By Luigi Avantaggiato, IEEE Spectrum
This giant bubble on the island of Sardinia holds 2,000 tonnes of carbon dioxide. But the gas wasn’t captured from factory emissions, nor was it pulled from the air. It comes from a gas supplier and lives permanently within the dome’s system to serve an eco-friendly purpose: storing large amounts of excess renewable energy until it’s needed.
Developed by the Milan-based company Energy Dome, the bubble and its surrounding machinery demonstrate a first-of-its-kind “CO2 Battery,” as the company calls it. The facility compresses and expands CO2 daily in its closed system, turning a turbine that generates 200 megawatt-hours of electricity, or 20 MW over 10 hours. And in 2026, replicas of this plant will start popping up across the globe.
We mean that literally. It takes just half a day to inflate the bubble. The rest of the facility can be built in less than 2 years and can be done just about anywhere with 5 hectares of flat land.
This article is part of our special report Top Tech 2026.
The first to build one outside of Sardinia will be one of India’s largest power companies, NTPC Limited. The company expects to complete its CO2 Battery sometime in 2026 at the Kudgi power plant in Karnataka, in India. In Wisconsin, meanwhile, the public utility Alliant Energy received the all-clear from authorities to begin construction of one in 2026 to supply power to 18,000 homes.
And Google likes the concept so much that it plans to rapidly deploy the facilities at all of its key data center locations in Europe, the United States, and the Asia-Pacific region. The idea is to provide electricity-guzzling data centers with round-the-clock clean energy, even when the sun isn’t shining or the wind isn’t blowing. The partnership with Energy Dome, announced in July, marked Google’s first investment in long-duration energy storage.
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