A promising new technology for economically capturing 90 percent of the carbon dioxide (CO2) emitted from a coal-burning power plant has begun pilot-scale testing.

Sponsored by the U.S. Department of Energy (DOE), the Polaris membrane system uses a specially designed CO2-selective membrane to separate CO2 from other gases such as nitrogen in a coal-burning plant’s flue gas. Developed by Membrane Technology and Research Inc. (MTR), Polaris relies on a micro-porous film that acts as a semi-permeable barrier.

The project, managed by the DOE Office of Fossil Energy’s National Energy Technology Laboratory (NETL) is the largest-scale CO2 membrane technology in the Department’s research portfolio. According to DOE, it has the potential to support the reduction of greenhouse gas emissions from coal-fired power plants while minimizing the increase in electricity price. Cost-effective carbon capture and storage from fossil-based power generation has been cited by some national and international experts as a critical component for arresting the rise in atmospheric CO2 concentrations.

According to DOE, the Polaris system is 10 times more permeable to CO2 than conventional gas-separation membranes. That means the membrane area can be reduced, cutting down the cost and size of the system. In addition, the membrane system does not use hazardous chemicals, so there are no emissions or disposal issues; it uses less water than other capture technologies; and the membrane has no moving parts.

The MTR membrane separation process has already completed 7,500 hours of small-scale (0.05 MW-electric) testing using actual flue gas. Successful testing at pilot scale (1 MW-electric) will be a major step toward meeting the Department program’s goal of capturing more than 90 percent of CO2 from flue gas at a cost of $40 per metric ton of CO2 captured and compressed to 2,200 psig (pounds per square inch gauge).

Pilot-scale testing of the technology, using actual flue gas, began in late January at DOE’s National Carbon Capture Center (NCCC) in Wilsonville, Ala., and will continue for two to three months. The NCCC, operated by Southern Company Services, includes a post-combustion carbon-capture facility that allows testing and integration of advanced CO2-capture technologies using flue gas from Alabama Power’s Gaston power plant Unit 5, an 880 MW pulverized coal unit.