📋 Project Overview
Ffestiniog is the world's first purpose-built pumped storage power station, opening in 1963 in Snowdonia. Built by the Central Electricity Generating Board (CEGB), it pioneered the concept of using off-peak electricity to pump water uphill, then generating when demand peaks. Its four 90 MW Francis reversible pump-turbines remain in operation over 60 years later. Today it is owned by First Hydro Company, an Engie subsidiary, and operates alongside the larger Dinorwig station in the Snowdonia pumped storage cluster.
Site Schematic
Schematic diagram — not to scale. Illustrative layout based on project specifications.
⚡ Key Facts
🔧 Technical Specifications
| Capacity (MW) | 360 MW |
| No. of turbines/units | 4 |
| Turbine / unit model | 4 × 90 MW Francis reversible pump-turbines |
| Unit capacity | 90 MW each |
| Upper reservoir | Llyn Stwlan (at 560m elevation, 2.2 million m³) |
| Lower reservoir | Tan-y-Grisiau reservoir (at 150m elevation) |
| Annual output | 830 GWh/year |
| Homes powered | 170,000 homes |
🔌 Grid Connection & Infrastructure
| Grid connection point | National Grid 400 kV via Pentir substation, Gwynedd |
| Voltage | 275 kV |
| CfD held | No (merchant / PPA) |
🏢 Development & Ownership
| Developer | First Hydro Company (Engie) |
| Owner / operator | First Hydro Company (a subsidiary of Engie) |
| Year consented | 1954 |
| Construction started | 1956 |
| Commissioned / target | 1963 |
| Location | Tanygrisiau, Gwynedd — Snowdonia, North Wales. Upper reservoir: Llyn Stwlan |
| Region | Gwynedd, Wales |
| Coordinates | 52.96°N, 3.97°W |
📅 Project Timeline
🌿 Environmental & Planning
Upper reservoir at Llyn Stwlan is within Snowdonia National Park. Environmental monitoring of Blaenau Ffestiniog area and visual impact management ongoing.