Energy storage is the process of capturing energy produced at one time and holding it for use later. Think of it like a rechargeable battery for the entire electricity grid – you charge it when there is plenty of power available (like a windy night when demand is low) and discharge it when the grid needs it most (like a calm evening when everyone turns on their heating).
Without storage, electricity must be used the instant it is generated. This has always been the fundamental challenge of running an electricity grid, but it becomes far more urgent as countries like Ireland shift toward wind and solar – sources that generate power based on weather, not demand. Energy storage bridges the gap between when renewable energy is produced and when it is actually needed.
🌿 Why Energy Storage Matters for Ireland
Ireland’s Climate Action Plan targets 80% renewable electricity by 2030, delivered through 9 GW of onshore wind, 5 GW of offshore wind and 8 GW of solar capacity. The challenge is that wind and solar are intermittent – they generate when conditions are right, not necessarily when people need power.
This creates two problems. First, there are periods when renewables produce more electricity than the grid can use. In 2024, roughly 14% of available wind energy across the island was “dispatched down” – turned off because the grid could not accommodate it. That figure has been rising steadily, up from 8.5% in 2022 and 10.7% in 2023. Every megawatt-hour of dispatched-down wind is replaced by fossil fuels, adding unnecessary emissions and cost.
Second, there are periods of low wind and solar output – known as “dunkelflaute” in energy circles – when the grid has no choice but to rely on gas-fired generation. Energy storage can absorb the surplus during high-output periods and release it during these gaps, reducing both wasted renewables and fossil fuel dependency.
As of January 2025, Ireland had 22 electricity storage systems connected to the grid with a combined capacity of over 1,048 MW. The oldest and largest is Turlough Hill in County Wicklow, a pumped hydro storage facility commissioned in 1974, providing 292 MW of capacity. The remaining 756 MW comes from 21 stationary battery energy storage systems (BESS) distributed around the country.
🌿 Types of Energy Storage
🌿 Battery Energy Storage Systems (BESS)
Lithium-ion batteries dominate Ireland’s current storage landscape. These are the same basic technology found in electric vehicles and smartphones, scaled up to grid level. A typical grid-scale BESS can charge and discharge within seconds, making it excellent for short-duration services like frequency regulation – keeping the grid stable at its operating frequency of 50 Hz.
Total operational battery storage capacity in Ireland exceeded 700 MWh in 2025, with forecasts suggesting this could reach 13.5 GWh by 2030 – a fivefold increase. In late 2024, EirGrid and SEMO updated the scheduling and dispatch system to fully integrate battery storage into the real-time electricity market, allowing operators greater access and giving grid operators better visibility of charging and discharging patterns.
🌿 Pumped Hydro Storage
Turlough Hill, nestled in the Wicklow Mountains, is Ireland’s only pumped hydro facility and a remarkably elegant piece of engineering. During periods of low demand, electricity pumps water from a lower reservoir up to an upper reservoir on the mountaintop. When power is needed, the water flows back down through turbines, generating electricity. The round-trip efficiency is around 75-80%, and the facility can go from standby to full output in roughly 70 seconds.
Pumped hydro is the most established form of large-scale energy storage globally, accounting for over 90% of all grid-scale storage worldwide. Its disadvantage is the need for specific geography – two reservoirs at different heights – which limits where it can be built.
🌿 Long-Duration Energy Storage (LDES)
This is where Ireland’s energy storage policy is focused. Long-duration energy storage refers to technologies that can discharge power for four hours or more, distinguishing them from short-duration batteries that typically operate for one to two hours. LDES is essential for handling the multi-hour and multi-day gaps in renewable generation that shorter batteries cannot cover.
The Irish Government published its Electricity Storage Policy Framework in July 2024, setting out ten actions to integrate storage into the national grid. A headline target is 500 MW of long-duration storage by 2030. EirGrid opened a consultation on LDES procurement in October 2025, though the proposed first tender covers a minimum of 201 MW (equivalent to at least 804 MWh) – below the 500 MW target, which the industry body Energy Storage Ireland has called out as insufficiently ambitious.
