Grid storage innovator Energy Dome closes $60M funding round

The Italian long-duration storage startup is racing to build commercial projects after proving out its CO2-based storage technology for a major Italian utility.
By Julian Spector

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An artist's rendering of a verdant hilly valley with many wind turbines and a squat white half-cylinder industrial building
(Energy Dome)

Italian startup Energy Dome has moved one step closer to commercializing its unusual energy storage technology by securing a total of $60 million in Series B financing, announced Thursday. It had raised an initial $44 million portion of that funding in April.

Energy Dome stores clean energy in the form of pressurized carbon dioxide gas to turn intermittent renewable power into a dependable, round-the-clock resource. It’s a relative newcomer to the cohort of long-duration storage companies striving to make clean energy storage radically cheaper than conventional lithium-ion batteries allow so that clean power will be available through extended lulls in solar and wind production.

Many exotic storage startups kick around in small-scale testing for a decade or more. But after launching in 2019, Energy Dome raised an $11 million Series A in late 2021 and built a megawatt-scale project the following year. The startup has moved swiftly by repurposing existing materials and machinery to build novel grid storage plants, rather than inventing new materials or electrochemical processes.

Our technology can play a key role in enabling humanity to address the urgency of climate change without waiting until 2030,” founder and CEO Claudio Spadacini said in a statement.

Energy Dome’s process goes like this: It stores carbon dioxide in large enclosures resembling indoor tennis bubbles, and excess electricity is used to pressurize this gas into a liquid form. Decompressing that gas spins a turbine and regenerates electricity as needed. All those industrial tools predate Energy Dome, but nobody had cobbled them together to store power before.

This design appealed to the venture investing arm of Italian oil major Eni, which co-led the first tranche of the Series B round in April. The newly announced investment brought in the technology investing branch of Oman’s sovereign wealth fund and the venture fund of Royal Vopak, which describes itself as the world’s leading tank storage company.” Energy Dome said the funds will let it enter full commercial scaling mode on a global basis.”

To even get to this stage, Energy Dome had to build a storage device that works at a meaningful scale. It did that in Sardinia last year when it constructed a 2.5-megawatt/4-megawatt-hour storage facility. That real-world demonstration convinced Italian utility A2A to order up a 20-megawatt/200-megawatt-hour facility, which Energy Dome is building with a target operational date of late 2024. That project would let the utility funnel renewable electricity into storage, then discharge 20 megawatts for up to 10 hours straight. Lithium-ion projects on the market typically provide four hours of storage or less (though in rare cases lithium-ion is reaching eight hours of peak discharge).

The next move for Energy Dome is to sign up other customers who are willing to take a chance on a power plant that looks and operates differently from anything they’ve seen before.

One way Energy Dome assuages cautious customers is by selling storage as a service,” in which the startup builds and owns the project, and the customer just pays to use it. That could come in handy as utilities and power producers experiment with how exactly to value a grid asset that doesn’t comport with existing market structures. But companies willing to sink their capital into a CO2 Battery” of their own can still buy it outright.

There’s no clear market winner yet for long-duration storage, except the legacy pumped-hydro systems that are extremely difficult to build these days. The breakthrough could be Energy Dome’s carbon-based storage, underground compressed air storage like Hydrostor’s tech, iron-air batteries like Form Energy’s — or something else entirely.

One thing these contenders do share is an eventual need to create business models that can monetize longer storage durations than the market is currently used to. Many companies have focused on developing in California, where regulators added a long-duration storage requirement on top of existing market structures. Elsewhere, vertically integrated utilities have stepped up to buy long-duration storage as they contemplate the influx of cheap renewables on their systems. But competitive wholesale markets remain unwelcoming to the early-stage tech.

For now, Energy Dome is off and running on its first big deals — the hard part will come after that.

Julian Spector is a senior reporter at Canary Media. He reports on batteries, long-duration energy storage, low-carbon hydrogen and clean energy breakthroughs around the world.