Difference the power station has made

Dinorwig was built to provide rapid response to sudden demands for electricity. The power station also stores cheap energy produced at night for use during times of peak demand.

The station significantly reduced the need for other power plants to hold ‘spinning reserve’ – the extra generating capacity of stations connected to the grid.

Dinorwig helped improve the stability of power supply in the UK and made it less likely that a surge in demand could lead to power cuts.

How the power station was built

The scheme was constructed in the abandoned Dinorwig slate quarry. To preserve the landscape in Snowdonia National Park engineers built the power station itself inside the mountain Elidir Fawr.

Early stages of the project saw engineers making extensive improvements to local roads and nearby Bangor harbour to help move materials to the construction site.

Protecting the environment was a key part of the plan. Work included moving fish from Llyn Peris (the lower reservoir for the plant) to other lakes nearby. The project also collected spores from local heather so the mountain side could be replanted after building was finished.

Engineers had to excavate 12m tonnes of rock from inside the mountain to build the station. The tunnels they dug had to be wide enough for 2 lorries to pass comfortably.

The construction team had to connect Dinorwig to the National Grid substation at Pentir. Rather than using transmissions towers or pylons – and spoiling the local environment – they buried the cables underground in tunnels approximately 10km long.