RWE Celebrates 120 Years of Power Generation at Historic Cwm Dyli Hydro Power Station

RWE, Wales’ largest power generator and operator of 78 MW of hydroelectric power capacity across the UK, is celebrating a remarkable milestone — 120 years of continuous operation at the historic Cwm Dyli hydro power station.

Built in 1906, Cwm Dyli holds a unique place in energy history as one of the UK’s longest continuously operating power stations. Nestled in the dramatic foothills of Yr Wyddfa (Snowdon), within Eryri (Snowdonia), the station stands as both a feat of early 20th-century engineering and a lasting example of the reliability of renewable energy.

For more than a century, Cwm Dyli has harnessed the natural power of water flowing from Llyn Llydaw, a mountain lake that receives an average of around 3,700 mm of rainfall each year. This abundant natural resource continues to provide clean, renewable electricity today, demonstrating how carefully designed hydro infrastructure can deliver sustainable power across generations.

Cwm Dyli was also a pioneer of electrical innovation. When it was commissioned in 1906, it became the first power station in the UK to generate electricity using alternating current (AC) — a technology that would go on to become the global standard for electricity transmission and distribution.

Today, the plant operates remotely and is managed from RWE’s Dolgarrog Hydro Operations Base, allowing the historic facility to continue generating power efficiently while maintaining its original engineering heritage.

To ensure the station can continue producing renewable electricity for decades to come, RWE has recently completed a major maintenance programme on the 2-kilometre-long pipeline that feeds water to the station.

The project presented significant engineering challenges. Located in steep, rugged terrain high in the mountains of Eryri, transporting equipment and materials required specialist helicopter lifts, while teams worked in remote and difficult conditions.

Safety was a top priority throughout the project. Engineering contractor Jennings worked closely with the Llanberis Mountain Rescue Team to develop a comprehensive emergency response plan, ensuring that personnel working in the challenging environment were fully protected.

Keith Moorcroft, RWE UK Hydro Plant Cluster Manager, said: “Cwm Dyli represents both a cornerstone of renewable energy and a source of flexibility you can count on. For 120 years it has demonstrated the incredible longevity and reliability of hydro power. We are proud to continue investing in this historic station so it can keep generating clean electricity for many years to come.”

RWE is the largest power producer in the UK and a leading renewable energy generator, operating a diverse portfolio that includes onshore wind, offshore wind, hydro, biomass, and flexible gas generation.

The continued operation of Cwm Dyli highlights the important role long-established renewable technologies like hydropower play alongside newer forms of generation in delivering a secure, sustainable energy system for the UK.

Pictures for media use (credit: RWE) are available at the RWE Media Centre.