[foota]

I imagine it's a closed system, so the question of where the CO2 comes from is kind of irrelevant.

[ElKrist]

In the article:

Spadacini adds: “The system is totally closed. We don’t consume any CO2, it’s just the working fluid that goes back and forth… for the life of the system, over 25 years. So we have no emissions in the atmosphere.”

So yes, it's a closed system

[modmans2nd]

but the CO2 has to come from somewhere.

[chess_buster]

Buy enough dry ice from the gas station.