It doesn’t generate CO2 because it is a closed loop, although a leak event is possible. Technically, (if no accident ever happens) then it is small scale sequestration (uses blow up tent). Technology is better than compressed air because it is stored as a liquid at room temperature, and has much better power density on turbine. Commercial viability is greatly enhanced by having a waste heat source, but it’s already better than CAES economically, even with the bubble storage.