Monday, March 28, 2011

'Artificial leaf' converts sunlight and water into electricity

An MIT chemist says he's formed an advanced solar cell — basically an artificial leaf that can mimic photosynthesis, the procedure by which plants breathe and produce power.

"A practical artificial leaf has been one of the holy grails of science for decades," Daniel Nocera, a Massachusetts Institute of Technology professor of chemistry and energy, said in a release.

"We consider we have done it. The artificial leaf shows exacting promise as an economical source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station," he said.

Nocera unveiled his leaf on Sunday at the National Meeting of the American Chemical Society in California.

About the mass of a very thin playing card, the silicon solar cell uses electronics and catalysts to go faster chemical reactions to change sunlight and water into electricity.

The cell is located in a gallon of water in full sun, where it cracks the water into hydrogen and oxygen. The hydrogen and oxygen gases are then stored in a fuel cell, which uses the two basics to produce electricity.

The artificial leaf is not a new idea. John Turner of the U.S. National Renewable Energy Laboratory in Colorado created the first one more than 10 years ago. But it used unusual, expensive metals and had a lifetime of barely one day.

Nocera said his leaf is made of cheap materials that are widely available, with catalysts made of nickel and cobalt. In a lab test, he showed that his leaf can operate endlessly for at least 45 hours without a drop in activity.

"One can imagine villages in India and Africa not long from now acquiring an affordable basic power system based on this technology," he said.

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