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Briefing sheet

Pumped hydro storage and the Coire Glas scheme

31 January 2017

An overview of pumped hydro storage (PHS) technology and its opportunities and a detailed look at a new large planned plant at Coire Glas in Scotland.

Pumped hydro storage and the Coire Glas scheme
Coire Glas pumped hydro storage, artist's impression: the reservoir is not visible from Loch Lochy or Invergarry (image from SSE)

Pumped hydro storage has the highest efficiency of all energy storage technologies currently available but can only be deployed large scale. When there is a low demand for power water is pumped to the upper reservoir while at high demand water is released through turbines to generate energy.

Pumped storage in the UK

  • Usually used to bridge short term variations in demand and generation
  • no existing schemes can generate at full capacity for an extended period
  • most of the UK storage capacity is pumped storage
  • no new storage has been built since the Dinorwig plant in 1984
  • 4 main PHS schemes in mainland UK: Dinorwig, Festiniog, Foyers, Cruachan
  • there's a need and good benefits for new PHS schemes

New pumped storage in the UK

  • PHS plants are planned at Sloy, Coire Glas, Balmacaan, Cruachan upgrade and Glyn Rhonwy
  • Coire Glas – planned pumped storage scheme
  • an idea developed by SSE near Loch Lochy, Fort Augustus, Scottish Highlands
  • unique for being able to store/send energy for far longer periods (~50 hrs)
  • significant elevation of ~500m between the upper and lower reservoirs
  • consent was granted in December 2013
  • but no final investment decision yet; a large investment (£800m) is needed

Further information and references

  • Colin Baird, retired