Water power: explore Snowdonia’s hydroelectric power stations

Water – Snowdonia has a lot of it! The combination of mountains and lakes makes it ideal for generating power via hydroelectric schemes, where water and gravity combine to turn massive turbines.

The biggest of all is within ambling distance of our hotel, and there are others too. There are more in the pipeline – ahem! – with a £100m scheme earmarked for the other side of Llanberis.

So if the wet stuff is falling from the sky, why not head underground and learn how it helps put your kettle on?

Dinorwig Power Station – Electric Mountain

Dinorwig, the power station the public can visit via the excellent Electric Mountain attraction, is a man-made marvel. Even though it’s more than two decades old (the turbines started turning in 1984) it’s still the largest hydroelectric scheme of its kind in Europe, in the continent’s largest man-made caverns.

The visitor tour takes you by minibus along 10 miles of underground tunnels, deep under Elidir Fawr mountain. You can get up close to the six massive generating units and the plant that regulates the flow of water through the turbines. All this inside a massive cavern measuring 51 metres (167 ft) high, 180 metres (590 ft) long, and 23 metres (75 ft) wide, known as “the concert hall.”

When power is needed, the station can fire up to maximum capacity (1,728 megawatts) in 16 seconds – so there’s no need to worry about not getting that cup of tea. When it’s not generating electricity, the turbines can pump in reverse, sending water back up the pipe to the Marchlyn Reservoir, 630m above sea level.

Building Dinorwig was a significant feat of engineering, let alone the excavation (12 million tonnes was dug out of the mountain). The station needed one million tonnes of concrete, 200,000 tonnes of cement and 4,500 tonnes of steel to construct.

Electric Mountain is Dinorwig’s Visitor Centre in Llanberis, just a few hundred yards from the hotel. Inside you’ll find a gift shop and café and the starting point for the power station tour. Admission to the visitor centre is free but charges apply for the hour-long tour of Dinorwig.

Just a few minutes walk from the hotel, you can explore Dinorwig Power Station on a guided tour.

Ffestiniog Power Station – the UK’s first of its kind

While Ffestiniog Power Station lacks a visitor centre, you can walk close to it or view it from the Ffestiniog Railway which passes close by. Just outside the village of Tanygrisiau, Ffestiniog Power Station and its feeder lake (Llyn Stwlan) can be explored while walking Moelwyn Mawr mountain.

Ffestiniog was the first pumped storage power facility in the UK – the same method of power generation as used at Dinorwig. Although older than Dinorwig (it was commissioned in 1963), Ffestiniog’s four generating turbines can still achieve a combined output of 360M megawatts of electricity – enough to supply the power needs of North Wales for several hours.

A total of 27 cubic metres of water per second is sent through the station and captured in Tan-y-Grisiau reservoir, then overnight it is pumped back up to Llyn Stwlan to complete the cycle.

You can read more about Ffestiniog Power Station here.

Follow the hairpin bends to reach Llyn Stwlan 1,650ft above sea level.

Maentwrog Power Station – 90 years old in 2018

Maentwrog is the oldest hydroelectric power station in Snowdonia. It was opened in 1928 and, unlike Ffestiniog and Dinorwig, it does not feature pumped water storage. Water simply rushes down a pipe from a high lake into a river and the sea below. Maentwrog leaves Mother Nature to do the water recycling!

In the village of the same name, on the banks of the Dwyryd Estuary, Maentwrog is able to generate 30 megawatts of electricity. When it opened its maximum output of 18 megawatts – generated by three turbines – was enough to power North Wales. An additional turbine was added in 1934 and its new output can power 12,000 local homes.

Maentwrog draws water from Trawsfynydd lake, which itself is fed by man-made channels (you can see these if you take any of the minor roads leading off the A470 to the right, south of Trawsfynydd village, when driving south towards Dolgellau).

From the lake the water travels down a mile-and-a-half long pipeline and drives two turbines, which you can see glimpses of if you drive the minor lane up from the A496 Harlech road just to the side of the power station.

As an aside, profits made from Maentwrog go towards the cost of nuclear decommissioning, with nearby Trawsfynydd’s old nuclear power station one such beneficiary.

The Maentwrog Pipeline is two miles long.

More hydro-power coming to Llanberis?

Glyn Rhonwy is the former slate quarry you pass driving from Caernarfon into Llanberis. There have been many ideas to transform the area and the latest, a new hydro-electric scheme, could start to become a reality in 2018.

The station would be of the pumped-storage variety, like Ffestiniog and Dinorwig, drawing water from a high lake and discharging into Llyn Padarn before pumping water back up at night. If it goes ahead, the £100m scheme will be capable of generating 700 megawatts of electricity, enough to supply seven hours of power to 200,000 homes every day.

Images courtesy: Dinorwig photo by Denis Egan via Flickr. Stwlan Dam by Arpingstone at English Wikipedia (transferred from en.wikipedia to Commons). Maentwrog Pipeline by © Copyright Ian Warburton and licensed for reuse under this Creative Commons Licence.