[4] The generating plant resides inside the mountain in a cavern measuring 250×70×90 feet (76×21×27 metres),[3] which houses four reversible pump turbines with a combined capacity of 292 megawatts.

[16] Concerns about the impact of the scheme on the scenery at the Wicklow Gap led to ESB, whose chairman and chief executive at the time, Tom Murray, was an enthusiastic supporter of the project, engaging the services of landscape architect Sylvia Crowe.

Objections to the lines, planned to run from Turlough Hill to the village of Hollywood, came from several quarters, including Bord Fáilte, the Irish tourist board.

[17] In the end, it was decided that they would run underground from Turlough Hill for c. 1 mile (1.6 kilometres), to preserve the view at the Wicklow Gap, before emerging overground on pylons along the King's River to Hollywood.

[21] Archaeological investigations near the Wicklow Gap during construction uncovered part of Saint Kevin's Road, the ancient path that brought pilgrims from Hollywood to the monastery at Glendalough.

[22] Following the completion of Turlough Hill, the ESB considered a number of sites – in the Wicklow and Comeragh mountains as well as around Lough Derg – for further pumped-storage schemes.

[23] However, Turlough Hill remains the only such scheme in Ireland to date, although the Commission for Energy Regulation has approved the construction of a 70MW facility at Knocknagreenan, County Cork.

"[26] The Irish Minister for Communications, Energy and Natural Resources reported to the Oireachtas on 15 January 2014 "... in Ireland we have the Turlough Hill pumped storage facility in County Wicklow, which has a capacity of 292 MW.