Beauty spots under threat 

A call to build a series of dams to store power from wind farms could see parts of national parks being submerged

Britain’s last remaining wildernesses could be hit by a network of huge hydroelectric schemes, designed to store green energy from wind farms when power is plentiful, and release it when the wind fails, under proposals from a government scientist.

The schemes, which would see dams built in mountainous regions of Wales and Scotland, are being proposed by Professor David MacKay, chief scientist at the Department of Energy and Climate Change (DECC).

Speaking at the Institution of Mechanical Engineers (IME) last week, he suggested that several such “pumped storage” systems could be built around Snowdonia in Wales and up to 13 in Scotland. Most of the energy generated would be supplied to England.

The idea will infuriate environmentalists. MacKay has suggested some of the schemes could be built in national parks such as Loch Lomond.

The proposal’s attraction, however, is that it is a well-proven technology. Britain has four pumped storage systems, of which the best known is at Dinorwig, in Snowdonia.

It works by pumping 247m cubic feet of water from one reservoir into a second, 1,600ft higher up. When demand surges, this is released to generate hydroelectric power.

Last week’s meeting was private but MacKay has also set out his ideas in print, where he said the new schemes should be much bigger than Dinorwig. “We are interested in making much bigger storage systems . . . We have to imagine creating roughly 12 new sites, each storing 100 gigawatt hours – roughly 10 times the energy stored in Dinorwig,” he said.

Why might Britain need so many new dams? The answer lies partly in the unreliability of wind but also in the scale of Britain’s commitment to green energy. The government has said that by 2030 Britain should have about 8,000 wind turbines with a maximum power output of about 10 gigawatts – roughly an eighth of what the country currently needs at any one time.

The problem is that if wind becomes such a big part of Britain’s power supply, it will have to be backed up for times when winds fail. One answer would be to keep lots of fossil fuel power stations on standby. However, a much greener and perhaps cheaper alternative would be to store energy from low-carbon sources, such as wind or nuclear power, when they are producing a surplus, in pumped storage systems.

In the latest edition of his book Sustainable Energy, Without the Hot Air, MacKay says: “Certainly, we could build several more sites like Dinorwig alone.”;

In Scotland he suggests that a huge scheme could be built using Loch Sloy and Loch Lomond, which are already linked by a hydroelectric power system. This would involve raising Sloy’s existing dam by 130ft. He suggests the mountains could easily provide 10 sites for similar projects.

MacKay also proposes even more ambitious schemes. One would see dams constructed across the mouths of “hanging valleys” around Britain’s sea cliffs. These could then be filled with seawater. Another would see a huge chamber constructed three-quarters of a mile beneath London, with water generating power as it pours in from a ground-level reservoir then being pumped out when power is in surplus.

Tim Fox, head of energy and environment at the IME, said MacKay was forcing Ed Davey, the energy secretary, to confront uncomfortable issues surrounding the green energy agenda. “There has been a step change in the DECC understanding of engineering since MacKay arrived,” he said.

Craig Dyke, strategy development manager at National Grid, said the demand for power would increase sharply by 2030 under government plans to replace most petrol and diesel cars with electric ones by 2025, and to heat buildings with low-carbon electricity rather than gas. “We are going to see the demand for power varying a lot more than it does now, so energy storage systems will be important,” he said.

The idea that parts of Britain’s remaining countryside should be sacrificed to Britain’s power industry angers environmentalists. Helen McDade, head of policy at the John Muir Trust, which campaigns to protect Britain’s last wildernesses, said: “These new dams would just be storage systems for wind energy, which is itself inefficient and highly subsidised. This agenda is driven by energy companies who have become subsidy junkies.”