Ireland's Giant CO2 Battery: A Lithium-Free Way to Store Renewable Power

 

Introduction

Google and Energy Dome are building a 23 MW/200 MWh carbon dioxide battery in County Offaly, Ireland — no lithium, no cobalt, no rare earths. Here's how it works and why it matters.

Most people think of batteries as boxes full of lithium and cobalt. Ireland is about to prove that idea wrong.

In County Offaly, on the site of an old peat-fired power station, Google and the Italian energy storage company Energy Dome are building something unusual: a battery that stores electricity using nothing more exotic than carbon dioxide. No lithium. No cobalt. No rare earth minerals. Just CO₂, some big domes, and basic physics.

Here's everything you need to know about the project, how the technology actually works, and why it could matter far beyond Ireland.

What Is the Ireland CO2 Battery Project?

Energy Dome and Google have signed their first direct commercial agreement to build a 23 MW / 200 MWh long-duration energy storage facility in the Irish Midlands. The site already has planning approval, land rights, and a 10-year grid capacity contract with EirGrid, Ireland's national grid operator. Construction is aimed at getting the plant running by 2028, and there are plans to add a second 200 MWh unit at the same location later on.

What makes the project notable is the location: it's being built on a decommissioned fossil fuel power plant. Instead of demolishing old energy infrastructure, the companies are repurposing it — turning a site that once burned peat into one that stores clean power.

How Does a CO2 Battery Actually Work?

The idea behind Energy Dome's technology is surprisingly simple once you break it down:

Charging:

When there's extra electricity on the grid — say, from wind or solar power that isn't being used — the system uses that electricity to compress carbon dioxide gas into a liquid state and store it in tanks.

Storing:

The compressed CO2 sits in storage, and the "spent," low-pressure gas is held separately inside the giant dome structure you see in photos of these facilities.

Discharging:

When the grid needs power, the liquid CO2 is allowed to expand and heat up, which drives it through a turbine. That turbine spins a generator and sends electricity back to the grid — while the gas returns to the dome, ready to be compressed again.

The whole system is a closed loop. The same CO2 is compressed and expanded again and again, which means the technology doesn't consume or emit the gas — it just uses it as a working medium, similar to how refrigerants work in an air conditioner.

Why Skip Lithium Altogether?

Lithium-ion batteries are great for short bursts of power, but they run into real limits for long-duration storage:

Supply chain pressure: Lithium, cobalt, and rare earth minerals are concentrated in a handful of countries, and mining them is slow, expensive, and environmentally messy.

Degradation over time: Lithium batteries lose capacity with every charge cycle.

Cost at scale: Storing large amounts of energy for many hours (not just minutes) gets very expensive with lithium.

CO2 batteries sidestep all three problems. The core material is a gas that's already abundant, the system doesn't degrade the way chemical batteries do, and the tanks and domes can be built at large scale using conventional industrial materials and manufacturing methods.

Why This Matters for the Grid

Ireland has set an ambitious target of generating 80% of its electricity from renewable sources. But wind and solar are inconsistent — they produce a lot of power sometimes and very little at other times. Long-duration storage like this CO2 battery lets the grid bank surplus renewable power and release it later, during high-demand periods, instead of wasting it or falling back on fossil-fuel backup plants.

This is also useful for large electricity consumers — including data centers, which are growing fast in Ireland — because it offers a more reliable way to smooth out power supply without straining the grid.

It's worth noting this isn't Energy Dome and Google's only project of this kind. A similar 19 MW/200 MWh CO2 battery, also built at a former fossil fuel site, was announced for Arizona, USA, just a month before the Ireland deal — suggesting this is becoming a repeatable model rather than a one-off experiment.

Frequently Asked Questions (FAQs)

1. Is a CO2 battery the same as a regular battery?

Not exactly. A CO2 battery doesn't use chemical reactions inside cells the way lithium-ion batteries do. Instead, it stores energy mechanically and thermally — by compressing and expanding carbon dioxide gas — making it closer to a mechanical energy storage system than a traditional battery.

 2. Is it safe? Does it release CO2 into the atmosphere?

The system operates as a sealed, closed loop. The same carbon dioxide is reused repeatedly for compression and expansion, so it isn't vented into the air during normal operation.

 3. How long can it store energy compared to lithium batteries?

CO2 batteries are designed for long-duration storage — typically many hours of continuous discharge — whereas most lithium-ion grid batteries are optimized for shorter bursts of one to four hours.

4. When will the Ireland project start operating?

The County Offaly facility is expected to begin operations in 2028.

5. Who is building it?

Energy Dome, an Italian long-duration energy storage company, will develop, own, and operate the plant, with Google as the commercial partner backing the project.

6. Could this technology replace lithium batteries entirely? 

Not entirely — the two technologies serve different purposes. Lithium-ion batteries remain better suited for short, fast bursts of power (like smoothing out sudden spikes), while CO2 batteries are aimed at storing large amounts of energy for many hours, which is where lithium struggles most on cost and scale.

Conclusion

Ireland's CO2 battery project is a good reminder that "battery innovation" doesn't always mean a smaller, denser lithium cell. Sometimes it means rethinking the whole approach — using abundant materials, repurposing old infrastructure, and designing for a different job (long-duration storage) instead of trying to force one technology to do everything. If this project performs as planned by 2028, it could become a blueprint for how countries handle renewable energy storage without depending so heavily on scarce minerals.