Google's first direct, multi hour battery storage deals spanning multiple continents — in Ireland and Arizona — mark a new phase in how major technology companies procure round the clock clean energy for their data centers.
Google has spent the last month turning a long-running clean-energy partnership into commercial procurement. Within roughly four weeks, the company signed bilateral agreements for the same long-duration storage technology on two continents: a 23 MW / 200 MWh CO2 Battery unit in County Offaly, Ireland, announced this week, and a 19 MW / 200 MWh sister project with Arizona utility Salt River Project announced earlier in June. The two deals together represent Google's first firm bilateral long-duration storage contracts with Italy's Energy Dome, and they point to a multi-continent procurement playbook rather than a one-off bet.
For a reader who doesn't follow grid storage, the doorway: long-duration storage (LDES) is the class of grid-scale batteries designed to discharge for many hours, not the minutes that lithium-ion systems cover. The category includes flow batteries, thermal storage, mechanical systems like compressed air, hydrogen round-trip setups, and CO2 Batteries like Energy Dome's. What these technologies are all chasing is the same gap on the modern grid: storing cheap midday solar and wind for delivery at evening peaks, during multi-day lulls, or when data-center demand spikes.
The Offaly project sits on a former peat-fired thermal power plant near Rhode, in the Irish Midlands, and will be developed with local Irish developer Lumcloon Energy on a grid node that feeds the Greater Dublin area. The site is a literal fossil-to-clean transition image: a fuel source the country is leaving behind, repurposed for the storage that the next phase of the grid will need. Energy Dome will own and operate the unit under its proprietary closed-loop CO2 cycle. Grid power compresses CO2 and stores it as a liquid; when power is needed, the CO2 is expanded through a turbine to send electricity back to the grid. The Offaly project is Google's first bilateral commercial deal with Energy Dome, but it builds on a multi-year partnership the two companies announced in 2025 to deploy CO2 Batteries at scale for Google's 24/7 carbon-free energy goal.
Ireland is one of the markets where the policy logic for LDES is most concrete. The government has named long-duration storage a key solution for grid reliability and published an electricity storage policy framework aimed at hitting 80% renewable electricity by 2030. With renewables already pushing past 40% of Irish generation in many hours, the next constraint is multi-hour dispatchability, and Dublin's demand center is where any storage shortfall will show up first. The Arizona site plays a complementary role in the US Southwest, where Salt River Project has been building out solar-heavy portfolios and using LDES to firm them. Same vendor, same ~200 MWh scale, same hyperscaler procurement logic, two very different grids.
The procurement pattern is what the wire copy doesn't quite name. Energy Dome has commercial deployments outside the Google relationship, and IEEE Spectrum's 2026 coverage documents CO2 Batteries as a commercial LDES class moving into multi-region deployment, not a single demo. The wider LDES field remains crowded, with flow, thermal, mechanical, hydrogen, and CO2 systems all chasing utility-scale long-duration contracts and academic reviews comparing compressed-CO2 options against compressed-air and Carnot Battery designs for engineering deployment. Google's move is not a verdict that CO2 Batteries will win the category. It is a verdict that hyperscalers are willing to put firm dollars behind multi-hour storage at specific grid nodes, and that a single vendor can now be picked across continents.
A few honest caveats. The 200 MWh figure is Energy Dome's stated nameplate for the Offaly unit; independent third-party cycling, round-trip efficiency, and degradation data for this specific site are not yet public. The Offaly announcement is a bilateral commercial press release, so the precise offtake structure, commercial operation date, grid-connection point, and any capacity payment or tolling terms are not disclosed. And there is a real procurement-strategy question in concentrating this much multi-hour capacity in a single vendor across two continents, given that Energy Dome is also pushing a follow-on CO2 Battery Plus product line as it scales beyond first-of-a-kind units.
What to watch: whether Google's Offaly unit reaches commercial operation inside Ireland's 80%-by-2030 window, whether SRP's Arizona project lands on a similar timeline, and whether the next hyperscaler LDES bilateral lands with a different technology. The two-deal-in-a-month pattern is the signal. Whether it becomes a fleet is the question.