First, to clean up power-plant emissions some, and then, to produce biofuels. What they do is set up one of their bioreactors – three meters tall glass tubes – so that the carbon-rich emissions from power plants can be fed to them, along with additional sun and water, and then they just watch the algae grow! Once they have enough, they harvest it and process it so that it becomes biofuel.
Of course, they then make money on both ends with sale of both the bioreactor and the biofuel. Fascinating!