AFAIU most of our industrial CO2 (for dry ice, soft drinks, etc) comes from refining natural gas exhaust. From there, if you want to make a dry ice block, you h

AFAIU most of our industrial CO2 (for dry ice, soft drinks, etc) comes from refining natural gas exhaust. From there, if you want to make a dry ice block, you have to take it through a very energy cooling process (similar to how air conditioning works) to create a liquid, and then through a second compression and cooling process to turn it into a solid. It is likely that the process of turning a given volume of CO2 into a solid would produce more emissions than it sequestered. You cannot assume that green energy will be used for this sequestration because if green energy were available at this scale, you wouldn't have the CO2 on your hands in the first place. On the demand side we already collect as much CO2 as we need from e.g. natural gas power plants. We don't have a use for any more. It will just sublimate and be re-released into the atmosphere, or into some containing vessel.