an electrical current using a Gore-Tex layer coated with a chemical. The current was similar to those generated by traditional systems using platinum, according to a study that will be published in the next edition of Science
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The technology creates electricity by separating the electrons and protons of a fuel, often hydrogen, in a chemical reaction with oxygen. The technology is being developed by Daimler AG and General Motors Corp. as a carbon-free replacement for fossil-fuel car engines. The cost of the technology is one of the biggest hurdles to expanding its use, said Mike Ramage, a former Exxon Mobil Corp. executive.

''A lot of the cost is due to platinum,'' said Ramage, who supervised a report on hydrogen and fuel cells by the National Academy of Sciences published earlier this month. ''Finding something to replace platinum with would be a major breakthrough.''