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Golden, Colo., April 16, 1998 A device developed by researchers at the U.S. Department of Energy's National Renewable Energy Laboratory uses two of the world's most abundant resources, water and sunlight, to directly generate hydrogen, a non-polluting and totally recyclable fuel.
The results of the research by Senior Scientist Dr. John Turner and postdoctoral fellow Dr. Oscar Khaselev will be published in the April 17 edition of the journal Science.
Their device splits water into hydrogen and oxygen with greater efficiency than other methods using sunlight. Currently available systems that use sunlight to divide water into its basic components link photovoltaic (PV) cells that generate electricity with an electrolyser to break down water. The all-in-one device reported by Turner and Khaselev is an advanced alternative to these PV/electrolyser systems, converting about 12 percent of available sunlight into hydrogen. Current PV/electrolyser systems use less efficient solar cells and loose efficiency by transferring electricity to the electrolyser. They convert about 4 percent to 6 percent of the available sunlight into hydrogen.
This means the photoelectrolysis device can reduce the cost of producing hydrogen from sunlight by combining the photovoltaics with the electrolyser. The advanced semiconductor material used in the device also was developed at NREL.
Hydrogen can power vehicles, generate electricity through fuel cells and otherwise be used to meet the world's energy needs. When hydrogen is used as an energy resource, it generates no emissions other than water, which can be used to make more hydrogen.
The device presently is not an economical way to produce hydrogen from water and sunlight. But because of the gains in efficiency and the potential for lower cost, it holds great promise that through further research the technology can bring down the cost of using water and sunlight to fuel a non-polluting, never-ending hydrogen-based energy economy.
The potential of hydrogen is enormous. Internal combustion engines can be run with pure hydrogen or hydrogen blended with natural gas and very few emissions. Hydrogen fuel cells, with no emissions, also can power vehicles and provide heat and electricity for homes and buildings.
The overall goal of the Department of Energy's Hydrogen Program is to replace 2 to 4 quads of conventional energy with hydrogen by 2010, and replace 10 quads a year by 2030. A quad is the amount of energy consumed by 1 million households in the U.S.
Editor's note: Science is the weekly peer-reviewed journal of the American Association for the Advancement of Science. To obtain a copy of the Science article, contact the journal directly at (202) 326-6440.