The Department of Energy Finds Algae Grown in Open Ponds Could Replace 17% of U.S. Oil Imports, But Clever Water Usage is a Must.

DOE researchers at the Pacific Northwest National Laboratory studying the potential for Algae grown in open ponds found that algae grown this way could replace 17% of oil imports. However, while algae is very land-efficient, it is water intensive. The study was published in Water Resources Research.

Lead author and PNNL hydrologist, Mark Wigmosta:

"Algae has been a hot topic of biofuel discussions recently, but no one has taken such a detailed look at how much America could make - and how much water and land it would require — until now. This research provides the groundwork and initial estimates needed to better inform renewable energy decisions."

Congressionally mandated targets are calling for a reduction in oil imports by a third and fresh water algae ponds alone could potentially meet half of this reduction. This equates to 21bn gallons of biofuel which could be produced on an area of land the size of South Carolina. However, one gallon of algal biofuel requires 350 gallons of water to produce. The study also found that if significantly more land and water were used it would be possible to replace 48% of fuel imports, though this would be much more difficult.

Driving a mile on algal biofuel has a water footprint of 8.6-50.2 gallons and bioethanol production has a similar water footprint. Water availability is one of the big challenges set to face the world in coming years and the fact that algae production is so thirsty will hinder algal biofuel unless water is managed carefully in this growing industry. A number of methods exist for minimizing water usage in algae cultivation, some of which will be considered in future studies by Wigmosta’s research group and projects that bear their water consumption in mind might be the most sustainable.

This study represents the first in-depth attempt to determine the potential for algal biofuel growth. Thirty years of meteorological data, high resolution topographical data and information on population and land use were analyzed, along with mathematical modeling of algal growth under various conditions. While there are many ways of producing algae, open freshwater ponds are the most common in the US. The limiting factors considered in the study were location and climate; growing algae is water intensive and warm climates are ideal for algae cultivation, as they require less water input in these conditions. Three areas were identified as well suited to growing algae; the Gulf Coast, Eastern Seaboard and the Great Lakes.

Future studies by the group are aimed at investigating more advanced algae cultivation technologies, such as the potential for salt-water algae development, the impact of using waste CO2 to enhance growth, algae cultivation in waste water, the use of greenhouse ponds for colder climates and economic factors. A number of projects are pursuing algae technologies that use less fresh water; for example a Spanish consortium which is using waste water and a biofuel facility in New Mexico using salt water. If the potential of these technologies is demonstrated by this research, it could help attract investment and reduce the water footprint of cultivating algal feedstocks. Data on the water savings of non-fresh water cultivation technologies would be valuable for the algae industry. There are also locations for a “perfect storm” of conditions for algae cultivation; a combination of good geography, adjacent sources of waste CO2, abundant sunshine, humidity and non-fresh water supplies. Identifying these sites could give algae development a boost as producers compete to get hold of the best locations.