Algae Biofuel Production Targets Waste

 .Analysis by Alyssa Danigelis


Mon May 17, 2010 07:04 PM ET

On the surface, algae is an attractive fuel source, especially since it doesn't cut into food crops. The problem isn't that the algae doesn't grow quickly--the high yield is remarkable--it's that production still requires lots of water and nutrients. An unlikely resource might be the answer.

Earlier this year, a group of scientists from the University of Virginia made waves when they found that between the water and nutrients, algae fuel production can end up generating more greenhouse gas emissions than it promises to prevent. Groan. Not what algae fuel proponents wanted to hear. Andres Clarens, an assistant professor of environmental and water resources engineering at the university who worked on that research, told me that his group is now evaluating two leading techniques for producing the fuel: closed photobioreactors and open ponds.

Open ponds are self-explanatory but photobioreactors tend to be large transparent tubes, often arranged in arrays, where the algae is cultivated. The idea behind these reactors is that since the process is closed there won't be evaporation, therefore saving water so algae can grow at higher concentrations. While Clarens is careful to say that their research is ongoing, preliminary results are showing that the reactors might not be as advantageous as they seem. For logistics reasons, the largest swaths of land that could house them affordably would be in sparsely populated areas.

"Imagine putting a large glass tube out in the desert," Clarens says. "You'd have algae soup." Keeping the reactors at the right temperature requires energy, adding to the expense. Open ponds have their own drawbacks, too, including that you probably wouldn't want to live right next door to one.

So where's the good news? Well, Clarens and his fellow scientists suggest that a smart way to reduce costs would be to pair production with wastewater bioremediation. Algae can handle chemicals that we want to avoid, making it a useful filter. "It's a two-for-one benefit," Clarens says. While securing acres of land for algae production next to wastewater treatment plants won't be easy, this is a case where constraints are leading to creative problem-solving. A first-of-its-kind pilot facility that was announced last year in Logan, Utah, aims to turn a 460-acre money-draining wastewater lagoon full of phosphates into an algae farm. There are thousands of these problematic lagoons across the country just waiting for help. I'm confident that a mixture of technology and algae can come to the rescue.