Dinorwic Pumped Storage Scheme
The Central Electricity Generating Board commissioned the project to provide a facility which could better match electricity supply and demand, providing extra capacity at times of peak demand and frequency control. It is one of Europe’s largest pumped storage schemes, circulating 6.6 million m3 of water over 5 hours between interconnected high and low-level reservoirs to smooth fluctuations. It has electrical capacity of 1728MW, with electrical storage capacity of 9.1GWh.
In order to protect the beauty of the surrounding area, the power station was located inside the mountain Elidir Fawr.
1974 The project, which cost £425 million, was the largest civil engineering contract ever awarded by the UK government at the time.
The work was undertaken by a consortium of Alfred McAlpine, Brand and Zschokke.
Twelve million tonnes of rock had to be moved from inside the mountain, creating 16 kilometres (9.9 mi) of tunnels as well as the enormous cavern for the turbines and generators.
The project took 10 years to complete.