NASA Grows Algae for Biofuel, Treats Waste

May 14, 2009 -- Take some NASA-developed plastic membranes, add algae and municipal waste water and float it out to sea. What have you got? An environmentally friendly alternative to U.S. dependence on foreign oil, says one NASA scientist.

Jonathan Trent, a researcher at NASA's Ames Research Center in Moffett Field, Calif., sees algae farmed at sea as a win-win-win scenario: The plants are oil-rich and easy to grow; sea-based nurseries leave land free for food production; and the process should take out more carbon from the atmosphere than what it puts in.

As an added bonus, the system purifies waste water now being pumped into the ocean.

"What we're doing is closing the loop in our own spaceship Earth environment," Trent told Discovery News. "The only catch is no one's ever done this before."

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Algae has become one of the hotter commodities in the quest for fossil fuel alternatives, said Michael Frohlich, a spokesman for the National Biodiesel Board, a Missouri-based trade organization.

Traditionally, algae is grown outdoors in large tanks of moving water, or inside bioreactors. The plants produce far more oil per acre than other crops, such as soybeans. Algae farming does, however, have a few technical hurdles to overcome, such as how to efficiently drain the water in which the algae grows, added Biodiesel Board technical adviser Alan Weber.

Trent's plan is to grow freshwater algae in nutrient-rich waste water inside semi-permeable plastic membranes. The natural salinity of the ocean will draw the freshwater out, retaining the plants and nutrients. The membranes prevent saltwater from getting inside and killing the plants, while ocean waves keep the algae mixed and healthy. The process treats the sewage water, which is then released into the ocean, and after the algae is harvested, the plastic bags can be recycled.

The concept already has been demonstrated in laboratories, in part supported by $400,000 from Google earmarked for NASA sustainable energy projects. This week, the city of Santa Cruz expressed support for letting its municipal waste water be used in a pilot demonstration project in the Pacific Ocean, Trent said. The project also is under consideration for an $800,000 alternative energy grant from the state of California.