I work in electricity and heat production, to me this sounds mainly green washing. Why use CO2 and plain pressure?
Storing this magical 200MWh, would require stupid amount of volume and pressure. We have better gasses, and hundreds of years on knowledge in heat pump tech with better efficiencies.
To my ear it sounds that they just picked CO2 for news articles/investors, not for science reasons.
CO2 is a nice substance for this due to its relatively high temperature of fusion at modest pressures (and cheap ubiquity). I’d wondered why this wasn’t more of a thing with air, using excess energy to liquefy it, to later let the LN2 to be vaporized/expanded in a turbine and the LOX to be used in rockets or something. But deep cryogenics are more challenging.
Or maybe use excess power to electrolyze water for fuel cell use later?
But yeah, CO2 makes a lot of sense despite its relatively poorer specific heat ratio for adiabatic expansion compared to mono and diatomic gasses.
Or maybe use excess power to electrolyze water for fuel cell use later?
Hydrogen storage presents a lot of challenges, because it tends to leak at normal temperatures found on Earth. So we either tolerate a lot of loss during storage, or we use lots of energy chilling it to a temperature where it won’t easily escape.
