Forthe past year, exhaust from MIT’s main power plant has been bubbling upthrough tubes of algae soup. The result? A dramatic cut in carbondioxide (CO2) emissions—and abundant algae that can beturned into biofuel for the power plant or a diesel vehicle. Utilitycompanies have been watching field trials of the algae-soup system withkeen interest, hoping to combine low-cost exhaust cleanup withrenewable-fuel production.
This novel technology isthe brainchild of Isaac Berzin, founder and chief technology officer ofGreenFuel Technologies Corp., which markets the system. As an MITpostdoc in chemical engineering, Berzin became intrigued with usingalgae to clean up exhaust from power plants burning fossil fuels,especially coal. Coal is an abundant resource but an undesirable fuelbecause of its high CO2 emissions. “Other types of emissions can now be controlled,” said Berzin, “but controlling CO2 at low cost is still a challenge.”
One option is algae. These fast-growing, single-celled organisms gobble up CO2during photosynthesis. Moreover, they split nitrogen oxides—a precursorto smog—into harmless nitrogen and oxygen. And they’re hardy creatures,thriving in conditions ranging from the Antarctic to the Yellowstonegeysers to the Great Salt Lake.
The installation onMIT’s 20-megawatt cogeneration plant demonstrates their abilities. Atopthe plant are thirty 3-meter-high triangles of clear pipe containing amixture of algae and water. Bubbling the plant’s flue gases through themixture has reduced CO2 emissions by 82 percent on sunnydays and 50 percent on cloudy days (during daytime) and has cutnitrogen oxides by 85 percent (on a 24-hour basis).
Thestory gets even better. Algae double in mass every couple of hours, sothey can be harvested and easily converted into biodiesel, a clean,storable fuel to use in the power plant or a diesel vehicle. Of course,burning the algae releases the carbon they captured from the fluegases. “All the original carbon will ultimately reach the environment,but you’ll have run the vehicle as well as the power plant,” saidBerzin. “Put simply, you’ve created two amounts of energy with oneamount of pollution.”
Using algae to capture CO2isn’t a new idea, but no one has found a commercially viable method ofdoing it. What’s Berzin’s secret? “We give an old idea a push withtechnology,” he explained.
For example, Berzin andhis coworkers “tailor” algae to perform well at a specific power plant.They use a terrestrial cousin of a miniature bioreactor designed forthe International Space Station. As algae grow inside the bioreactor,their environment is gradually shifted to conditions they willencounter at the plant. Within three months, the tailored algae arethriving on flue gases instead of air. No genetic engineering isinvolved. “We just use the natural tendency of algae to adapt to anyenvironment,” said Berzin.
In fall 2005, the algaesystem was installed at a 1000-MW power plant in the Southwest. Initialfield trials at the plant were successful, and testing is now movinginto a pilot phase. Berzin estimates that more than 1000 power plantsin the United States have enough flue gas, water, and land to host acommercial-scale installation. Many other industrial facilities wouldno doubt also qualify.
Berzin credits much of hissuccess to MIT, where he collaborated with experts ranging frombioengineers to manufacturing specialists. Among his biggest supporterswas Peter Cooper of MIT‘s Department of Facilities, who oversaw thecogeneration-plant installation. While there‘s no real opportunity forsignificant scale-up at MIT, the MIT "beta test" is demonstrating thesystem‘s technical viability and potential business advantage. "It‘sperforming even better than we expected," said Cooper. "This newtechnology is an important and promising step toward addressing theglobal warming problem, and we’re pleased to be part of its launch.”
It’shard not to find the algae system appealing. “If you look at thisprocess from beginning to end, you’ve turned your pollution intostorable green fuel,” said Berzin. “The technology is exciting becauseit touches on both energy and the environment in a unique way.”
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