Energy Dome Patented CO2 Long-Duration Battery System
The compressed gas energy storage technology achieved a 75 percent operational efficiency in trials.
Updated on Sept. 29, 2026 in Energy
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Energy Dome developed a CO2-based battery that stores energy by compressing gas within a dome structure. This research-stage technology demonstrated an operational efficiency of approximately 75 percent at a 2.5 MW by 4 MWh plant that opened in Ottana, Italy, in 2022.
Why it matters
The system aims to address renewable energy intermittency by providing long-duration electricity storage capable of powering 14,000 families. It offers a scalable alternative to traditional chemical batteries with an expected 30-year operational life.
The system reaches 400 degrees Celsius during compression to store energy in high-pressure tanks, achieving a net efficiency of 75 percent. It uses 2,000 tons of CO2 across a 5-hectare site in Ottana.
The players
Energy Dome
An Italian energy storage startup focused on CO2-based battery technology and turbine integration.
Breakthrough Energy Catalyst
An investment fund founded by Bill Gates focused on scaling climate-tech infrastructure.
A global technology conglomerate that joined Energy Dome's project development in 2025.
The details
The technology functions by using excess renewable energy to compress CO2 gas, which is then stored in a flexible dome structure. During discharge, the stored gas is heated and passed through a turbine to generate electricity, integrated with waste heat to optimize efficiency. The infrastructure is engineered to withstand wind speeds of up to 160 kilometers per hour.
Timeline
2021: Announcement of an 11 million euro funding round.
June 2022: Validation of the demonstration plant in Ottana, Italy.
End of 2023: Breakthrough Energy Catalyst invested 35 million euros.
2025: Commercial project expected to become operational in Ottana.
2026: Planned completion of an energy plant in India.
The Tech Race
Energy Dome follows a trajectory established by the European Innovation Council's energy storage grants, which provided 17.5 million euros to scale the technology. The company competes in a crowded sector for long-duration grid storage, aiming to surpass existing chemical battery limits by 2026.
The technology aims to stabilize electricity costs for the public by balancing grid intermittency through long-duration storage. Commercial-scale implementation is currently targeting 2025 for the next phase in Italy.
The takeaway
Energy Dome aims to prove that CO2 can serve as a viable mechanical storage medium for long-duration grid support. Stakeholders should track the 2025 commercial project results in Ottana to confirm the projected 30-year operational lifespan.
What happens next
A 20 MW by 160 MWh plant is scheduled for completion in India by 2026.
Further reading
Learn more about the latest developments in grid-scale storage at Energy.
Source note: This article includes information reported by The Vermilion.
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