Last Meeting (10/14/20)
This week we spoke with Noah McQueen, a graduate student at UPenn currently researching direct air capture, who talked to us about- likely enough- direct air capture ! We discussed the abilities of direct air capture, one of the NET space’s most interesting options. Direct air capture, or DAC, has two primary routes that it uses to pull CO2 out of the ambient air; the first is using sorbents (solid reactants) to adsorb with CO2 and pull it out of the air, while the second is using dripping liquid solvents to absorb the CO2. Each method has the benefit and detriments, as liquid solvents can be scaled up more easily, solid sorbent systems can be more modularized.
One of the largest problems for both solid and liquid systems is that they have to absorb/adsorb CO2 and the desorb them through a different process. This often means heat swings, pressure swings, and sometimes moisture swings to get the CO2 to release from whatever attachment it has. Specific to solid sorbent, this means picking the solid that CO2 binds to is important, and is often the most costly, inefficient, and wasteful part of the system. On the other hand, the liquid solvent solution is not near cost effective enough either, as it still takes about $500-$600 / tco2. Interestingly enough that hasn’t stopped the construction of massive liquid DAC systems.
Some of the most interesting developments in this DAC space is that we can use moisture swings with certain sorbents now to desorb the CO2. There is also the potential of electrochemical DAC which would allow for a much quicker, less costly desorbing process. Finally one of the most interesting pieces Noah shared was about the idea of a perpetual magnesium oxide adsorbing loop that relied on a heat swing to release the CO2. The benefit of this idea is that magnesium oxide can adsorb CO2 just as a standalone rock, requiring no extra equipment.
For anyone who missed the meeting please go to the google drive > Membership > Meeting Videos and watch the general meeting 3 there !
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