Tyler Hamilton of Clean Break has an article in Technology Review about a Canadian company called CO2 Solution (CDNX: CST.V), who has developed a bioreactor for capturing CO2 from the exhaust from power plants and industrial facilities.
The bioreactor contains packing that has an enzyme, extracted from genetically engineered E. coli, attached to it, that can absorb CO2 and convert it into bicarbonate, which is an environmentally safe product. Water flows counter current to the CO2 rich gas, the bicarbonate-rich solution is then removed.
The bicarbonate ions can be extracted for making everything from baking powder (sodium bicarbonate) to calcium carbonate (limestone) or the CO2 can be taken out of the solution and sequestered.
Quoting from Technology Review is this more detailed process description:
The bioreactor is a long cylinder containing a packing material that acts as a solid support for the enzyme. The surface of this material has been chemically modified so that the enzymes attach securely. At the top of the cylinder, a water solution is pumped in and flows around the packing material, while gases from a smokestack enter the bottom of the cylinder and bubble up through the solution. The carbon dioxide is absorbed into the solution and then interacts with the enzymes, which convert the greenhouse gas into bicarbonate ions. To end the process, cleaned up air escapes from the top while the bicarbonate solution is extracted [from the bottom] for further processing--either back into pure carbon dioxide for long-term geological storage or into a carbonate compound, such as limestone, that can be used by industry.
This process differs from other systems of capturing CO2 from smokestacks, the others capturing it by growing algae, which can be converted to biodiesel or dried and burned.
The process has already been tested on a small municipal incinerator and an Alcoa aluminum smelter. In small-scale tests at Alcoa the system removed 80% of the CO2. They are now working with Babcock and Wilcox (B & W) to adapt the technology to a coal-fired power plant. B & W believes that the technology is better than the algae systems because it takes less land.
Current work is aimed at improving the system efficiency, scaling up the reactor for use in power plants and producing the enzyme in large quantities