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 scenari 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.
美国宇航局位于加州Moffett Field的Ames研究中心的研究员Jonathan Trent认为，“种”海藻是一种多赢的举措。首先这种植物富含植物油而且很容易种植；其次在大海里种植节省了土地，节省下来的土地就可以用来种其他的作物；而且这个种植的过程中吸收的大气中的碳比其产生的要多，因而也就能改善大气的含碳量。
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."
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.
"The big problem is going to be scaling it up ... and figuring out how to deal with storms at sea," Trent said.
"But this country is good at engineering things," he added. "To quote Harry Truman, 'There's no limit to what you can accomplish if you don't care who gets the credit.'"
An offshore algae farm could have some serious environmental issues, points out Carmela Cuomo, a marine scientist at the University of New Haven in Connecticut who is researching algae strains for biofuel use.
"I'm not knocking the idea, but I'd want to know a lot more about it," she told Discovery News.
Cuomo said waste water that has been treated enough to be dumped into the ocean probably wouldn't have enough nutrients for algae to thrive, and untreated waste water could pose a threat if the membrane should rip. She also pointed out that the algae farms would have to be fairly close to the ocean's surface for sunlight to penetrate, which could be an issue for boaters.
The main problem with algae, whether grown on land or sea, is how to get enough of it. "To be able to replace a Shell (Oil Co.), you're going to need a lot of algae."