Dinorwig Power Station entrance, Llanberis
If you’ve just scanned the QR codes and are looking out over the lake (Llyn Peris), you’re pretty close to one of Europe’s largest pumped-storage power stations. It’s hard to spot despite its size, as most of the infrastructure is under ground!
The power station’s story is linked to that of the huge Dinorwig slate quarry, to the left of the lake as you look east from here. After its closure in 1969, it provided an ideal location for a hydro-electricity station similar to the smaller Ffestiniog Power Station, which opened in 1963.
Dinorwig Power Station was fully commissioned in 1984. It includes 16km of underground tunnels, deep below Elidir mountain. Six powerful generating units stand in the largest man-made cavern in Europe. The construction project involved a million tonnes of concrete and 4,500 tonnes of steel.
Power is generated by the force of water falling from Marchlyn Mawr, on the far side of Elidir. The water turns turbines before it flows into Llyn Peris, which was modified for its new function. Works included diverting the inflow river near the site where legendary strongwoman Marged ferch Ifan used to load her self-made boat with copper ore in the 18th century.
When demand for electricity is low, usually at night, water is pumped back up to Marchlyn Mawr – where it will be ready to generate electricity again when required. The pumps are driven by electricity which is produced at other UK power stations.
A ventilation shaft reaches the surface in the centre of the old quarry, high above the power station.
Dinorwig and Ffestiniog power stations are owned by First Hydro Company, (First Hydro Company is jointly owned by GDF Suez and Mitsui & Co., Ltd). There is no public access to the power station along the road beside the lake, but public tours of the Dinorwig Power Station complex are available from the Electric Mountain visitor centre - follow the link below for information.