Magazine article Science News

Device Ups Hydrogen Energy from Sunlight

Magazine article Science News

Device Ups Hydrogen Energy from Sunlight

Article excerpt

Here's a recipe for a cleaner, healthier planet: Take some water, add solar energy, extract hydrogen, and use it to power fuel cells for running cars and other machines. Then, collect their water emissions and start the procedure again.

One look at the list of ingredients in today's fuel cells, however, shows that this ideal isn't yet being followed. Because processes that use sunlight to extract hydrogen remain costly and inefficient, fossil fuels still supply the hydrogen in most fuel cells.

Hoping to break the fossil fuel habit, a team of Israeli, German, and Japanese scientists has created a device that boosts the efficiency of solar-powered hydrogen extraction by 50 percent.

The group placed a photovoltaic cell on top of two flat, finger-long electrodes. The combination "is very efficient in converting solar energy [into an electric current] but also provides nearly the ideal voltage for splitting water" into hydrogen and oxygen, says team leader Stuart Licht of the Technion in Haifa, Israel. A water molecule splits, or undergoes electrolysis, at only 1.23 volts.

Licht and his colleagues describe their device in the Sept. 14 JOURNAL OF PHYSICAL CHEMISTRY B. The gadget converts sunlight to an electrolysis current with 18.3 percent efficiency. In turn, the current creates hydrogen gas as it passes through acidic water.

The device is "showing the pathway towards higher efficiencies for direct solar-to-hydrogen production," comments John A. Turner of the National Renewable Energy Laboratory (NREL) in Golden, Colo. The newly achieved efficiency may already be high enough for commercial hydrogen generators to be feasible. "That still needs to be figured out," Turner says.

In 1998, he and Oscar Khaselev, then also of NREL, demonstrated a novel apparatus for solar-to-hydrogen conversion (SN: 4/18/98, p. …

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