This CO2 battery can store renewable energy for extended periods and release it quickly at a cost of less than half that of large lithium batteries.
The basis of the CO2 battery technology from Energy Dome is that CO2 expands rapidly when transitioning from liquid to gas. At room temperature, 2.5675 liters of liquid CO2 held at a pressure of 56 atm will expand to 1,000 liters of CO2 gas, nearly 400 times larger. Energy Dome’s battery utilizes massive domes with elastic balloons filled with CO2 gas. The company “charges” the battery by using energy to operate an electric compressor, reducing the gas volume until it condenses into liquid form, stored under pressure at room temperature. This charging process generates waste heat, which is captured in a thermal energy storage system.
Energy Dome’s 4 MWh renewable energy storage system prototype. (Image: Energy Dome)
As long as the pressure remains unchanged, CO2 can stay in liquid form for a long time. When energy is needed, the system uses the stored heat to vaporize the CO2. A series of turbines capture energy as the CO2 gas expands and returns to the balloon dome.
According to Energy Dome, the round-trip efficiency of this solution is over 75%. In this aspect, the system cannot compete with large lithium batteries. However, the storage cost is only between 50 – 60 USD/MWh for a few years, significantly lower than the 132 – 245 USD/MWh for lithium batteries. The CO2 battery has a reaction speed comparable to that of lithium batteries, while also storing energy for longer durations and experiencing less degradation.
Since its establishment in February 2020, Energy Dome announced the construction of its first plant in Sardinia, which became operational in 2022. The Sardinia plant is relatively small, storing only 4 MWh of electricity but proving that the design works well. Energy Dome’s next goal is to build a full-scale facility capable of storing 200 MWh of electricity and to have it operational before the end of 2023.
