The mountain in North Wales that tried to stop the UK’s blackout

Elidir Fawr, the mountain in question. Image: Jem Collins.

Last Friday, the UK’s National Grid turned to mush. Not the official term perhaps, but an accurate one after nearly one million people were left without power across the country, with hundreds more stranded at train stations – or even on trains (which isn’t nearly as fun as it might immediately sound). 

Traffic lights stopped working, back-up power failed in hospitals, and business secretary Andrea Leadsom launched an investigation into exactly what happened. So far though, the long and short of it is that a gas-fired power station in Bedfordshire failed just before 5 o’clock, followed just two minutes later by Hornsea offshore wind farm. 

However, amid the resulting chaos and inevitable search to find someone to blame for the outage, a set of mountains (yes, mountains) in North Wales were working extremely hard to keep the lights on.

From the outside, Elidir Fawr, doesn’t scream power generation. Sitting across from the slightly better known Mount Snowdon, it actually seems quite passive. After all, it is a mountain, and the last slate quarry in the area closed in 1969.

At a push, you’d probably guess the buildings at the base of the mountain were something to do with the area’s industrial past, mostly thanks to the blasting scars on its side, as I did when I first walked past last Saturday. 

But, buried deep into Elidir Fawr is the ability to generate an astounding 1,728 megawatts of electricity – enough to power 2.5 million homes, more than the entire population of the Liverpool region. And the plant is capable of running for five hours.

Dubbed by locals at the ‘Electric Mountain’, Dinorwig Power Station, is made up of 16km of underground tunnels (complete with their own traffic light system), in an excavation which could easily house St Paul’s Cathedral.

Instead, it’s home to six reversible pumps/turbines which are capable of reaching full capacity in just 16 seconds. Which is probably best, as Londoners would miss the view.

‘A Back-Up Facility for The National Grid’

And, just as it often is, the Electric Mountain was called into action on Friday. A spokesperson for First Hydro Company, which owns the generators at Dinorwig, and the slightly smaller Ffestiniog, both in Snowdonia, confirmed that last Friday they’d been asked to start generating by the National Grid.

But just how does a mountain help to ease the effects of a blackout? Or as it’s more regularly used, when there’s a surge in demand for electricity – most commonly when we all pop the kettle on at half-time during the World Cup, scientifically known as TV pick-up.

The answer lies in the lakes at both the top and bottom of Elidir Fawr. Marchlyn Mawr, at the top of the mountain, houses an incredible 7 million tonnes of water, which can be fed down through the mountain to the lake at the bottom, Llyn Peris, generating electricity as it goes.


“Pumped storage technology enables dynamic response electricity production – ofering a critical back-up facility during periods of mismatched supply and demand on the national grid system,” First Hydro Company explains.

The tech works essentially the same way as conventional hydro power – or if you want to be retro, a spruced up waterwheel. When the plant releases water from the upper reservoir, as well as having gravity on their side (the lakes are half a kilometre apart vertically) the water shafts become smaller and smaller, further ramping up the pressure. 

This, in turn, spins the turbines which are linked to the generators, with valves regulating the water flow. Unlike traditional UK power stations, which can take hours to get to full capacity, at Dinorwig it’s a matter of 16 seconds from a cold start, or as little as five if the plant is on standby.

And, designed with the UK’s 50hz frequency in mind, the generator is also built to shut off quickly and avoid overloading the network. Despite the immense water pressure, the valves are able to close off the supply within just 20 seconds. 

At night, the same thing simply happens in reverse, as low-cost, surplus energy from the grid is used to pump the water back up to where it came from, ready for another day of hectic TV scheduling. Or blackouts, take your pick.

Completed in 1984, the power station was the product of a decade of work, and the largest civil engineering project commissioned at the time – and it remains one of Europe’s largest manmade caverns. Not that you’d know it from the outside. And really, if we’ve learned anything from this, it’s that looks can be deceiving, and that mountains can actually be really damn good at making electricity. 

Jem Collins is a digital journalist and editor whose work focuses on human rights, rural stories and careers. She’s the founder and editor of Journo Resources, and you can also find her tweeting @Jem_Collins.

 
 
 
 

Here are my five favourite London council estates

The Dunboyne Road estate. Image: Steve Cadman/Wikimedia Commons.

The author is a Labour member of the London Assembly. In the name of impartiality, CityMetric would like to extend the invitation to write similar columns to representatives of other political parties.

From successful post-war efforts to move families out of slums and into modern homes, to today’s efforts to construct a new generation of social housing, there’s much to be celebrated in London’s precious council housing stock.

This year we celebrate the centenary of the Addison Act, which established a national building programme with government funding for the first time. So here – in no particular order – are my top five London estates:

1. Dunboyne Road

In 1965, the newly established London Borough of Camden was bold and radical when it came to public housing. Their architect’s department boasted 98 staff, led by Sydney Cook. The Grade II listed Dunboyne Road (pictured above) was Britain’s first high-density, low-rise estate. Designed in the late 1960s and completed in 1977, it was the first major work by architect Neave Brown.

Its concrete construction and geometric layout are eye-catchingly modernist, but the 71 flats and maisonettes fit neatly into their surroundings; a reimagining of the classic London street for the 1960s. Each has a private terrace and own entrance onto the central pedestrian walkway and communal gardens, with stepped levels and dual-aspect windows creating light throughout.

