French utility Engie has entered a pioneering deal to take power from a first-of-its-kind CO2 battery backed by Bill Gates’ energy innovation fund.
Developer Energy Dome announced that it has signed a commercial offtake agreement for its Sardinia-based CO2 Ottana battery with Engie, which will optimise and dispatch the stored energy in the Italian power markets.
Energy Dome said that, when the battery is commissioned early next year, it will be one of the few operational energy storage assets globally – with the exception of pumped-hydro – that can store power for 10 hours and has a commercial offtake agreement.
Ottana features a 20MW/200MWh CO2 battery capable of providing electricity for approximately 14,000 households for 10 hours. Energy storage is critical to supporting variable wind and solar generation and the amount of time power can be stored is crucial.
“We are making history,” Claudio Spadacini, CEO of the Italian start-up, wrote on LinkedIn. “This contract, other than being unprecedented in the global market, confirms our deployment readiness, validates our business model, and underlines the market-leading value proposition of our technology.”
Energy Dome has developed a thermodynamic liquid-CO2 system to store excess green energy from wind and solar farms.
Another rendering of the Energy Dome facility on the Italian island of Sardinia.Photo: Energy Dome
The system CO2 compresses until the gas is heated up to 300°C liquid. Heat is then extracted and stored in “bricks” made of steel shot and quartzite for later use, cooling down the CO2 to an ambient temperature. The gas is then condensed into liquid form and stored in carbon steel tanks.
When power is needed, the liquid CO2 is run through an evaporator to turn it back into a pressurised gas. This is re-heated before going through an expansion turbine, where it rapidly expands at atmospheric pressure to drive a power-generating rotor.
The uncompressed CO2 is then stored in a flexible dome—hence the company name—at ambient temperature and pressure for later reuse.
Breakthrough Energy Catalyst – set up by Microsoft billionaire Gates to back promising energy technologies – last year pledged up to €35m ($38m) for the “first-of-a-kind” project Energy Dome is building on the Italian island of Sardinia, with the EU also lending its support.
“Scaling first-of-a-kind projects is immensely complex and requires not just technological innovation but new commercial and market approaches,” said Mario Fernandez, head of catalyst at Breakthrough Energy.
“This partnership is a tangible example of a replicable commercial innovation and confirms the Ottana CO2 Battery is not just a demonstration but a viable facility, which will unlock Nth-of-a-kind opportunities that can lead to true global scale.”
In October, Energy Dome won its first contract in the US with utility Alliant Energy for another 20MW/200MWh battery in Wisconsin.
