When algae is discussed as an alternative source of biofuel, it's often in tones of breathless excitement; many green tech boosters believe that the slimy goo can be turned into fuel superior to that made from corn, canola, or switch grass. You don't need vast tracts of land to cultivate algae for biofuel, the thinking goes, all you need is the right strain of algae, water, sunlight, and carbon dioxide. Even Exxon and Dow Chemical recently joined the biofuel brigade, and are now investing millions in algae operations. But a new study suggests that while algae might produce good fuel, the environmental costs involved in the production would be heavy. A life-cycle assessment published in the journal Environmental Science and Technology argues that algae production consumes more water and energy than other biofuel sources like corn, canola, and switch grass, and also has higher greenhouse gas emissions. While the study's results are sobering, they're also being met with harsh criticism from alage-based biofuel companies and their trade group, the