May 20th, 2009 - NASA is planning to grow biofuel by putting sewage and algae together in a plastic bag and floating it in the ocean. Jonathan Trent, the lead researcher on the OMEGA project at NASA's Ames Research Center in California, says the technology is nearly cost-competitive with land-based methods.

Trent explains, "We're functioning on at least three different levels: making the products...then wastewater processing and carbon sequestration. The economic model becomes more reasonable."

The algae eat (and treat) the sewage, producing up to 2,000 gallons of oil per acre per year. Today, the main biofuel crops are soy (50 gallons per acre per year), canola (150 gallons), and oil palm (600 gallons). The semi-permeable bags are "forward osmosis", allowing fresh water to flow out and isolating the fresh-water algae from the salt water ocean. The bags also allow gas exchange for normal photosynthesis, so CO2 goes in and oxygen comes out. After two or three years they would turn the inexpensive bags into mulch.

This model would not displace agricultural land the way other biofuel crops do, it stacks the functions of waste treatment and fuel production, but the membrane technology is not finished, and the potential impact on the ocean ecosystem of bringing the technology to scale is unclear. Trent hopes to have a demonstration project finished next year.

Companies in the aviation sector may be particularly interested in the idea as many have been experimenting with biofuels this year in anticipation of another sharp rise in fuel prices sometime soon.

Join NASA's Steve Zornetzar, associate director of the Ames Research Center, at the Sustainable Brands 09 conference where he will be participating in a panel about the built environment.