Environmental Engineers Use Algae To Capture Carbon Dioxide

Engineers have designed a simple, sustainable and natural carbon sequestration solution using algae. A team at Ohio University created a photo bioreactor that uses photosynthesis to grow algae, passing carbon dioxide over large membranes, placed vertically to save space. The carbon dioxide produced by the algae is harvested by dissolving into the surrounding water. The algae can be harvested and made into biodiesel fuel and feed for animals. A reactor with 1.25 million square meters of algae screens could be up and running by 2010.

Global warming's effects can be seen worldwide, and many experts believe it's only going to get worse. In fact, America is by far the largest contributor to global warming than any other country -- releasing a quarter of the world's carbon dioxide -- the primary cause of global warming. But now engineers have found a natural way to eliminate one of the worst contributors to our environment's decay.
What's coming from power plants, traffic jams and industrial smog is causing our ozone to disappear, ice caps to melt, and temperatures to rise. The latest international report says carbon dioxide responsible for 60 percent of the greenhouse gases.
Now engineers say a simple, sustainable and natural solution may come from algae. "If this sort of technology can be developed, it can be deployed anywhere there's sunlight," David Bayless, a professor of mechanical engineering at Ohio University in Athens, tells DBIS.
Bayless, with a team at Ohio University, created a photo bioreactor that uses photosynthesis to grow algae just like a plant would take carbon dioxide up and, through the energy of the sun, convert that into oxygen.
"That passes the carbon dioxide over these membranes," Ben Stuart, an Ohio University environmental engineer, tells DBIS. "These membranes are fabric just like your shirt. It's a woven material, and as the carbon dioxide pass by them, that carbon dioxide dissolves into the water."
That carbon dioxide is broken down by the algae. Nitrogen and clean oxygen are released back into the atmosphere. But to capture the CO2 created from a power plant, algae would have to fill a building the size of Wal-Mart.
"The size of these things would be enormous, about an acre worth of land space. And so the flu gases would run through this huge building and the algae would be growing on the suspended vertical surfaces." Stuart says.
But what makes it cost effective? The algae can be harvested and made into biodiesel fuel and feed for animals.
Bayless says, "You are talking about definitely home-grown fuel, a win-win thing. You know, you are taking a potentially very negative thing in carbon emissions and turning it into a fuel that we can use domestically." He says a full-scale reactor with 1.25 million square meters of algae screens could be up and running by 2010.
There are already some test facilities working right now -- and just in time! In the past 50 years, the U.S. carbon dioxide emissions have almost doubled. Texas ranks first in the nation for the highest emissions ... And just remember, once carbon dioxide is released into the atmosphere, it stays there for about 100 years.
The American Geophysical Union, American Society for Microbiology, and the Optical Society of America contributed to the information contained in the TV portion of this report.

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BACKGROUND: A researcher at Ohio University's Ohio Coal Research Center has developed a bioreactor that cleans up carbon dioxide emissions from fossil fuel exhaust with the help of heat-loving algae and hybrid solar lighting. David Bayless believes that the easiest way to eliminate CO2 from coal-burning power plants is to use the natural process of photosynthesis.
HOW IT WORKS: Bayless designed a box packed with blue-green algae spread onto vertical screens. The algae use the CO2 and water from the power plant to grow new algae, giving off oxygen and water vapor in the process. The organisms also absorb components of acid rain, such as nitrogen oxide and sulfur oxide. Building a workable prototype had its share of challenges. For instance, there was a problem of limited space -- it just wasn't possible to cover an area of around 100,000 acres with algae. So Bayless instead placed screens of woven fiber with algae vertically. Since algae need sunlight to thrive he brought in hybrid solar lights that collect sunlight with curved mirrors and then channel it through the reactor via optical fibers.
And instead of trying to genetically modify any kind of algae, he found a species that naturally thrives in the hot springs of Yellowstone National Park, and does equally well in the exhaust of a power plant. A remaining challenge is how to dispose of the large quantities of algae produced by the bioreactor; one option is to collect it and use it as a biologically derived fuel.
ALL ABOUT ALGAE: Algae are relatively simple organisms that capture light energy through photosynthesis and use it to convert inorganic substances into organic matter. Photosynthesis is the process of producing sugar from sunlight, carbon dioxide and water, with oxygen as a waste product. Nearly all life depends on this complex biochemical process, which occurs most famously in plants, but also in phytoplankton, algae, and some bacteria, among other organisms. They are usually found in damp places or bodies of water. They vary from single-celled forms to complex forms made of many cells, such as giant kelps, which can grow as much as 65 meters in length. It is estimated that algae produce between 73% to 87% of the net global production of oxygen.

This story and accompanying video were originally produced for the American Institute of Physics series Discoveries and Breakthroughs in Science by Ivanhoe Broadcast News and are protected by copyright law. All rights reserved.