Beyond lithium-ion, other LDES technologies being explored include compressed air energy storage, flow batteries, liquid air energy storage and green hydrogen – which can store energy for weeks or months rather than hours.
🌿 The SNSP Limit and Why Storage Helps
Ireland’s electricity grid operates a System Non-Synchronous Penetration (SNSP) limit – currently set at 75%, which is among the highest in the world. This means that at any given moment, no more than 75% of electricity on the grid can come from non-synchronous sources like wind and solar. The remaining 25% must come from synchronous generators (typically gas or hydro) that help maintain grid frequency stability. EirGrid is working to raise this limit to 80%, and has already reduced the minimum number of conventional generators required from five to four.
When wind output pushes above this limit, EirGrid must curtail renewable generation – instructing wind farms to reduce output even though the wind is blowing. Battery storage helps address this by absorbing excess renewable generation that would otherwise be curtailed, then releasing it when renewable output drops below demand. Advanced battery systems can also provide synthetic inertia and frequency response services that were traditionally the preserve of fossil fuel generators.
🌿 Home Energy Storage
Energy storage is not just a grid-scale concept. Home battery systems, often paired with solar panels, allow households to store electricity generated during the day for use in the evening when solar output drops and electricity prices peak.
A typical home battery system in Ireland stores 5-13 kWh of energy – enough to power average household lighting, appliances and electronics for several hours. When combined with a smart tariff that charges different rates at different times of day, a home battery can also charge from the grid during cheap overnight periods and discharge during expensive peak hours.
The economics of home batteries depend on electricity tariff structures, solar panel output and household consumption patterns. As time-of-use tariffs become more common in Ireland and the Clean Export Guarantee allows households to sell excess solar generation back to the grid, the business case for home storage continues to improve.
🌿 What Comes Next
Ireland faces a critical period between now and 2030. The country needs to roughly triple its renewable generation capacity while simultaneously building the storage and grid infrastructure to use that generation effectively. Without adequate storage, more and more renewable energy will be wasted through dispatch-down, undermining both climate targets and the economic case for new wind and solar projects.
The Government’s storage policy framework, EirGrid’s LDES procurement process and the rapid growth of battery storage all point in the right direction. Analysts forecast that batteries alone could discharge up to 5 GW at any given time by 2030. Combined with grid upgrades like the second North-South Interconnector and increased interconnection with Britain and the EU, storage is one of the critical enablers of Ireland’s climate mitigation strategy.
🌿 Frequently Asked Questions
🌿 What is the difference between short-duration and long-duration energy storage?
Short-duration storage (typically lithium-ion batteries) discharges for up to two hours and is mainly used for grid frequency regulation and peak shaving. Long-duration storage discharges for four hours or more – and in some technologies, days or weeks – making it suitable for balancing longer periods of low renewable generation. Ireland’s 500 MW target specifically focuses on long-duration storage because that is the gap in the current system.
🌿 How does energy storage reduce electricity costs?
Storage reduces costs in several ways. It captures cheap renewable electricity that would otherwise be wasted and releases it during expensive peak periods, lowering wholesale prices. It reduces the need for expensive gas-fired peaking plants. And it prevents curtailment, meaning more of the renewable infrastructure Ireland has already invested in is actually used. EirGrid modelling suggests that several gigawatts of storage could cut system generation costs by billions over time.
🌿 Can I get a grant for a home battery in Ireland?
SEAI grants currently focus on insulation, heat pumps and solar panels rather than standalone battery storage. However, home batteries paired with solar PV installations are becoming increasingly popular. Check the latest SEAI grant conditions as the programme evolves – battery support has been discussed in various policy reviews. The economic case often works even without a grant if you have solar panels and a time-of-use electricity tariff.
🌿 Is Turlough Hill the only pumped hydro site in Ireland?
Yes, Turlough Hill in County Wicklow is currently Ireland’s only pumped hydro storage facility, operational since 1974 with 292 MW capacity. While Ireland’s geography limits the number of suitable sites compared to mountainous countries like Norway or Switzerland, other locations have been assessed over the years. The current policy focus is on battery storage and other LDES technologies rather than new pumped hydro.