When researchers conceived of turning algae into diesel fuel three decades ago, the idea sounded like something out of the old sci-fi movie Soylent Green. But in July, ExxonMobil teamed up with biologist Craig Venter’s Synthetic Genomics to take algae biofuel to the marketplace. ExxonMobil has invested $600 million to design better strains of algae and to convert them into fuel. Meanwhile, several start-up companies—including Aurora Biofuels and Solix Biofuels —have built pilot plants that prove it is possible to brew algae-derived diesel fuel in large quantities. “At the beginning we’d tell people, ‘I know this sounds crazy,’” says Bryan Willson, a Colorado State University engineer and cofounder of Solix Biofuels. “But with the ExxonMobil investment, algae is entering the mainstream.”
Traditional biofuel crops such as soybeans yield 50 to 150 gallons of fuel per planted acre per year, but Solix’s facility near Durango, Colorado, is producing more than 2,000. The centerpiece is a sealed growth chamber, or photo-bioreactor, made from a clear polymer to let sunlight through; inside is a strain of algae selected for its high rate of oil production. (Closed reactors are less susceptible to contamination by outside algae than are open-pond systems.) After the algae are harvested, their oils are extracted and refined into renewable diesel. Besides sunlight, the algae require little more than carbon dioxide from nearby power plants, so operating expenses should be low.
Willson predicts his company’s algae fuel (and its coproducts, which are to be sold for animal feed) will be cost-competitive with petroleum diesel within five years. “It represents a large-scale solution to a global problem,” he says.