One of Ireland’s most exciting and important energy projects is quietly being developed at a remote outpost in Donegal, not far from Malin Head. FuturEnergy Ireland, a joint venture between Coillte and ESB, has been granted planning permission to build Europe’s first iron-air battery facility, a new technology that promises to store renewable energy for weeks while enhancing and supporting the electricity grid.
Known as the Ballynahone Energy Storage project, it will look modest – a collection of weatherproof containers on a three-hectare site beside an electrical substation – but what it represents could be transformative.
Iron-air batteries are a new form of long-duration energy storage (LDES) that is needed to help Ireland reduce its dependence on fossil gas and keep the lights on during the so-called Dunkelflaute – periods of still, dark weather when neither wind nor solar can contribute meaningfully to electricity supply.
Ireland is particularly vulnerable to such events. We lack large hydro dams or the kind of strong power grid interconnection that allows countries like Denmark or the Netherlands to share surpluses with neighbours. We remain deeply reliant on gas, an increasingly insecure and volatile source of energy, with rising prices, geopolitical risks and high emissions. Plans to allow liquefied natural gas terminals and gas-fired power-generation capacity risk locking us into this dependency for decades.
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New batteries based on rusting will help make Ireland’s energy secure and clean
There are two main routes away from this: interconnection and storage. Both are needed. Mass interconnection was the cornerstone of the late Eddie O’Connor’s vision for a pan-European “supergrid”, where electricity flows freely across borders, smoothing out supply and demand of renewable energy. But even that won’t cover us when entire regions are becalmed and dark.
Until recently, most storage solutions were either short-duration lithium-ion batteries or pumped hydro schemes – both useful, but limited to hours, rather than days or weeks. A new generation of long-duration storage technologies is emerging. Iron-air batteries, like those planned in Donegal, work on an elegant principle: they store electricity through reversible rusting. They’re slow, responding over hours and days, not seconds – but that’s exactly what’s needed to back up renewables over longer timescales.
The key material, iron, is cheap, abundant and non-toxic – unlike lithium or cobalt, which are costly and face supply constraints. Lithium-ion batteries are more suitable for cases where size and weight are a priority, like electric vehicles and phones, whereas iron-air is more suitable for stationary storage. Form Energy, the US firm behind the iron-air technology in Donegal, say their batteries will store electricity at one-tenth of the cost of lithium-ion. They also say it is very safe, with no risk of thermal runaway.
Donegal was chosen for a good reason. A greater share of wind energy is curtailed there than anywhere in Ireland, because the electricity grid can’t absorb it. This lost energy, known as curtailment, increases our electricity bills, discourages investment in renewables and triggers the need for costly and controversial overhead transmission lines. Batteries located near substations, like Ballynahone, can soak up surplus power locally, reducing curtailment and pressure on the grid.
This won’t be a silver bullet. A hundred projects like this would be needed to replace the generation capacity of Moneypoint, which has long been a bedrock of Ireland’s electricity security – albeit a highly polluting one.
Ireland’s energy future depends on more than just building wind and solar farms
A critical challenge now is how clean storage can compete with fossil gas, when today’s infrastructure and market is built around it. While Form Energy says the technology can compete with legacy power plants, the cost of the project in Donegal has not been disclosed and the technology is only at the cusp of commercial development. Ireland also already has a pipeline of new gas-generation capacity which is designed to fill the gaps in wind and solar, diminishing the immediate case for clean storage.
That said, legal challenges to new gas infrastructure may shift the balance. Friends of the Irish Environment has recently lodged a judicial review of a proposed 600 megawatt gas power plant at the proposed site of the Shannon LNG terminal, in a case that could set precedent. If gas projects are delayed or blocked on climate grounds, clean alternatives like storage may have more space to scale. Battery technologies, being modular and factory-built, also have the advantage of rapid deployment and steep cost declines – as we’ve seen with solar panels and lithium-ion.
Other storage technologies may yet outcompete iron-air. I’m sceptical that hydrogen will play any role in everyday energy use, but it could become a strategic storage option. Likewise, there are exciting developments in battery chemistries based on sodium, zinc or flow technology, and systems that store energy via heat, gravity or air compression.
Ireland’s energy future depends on more than just building wind and solar farms. We need energy to be both clean and dependable – when the wind blows and when it doesn’t. That requires strategically located, long-duration storage. Donegal’s rusting battery containers might be a critical step towards that future.
Prof Hannah Daly is professor of sustainable energy at University College Cork
