RWE is moving ahead with what could become the biggest battery energy storage project in the United Kingdom — a facility known as Pembroke Battery Storage, part of its broader decarbonization initiative at the Pembroke Net Zero Centre decarbonization hub in South Wales.
The storage project, backed by a roughly £200 million (~$264.5M) investment, has already secured planning consent (January 2025) and successfully cleared the latest Capacity Market auction, giving it a reliable path to market. Construction is slated to begin in the first half of 2026, with commissioning and operations targeted for the second half of 2028 — provided the grid connection is completed on schedule.
Located on a 5.1-hectare (~12.6 acre) site just south of the existing Pembroke Power Station, the battery installation will consist of 212 lithium-ion battery containers. Once fully operational, it is designed to deliver up to 350 megawatts (MW) of power directly on the grid for a two-hour duration — equivalent to 700 megawatt-hours (MWh) of stored energy. That capacity gives the facility the ability to supply significant discharge power during periods of peak demand, helping balance supply and demand on the grid.
Leaders at RWE emphasize the strategic importance of the Pembroke Battery project for the UK energy system. In their view, large-scale battery storage is vital for stabilizing a grid that increasingly relies on intermittent renewable generation. The project’s flexibility and rapid-response capabilities could help smooth out swings in supply as renewable output fluctuates.
“In a dynamic energy world with more and more renewable energy, there is an increasing need for mature technologies that can instantly support the electricity grid. Battery storage systems are ideal for this because they are fast, efficient and competitive. Our Pembroke Battery is our UK flagship storage project and will make an important contribution to stabilising the UK energy market by efficiently storing surplus energy and feeding it into the national grid in a targeted manner when required.” – Nikolaus Valerius, CEO, RWE Generation SE
Beyond energy output, the project is slated to deliver environmental and community benefits. As part of its development plan, provisions include meadow planting, native woodland and shrub planting, and the creation of a new pond to support local wildlife — efforts intended to preserve and enhance biodiversity around the Pembroke site.
Officials from government and industry have welcomed the project. The announcement came during the Wales Investment Summit, underscoring the Welsh government’s commitment to infrastructure investment that supports decarbonization and economic development.
For RWE, Pembroke Battery represents a flagship in the UK’s shift toward clean, flexible infrastructure — a concrete step toward integrating storage at scale alongside generation, and toward building a more resilient, low-carbon electricity system.
The number one renewable energy generator in Wales is RWE. The company is currently involved in over 3 GW of energy across 12 sites, of which approximately 1 GW is renewable. The existing renewable energy portfolio generates roughly a quarter of Wales’ renewable energy production.
Source: RWE to build its largest UK battery energy storage facility
Photo Credit: RWE
