Study: Algae could replace 17% of U.S. oil imports
Choosing optimal growing locations limits algal biofuel's water use
A new PNNL study shows that 17 percent of the United States' imported oil for transportation could be replaced by biofuel made from algae grown in outdoor raceway ponds located in the Gulf Coast, the Southeastern Seaboard and the Great Lakes. This June 2010 photo shows raceway ponds in Southern California and was taken by the QuickBird satellite.
Algae-derived oils have the potential to replace 17 percent of the nation's imported oil for transportation, according to a study published in Water Resources Research. But growing algae - or any other biofuel source - can require a lot of water. A study by researchers at Pacific Northwest National Laboratory found that water use is much less if algae are grown in the U.S. regions that have the sunniest and most humid climates: the Gulf Coast, the Southeastern Seaboard and the Great Lakes.
Why it matters:
High oil prices and environmental and economic security concerns have triggered interest in using algae-derived oils as an alternative to fossil fuels. Biofuels can create fewer overall greenhouse gas emissions than fossil fuels and they can be made here in the United States. In 2009, slightly more than half of the petroleum consumed by the U.S. was from foreign oil.
"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," said Mark Wigmosta, lead author and a PNNL hydrologist. "This research provides the groundwork and initial estimates needed to better inform renewable energy decisions."
The team analyzed previously published data to determine how much algae can be grown in open, outdoor ponds of fresh water while using current technologies. Much of today's commercial algae production is grown in open ponds.
First, the scientists developed a comprehensive national geographic information system database that evaluated topography, population, land use and other information about the contiguous United States. That database contained information spaced every 100 feet throughout the U.S., which is a much more detailed view than previous research. This data allowed them to identify available areas that are better suited for algae growth, such as those with flat land that isn't used for farming and isn't near cities or environmentally sensitive areas like wetlands or national parks.
Next, the researchers gathered 30 years of meteorological information. That helped them determine the amount of sunlight that algae could realistically photosynthesize and how warm the ponds would become. Combined with a mathematical model on how much typical algae could grow under those specific conditions, the weather data allowed Wigmosta and team to calculate the amount of algae that could realistically be produced hourly at each specific site.
The researchers found that 21 billion gallons of algal oil, equal to the 2022 advanced biofuels goal set out by the Energy Independence and Security Act, can be produced with American-grown algae. That's 17 percent of the petroleum that the U.S. imported in 2008 for transportation fuels, and it could be grown on land roughly the size of South Carolina.
Next up for Wigmosta and his colleagues is to examine non-freshwater sources like salt water and waste water. They are also researching greenhouse ponds for use in colder climates, as well as economic considerations for algal biofuel production.
The paper describes research funded by DOE's Office of Energy Efficiency and Renewable Energy.
Mark S. Wigmosta, Andre M. Coleman, Richard J. Skaggs, Michael H. Huesemann, Leonard J. Lane. National Microalgae Biofuel Production Potential and Resource Demand. Water Resources Research. Published online April 13, 2011.http://www.agu.org/journals/wr/wr1104/2010WR009966/. DOI:10.1029/2010WR009966.
For more information, see PNNL's news release at http://www.pnnl.gov/news/release.aspx?id=859.