German energy giant RWE has made a final investment decision to build its largest battery storage project in the United Kingdom to date. The approximately £200 million Pembroke Battery Storage facility represents significant progress in Wales’ clean energy transition and marks an important step toward RWE’s goal of achieving 6GW of global battery storage capacity by 2030.
Project Scale and Technical Specifications
The Pembroke Battery Storage project, located adjacent to RWE’s Pembroke Power Station, will occupy a 5.1-hectare site and install 212 lithium-ion battery containers. The facility employs a two-hour storage system design with peak output capacity of 350MW and total storage capacity of 700MWh. This means the facility can continuously deliver 350MW of power to the grid for two hours, sufficient to power nearly 300,000 typical UK homes for two hours.
The project has secured planning consent and was successful in the UK’s latest Capacity Market auction, ensuring a critical route to market. According to the schedule, construction will begin in the first half of 2026, with commissioning expected in the second half of 2028, subject to receiving an updated grid connection.
Rapid Growth in UK Battery Storage Market
The advancement of the Pembroke project comes at a time of flourishing growth in the UK battery storage market. As of 2025, the UK has over 6.8GW of operational battery storage capacity, with 79% in England, 16% in Scotland, 3% in Northern Ireland, and only 2% in Wales. Notably, approximately 1,405MW of new battery storage capacity has been commissioned in 2025 to date, already surpassing the 2024 total of 1,249MW.
The UK government has set a target of achieving approximately 27GW of battery storage installed capacity by 2030 to support the construction of a clean power system. In the first half of 2025, over 31GWh of storage project capacity was approved in the UK, bringing the cumulative capacity of approved but not yet completed projects to over 130GWh, with 71% coming from approvals made since the start of 2023.
In terms of the Capacity Market, in the T-4 auction in March 2025, approximately 1.8GW of derated battery energy storage system capacity secured 15-year contracts, nearly double the procurement volume from the previous year, demonstrating strong policy support for storage projects.
Supporting Grid Stability and Net Zero Goals
Nikolaus Valerius, CEO of RWE Generation SE, emphasized that as the proportion of renewable energy in the energy system continues to increase, there is growing need for mature technologies that can instantly support the grid. He noted that battery storage systems are ideal solutions due to their speed, efficiency, and competitiveness. The Pembroke Battery Storage project will make an important contribution to stabilizing the UK energy market by efficiently storing surplus energy and feeding it into the national grid in a targeted manner when required.
First Minister for Wales Eluned Morgan announced the project at the Wales Investment Summit, stating that this significant investment demonstrates Wales’ central role in the UK’s transition to clean and renewable electricity. The facility will support Wales’ ambitions for a cleaner, more secure energy future while creating opportunities for good jobs and long-term economic benefits to communities across South Wales.
Tom Glover, RWE UK Country Chair, added that Wales has significant potential to lead the UK’s clean energy transition across wind, solar, storage, hydro, and emerging technologies. Despite the challenges facing energy projects everywhere, the Welsh Government is determined to unlock this opportunity for the benefit of communities across Wales—something RWE strongly supports.
Pembroke Net Zero Centre Strategic Framework
The Pembroke Battery Storage project is a key component of RWE’s broader Pembroke Net Zero Centre decarbonization hub strategy. The Pembroke Net Zero Centre is a comprehensive multi-technology decarbonization initiative comprising three main pillars: large-scale green hydrogen production, floating offshore wind development in the Celtic Sea, and decarbonization of the Pembroke Power Station itself.
The Pembroke Phase II hydrogen project is a 200MW electrolytic hydrogen production facility that will supply local offtakers with low-carbon hydrogen, resulting in an emissions reduction of 160,000 tonnes of CO2 equivalent each year and creating up to 40 new jobs, with operations expected in the late 2020s. According to an economic report by Cardiff Business School, under a medium activity scenario, the Pembroke Net Zero Centre is estimated to support annual Welsh construction activity of £46m–£77m per annum during the construction phase (assumed to be 2023-2038).
