It has a storage capacity of about 9.1GWh.
The upper reservoir (https://en.wikipedia.org/wiki/Marchlyn_Mawr) holds 9.2 million cubic meters of water.
So 1 million cubic meters of water provides ~1GWh.
We can see how that compares in terms of raw GPE (Gravitational Potential Energy):
1 million cubic meters of water = 1E6 * 1E3 kg = 1E9 kg
There's roughly a 500m vertical drop between the upper and lower takes at Dinorwig so:
1E9 kg * 500 m * 9.8 m/(s^2) = 4.9E12 J =~ 1.36GWh
As for water towers, if you look at something like the Roihuvuori tower in Helsinki (from https://en.wikipedia.org/wiki/Water_tower) which is one of the largest:
Height: 52m, Capacity: 12000 cubic meters
If we are generous and say that all of the water is stored at the maximum height then:
12000 * 1E3 kg * 52m * 9.8 m/(s^2) =~ 1.7MWh
You'd need over 5000 of them to match what Dinorwig can provide.
It has a storage capacity of about 9.1GWh.
The upper reservoir (https://en.wikipedia.org/wiki/Marchlyn_Mawr) holds 9.2 million cubic meters of water.
So 1 million cubic meters of water provides ~1GWh.
We can see how that compares in terms of raw GPE (Gravitational Potential Energy):
1 million cubic meters of water = 1E6 * 1E3 kg = 1E9 kg
There's roughly a 500m vertical drop between the upper and lower takes at Dinorwig so:
1E9 kg * 500 m * 9.8 m/(s^2) = 4.9E12 J =~ 1.36GWh
As for water towers, if you look at something like the Roihuvuori tower in Helsinki (from https://en.wikipedia.org/wiki/Water_tower) which is one of the largest:
Height: 52m, Capacity: 12000 cubic meters
If we are generous and say that all of the water is stored at the maximum height then:
12000 * 1E3 kg * 52m * 9.8 m/(s^2) =~ 1.7MWh
You'd need over 5000 of them to match what Dinorwig can provide.