Engie signs offtake contract for long-duration CO2 Battery project in Sardinia, Italy

December 19, 2024
LinkedIn
Twitter
Reddit
Facebook
Email

Engie has signed an ‘energy storage as a service’ contract with technology provider Energy Dome for a long-duration energy storage (LDES) project in Sardinia, Italy.

The French multinational utility and the Italian startup announced the commercial offtake agreement for Energy Dome’s 20MW/200MWh CO2 Battery this morning.

The 10-hour duration project in the Sardinian municipality of Ottana is currently under construction and is the first large-scale system using Energy Dome’s technology. It follows a couple of years of operation of a 2.5MW/4MWh commercial CO2 Battery demonstrator, also in Sardinia.

The project is due to be completed by the end of the first quarter of 2025. It has received funding through a partnership between European Union (EU) entities, including the European Investment Bank (EIB) and the Catalyst programme for supporting sustainability technologies run by Bill Gates’s Breakthrough Energy venture capital (VC) group. The programme invested €60 million (US$65.37 million) into the project last December.

This article requires Premium SubscriptionBasic (FREE) Subscription

Try Premium for just $1

  • Full premium access for the first month at only $1
  • Converts to an annual rate after 30 days unless cancelled
  • Cancel anytime during the trial period

Premium Benefits

  • Expert industry analysis and interviews
  • Digital access to PV Tech Power journal
  • Exclusive event discounts

Or get the full Premium subscription right away

Or continue reading this article for free

The CO2 Battery, designed by Energy Dome’s CEO, inventor, and entrepreneur Claudio Spadacini, stores energy through adiabatic compression of carbon dioxide gas, which is liquified during charging and evaporates during discharge in a thermodynamic cycle.

The startup has claimed the technology is simple and safe, built using a combination of off-the-shelf components and techniques taken from existing industries, using abundant and easy-to-source raw materials.

Energy Dome intends to also build projects which it will sell on to customers to own, but the Engie deal falls under the storage as a service business model the Italian startup has also been marketing.

Energy Dome will continue to own and operate the asset, although Engie will optimise its dispatch into Italy’s power markets.

The company is also developing an identically designed project in Wisconsin, US, and signed a contract with utility Alliant Energy in October. The US project is scheduled to begin construction in 2026 and start commercial operation in 2027.

Energy Dome was the winner in the LDES Company of the Year category at the 2024 Energy Storage Awards, which were hosted by Solar Media, our publisher.

Engie meanwhile noted that the CO2 Battery resource will be added to its portfolio of energy storage resources in Italy that so far comprises 43MW/48MWh of lithium-ion (Li-ion) battery energy storage systems (BESS).

“The European Investment Bank plays a key role in accelerating the green transition by financing breakthrough technologies like Energy Dome’s CO2 Battery,” EIB vice president Gelsomina Vigliotti said.

“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,” head of Breakthrough Energy’s Catalyst accelerator Mario Fernandez said.

Financial terms of the deal were not disclosed.

1 December 2026
Italy
Battery Asset Management Summit Europe is the annual meeting for owners, operators, investors, and optimisation specialists working with operational BESS assets across the continent. The Summit focuses on how to maximise performance and revenue, manage degradation, integrate advanced optimisation software, navigate evolving market and regulatory frameworks, and plan for repowering or end-of-life strategies. With insights from Europe’s most active storage markets, it equips attendees with practical guidance to run resilient, profitable battery portfolios as the sector scales.

Read Next

Premium
December 10, 2025
Clearway Energy Group has negotiated tolling agreements with SDG&E for one of its solar and storage complexes in Kern County, California.
December 10, 2025
NHOA Energy has secured contracts from Engie for an 80MW/320MWh BESS at Engie’s Drogenbos power station, near Brussels, Belgium.
December 9, 2025
European energy independence is achievable if long-duration energy storage is factored into the mix, writes Oonagh O’Grady of Hydrostor.
Premium
December 9, 2025
A Western Australian government initiative to deploy the largest vanadium redox flow battery (VRFB) project outside China is a “pivotal moment,” one technology provider has said.
December 4, 2025
Jason Beer of Fluence Australia, discusses some energy trends in Australia that are set to influence the development of the storage market.