Ireland’s renewable expansion is facing growing storage challenges, with a proposed €2 billion LDES facility in County Carlow aiming to convert surplus renewable power into green hydrogen for later electricity generation.
The Rathrush Green Energy Park, developed by Irish company Net Zero Energy (NZE), is planned as a 600MW energy storage facility outside Rathoe. The project is designed around a model increasingly considered critical for high renewable penetration grids: using excess wind and solar output that would otherwise be curtailed, converting it into hydrogen through electrolysis, storing the hydrogen, and reconverting it into electricity during periods of supply shortages.
The proposed facility reflects a growing shift in energy storage strategies. While lithium ion batteries are increasingly deployed for short duration balancing services, long duration storage technologies are being explored to manage multi hour, multi day, or seasonal variability in renewable generation. Hydrogen based storage remains one of the few options capable of storing large quantities of energy over extended periods, although efficiency losses and infrastructure costs remain key industry considerations.
According to NZE, the facility could prevent approximately 180,000 tonnes of CO₂ emissions annually, equivalent to removing around 40,000 passenger vehicles from the road. The emissions impact would depend largely on the carbon intensity of the electricity used for hydrogen production and the operational profile of the system, as hydrogen produced from curtailed renewable energy generally provides stronger climate benefits than hydrogen produced from grid electricity with fossil fuel generation.
The project is being positioned as a response to Ireland’s growing renewable energy curtailment problem. As wind and solar capacity expands, periods of high generation can exceed grid demand or transmission capacity, forcing operators to reduce renewable output. Rather than allowing this electricity to be lost, the Rathrush proposal would redirect surplus power toward hydrogen production.
The stored hydrogen would be held underground in lined rock caverns before being converted back into electricity and supplied to the national grid. Underground hydrogen storage is already used in some industrial applications, but large scale energy storage projects require careful consideration of geological conditions, leakage risks, safety systems, and conversion efficiency.
NZE Chief Executive Peter Harte said the project could contribute to both energy security and grid decarbonization by using renewable electricity that is currently underutilized. The proposal comes amid continued concern over Ireland’s reliance on imported fossil fuels and exposure to international energy price volatility following events such as the European energy crisis triggered by Russia’s invasion of Ukraine in 2022.
Energy security has become a central issue for countries attempting to accelerate electrification while maintaining reliable supply. Ireland’s relatively isolated electricity system creates additional challenges, with limited interconnection compared with larger continental markets. Long duration storage technologies are therefore being evaluated as part of broader strategies to reduce dependence on fossil fuel generation during peak demand periods.
The developers estimate that the facility could provide up to 600MW of dispatchable renewable power, potentially covering around 10% of Ireland’s peak electricity requirement. The scale would exceed existing energy storage and generation benchmarks in the country, with NZE stating that the project would store around thirty times more green energy than Turlough Hill Pumped Storage Station and have seven times the generation capacity of Ardnacrusha Hydroelectric Power Station.
However, the economics of hydrogen based storage remain a major factor in determining whether such projects can compete with alternative flexibility solutions. Electrolysis, compression, storage, reconversion through turbines or fuel cells, and grid integration all introduce energy losses. The business case depends heavily on electricity market conditions, future renewable oversupply, carbon pricing, and the value placed on grid reliability.
The project also highlights the increasing overlap between renewable energy development and industrial policy. NZE argues that large scale storage capacity could support investment decisions by energy intensive companies seeking access to lower carbon electricity supplies. As data centers, manufacturing facilities, and electrification projects increase electricity demand, grid flexibility is becoming a key factor in attracting new infrastructure.
Construction of the Rathrush Green Energy Park could involve up to 1,500 workers at peak activity, while approximately 70 permanent skilled roles are expected once operational. The developer plans to complete community consultation before submitting a planning application.
