Why This Giant Bag of CO2 is Actually Useful

Because compressed-CO2 systems use standard compressors, tanks, and turbines rather than novel hardware, they can be deployed faster and with lower supply-chain risk than entirely new technologies.

CO2 is well suited to that approach because it liquefies at room temperature under pressure, which packs more energy per volume than air and enables phase-change driven recovery.

Compressed-CO2 'bubble' systems store energy by using electricity to compress CO2 into a liquid for storage, then evaporating and expanding that CO2 through turbines to generate power when needed.

Iron-air systems enable very long-duration storage because the iron to iron-oxide chemistry can hold energy for tens to hundreds of hours, but the chemical conversion incurs losses so round-trip efficiency is typically around 50–60%.

Iron-air batteries store and release electricity via reversible iron oxidation because discharging lets iron react with oxygen to release energy, and charging uses electricity to reduce the iron oxide back to metal.

Gravity batteries replicate pumped hydro without water because surplus electricity is used to lift heavy masses and the descending mass later drives generators to recover energy.

Pumped hydro is constrained because it requires costly civil works, specific elevation and land for reservoirs, and faces losses or reduced capacity from evaporation or water being reallocated.

Pumped-storage hydropower stores electricity as gravitational potential because surplus power pumps water uphill into a reservoir, and that water is released through turbines to generate electricity when needed.