RWE is celebrating 120 years of continuous operation at Gwynedd’s 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 foothills of Yr Wyddfa, 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.

When it was commissioned in 1906, Cwm Dyli 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 two 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. 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 from RWE 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.”