If the alliance is successful, pumping algae-based gasoline at Exxon service stations is still several years away and will mean additional, multibillion-dollar investments for mass production.

Money talks, but how can we know what it's saying? Exxon Mobil is investing $600 million into a 5- to 6-year algae biofuel project with biotech company Synthetic Genomics. The biofuel will be made ...