4 ms·
Why not skip the calcination bit? NaOH solution will directly absorb CO2. The chlorine byproduct issue is not trivial, though.
by lambdatronics 5y ago
Why not skip the calcination bit? NaOH solution will directly absorb CO2. The chlorine byproduct issue is not trivial, though.
- kragen 5y agoThis is an excellent point! I'm sort of hoping that the calcination approach combined with some cheaper form of sequestration (pyroxenite carbonatation or whatever) will end up being significantly more efficient, and you can run it off thermal energy rather than electrical energy. (Of course lower-temperature scrubber materials like the ethanolamines also require much less energy to regenerate, but they're orders of magnitude more expensive than lye or quicklime.) My thought about chlorine disposal is that it's easy enough to burn it in hydrogen (obtained at an additional energy cost from water electrolysis, only two thirds of which do you get back from the combustion), at which point the chlorine has been reduced to a harmless chloride ion; then you just need to neutralize its acidity --- without releasing carbon dioxide in the process! So carbonates are out. Borax would be fine but I'm not sure it's abundant enough. I think probably the best option is to use it to convert apatite to insoluble dicalcium phosphate fertilizer and filter off the resulting neutral calcium chloride.