Hydro-electric power

Perth-based Scottish and Southern Energy is to develop Scotland’s first conventional large-scale hydro-electric power station for 50 years.

The new hydro-electric scheme is at Glendoe in the western end of the Monadhliath mountains, to the east of FortAugustus in Invernessshire. The power station itself, which will be built under ground, will be located close to the south east corner of Loch Ness.

With an installed capacity of around 100MW, Glendoe will be Scotland’s second largest conventional hydro-electric station and the first large-scale station to be built since 1957, when the Errochty station in Perthshire, which has a capacity of 75MW, was opened.

The power station will produce around 180 million units of electricity in a year of average rainfall. When synchronised, it will be able to start generating electricity at full capacity in 30 seconds and when operating at maximum capacity, Glendoe will be able to generate enough electricity to power almost 250,000 homes.

The scheme involves collecting water from around 75 square kilometres – either directly or via 8 km of underground tunnels – in a new reservoir over 600 metres above Loch Ness.

The drop from the reservoir to the turbine at the side of the loch – the ‘head’ – is, at over 600 metres, the biggest of any hydro station in the UK. The efficiency of a hydro station increases with the size of the head, which will make Glendoe the most efficient hydro scheme in the country.

The new reservoir will be situated at the head of Glen Tarff and will be impounded by a dam approximately 1,000 metres long.The dam will be shaped to suit the topography and geology of the area and will be 35m at its highest point.

The overall cost of the project is expected to be around £140m. Construction will start in the spring of 2006. Construction itself is likely to take around three years, followed by a period of commissioning which is expected to be completed towards the end of 2008. Up to 400 jobs are expected to be created during the construction phase.