Well, the environmentalists, myself included, care about CO2. Also, every living thing should care about CO2 since it’s either required for generation of life-sustaining sugars (see: plants) or in great enough concentrations it will cause asphyxiation and death (see: humans, and likely other O2-breathing animals as well. I wonder if animals which do not breathe but rely on transfusion across their membranes [see: cnidarians] also would suffocate in a CO2-rich atmosphere, or if presence of O2 is sufficient, regardless of concentration of CO2 in their surroundings).
So I didn’t come here to talk about climate change or jellyfish- but rather, I just found out about NASA’s Centennial Challenge to convert CO2 to sugars.
Why?
Because microorganisms + sugar —> fermentation —> useful molecules.
Since Mars’s environment is rich in CO2, if there was a way to convert local CO2 into bio-available nutrients, it would eliminate the need to transport foodstock from Earth for microorganisms, and microorganisms can be used to create all kinds of useful products (for textiles, enzymes, medicines etc. I know that there is a company in Emeryville using microbial fermentation to generate spider silk-like polymers, for example).
Very cool! I can’t wait to see what technologies scientists are working on.
The other time CO2 came up today was earlier this morning when I was reading a paper published in 2000 by Joseph DeSimone on the usefulness of CO2 as a solvent in polymer synthesis. Apparently CO2 is an excellent solvent for polymer synthesis because several monomers can dissolve in it (when the CO2 is in its supercritical state), but the resulting polymers formed are insoluble and thus can be extracted. In the past, CFC’s were used as a solvent, but the resulting extraction of radical hydrogen has been shown to deplete the ozone layer. Yikes! CO2 does not contain hydrogen, and therefore there are no dangerous radical H produced.
CO2 is interesting- what if we could use turn CO2 in the atmosphere into useful products like plastic and gasoline (two things that I hated in college) instead of mining them from the Earth? This could be useful technology not only in outer space, but in more terrestrial applications.
ADDENUM:
When I decided on a picture for this blog post, and picked a headshot of NASA Environmental Scientist John Hogan (he sits on the judge panel for the CO2 Centennial Contest), I went back and had to look up why his name sounded so familiar. Bingo! It was from reading Mary Roach’s book Packing for Mars, which I highly recommend, and it is all about the challenges associated with a human mission to Mars.
After reading this interview with John recorded 2 years ago, I learned about some interesting chemistry regarding maintaining breathable air for astronauts:
If you were to breathe air in a sealed, confined space, you would eventually suffocate- not only from lack of O2, but from the proliferation of CO2 as you exhale (humans exhale about 1 kg of CO2 per day!) and the proliferation of H20 as well in an increasingly humid environment (not good). Astronauts used to rely on canisters of lithium hydroxide to absorb the excess CO2, but this was a wasteful, non regenerative system, and now, scientists like John Hogan are working on a regenerative system. The system is called CDRA, and basically the flow goes like this:
Wet air—>2H2O pulled off —> split into H2 and O2 via hydrolysis
Dry air goes to CO2 bed —> CO2 heated with H2 in Sabatier process—> CH4 (methane) and water are produced (water can be split for use in future reactions)
Wikipedia shows the overall reaction nicely:
VERY COOL!!!
If you read the Wiki article on the Sabatier process you can see possibilities for making this reaction completely closed loop (as you can, the reaction as written above requires additional H2 input, which is the current state of things on the International Space Station).
