Grid-scale energy storage is evolving with the rise of “CO2 batteries,” a promising technology that uses carbon dioxide in place of traditional chemicals to store electricity for long periods, tells IEEE Spectrum. These systems are a form of long-duration energy storage, designed to capture excess electricity from solar and wind farms and release it when renewable generation is low or demand peaks. The approach aims to support grid reliability and cleaner power usage without the limitations of lithium-ion and other conventional battery technologies.
One of the first commercial implementations opened in Ottana, Sardinia, where a 20-megawatt plant began operating in mid-2025. It demonstrates how CO2 can be compressed, cooled, and condensed into a liquid state for storage, then expanded through a turbine to generate electricity on demand. This thermodynamic cycle, though mechanically straightforward, leverages CO2’s properties to store and retrieve large amounts of energy efficiently.
Energy Dome, the Milan-based company behind the project, has drawn global interest. Google has invested in scaling the system near its major data centers in North America, Europe, and Asia-Pacific, aiming to deliver round-the-clock clean power with plug-and-play installations. Google’s energy strategy team notes that standardization and broad regional deployment could accelerate adoption.
CO2 batteries come with several advantages over other long-duration storage options. They don’t depend on rare minerals like battery chemistries do, and their expected lifespan is roughly three times longer than that of lithium-ion systems. Scaling up capacity also drives down cost per kilowatt-hour, which analysts say could make CO2-based storage more competitive with pumped hydro and other established methods.
That said, these installations require a significant physical footprint and infrastructure. The domes can be large and visible, which may affect siting decisions. Still, with global interest and planned replications across continents in 2026 and beyond, CO2 batteries are transitioning from pilot projects into commercially viable components of renewable grids, offering a new pathway to reliable and flexible clean energy storage.