Hydropower Scotland

Case Study:

The British Hydropower Association is the trade association for the UK hydropower industry. The BHA represents about 120 companies with a wide range of interests: consulting engineers, manufacture, design, investment and operations as well as specialist service providers (e.g. legal firms). Hydropower accounts for about 40% of electricity that is generated from renewable sources at present in the UK.

Overall description of organisation’s interaction with the water environment

Hydropower uses water to generate electricity in three main methods:

• Reservoir fed power plants. Storage hydropower plants involve a dam or weir across a valley or loch impounding a reservoir of water and enabling a regulated flow through turbines at the base of the dam or at a point lower down the valley. Storage hydropower plants in Scotland tend to be medium to small in output. Most of the storage plants in the UK are in Scotland. Storage schemes allow the energy to be generated when it is required and may be used to balance the intermittent output from wind and run of river hydro.

• Run-of-river plants. Run-of-river plants use the flow, or part of the flow, of a river. They often require a small barrage to regulate the flow. Overseas they can be large generators but in the UK they are small units many of which make use of existing structures, such as weirs for flood control or navigation or built on the site of disused water mills. There are many potential sites (possibly thousands) in the UK, particularly in England. The visual impact of run-of-river plant is lower when compared with the larger storage hydropower plants.

• Pumped-storage plants. Pumped storage hydropower comprises an upper storage reservoir and a lower storage reservoir connected by tunnels. In general, the greater the difference in elevation between the upper and lower reservoirs the more economical the scheme. It is the only proven technology for large-scale energy storage and could be used to store power generated by intermittant generators (such as wind) at times of low-demand for use when demand is high.

Excluding pumped storage, there is about 1,376MW of hydropower capacity generating over 40% of electricity from renewable resources. There is approximately 1, 274MW in Scotland. Additionally, there is 699MW in pumped-storage plants in Scotland out of a total of 2,787MW.

Context

The BHA has links to other trade associations active in electricity generation (e.g. the Association of Electricity Producers) or in renewable energy (Renewable Power Association).

Hydropower has a long history in Scotland where the first schemes were small schemes built by landowners building to provide power for their estates. The first public electricity supply scheme in Scotland began operations in 1890 by the extension to the villages of a private scheme built by the Benedictine monks at Fort Augusta Abbey and the first commercial hydropower scheme in the Highlands was developed by the British Aluminium Company (BAC) at the Falls of Foyers in 1896.

War, and the need for large amounts of aluminium in the defence industry, was the spur to expansion of the hydropower industry in the early part of the last century and in the inter-war years. In 1941 the Cooper Committee, appointed to investigate the potential for the development of hydropower in the Highlands, identified 102 potential schemes. The Hydro-Electric Development (Scotland) Act 1943 established the North of Scotland Hydro-Electric Board and the Board’s Development Plan, carried out between 1943 and 1965, saw the development of more than 1,000MW in seven schemes. By 1960 there were still 50 schemes left undeveloped out of the 102 the Cooper Committee had identified. In southern Scotland the 16MW Falls of Clyde run-of-river scheme was completed in 1927 and the 83MW Galloway scheme in 1936.

Pumped storage in Scotland has a long history too. The earliest recorded pumped storage scheme in Scotland was a small private power station built in the 1920s to power a textile mill at Walkerburn in the Borders. At the 399MW Cruachan pumped storage plant, 12% of generation is from natural flow and at the 300MW Foyers plant 30% is generated from natural flow. The Hunterston and Torness nuclear plants and the coal-fired plant at Longannet were the original, external sources of power at the Cruachan pumped storage plant. Both plants currently fulfil an important role in balancing the energy on the grid system. This role may become even more important with the increase of intermittent renewable sources.

There is potential to build an estimated 300MW–500MW of larger hydropower plant and there are former water mill sites, water utility and riverine structures that offer potential for small hydropower developments where the BHA believes there is potential to build an additional generating capacity of 250MW-500MW.

Aggregate use and values of water use

In general hydropower is a non-consumptive user of water but in many schemes there is transfer of water between catchments.

The direct benefit of hydropower is the generation of emissions-free electricity. The existing hydropower capacity in Scotland saves approximately 21,670 tonnes/year in greenhouse gas emissions. Development of 750MW-1,000MW of new hydropower plant would save an additional 11,800-15,750 tonnes/year and would have the potential to substitute for imported natural gas, contributing to energy security and a saving to the balance of payments in the future.

The main employment benefits from hydropower plants are at the time of construction. The operations of hydropower plants are often managed remotely, making operational costs low. There are indirect socio-economic benefits, e.g. through tourism and recreation.

Measures to improve water quality available to the hydropower sector

Apart from a slight almost immeasurable rise in temperature and aeration the quality of water passing through hydropower plants is virtually unchanged. Indeed there are good examples of hydro schemes being developed between upper and lower reservoirs providing drinking water to towns and cities without any deterioration in water quality. New developments in equipment design mean that oil-free operations are common protecting from accidental oil spillage or oil releases at maintenance. Hydropower plant operators take a range of measures to safeguard the general quality of the water environment such as maintaining minimum flows through channels beyond the point of diversion.

Range of potential costs

Construction of hydro stations can fall into various categories of cost but in general smaller developments can range in cost from £2,000-£3,000 per kilowatt installed compared to larger schemes which can be installed at a lower cost of between £1,500-£2,000 per kilowatt.

Range of potential benefits

Hydro can offer a number of potential benefits from its operation –

a) larger storage schemes can be used to balance the transmission system and can be turned on and off at short notice.

b) storage schemes in particular can assist in buffering the impacts from flooding by holding back flood waters and releasing them in a regulated manner.

c) new hydro developments, especially storage, can have the benefit of buffering against available output from wind schemes.

d) the major benefit in operating hydro schemes is reduction in greenhouse gas emissions compared to other forms of fossil fuel generation.

Other

1 Hydro has been criticised for its landscape and visual effects. Equally however, it can be argued that over time, with the restoration of vegetation and ground impacts, the hydro schemes themselves become a tourist attraction and can be quite pleasant from the visual impact.

2 There is no doubt that hydro, can have impacts on fish, invertebrates and other aquatic species however in economic terms the benefits from its development far outweigh the concern caused by its negative impacts.

3 Hydro is of course dependent on climatic considerations, especially rainfall and storage schemes are more efficient in availability compared to run of river schemes because of their ability to store water. This of itself can have other positive and negative environmental impacts.