RWE is already the leading renewable energy generator in Wales, with more than 3GW of capacity across 12 sites. Around 1GW of this is from renewable sources, accounting for roughly one-quarter of Wales’ renewable energy output. The company employs around 300 people in Wales and has invested more than £21 million in local communities through wind farm benefit funds.
Biodiversity Protection Measures
RWE plans to integrate biodiversity measures into the project, ensuring that the new facility coexists harmoniously with the surrounding natural environment. Planned initiatives include meadow planting, native woodland and scrub restoration, and the creation of a new pond to enhance wildlife habitats around the site.
This approach aligns with the latest trends in the UK battery storage industry. For example, the Winking Hill battery storage project is expected to achieve a 77% increase in habitat units and a 66% uplift in hedgerow units, exceeding national Biodiversity Net Gain (BNG) policy requirements. The UK government is consulting on implementing biodiversity net gain for nationally significant infrastructure projects, proposing to introduce BNG requirements for such projects from May 2026.
RWE’s Global Storage Expansion Strategy
The Pembroke project is a key part of RWE’s “Growing Green” global growth strategy. Currently, RWE operates 1.2GW of battery storage capacity, with an additional 2.7GW under construction. As part of its long-term growth strategy, RWE aims to significantly expand its global battery storage footprint to 6GW by 2030 to support the accelerating energy transition.
Globally, RWE is actively expanding its storage business across multiple markets:
- US Market: Construction has begun on three battery storage projects in Texas with a combined capacity of 450MW power and 900MWh storage, expected to be operational by the end of 2025, supporting the stability of the Electric Reliability Council of Texas (ERCOT) grid.
- German Market: Construction has started on a 400MW/700MWh battery storage project in Bavaria, Germany’s largest under construction, with an investment of approximately €230 million, expected to be operational in 2028. Additionally, a 220MW/235MWh battery storage facility was built at Neurath and Hamm in North Rhine-Westphalia, commissioned in 2024.
- Australian Market: Approved the first 8-hour storage project Limondale, with 50MW capacity and 400MWh storage, expected to be operational by the end of 2025.
Evolution of UK Storage Market Revenue Structure
The revenue structure of the UK battery storage market is undergoing significant changes. In January 2025, battery energy storage revenues in Great Britain reached a rate of £88k/MW/year, a 5% increase from December 2024 and a two-year high. This was primarily driven by surging wholesale trading revenues, with wholesale price spreads increasing by 42% to reach a two-year high.
Notably, the share of frequency services in the revenue stack has decreased significantly from 80% in 2022 to just 20% in 2024, due to market saturation. Meanwhile, the importance of energy arbitrage is increasing. Despite declining frequency service revenues, through diversified revenue streams, unlevered returns for contracted projects remain at 12-17%, demonstrating the sector’s strong attractiveness.
Industry Development Outlook
The UK battery storage market continues to maintain strong growth momentum. In the first half of 2025, project completions increased by 78%, planning submissions rose by 25%, and project approvals surged by 49%. Currently, approximately 6.5GW of capacity is under construction, with over 60GW of capacity already consented.
Project sizes are also continuing to grow. The average capacity of projects submitted in 2025 was 300MWh, compared to 230MWh in 2024. 41% of submitted projects exceeded 100MW, compared to just 22% in the same period last year. Multiple developers have proposed projects exceeding 1GWh, such as Fidra Energy’s 2.4GWh battery storage project in Lincolnshire and NatPower’s 2GWh Brant Energy Storage project.
The continued decline in battery costs also provides favorable conditions for industry development. Lithium-ion battery costs have fallen steadily over the past decade and will continue this trend in the future, enabling new battery storage projects to offer more competitive bids at lower costs.
As the UK accelerates toward its Clean Power 2030 goals, large-scale battery storage projects like Pembroke will play a crucial role in maintaining security of supply and supporting the growth of renewables. By responding instantly to fluctuations in renewable output and energy demand, large-scale storage enhances grid stability and supports the wider adoption of renewable energy, laying a solid foundation for the UK to achieve its net zero targets.
