Hydro renaissance: An old solution to fix a new problem

Pumped-storage hydropower is a cornerstone of Scotland’s renewable energy strategy and unusually has its place set in literature with the tales of men like Seán Doyle, a fictional character from Patrick Campbell’s novel Tunnel Tigers.

Doyle is based on the stories of sacrifice by Irish migrant workers who tunnelled through Ben Cruachan to build the Cruachan Dam – Scotland’s first hydro-pumped facility opened in 1965 – and paints a wonderful description of the human endeavour involved. The Tunnel Tigers were given their moniker for unrivalled bravery, resilience and skill working with dynamite and heavy equipment to create what is still known today at the Hollow Mountain. It was essential but perilous work.

The story is not just about the human cost of the engineering marvel, but also of the workers’ contribution to Scotland’s energy future. While Doyle is fictional, he is a composite of the experiences of countless real-life men. His character offers a lens into the immense physical and emotional challenges faced by those who built the first wave of hydroelectric power stations. 

My own great grandfather, James McDaid, was a Tunnel Tiger. Like his fictional counterpart Doyle, he was a dynamiter, his daughter, my grandmother, Maureen Stevenson recalls. It was “very hard, physically, and the air quality was poor” but “it was good money”, she says. 

McDaid lived on-site, working every day on the tunnelling for months. The constant nature of that hard work took its toll.

“My father got lung cancer not long after [finishing working as a dynamiter]. There was no health and safety to speak of then. He worked on a lot of big projects where he was blasting and drilling, lots down in England, but that one [tunnelling at Cruachan] forced him to retire, he was done with his chest.  

“Work like that was good money, but a lot of them they paid for it.” 

The existing hydroelectric network stands as a testament to the Tunnel Tigers as Scotland embarks on a new era of pumped-storage hydropower. There is a great deal of pride felt by the public in the types of projects that were built in the Highlands.  

Projects like Cruachan transformed the surrounding area, providing energy security for post-war Scotland and laying the early foundations for the green energy revolution. It’s a legacy that is multilayered – not just one of the workers’ endeavours, but of genuine societal improvements in the communities around the construction of the projects and, of course, more widely across Scotland.  

It’s been around 40 years since the last pumped-storage hydropower project was completed in the UK. The construction era that began in the 1950s came about as a result of the 1947 Electricity Act, a landmark piece of legislation that nationalised the electricity supply industry. That shift in strategy prompted the first wave of hydropower facilities, and now, eight decades on, the green energy transition has prompted plans for more. 

Both the Scottish and UK governments have emphasised the role the technology will play in increasing energy security as they rapidly scale production of wind and solar power.  

In January, the Scottish Government published figures showing that renewable energy generated the equivalent of 113 per cent of the country’s overall energy consumption in 2022. This was a 26 per cent increase on the previous year. 

However, it is well known that energy demand at a time when wind generation is also high does not always correlate. There are times when electricity demand is high, but wind generation is not. Pumped-storage hydropower offers a way to store energy when a surplus is being generated.  

Andy Sloan, managing director of COWI, a consultancy firm that specialises in engineering and environmental science and is working on one of the largest hydropower projects in the UK, Coire Glas, describes it as “the most efficient way to store electricity in the long term”.

“Historically, the need for large batteries has not been in the makeup of the UK’s energy supply providers. But with the huge increase in potential for the development of renewable energy, particularly in offshore wind, and the huge abatement of costs that go with that – developers are paid substantial and increasing amounts of money every year not to generate electricity [due to grid constraints] – it would seem sensible to create electricity and store it.  

“It’s that surplus that’s driving the need for long-term storage, and the best and most efficient way to do that is by pumped-storage hydropower, which provides 80-plus per cent efficiency.” 

The energy storage system acts like a large rechargeable battery. It has two bodies of water situated at different elevations – most commonly referred to as an upper reservoir and a lower reservoir. When energy demand is low, surplus energy from the grid fed by renewable energy sources will power pumps to move water from the lower reservoir to the upper reservoir, in effect storing the energy. When energy demand is high, the water is released back down through turbines, generating electricity.  

Scotland offers the ideal typography and geography for these facilities – mountains, rainfall, and large existing bodies of water. Sloan says the potential in Scotland could make it a “pumped-storage superpower”.  

“Being mountainous and having lots of rainfall, those two things conspire to help with the development of hydroelectric and pumped storage in particular.  

