NASA's plastic bags are designed to last up to three years, Trent said. After that, they could be recycled as plastic mulch or chopped and used to improve soil quality and help retain moisture.
"We don't think this would be cost-effective if we just go after the fuels," Trent said. "But we're functioning on at least three different levels: making the products – fuel, fertilizers – then wastewater processing and carbon sequestration. The economic model becomes more reasonable."
In fact, Trent said, the technology is nearly cost-competitive with land-based production methods for algae biofuels that require vast industrial-scale, open-air pond farms or in closed bioreactors.
But land-based methods have limits, Trent said. Open-air ponds and bioreactors gobble up large tracts of land that would be taxed and could potentially compete with agriculture. And even in deserts, where farming is less likely, evaporation of open-air ponds is a threat. Closed bioreactors face similar hurdles. They must be extremely robust in order to hold large amounts of water against air.
"We've solved the problem of evaporation, weeds, structure," Trent said. "And we think we've added other benefits like processing sewage and sequestering carbon."
Trent envisions the OMEGAs producing enough fuel to fill U.S. aviation needs – 21 billion gallons a year. Doing so would require about 10 acres of ocean, he said.
"It seems huge, but it's a small area in the overall oceans," he said. "And we imagine [the OMEGAs] distributed around, locally distributed ... or franchised and monitored by fishermen."
But the technology faces challenges.
Trent and his fellow researchers are still trying to find plastic capable of withstanding pounding waves and cold temperatures without becoming too brittle for osmosis.
And then there is the matter of money. Venture capitalists are wary, Trent said, but his team has had some luck with the California Energy Commission. A state grant is slated to kick in this August.
The grant should help Trent and the other Ames researchers create a demonstration project within a year. That would let the technology get wider scrutiny and be compared with other renewable-energy technologies.
"On a planet with a population growing at exponential rates and resources dwindling, we're almost in a state of emergency on a timeline measured in decades," Trent said. "I think it's important, this process of coming up with alternatives. ... I don't know if OMEGA is the solution, but it's something that should be carefully scrutinized."
Reprinted from Greenwire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500