Algae at the climatic Rubicon

Julius Caesar had his legions; Constance Senior and Mark Huntley hope to muster millions of legions in their campaign against climate change.

The two researchers and their companies want to draft billions of tiny algae to scrub power-plant smokestacks clean of carbon dioxide - a byproduct of burning coal, oil, and natural gas that many scientists say is responsible for earth's warming climate.

The idea may sound a bit exotic. Indeed, the US Department of Energy, which is funding a wide range of research projects to get rid of carbon dioxide, lists this effort under its "advanced concepts" column.

To Dr. Huntley, however, the logic for harnessing algae is compelling. "Ask yourself: What kinds of biological means for getting rid of carbon dioxide might be the most effective?" he says. His answer: algae. Cover a square meter of surface area with algae, he says, and each day the tiny plant-like organisms will gorge themselves on carbon dioxide 100 times faster than a square meter's worth of trees.

Huntley, a former Scripps Institution of Oceanography researcher who is now chief executive officer of Aquasearch Inc., in Kailua-Kona, Hawaii, has pioneered a relatively inexpensive technology to "farm" algae. His initial objective was to tap algae that produce biochemicals useful to pharmaceutical companies. Along the way, however, it became clear that if one picks the right type of algae, the critters wouldn't care if their daily ration of CO2 came from a steel storage tank or power-plant gases. Indeed, the nitrous oxide, and perhaps even the sulfur dioxide in the stack's exhaust also could be used as algae fodder.

Dr. Senior, a chemical engineer with Physical Sciences Inc., in Andover, Mass., holds that scrubbing CO2 with algae makes sense for another reason. Some of the carbon-sequestration concepts "people are looking at are silly because they require a lot of energy," she says. "And that energy is generated by burning fossil fuel."

An algae-based approach is no free lunch. Yet the researchers say costs could fall substantially if, in addition to soaking up carbon dioxide, the algae produce marketable biochemicals. Nor would this approach work at every power plant. Yet Senior notes that since the sun is the algae's major energy source, the approach would work best in the tropics and subtropics, which include much of the developing world.

With funding from the DOE and from their own companies, the team (which includes scientists from the University of Hawaii) plans to spend the first year finding the right type of algae.

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