Canadian Company Testing Enzymatic CO2 Capture
Is carbon sequestration a promising development for minimizing CO2 emissions, or a "counter-productive red herring?" The jury's still out, but a very early-stage technology being tested by Quebec City's CO2 Solutions could make sequestration a reality, or even transform carbon emitted from smokestacks into raw materials such as "baking soda, chalk, or limestone." According to Technology Review, the company's prototype bioreactor uses an enzyme harvested from genetically modified E. coli bacteria to turn CO2 wastes into bicarbonate:
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 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.So far, the company has tested the bioreactor on a small municipal incinerator and an Alcoa aluminum smelter, and CO2 Solution scientists are now working with Babcock and Wilcox, a manufacturer of power-plant equipment, to adapt it for use on coal-fired power plants. An Alcoa representative claimed that in a small-scale test, the technology "worked well," and removed 80% of the CO2 from emissions discharged from an air outlet connected to a smelter's emissions-scrubbing system. In theory, a mature version of the technology could create a closed loop for CO2 in cement plants, extracting the greenhouse gas from emissions, and "...converting it into bicarbonate and eventually limestone--a key ingredient in manufacturing the cement itself."
Only time and testing will tell if this is a promising development, or another misfire. One commenter at TR already claims the theory behind the bioreactor represents "half a solution," because making limestone would also require large amounts of calcium or or other cation to combine with the resulting bicarbonate. However this experiment turns out, we hope efforts to reduce CO2 emissions stay on course. ::Technology Review via jiltedcitizen at Hugg