As the world works to adopt renewables as its main source of power, we need to develop reliable and cheap ways to store and release green electricity on demand. As counterintuitive as it sounds, carbon dioxide may just be a promising candidate in helping us achieve that.

At least that’s the idea pushed by Italy’s Energy Dome, a company claiming that its CO2 batteries are able to store energy at less than half the cost of lithium “big batteries,” while also being very responsive to load demand.

Although CO2 emissions are one of the most pressing challenges facing our planet right now, Energy Dome proposes them as a solution, by tapping into the dramatic expansion that CO2 undergoes when shifting between a liquid and a gaseous state.

As reported by New Atlas, the idea essentially involves a giant, flexible bladder full of CO2 gas stored in a big dome. By feeding energy into the system, electric turbines compress the gas into increasingly tighter volumes. This compression then generates heat that’s drawn off into a thermal energy storage system, and the gas is condensed into a liquid, which can be stored under pressure at ambient temperatures.

According to the company, the domes can be run in a variety of sizes and configurations, but a full-scale plant would be able to make around 25 MW and store between 100 to 200 MWh of energy. Most importantly though, these CO2 batteries can operate at high speed, absorbing and releasing energy nearly instantly if needed.

Image source: Energy Dome