Ffestiniog Pumped Storage Scheme
1954 The Central Electricity Generating Board decided to build the Ffestiniog Pumped Storage Scheme, the UK's first major pumped storage power facility. The scheme included the lower reservoir, Tan y Grisiau (Llyn Ystradau), which flooded part of the northern end of the Ffestiniog Railway line. Water is captured in Tan-y-Grisiau and pumped back to Llyn Stwlan, usually overnight, to complete the cycle.
1963 Plant commissioned with four generating units with a combined output of 360MW of electricity and storage capacity of 1.3GWh. The English Electric Co motor/generator units are each rated at 90 MW (0.95 PF) as generators, 75 MW (1.0 PF) as motors, at 428 rpm. [1]
1972 The Festiniog Railway Company obtained compensation for the disruption caused by the construction of the pumped storage scheme. This involved the second-longest legal battle in British legal history, which took eighteen years and two months.