Energy Dome’s CO2 Battery Wins Where Lithium Can’t

Somewhere inside Google’s energy procurement group, someone signed a ten-year contract for a technology that did not exist at commercial scale eighteen months ago. On June 23 the company announced its first bilateral deal with Energy Dome: a 23-megawatt, 200-megawatt-hour CO2 battery in County Offaly, Ireland, due online in 2028 and backed by a ten-year capacity contract with the grid operator EirGrid. The easy way to read that is corporate climate theater. The more useful way is to ask why a buyer with the pick of every storage technology on earth would underwrite a category that lithium does not occupy.

A buyer underwrote it, not a lab

The Ireland deal is not a one-off. Earlier in June, Energy Dome, Google, and the Arizona utility SRP announced a 19-megawatt, 200-megawatt-hour project, and Energy Dome’s first full-scale plant has been running in Ottana, Sardinia since July 2025 at 20 megawatts and 200 megawatt-hours, good for about ten hours of storage. The technology itself is almost dull to describe. You compress carbon dioxide into a liquid when power is cheap, then let it expand back through a turbine when the grid needs the power returned.

What is not dull is who is paying for it. A hyperscaler signing a decade of offtake is a different kind of signal than a pilot grant or a Series C. A pilot proves a machine runs. A ten-year contract proves a buyer will bet its own balance sheet on the machine still running in 2038. That second kind of proof is the one founders actually need, and the one that is hardest to manufacture.

Energy Dome did not build a cheaper lithium cell

Lithium is very good at short bursts, the one-to-four-hour band that smooths a cloudy afternoon or an evening demand peak. Its economics get worse the longer you stretch the duration, because every extra hour means more cells. Energy Dome did not pick that fight. It went after the eight-to-twenty-four-hour band where lithium gets expensive, with a machine that runs roughly thirty percent cheaper than lithium for that job, lasts about three times as long, fits on five hectares, and gets built in under two years.

This is the trap I warn surgical-robot founders about, and it moves over to grid hardware without losing much. The losing move is to pitch a new robot as a smaller, cheaper version of the market leader. The moment you line up against the incumbent on its own terms you lose, on installed base, on budget, and on the buyer’s mental model of what the thing even is. The winning move is to find the work the leader serves poorly and own that ground instead. Energy Dome is not a cheaper lithium battery. It is the thing lithium cannot affordably be.

What this means for climate-hardware founders

If you are building long-duration storage, grid hardware, or any capital-heavy machine a utility or a hyperscaler has to underwrite, your spec sheet is not the product. The economic case is. Nobody writes a ten-year contract because your round-trip efficiency is elegant. They write it because the duration you serve is one they cannot buy cheaper anywhere else, and because the payback math holds over the life of the deal. Build the buyer’s economic story before you optimize the engineering, and aim at the duration or the geography where the incumbent’s economics fall apart, not the spot where they are strongest. The category you can defend is the one the leader does not want.

Dave Saunders is the founder of Base Reality Group and a Fractional CPO for hard-tech founders. He was a founder and operator at Galen Robotics, where the surgical-robotics platform earned FDA De Novo authorization in 2023, and he managed a 35-patent portfolio licensed from Johns Hopkins. He wrote Founders Who Finish and publishes The Build. More about Dave →