Coire Glas pumped hydro storage, Scotland

Getting the UK one step closer to net zero

About

Challenge

To fully utilise the potential of renewable energy, we need to bridge the gap at transmission level during periods of low offshore wind output and be able to store excess wind energy during high wind periods.

Solution

A pumped hydro scheme that will use surplus renewable energy to pump water to the upper reservoir and promptly provide electricity to the grid when needed for long periods of time.

Value

With its 30 GWh of storage capacity, Coire Glas would more than double Great Britain’s existing electricity storage capacity and power up to three million homes.

Specifications

Capacity

1,500 MW

Pumped hydro storage scheme

The 1,500 MW scheme will act as a battery for renewable energy, capable of providing electricity to the grid promptly when needed, and for long periods of time.

Location

Loch Lochy, Scottish Highlands

Period

2021–2033

Country

Scotland, UK

Partners

SSE and Stantec

Services

Reference design of the underground structures; geotechnical baseline report preparation; geotechnical ground investigations; exploratory adit design.

Powering three million homes

Coire Glas is the first large-scale pumped storage scheme to be developed in the UK in more than four decades and would more than double Great Britain’s existing electricity storage capacity.

The move from carbon-intensive to renewable electricity generation is changing the role that pumped storage can play in supporting the reliability of the UK’s electricity grid.

“Coire Glas represents a hugely exciting project for the UK. Not only will it play a vital role in enhancing the UK’s grid reliability, but it will also be pivotal in creating the flexibility needed to bring more offshore wind resources online in support of the country’s net-zero goals."

Andy Sloan, Managing Director, COWI in the UK

As the world’s largest, most proven and cost-efficient large-scale storage technology, pumped storage’s rapid response time and capacity allow it to effectively support the grid, providing vital cover for sudden surges in demand for energy, while also having the capability to avoid the inefficient curtailment of surplus renewable electricity.

“To deliver a project of this scale and ambition requires cross-stakeholder collaboration – from de-risking investments to deploying best-in-class engineering to ensure the project is delivered on time, budget and specification. As the first project of its kind in the UK in over three decades, it has a lot to live up to, but with international expertise at its fingertips, the project is set for success.”

Andy Sloan, Managing Director, COWI in the UK

In doing so, it helps to unlock even greater potential for offshore wind by providing the necessary support to maintain grid reliability in the face of increasing generation intermittency. Coire Glas would start generating power from standby operation in under ten seconds and reach full generating capacity in under 60 seconds, rapidly supporting grid stability.

The scale of the project is unprecedented in terms of size, technicalities and location. Underground construction will take place nearly a kilometre below ground, while the over 90-metre-high dam will become the largest in the UK. The underground cavern that needs to be excavated to house the power plant will be equivalent to the size of Glasgow Cathedral.

“Furthermore, to overcome many of the project’s other complexities, the team is undertaking one of the most extensive ground investigations of its time, allowing for the analysis of a huge volume of geotechnical data before construction begins. This is even more necessary given the site’s proximity to the Great Glen fault line; a fault line so prominent it can be seen from outer space. The geotechnical data will observe ground conditions to inform on the potential risks and challenges posed to delivering the project.”

Andy Sloan, Managing Director, COWI in the UK