Dinorwig Power Station
The Electric Mountain. Dinorwig Power Station is a 1,800 MW pumped-storage station in Wales, operated by Engie Power. The UK government lists it as operational in its register of power stations (DUKES table 5.11, May 2025).
- Wales
- Commissioned 1984
Key facts
- Installed capacity
- 1,800 MW
- Status
- Operational
- Technology
- Pumped-storage
- Operator
- Engie Power
- Region
- Wales
- Country
- Wales
- Coordinates
- 53.1186, -4.1023
- Commissioned
- 1984
- Turbines
- 6
- Response time seconds
- 16
- Head metres
- 600
- Upper reservoir
- Marchlyn Mawr
- Lower reservoir
- Llyn Peris
- Storage hours
- 6
Location
Map position from the published coordinates. For small sites this can be an approximate point rather than the exact boundary. Map Β© OpenStreetMap contributors.
How Dinorwig Power Station compares
Pumped-storage stations work like giant batteries: they pump water uphill into a reservoir when electricity is cheap or plentiful and release it through turbines when demand is high.
All UK hydro schemes and pumped-storage stations Hydro schemes and pumped-storage stations in Wales All run by Engie PowerAbout Dinorwig Power Station
History
Built between 1974 and 1984 inside the disused Dinorwic slate quarry, it took ten years and ten million tonnes of excavation. The station uses two reservoirs β Marchlyn Mawr above and Llyn Peris below β with a 600m head. At the time it was the largest civil engineering project ever undertaken by the UK government.
Did you know?
- Cavern hall is 180m long and 60m high β taller than St Paul's Cathedral dome
- Used to stabilise the grid during TV ad breaks
- Contains 16km of underground tunnels
- Can power 2.5 million homes for 6 hours
Nearby generating sites
- Cwm Dyli Β· 9.9 MW hydroelectric station1.5 km
- Parciau Β· 12.7 MW solar farm10.6 km
- Garnedd Β· 0.56 MW small hydro scheme12.4 km
- Croesor Β· 0.51 MW small hydro scheme15.0 km
- Ffestiniog Power Station Β· 360 MW pumped-storage station17.7 km
- High Head Β· 17 MW hydroelectric station19.1 km
- Low Head Β· 15 MW hydroelectric station19.1 km
- Dulyn Β· 0.51 MW small hydro scheme20.1 km
Also operated by Engie Power
Engie Power operates 11 sites in the register. Largest first:
- Ffestiniog Power Station Β· pumped-storage station360 MW
- Scotia Wind (Craigengelt) Ltd Β· onshore wind farm20 MW
- Sober Hill Wind Farm Ltd Β· onshore wind farm12.3 MW
- Blantyre Muir Wind Energy Ltd Β· onshore wind farm12.3 MW
- Cairnborrow Wind Energy Ltd Β· onshore wind farm10.3 MW
- Barlockhart Moor Wind Energy Ltd Β· onshore wind farm8.2 MW
- Carsington Wind Energy Ltd Β· onshore wind farm8.2 MW
- Flimby Wind Energy Ltd Β· onshore wind farm6.15 MW
Planning history
From the government's Renewable Energy Planning Database (REPD), matched to this site by location, capacity and name.
- Planning status
- Operational
- Site name in planning record
- Dinorwig
- Developer / operator
- First Hydro Company
- Planning authority
- Gwynedd
- Construction started
- 1 January 1978
- Began operating
- 1 January 1983
- Capacity in planning record
- 1,728 MW
- Address
- Snowdonia, Conwy, LL55 4TY
- REPD reference
- 6839
Source
Department for Energy Security and Net Zero (DESNZ), Digest of UK Energy Statistics (DUKES), table 5.11: power stations in the United Kingdom.
Capacity is installed capacity as published, not current output. Status reflects the source date, not live operation.
View the original source
Last checked by Octary: 15 July 2026
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