Long-duration energy storage is necessary to enable widespread renewable energy deployment but remains expensive and a small segment of the overall storage market.
Energy Dome SpA is developing a low-cost and efficient system for long-duration electricity storage using liquid CO2. Their system can store energy from solar or wind generation to supply power overnight or across multiple days, if needed. CO2 is compressed and liquified while excess electricity is available, then returned to a gas through an expansion turbine to generate power when needed. With a 30-year lifetime and roundtrip efficiency of 70–80%, this system could store electricity at a levelized cycle cost below $0.01/kWh, not including the cost of electricity for charging.