As I’ve explained in this post, I’m intrigued by the concept of storing frozen CO2 in Antarctica. I got interested in it by reading about this paper at Climate Etc. I’ve since learned a few interesting things about frozen CO2.
To make dry ice, CO2 is pressurized into a liquid. When this pressure is released, some of the CO2 evaporates and draws heat away from the rest of the CO2 causing it to freeze into snow. This snow is then pressed and shaped into dry ice. Most of the energy used is for liquefying the CO2. The implications of this for my plan to store CO2 as ice in Antarctica is that a lot of the energy used would not have to be expended in Antarctica. It would be used where the CO2 is collected and liquefied. This liquid would then be shipped or piped to Antarctica. The paper mentioned above calls for freezing and precipitating CO2 out of the air. My scheme would provide readily frozen CO2 and a rich source of CO2 gas that can be frozen and precipitated.
Another thing about liquid CO2 is that it maintains a constant vapor pressure. This makes it useful for things like CO2 cartridges for air guns. This might simplify the engineering of creating an infrastructure for piping and shipping liquid CO2.