ALGAE
M
ore and more power plants are exploring options for carbon mitigation as humankind steers toward a more environmentally friendly existence. While still in its infancy, algae’s mitigation potential has garnered attention from plant operators and government agencies alike. Even so, some say the practice is not a solution for carbon dioxide emissions and should be studied from the point of bioproducts manufacturing instead. An Arizona Public Services’ project at Cholla Power Plant in Holbrook, Ariz., is set to be the first integrated pilot-scale demonstration of capturing CO2 from a coal-fired power plant with algae in the U.S., according to Daniel Cicero, senior management and technology advisor for the U.S. DOE’s National Energy Technology Laboratory in West Virginia. The 25-acre raceway pond project, which should be completed and operating in the next three to four years, is an expansion of APS’s research and development endeavor at its natural gas-fired Redhawk Power Station near Phoenix, according to Cicero. “The algae technology is being considered to be an integral part of the electric power plant for its mitigation of CO2 emissions and for further reuse of the CO2 into a coproduct (substitute natural gas) with the electric power from the plant,” he says. Researchers expect that the Cholla algae farm will reuse CO2 at a rate of 70 metric tons per acre per year.
‘All these power plants will be penalized if they don’t have a solution for taking CO2 and using it. You can’t emit carbon dioxide anymore. If you can’t emit carbon dioxide, then you don’t have an industry. Everything emits carbon dioxide.’ —Sharon Miller, vice president, Bard Holding Inc.
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The project received $70.5 million from the American Recovery and Reinvestment Act, one of many algal carbon mitigation endeavors awarded federal funding. “We began a program several years ago about using algae to absorb CO2 from power stations and further use that CO2 as opposed to just emitting it,” says Cicero, who works in the DOE’s Office of Fossil Energy. The ARRA also awarded a total of $7.02 million for design and evaluation of algae growth projects at industrial emitters, including some power plants, in Hawaii, Virginia, Ohio, Texas and California. More funds will be awarded after another competitive process to determine which projects will see the remaining three phases of development—detailed design, construction and operation. Those projects are expected to come on line shortly after the Cholla application, although they will be smaller. Cicero sees promise for the practice from bench-scale results, but acknowledges work left to be done. “It’s going to take a lot of land mass to capture significant amounts of CO2,” he says, adding that some areas are more amenable to algae growth than others and applications must be tailored to specific locations. “We have been able to demonstrate that depending on the strain of algae you choose, it can be very effective in [certain areas], but you have to be careful which strains of algae are chosen and how you process those algae.” On average, about 60 percent of the carbon dioxide can be captured daily, according to the Office of Fossil Energy. The algae grown with carbon emissions can enhance domestic biofuel production and contribute to energy security, but carbon dioxide abatement is the most important benefit, according to Cicero. “Our primary focus is on CO2 capture and helping companies get renewable energy credit,” he says.
Abandon All Hope But some researchers believe that the focus should be changed, including