Gas-busters: Algae comes to the aid of coal-fired plants

This bioreactor provides research data for the Photosynthetic Greenhouse Gas Control Project

By Environmental News Network staff

In an effort to mimic the ways of nature, a team of scientists at Ohio University is working on technology that uses algae, sunlight and the natural process of photosynthesis to absorb carbon dioxide from the combustion of coal.

The result: reduced greenhouse gas emissions.

Carbon dioxide has been identified as the biggest single contributor to global climate change. The Ohio University researchers, whose work is supported by a $1.07 million U.S. Department of Energy grant, estimate their method could lower emissions from an average-sized power plant by 20 percent.

"The concept is to use something in nature to control carbon dioxide emissions," said David Bayless, assistant professor of mechanical engineering and lead researcher on the project. "Everyone is trying to do something chemically driven. We are trying to look at a way to augment nature's carbon recycling processes. In the long term, that is the way we really ought to look at things."

"This technology could be applied to any fuel-burning power plants," he added.

The fizzy water is then forced through a bioreactor that contains a series of screens covered with living algae.

The screens are exposed to sunlight filtered by a special system of solar panels, satellite dishes and fiber optic cables. Scientists at the Oak Ridge National Laboratory, a partner in the project, developed the filtering system, which is also designed to redirect infrared light for use in photovoltaics.

A microscopic view of cyanobacteria, commonly known as blue-green algae, which lives in water

The sunlight aids the algae in photosynthesis, the process by plants create food necessary for growth.

"The algae basically drink the bicarbonates," Bayless said. "They get carbon through this system much quicker than trying to get it out of the air."

After the algae matures, it falls to the bottom of the bioreactor, where it can be harvested for use in energy or agriculture.

For instance, the algae can be used as fuel for biomass incinerators. The Department of Energy also has developed a method to collect hydrogen from vats of fermenting plant organisms such as algae, according to Bayless. The hydrogen can then used as an energy source for fuel cells.

"If (the mature algae) can't be used as fuel or a hydrogen source," he said, "it can be used as a fertilizer or soil stabilizer."

An average-size power plant could produce as many as 200,000 tons of algae per year using this technology.

The researchers have developed a small-scale prototype in which they have grown about two pounds of algae in a direct stream of carbon dioxide exhaust under fluorescent lights. The DOE grant money will help them add the bioreactor and the sunlight systems.

Bayless expects the technology could be implemented in about five years. He estimates that the cost of the system, averaged over 30 years, would be $5 to $7 per ton of carbon dioxide removed from the exhaust.

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U.S. Department of Energy
Ohio University
   •Department of Mechanical Engineering
   •David Bayless
Oak Ridge National Laboratory
Ohio Coal Research Center
National Energy Technology Laboratory

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