Can the cultivation of microalgae meet U.S. energy demands?

As biofuels such as ethanol and esters become increasingly attractive alternatives to nonrenewable resources such as oil and coal, scientists have become interested in determining the feasibility of biofuels to help meet U.S. energy demands in light of governmental efforts to develop cleaner‐burning, renewable fuels. Of particular interest are microalgae—single‐celled, photosynthetic organisms—which have been shown to have high biomass yields per acre cultivated. But does the United States have the resources to cultivate microalgae as a viable alternative to fossil fuel consumption? To answer this question, Wigmosta et al. sought to quantify how much water and land would be needed for commercial‐scale algal biofuel production, based on where production could feasibly occur. They find that with current technology, the United States has the potential to produce 220 billion liters per year of microalgal oil, equivalent to about 48% of current domestic imports. However, they caution that meeting this potential would require that roughly 5.5% of land in the continental United States and 3 times the amount of water currently used for irrigation be devoted to algal production, though optimizing the locations of microalgae production to maximize efficiency of water usage could significantly reduce water demands. These optimal locations include areas around the Great Lakes, the Gulf Coast, and the southeastern seaboard; these coastal locations would allow a 75% reduction in freshwater use and a 67% reduction in land use to cultivate biofuel resources. Moreover, biofuel production through these optimized locations could substitute for up to 17% of oil currently imported for transportation, indicating that with proper planning, U.S. goals for renewable fuels could be met. ( Water Resources Research , doi:10.1029/2010WR009966, 2011)