“Take Norway for example. Everyone thinks of it as being hydro-rich, having a circuit of electricity and interconnectors to sell, but they have next to no pumped-storage. They are now in a race to develop it, and arguably Scotland has the opportunity to become a pumped-storage superpower in Europe and beyond. We need to be looking at ourselves in that context.” 

While pumped-storage hydropower is a form of green technology, there are environmental concerns relating to the disruption of local wildlife habitats and aquatic life such as fish migration patterns. Earlier this month, the Ness District Salmon Fishery Board (DSFB) raised concerns about proposed plans for a hydropower scheme at Loch Ness.  

The DSFB criticised Statera Energy’s latest proposals for a pumped-storage hydropower facility, which it said would change “the character” of Loch Ness and the River Ness. The energy company had signalled its intention to modify and raise the weir at the head of the River Ness, thus giving it the ability to hold a greater volume of water in Loch Ness, in order, it claimed, to “better optimise the efficiency of existing and future pumped-storage hydropower” and “provide future resilience against the impacts of climate change” – something the DSFB say was not in the original proposals.  

Brian Shaw, director of the DSFB, said: “Raising the level of Loch Ness is not going to reduce the incidence of low water levels, instead the pumped-storage hydropower schemes will be able to draw down the level of Loch Ness even more frequently, with daily fluctuations down to the navigational limit. The busy summer tourist season will be plagued with frequent drawdowns to rock bottom levels, disrupting cruise boat operators as well as causing severe ecological damage.” 

The board has called for a temporary halt on any further pumped-storage schemes on Scottish lochs until the impact on wild salmon populations is properly understood. 

It’s clear these projects require buy-in from the people who live and work in the surrounding areas if they are going to be successful. Director of Glen Earrach Energy, Roderick MacLeod, whose family own the Balmacaan Estate where his company’s project plans to build, tells Holyrood it has held four community engagement sessions, which already have led to some major changes to where the entrance, cable and ventilation tunnels were situated. MacLeod says the engagement has “massively improved the design of the project”.  

“Initial designs placed certain elements of the project closer to Loch Ness and nearby habitation, which raised understandable concerns, particularly around water supply. As we engaged further and conducted more detailed geological assessments, it became clear that a revised location not only addressed these concerns but also made better sense from a technical and environmental perspective. This collaborative process has been crucial to ensuring the project minimises impact and maximises benefits.” 

The project is still in the consultation and design phase, but it proposes to utilise Loch Ness and Loch nam Breac Dearga for its operations. Its current site designs are centred around minimising environmental and visual impact, and includes no visible above-ground structures; whole natural materials will disguise the dam components. It’s the beginnings of an impressive project that aims to begin construction in 2026, be part-operational by 2030, and fully operational by 2032. If it goes to plan it will be one of the largest facilities of its kind in the UK and at full capacity could provide 1GW of power continuously for 30 hours. It also represents an investment of more than £2bn and will create hundreds of construction jobs, as well as green jobs once operational.  

Sloan describes this period as a “renaissance” for pumped-storage hydropower, but he says “it’s not being discussed enough amongst politicians”. “I wonder whether politicians really understand the benefits of the investment in the Highlands that is coming.” 

He continues: “We have gone through a green transition in Scotland already. If you look back at the initiation of the Hydro Board of Scotland, it was heavily invested in eight decades ago and when it asked Westminster for more money in 1953, Hansard shows every Highland MP, everyone to a man, highlighted the wider societal benefits of a green transition. 

“It wasn’t simply about electricity, it was about reversing depopulation, developing roads, the increase in quantity and quality of food, and transforming women’s lives.  

“Looking at the holistic picture, we will benefit MSPs and MPs talking more broadly about the societal impact. And of course, the infrastructure of the Highlands is creaking, as we know.

“Politicians need to understand the green transition also requires investment in our civil infrastructure because the influence of the Highlands and islands will only increase.” 

The Glen Earrach Energy Project is one of many that want to benefit the communities around it. Despite being in the early stages of the project, it has entered early discussions about community wealth building, MacLeod says. 

“The scale and efficiency of the Glen Earrach project enables us to deliver a substantial community benefit fund,” he explains. “We’re engaging privately with local stakeholders, including those in the immediate vicinity and other communities around Loch Ness, as well as with regional partners such as the Highland Council. This early phase involves individual meetings to understand priorities and concerns. As we progress, we’ll work collaboratively to design and manage a community benefit package that reflects the needs and aspirations of the local and regional community. It’s an exciting journey, and we’re committed to getting it right.”