ATHENS, Ohio – Greenhouse gas emissions are an environmental concern and acostly problem for coal-fired power plants, which are facing tighter federal pollution laws. But scientists at Ohio University are looking to nature to develop a cleaner, inexpensive way of removing carbon dioxide from smokestacks.
The researchers, supported by a new $1.07 million grant from the U. S. Department of Energy, are studying how algae and sunlight, in a natural process known as photosynthesis, can absorb some of the carbon dioxide produced after coal is burned. Though other scientists have used lakes filled with algae to absorb gas emissions, the Ohio University team has proposed growing and harvesting the organisms directly in the exhaust gas from power plants.
Algae is not only cheap and plentiful, but could be collected from the power plants for use by agricultural industries, says David Bayless, an assistant professor of mechanical engineering and lead researcher on the project.
"We're storing carbon dioxide in organisms that exist in your backyard," Bayless says. "Once the algae is grown, if it can't be used as fuel or a hydrogen source, it can be used as a fertilizer or soil stabilizer."
The process, he says, would work something like this: As the carbon dioxide exhaust moves toward the smokestacks, it would pass through tubes of running water, creating bicarbonates that would bubble in the water like soda pop. The water then flows through a bioreactor that contains a series of screens on which algae grow. "The algae basically drink the bicarbonates," says Bayless, who also serves as associate director of the university's Ohio Coal Research Center. "They get carbon through this system much quicker than trying to get it out of the air."
Using a system of solar panels, satellite dishes and fiber optic cables developed by scientists at the Oak Ridge National Laboratory, a partner in the project, only visible sunlight would be emitted into the bioreactor, helping the algae to use carbon dioxide for fuel – a process known as photosynthesis.
Once the algae grow to maturity, they fall to the bottom of the bioreactorand are harvested for other uses, says Bayless, who is collaborating on the project with Morgan Vis-Chiasson, an assistant professor of environmental and plant biology who specializes in algae research, and Gregory Kremer, an assistant professor of mechanical engineering, both at Ohio University.
Until now, the Ohio University team has tested the method on a small scale, growing about 2 pounds of algae in a direct stream of carbon dioxide exhaust with the aid of fluorescent lights. The new, three-year Department of Energy grant will allow them to add the bicarbonate and sunlight systems to the project.
Researchers will use blue-green algae collected by Montana State University colleagues at Yellowstone National Park – where it survives near boiling point temperatures in hot springs, a climate similar to that of a coal-fired power plant. But their ultimate goal is to create technology that can use any type of algae found in abundance in the world.
"We hope to make this a process that doesn't depend on any specific organism, to be used by any power plant," Bayless says.
No one technology can solve the carbon dioxide problem for coal-burning power plants, Bayless stresses, but the algae-fueled bioreactor could serve as an efficient, cost-effective part of the gas emission reduction strategy. He estimates that an average-size plant using this technology could process 20 percent of its carbon dioxide emissions and produce 200,000 tons or more of algae per year.
The bioreactor is one of several energy technologies being developed by Bayless and other scientists with the university's Ohio Coal Research Center to make Ohio coal a cleaner, more viable fuel source. In other projects supported by the Ohio Coal Development Office, the researchers are exploring ways to reduce toxic sulfur emissions by changing the chemical composition of the exhaust gas, and are developing a new device that could more efficiently collect additional heavy metal particles from the exhaust stream.
Bayless and Kremer hold appointments in the Russ College of Engineering and Technology. Vis-Chiasson holds an appointment in the College of Arts and Sciences.
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