Magazine article Science News

Power Plants: Algae Churn out Hydrogen

Magazine article Science News

Power Plants: Algae Churn out Hydrogen

Article excerpt

Could the green scum that grows on the walls of a fish tank produce the fuel of the future? Some scientists think so. They've found a way to coax green algae into producing significant amounts of hydrogen gas. In these researchers' view, large pools of algae could generate clean-burning hydrogen fuel for cars and other applications.

As microscopic plants, algae use photosynthesis to create sugars from water, carbon dioxide, and sunlight. Algae also have the biochemical machinery to produce hydrogen, notes Tasios Melis of the University of California, Berkeley. Under some conditions--in the absence of oxygen, for example--algae strip hydrogen from some of their proteins. This process allows the cell to maintain its production of adenosine triphosphate, or ATP, an energy molecule that powers many cell functions.

Scientists trying to tap the hydrogen-making potential of algae faced a difficult problem. Plants produce oxygen during photosynthesis, and oxygen deactivates the enzyme that makes hydrogen.

"The algae know that hydrogen and oxygen don't mix," Melis says. The two gases react easily to give off a burst of heat. The enzyme probably evolved its sensitivity to oxygen to protect against that danger, he says.

Melis and his coworkers discovered a way around this dilemma. By depriving the algae of sulfur, which the cells need to make several important proteins, the researchers can turn off normal photosynthesis. This shuts down the algae's oxygen production and forces the cells to make hydrogen instead. …

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