Hydropower is an important but relatively small part of the renewable energy mix in Wales. The country’s mountainous terrain and high rainfall—especially in the north and mid-Wales regions—create good conditions for hydroelectric generation. Here is a clear overview.
Overall hydropower capacity in Wales
- Total installed capacity: about 170 MW across roughly 380 hydropower sites.
- Annual generation: around 330–350 GWh of electricity.
- This is enough to power tens of thousands of homes each year.
Most of the hydropower capacity is concentrated in North Wales and Mid Wales, where mountainous areas such as Snowdonia (Eryri) and the Cambrian Mountains provide strong river flows and elevation differences.
Types of hydropower in Wales
Wales uses two main types:
A. Conventional hydropower
- Water flows through turbines in rivers or dams to generate electricity.
- Usually small-scale schemes (<1 MW), often community or farm projects.
Example:
- Ystradffin Hydro (1.8 MW) on the River Towy, completed in 2020, generates about 8 GWh per year.
Many projects were built during the 2010s after the UK Feed-in Tariff incentive, leading to hundreds of micro-hydro installations.
B. Pumped-storage hydropower
This is different from normal hydro—it stores energy rather than relying on river flow.
Water is:
- Pumped uphill to a reservoir when electricity demand is low
- Released through turbines when demand is high
Major examples in Wales:
- Ffestiniog Power Station – about 360 MW capacity and one of the UK’s first pumped-storage plants (1963).
- Dinorwig Power Station – around 1.8 GW, one of Europe’s largest “grid battery” facilities used to stabilise the electricity system.
These plants can start generating power in seconds, helping balance wind and solar variability.
Geographic distribution
Hydropower is concentrated in a few regions:
- Gwynedd – highest number of projects (~60 MW capacity).
- Ceredigion – among the highest total capacity due to large plants.
Together these areas host over half of Wales’s hydro capacity.
Development trends
- Most large hydropower stations were built between 1924 and 1989.
- New development today is mostly micro-hydro (<1 MW) projects.
- Very few large new dams are being built because of environmental constraints and cost.
Recent example:
- Bonwm community hydro project (0.1 MW) in North Wales to power ~130 homes.
Conclusion:
- ~170 MW total hydropower capacity in Wales
- ~330–350 GWh annual electricity generation
- Majority in North and Mid Wales
- Mix of small river hydro schemes and large pumped-storage plants used for grid balancing.