Canadian Company Testing Enzymatic CO2 Capture
by Jeff McIntire-Strasburg, St. Louis, MO on 02.23.07
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
Something vary basic is wrong with this picture. The use of a packed tower with counter current exchange is old hat in pollution control. Limestone, if an ultimate byproduct, is calciium carbonate. You have to get the calcium ion from somewhere to react C02 with it. The most likely source of calcium ion twould be slaked lime, which is made by baking calcium carbonate in a cement kiln, which is emits large amounts of C02, getting us right back where we started.
If inventors want to generate publicity they need to file for a patent and then disclose sufficiente details to establish basic credibility.
It only mentioned limestone as a possible end use of the bicarbonate ions the reactor makes.
What I want to see is a way to take CO2 into a process, and get out O2 and C2 for sequestration far underground. Pure C2 is very environmentally stable, and would stay put underground without pressurization for eons. And they way we're killing off Earth's natural oxygen producers, we could always use the O2.
I'm no Chemist, is bicarbonate a gas? If so, is it a known greenhouse gas? If not, why not just release the bicarbonate into the atmosphere?
If it's not a gas, what is it? Liquid? Solid? Is it highly reactive?
I mean, if it's a non reactive liquid or solid, couldn't it just be disposed of in landfills? Why do anything at all with it?
The only reason I can think of why anyone would even consider using the bicarbonate for anything at all is if it's unstable and will just revert back to co2 if disposed of in some inexpensive way...
bicarbonate is a solid, you know it as "baking soda".
The reason to further process it is so that it can be recycled and used over and over internally as a catalyst.
A neat powered black box where smokestack emissions go in one end, and concentrated CO2 for sequestration comes out the other end - no additional chemicals needed.