Coire Glas pumped storage one step nearer

Scotland's largest ever hydro project has been given the go-ahead by the Highlands council. Natasha Wiseman reports on the proposed £800m scheme.

SSE Renewables has welcomed a decision by the Highland Council “to raise no objection” to the Coire Glas pumped storage hydroelectric scheme proposed for the Great Glen in Scotland.

The final decision on the proposal rests with Scottish Ministers, but as the scheme would be located in the Highlands, the local authority’s opinion is taken into consideration.

The scheme would be the largest hydro project to be built in Scotland and the first new pumped storage scheme to be developed in the UK since the Dinorwig scheme in North Wales, which began in 1974.

With a cost currently estimated at around £800m it would also be one of the largest construction projects in Scotland.

Some 24 objections were raised against the project. Environmental charity John Muir Trust, claimed the project could not be classed as a renewable scheme because it will use more energy to pump water uphill than will be produced. Pumped storage schemes involve two bodies of water at different heights.

During periods of low demand for power, electricity is used to pump water from the lower loch to the upper reservoir.

The water is released to create energy at a time when demand is high. A key advantage of developing a pumped storage scheme at Coire Glas is the site’s proximity to a large lower reservoir, Loch Lochy.

The proposed scheme involves constructing a dam and the creation of a new reservoir formed at Loch a’ Choire Ghlais. Water will be transferred between the new reservoir and an underground cavern power station via a headrace tunnel; and between the power station and Loch Lochy via a tailrace tunnel.

Colin Nicol, SSE’s director of onshore renewables, said, “We welcome the news that the Highland Council South Planning Committee has unanimously agreed to raise no objection to our proposal for Coire Glas. The report presented to the committee recognises that the scheme would be of overall benefit to the Highlands.

“We believe it would also make a valuable contribution to meeting our future energy needs by allowing surplus energy to be stored and made available at times of high demand. A project of this scale would bring significant positive benefits to the communities which surround it and we are committed to maximising these benefits to the local communities, businesses and suppliers should the scheme be consented by Ministers.”

SSE had originally developed three principal options: a 60MW scheme as part of its 152MW Sloy conventional hydroelectric power station; a scheme of up to 600MW at Balmacaan, near Loch Ness and a scheme of up to 600MW at Coire Glas, near Loch Lochy.

The company has decided not to proceed with the Sloy scheme in case it should jeopardise the operational effectiveness of the existing power station and it has decided that it should seek to build only one of the pumped storage schemes in the Great Glen.

In October 2012, the Highland Council confirmed it had no objections to the development of the Coire Glas scheme, which will now be determined by the Scottish Ministers.

SSE has concluded that Coire Glas is its preferred option for pumped storage development.

A decision on whether to construct Coire Glas will not be taken before 2014 and construction is expected to take five years.

Technology focus: pumped storage

A pumped storage scheme is, in effect, a large storage battery consisting of two bodies of water reservoirs at different heights. During periods of low demand for power, surplus electricity is used to pump water from the lower reservoir to the upper reservoir.

During periods of high electrical demand, the stored water is released through turbines to generate energy when it is needed. As more wind farms are constructed it is anticipated that there will be periods when the energy generated will exceed demand (for example, when the wind is blowing across a wide area of the country) and this will be wasted unless it can be stored.

A pumped storage scheme can use this energy to pump water from the lower reservoir to the upper reservoir, ready to be used for generation at times of high demand. Although no way of storing electricity is 100% efficient, SSE says pumped storage has the highest efficiency of all the technologies currently available. It is the only one that can be deployed on a large scale.

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