Neave Brown himself lived on the estate in the final years of his life remarking, “Who am I to say, but it’s beautiful”.

2. Lilington Gardens

Located just off Vauxhall Bridge Road, the fourteen blocks at Lilington Gardens were built between 1964 and 1972. Between three and eight storeys each, it was again a rejection of the tower blocks which dominated the era, showing that mid-rise housing could provide both beauty and density.

Image: Ewan Munro/Wikimedia Commons.

At a time when Westminster could be proud of the quality of its housing, John Darbourne and Geoffrey Darke won a competition to design the new estate. The result was something special, eschewing modernist forms for something more rugged and layered. The layout allows for secluded green spaces, while the red brick cladding echoes the neighbouring Victorian church of St James the Less. Like all good estates, it included a pub – the Grade II*-listed Pimlico Tram (now The Cask). It was included not as an afterthought, but an integral part of the estate’s design.

3. Ossulston Estate

By the early 1950s, the London County Council’s architect’s department was the biggest in the world, building housing on a huge scale in addition to showp iece projects such as the Southbank Centre.

Though their suburban estates – Downham in Bromley, and Becontree in Barking and Dagenham – were pioneering examples of low-rise of modernity in metroland, these efforts did not always suit the needs of poor city dwellers who weren’t able to move further out. The Ossulton Estate, however, built between 1927 and 1931 on the site of a Somerstown slum and located between Euston and St Pancras stations, did exactly that.

Image: Stephen McKay/Wikimedia Commons.

Chief architect George Topham Forrest’s work was inspired by visits to ‘Red’ Vienna and Ossulston bears distinct similarities to Karl Marx-Hof, which was constructed at the same time. While the roofs and windows have traditional elements, the overall aesthetic is a modernist classic. Like many estates in post-war years, it suffered from neglect and a lack of investment, but following a £6m improvement programme by Camden Council in 2004, the Ossulston is now back to its brilliant best.

4. Alton Estate

Roehampton’s Alton Estate, completed in 1959, was designed by a team led by Rosemary Stjernstedt – the first woman to serve as a senior public sector architect in Britain.

The two parts of the estate – East and West – are the crown jewels of British post-war council housing. Alton West was Le Corbusier in Albion: six ultra-modernist blocks modelled on the Unité d’habitation in Marseille, set among the landscape inherited from the Georgian Mount Clare house. Alton East was a softer, Scandinavian-inspired design of the “new Brutalists” in the LCC.

Image: Stevekeiretsu/Wikimedia Commons.

Rising above the trees to the north east of Richmond Park, the Alton Estate stands testament to the visionary idealism of post-war council housebuilding. On its completion, visitors flocked from across the globe, with American critic G.E. Kidder Smith calling it “probably the finest low-cost housing development in the world”.

Sadly, Alton West however is now at risk from ‘regeneration’ proposals which would see 288 existing homes lost. While council estates should not be fetishised, with investment, improvement and expansion encouraged, any change must be done sensitively and with residents’ backing. I hope that Wandsworth Council and Redrow will follow the mayor’s Good Practice for Estate Regeneration and hold a ballot before plans go ahead, and that if they do, they build on Rosemary Stjernstedt’s legacy.

5. King’s Crescent

When it comes to regeneration Hackney Council have taken an altogether different approach to Wandsworth.

Located on Green Lanes opposite the magnificent Clissold Park, King’s Crescent’s route to a successful and well-supported regeneration project hasn’t always been an easy one. The early 1970s estate was blighted by poor construction, navigability issues and an ill-fated partial demolition in 2000 which turned much of the landscape into hoardings and rubble. But thanks to a step-change in resident engagement and a transformation programme funded by Hackney Council, by 2023 it will be host to 765 new and refurbished homes.

Image: David Holt/Wikimedia Commons.

In the era of government-imposed cuts to local authority budgets, councils have to be pragmatic about funding choices and the new King’s Crescent does include homes for private sale. This is understandably a source of some consternation, but it’s also the source of funding which has made the regeneration possible. Hackney has ensured that more than 50 per cent of the new homes are genuinely affordable, with 97 brand new council homes for social rent.

The new developments have greatly enhanced the area, using both new build and renovation to stitch the estate better into its Victorian surroundings. Existing homes have been retrofitted with balconies, while disused garage space has been repurposed for modern flats. Hackney have clearly thought carefully about character and open spaces, as well as ceiling heights, windows and internal storage.

It is an exceptional project – one of a growing number of new schemes now being spearheaded by ambitious councils across the capital. In 2018-19, the Mayor of London funded the start of 1,916 new council homes – the highest figure since 1984-85.


…what about the Barbican?

On the fiftieth anniversary of its opening, it would be remiss not the mention the Barbican. It’s a brutalist masterpiece and a fantastic feat of post-war planning and design. The location and design are clearly outstanding, but it’s the bright and modern interiors which are truly to die for.

So why is it not on the list? Although it was built by the City of London Corporation, not one of the flats was ever available at a social rent. The properties were built to let at market rents to workers in the City, who later found themselves in the fortunate position of being able to snap them up under the Right to Buy – still the fate of far too many of London’s vital social homes.

Tom Copley is a Labour member of the London Assembly.