Hydro power produces about 12% of Scotland’s electricity, with considerable potential remaining to introduce new hydro schemes and expand or improve the efficiency of existing facilities.
More than half of Scotland’s 145 hydroelectric schemes are in the Highlands and Islands area, with the most modern plants achieving energy conversion rates topping 90%.
Total hydro generation capacity in Scotland is about 1,500 megawatts (MW), a figure that was overtaken by the country’s faster-growing windpower capacity in 2009.
Though hydro’s once-rapid growth has slowed, new major development opportunities are in hand, and scope has been identified for thousands of smaller schemes.
Two large-scale new pumped storage schemes are being planned for the Great Glen area of the central Highlands by power generation, distribution and supply company Scottish and Southern Energy (SSE).
The plants, with a combined generation capacity of some 900MW, are planned for Coire Glas, north-west of Loch Lochy, and Balmacaan, near Invermoriston. They would be able to provide more than 1,000 gigawatt hours of electricity annually to help meet peak demands. With environmental impact investigations under way, SSE aim to submit planning applications in 2011.
They would be the first schemes developed in Britain for more than 35 years to use the pumped storage technique. During low power demand periods, water is pumped by electricity from a loch to an upper reservoir and is then released to generate power during high demand periods.
SSE already operates a 300MW pumped storage scheme at Foyers, on the south side of Loch Ness. In 2008, the company completed Britain's first large-scale conventional (non-pump storage) hydro electric station for more than 50 years; the £150m, 100MW Glendoe plant, near Fort Augustus.
Despite a widespread assumption in recent years that Scotland’s hydro-power development was at or near its limits, significant new potential has been identified to address Scotland’s sustainable power aims, and contribute to local community development needs, through small-scale hydroelectric schemes.
A report to the Scottish Government, published in January 2010, showed a substantial range of viably developable small hydro schemes with a combined potential capacity of 1, 204MW, sufficient to supply around 1million homes.
The study describes considerable untapped potential amongst more than 7,000 possible schemes, almost all of them smaller than 5MW capacity.
It sets out potential by Scottish localities, with the Highlands and Islands area accounting for a major proportion of the identified schemes. These imply significant skilled and semi-skilled employment in construction, maintenance and other areas, though development activity may be limited by factors including grid capacity, consents and licensing, and environmental constraints.
Forestry Commission Scotland (FCS), whose estate covers nearly 10% of Scotland, is seeking developers to create new run-of-river hydroelectric schemes. FCS considers that there is at least 50MW of potential at sites identified on their ground, much of this in the Highlands and Islands.
The Scottish Government has permitted other hydro projects within the Highlands and Islands, including: