£1bn plan to double output of Scotland’s ‘Hollow Mountain’

By Ian Fraser

Published: The Herald

Date: 11 February 2014

Picture: The Herald

Picture: The Herald

Up to 1000 jobs could be created as part of a £1 billion plan to double the amount of electricity that can be produced from a hydroelectric scheme half a mile underneath a Scottish mountain.

The Cruachan pumped storage facility on Ben Cruachan, east of Oban in Argyll, is known as the “Hollow Mountain” and operates in a gigantic man-made cavern. But the site’s capacity could be more than doubled if plans being considered by ScottishPower to construct a second huge cavern in the mountain go ahead. Up to 1000 jobs would be created at the height of the 10-year construction phase.

The Cruachan pumped storage hydro-electric scheme has a capacity of 440 megawatt but this could rise to over 1000 MW if Scottish Power’s plans go ahead. That is just under half the capacity of the company’s largest generating asset, the 2,400 MW Longannet coal-fired power station in Fife. The firm’s largest wind farm in Scotland is the 540 MW Whitelee near Glasgow. Scottish Power, owned since 2006 by Spanish energy giant Iberdrola, has identified a need for more pumped storage capacity Scotland in order to “store” the excess output from renewable energy sources including wind power.

First Minister Alex Salmond, who was in Spain yesterday to visit Iberdrola’s recently upgraded La Muela pumped storage plant near Valencia, said: “This major announcement heralds a renaissance in hydro and pump storage energy, and opens another chapter in our outstanding history of harnessing renewables. The Scottish Government recognises the potential for future development at Cruachan and other similar proposals for hydroelectric storage to contribute to a balanced mix of energy generation across Scotland. This could see hydro power generate up to one third of Scotland’s entire generating capacity in the next decade.

The plans under consideration would involve the construction of a second, cavernous, subterranean turbine hall underneath the 1,126m (3,694 foot) Ben Cruachan, adjacent to the company’s existing turbine hall, which was opened bv the Queen in 1965. They would also see the enlargement or reconstruction of the existing Cruachan dam, 396 metres above Loch Awe, to give the enlarged scheme sufficient water capacity in its upper reservoir, as well as a series of new tunnels enabling thousands of gallons of water to surge up and down between the two lochs. If it goes ahead the project would become one of the UK’s largest ever civil engineering projects.

Last October Scottish Power’s parent company Iberdrola completed a seven-year €1.2 billion project to double the capacity of its largest pumped storage scheme, with the construction of new turbine hall and the installation of four new turbines at La Muela, near Valancia. The capacity of La Muela, originally opened in 1989, was increased to 1,800 megawatts – meaning it surpassed the 1,728 MW Dinorwig facility in North Wales as Europe’s largest pumped storage scheme. Ignacio Galan, Chairman of Iberdrola and ScottishPower, said: “The project to double the capacity of La Muela plant was a major engineering achievement  …. We see a new generation of pump storage hydro as being a major asset for electricity systems worldwide as more renewable electricity continues to come on stream.”

The reversible turbines at Cruachan, originally built in 1959-65, use cheap electricity during the night to pump water up from Loch Awe at the foot of the mountain to the upper reservoir above, in readiness for driving the turbines to meet peak electricity demand next day. Pumped storage technology was first adopted after world war two, as it enabled  power firms to make use of the output of nuclear power stations at times of low energy demand. Increased reliance on renewable energy – whose output fluctuates with the weather – has once again increased its relevance of such plants and is giving rise to a new dawn for hydro power.

Scottish Power’s multi-year feasibility study will include consultation with interested parties, including Argyll & Bute Council, consumer groups and environmental NGOs. Scottish Power chief corporate officer Keith Anderson said: “We’ve already had initial discussions with one or two environmental groups. However, we believe in being open with all local community and stakeholder groups, which is why we’re announcing this today. We expect the feasibility study to take between 12 and 18 months. This is a major infrastructure project in a competitive energy market. If it goes ahead, construction would probably take between five and six years.”  The scope for enlarging the current dam on Ben Cruachan and the reservoir behind it is expected to be a major focus.

Two months ago Scottish Power axed another major project it had for Argyll, the £5.4bn Argyll Array an offshore wind farm off the coast of Tiree. The company cited technical and environmental concerns including the presence of “a significant presence” of basking sharks in the area. A Scottish Power spokesman insisted the company remains committed to offshore wind projects in the UK — including the 389MW West of Duddon Sands wind farm in the Irish Sea, which is currently under construction.

In his book Sustainable Energy – Without The Hot Air, Professor David JC Mackay, Regius professor of engineering at Cambridge University and chief scientific advisor to the DECC, identified 13 locations in Scotland with potential for pumped storage, most of which had existing hydro-electric facilities. According to a research report for the Scottish government, Energy Storage and Management, published in November 2010, pumped storage is “the most suitable energy storage option available to Scotland.” The report added: “The economic appraisal of energy storage is challenging as limited data exists … [but] there is no real need to provide financial incentives for large-scale energy storage.”

Yesterday UK energy secretary Ed Davey slammed power companies including Centrica and Scottish Power, urging the energy regulator Ofgem to look into the profits they are making through the supply of gas to UK households.

An edited version of this article was published on page 5 of The Herald on 11 February 2014. The Herald also produced a handy graphic to explain how the Cruachan pumped storage facility works


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