Coire glas hydro scheme

  • Category: Renewables
  • Energy type: Hydro
  • Project type: Project

First new large scale pumped storage scheme to be developed in UK for over 30 years

Coire Glas 600MW pumped storage scheme, near Loch Lochy, gained consent in December 2013 and would more than double the total volume of current pumped storage capacity in the UK. The scheme is capable of delivering 30GWh of electricity to the system, meaning that, at maximum capacity, the water in the upper reservoir could provide up to 450MW of power to the grid for nearly three days.

Hydro pumped storage, a technology which has been around for over 100 years and has proven itself to be indispensable to the electricity system, can respond very quickly if the system requires it, similar to other forms of storage.  But its unique benefit is that it can store and then flexibly generate a lot of electricity over a sustained period of time.

Project Overview

  • £800m project
  • 600MW capacity
  • 500m between the upper and lower reservoir sites
  • Helps balance the grid

Coire Glas Scoping Report Submission

Coire Glas Hydro Pumped Storage Ltd, a wholly owned subsidiary of SSE, has submitted a scoping request to The Scottish Government for a revised planning application for the previously consented pumped storage scheme at Coire Glas.

In December 2013 the Scottish Government approved SSE’s application to construct and operate a 600 megawatts (MW) hydroelectric pumped storage hydro scheme at Coire Glas. SSE considers there to be clear benefits to society in the delivery of new pumped storage projects. Despite receiving planning consent in 2013 Coire Glas has faced a number of commercial and regulatory challenges which have prevented the project being progressed. The revisions to the consented scheme now being proposed are intended to help in providing options for better aligning the project with the current market framework and thereby aiding delivery of the project.

What we are proposing is to increase the generating/pumping capacity of the project from the consented 600 Megawatts (MW) up to around 1500MW to maximise the potential of the site. Whilst the increased capacity from 600MW to 1500MW would appear to be a significant change we can highlight that: 

  • The majority of the change to the scheme will be in the underground space required to house the larger turbines and pass the increased flow rates of water, and as such will not be visible;
  • There is no proposal to increase the size of the previously consented upper reservoir;
  • All access routes in and out of the site would remain the same as previously consented, with little  anticipated additional traffic during the operation life of the scheme;
  • There is no proposal for the maximum and minimum levels in either the upper or lower reservoirs to be outside the limits previously consented.

Following the submission of the scoping report for the revised project on Friday 12th May, the Scottish Government will seek guidance from statutory bodies (Highland Council, SEPA and SNH) who will then define the scope for the Environmental Impact Assessment (EIA) required for the proposed larger scheme.  The EIA is expected to take the majority of 2017, and we anticipate making a new application to the Scottish Government for consent in December 2017.  Development of the details of the new scheme is still at an early stage and as such, the information that we are able to provide at the present time may be limited.  

The previously consented development has been the subject of rigorous consultation with The Highland Council, all statutory bodies and the local community during the development and consenting process. This dialogue has been an important aspect of the development of the scheme and will continue with this planned revised application. SSE will engage with the local community and relevant community groups and will hold project exhibitions later in the year.

If you do have any questions, please do not hesitate to email:

Quick overview

Pumped storage schemes involve two bodies of water at different heights. During periods of low demand for power, electricity is used to pump water from the lower loch to the upper reservoir. The water is released to create energy at a time when demand is high. A key advantage of developing a pumped storage scheme at Coire Glas is the site's proximity to a large lower reservoir (Loch Lochy). There is significant elevation of around 500m between the upper and lower reservoir sites over a relatively short distance.

Latest news

In May 2017 a scoping request was submitted to The Scottish Government for a revised 1500MW Coire Glas pumped storage scheme. On 28th May 2017 we held a public exhibition to give members of the community and interested parties an opportunity to meet the project team and discuss the project.

Exhibition materials can be view here.


We recognise that our investments in new electricity generation benefit from the co-operation of the local community in a variety of ways, particularly during the construction phase. In recognition of this, our policy is to establish long-term funds to support community projects in areas where we are developing generation projects. 

Please visit our Community page for more information. 

More information

Project information

Coire Glas 600*300

The proposed scheme involves constructing a dam and the creation of a new reservoir formed at Loch a' Choire Ghlais. Water will be transferred between the new reservoir and an underground cavern power station via a headrace tunnel; and between the power station and Loch Lochy via a tailrace tunnel.

It could offer significant benefits to the GB electricity system in terms of capacity, balancing services and flexibility, particularly as the energy system moves towards an increasing amount of variable generation capacity.

Coire Glas 3 - 600*300

The Scottish Ministers granted Coire Glas consent in December 2013 meaning it could be the first new large scale pumped storage scheme to be developed in Great Britain for over 30 years.

The combination of the size, flexibility and short response time means that Coire Glas, and pumped storage schemes generally, can provide a range of benefits across the whole GB electricity system in a way that no other proven technology can. However, despite the obvious benefits that pumped storage offers, making a Final Investment Decision to progress the Coire Glas scheme will require overcoming a number of commercial and regulatory challenges. These include changes in the existing transmission charging regime for pumped storage and a satisfactory and supportive long-term public policy and regulatory framework.

All of this means that a decision on whether to progress with Coire Glas will not be taken until late 2017 at the earliest.

Important documents

Pumped storage briefing - November 2013

Figure one location map - February 2012

Figure two scheme overview - February 2012

Figure three visualisation - February 2012

Figure four visualisation - February 2012

Non technical summary - February 2012

Exhibition boards - November 2011

Flyer - November 2011

Scheme location - May 2009

Context - May 2009

Preliminary scheme arrangement - May 2009