Energy From Algae?

The endless quest for an alternative to petroleum has dipped a toe in a rather slimy source: pond scum, reports science journalist Neil Savage.

There’s plenty to like about the green- and red-colored organisms as a possible fuel source. Unlike many biofuel sources, such as corn and sugar cane, which require land that could be used to grow food, algae can easily grow in areas not suitable for farming as long as water is supplied. Algae even do well in polluted water. They are also incredibly productive: Researchers estimate that algae could produce 61,000 liters (around 16,110 gallons) of biofuel per hectare; by comparison, soybeans only yield 200 to 450 liters.

Lots of problems must be resolved before algae-based biofuels become more than a novelty. For one thing, because algae need sunlight, the surface area required to cultivate meaningful amounts is tremendous. Europe would need an algae farm the size of Portugal to produce enough fuel to fully supply just its transportation systems. And the water requirements of algae farms are immense, dwarfing those of more traditional forms of agriculture. Combined with a slow and delicate harvesting process, in which algae cells are broken apart to extract oil that can be turned into fuel, these factors make current algae biofuels too financially and environmentally expensive to compete.

Some scientists say that the algae cultivation process can be tweaked to overcome current production difficulties. One renewable energy company in San Francisco has engineered a way to overcome the inefficiencies of photosynthesis that hamper algae’s production of fuel-packed oil. Another company believes that the future lies with blue-green algae (which are actually photosynthetic bacteria) that naturally secrete oil and thus don’t need to be destroyed in the harvesting process.

Proponents of algae biofuels insist that algae’s depths have yet to be plumbed. Photosynthesis converts barely more than one percent of the sunlight reaching the Earth into chemical energy that humans can use, but a share closer to 10 percent is possible. Both the government and the private sector are listening: The U.S. Department of Energy recently granted a research consortium $44 million to develop algae energy technology, and companies such as ExxonMobil and Boeing have devoted funds to similar research. Algae may be mucky, but they have the potential to be as good as gold.

THE SOURCE: “The Scum Solution” by Neil Savage, in Nature, June 23, 2011.

Photo courtesy of Flickr/Daniel Ramirez