Reserve power. Once this valley in western Ireland (left) is dammed (artist's rendition, right), stored seawater behind the dam will provide renewable power when it's needed for the U.K. electrical grid.

Igor Shvets

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Massive Energy Storage, Courtesy of West Ireland

VANCOUVER, CANADA—An Irish company has hatched an ambitious plan to dam five coastal valleys in the west of Ireland, use wind power to pump seawater behind the dams, and release it to create hydropower. The project, which could cost nearly $2 billion to construct, would create the largest water-powered energy-storage facility in the world, quadrupling Europe’s existing energy-storage capacity. It would generate three-quarters of the power of the Hoover Dam. That much power could help the United Kingdom slake its thirst for renewable energy while giving the west of Ireland a much-needed economic boost, the company’s founder announced here yesterday at the annual meeting of the American Association for the Advancement of Science (which publishes ScienceNOW).

Bigger and better forms of energy storage are needed if utility companies are to succeed in ramping up the portion of electricity produced from renewable sources such as wind and solar. That’s because the sun doesn’t always shine and the wind doesn’t always blow, so these companies need a way to store energy between when it’s produced and when it’s delivered as electricity. Such storage capacity is scarce on today’s power grid. Even Europe, with its push toward renewables, stores only 10% of the energy it produces, far too little to enable renewable energy sources such as wind and solar to smoothly replace fossil fuels.

The most common method of storing electricity, called water-powered energy storage, or simply pumped hydro, involves pumping water uphill from a lower lake to a lake about 100 meters uphill, storing it, and letting it run downhill to create power. But existing pumped hydro facilities are complex and expensive to build. They require constructing two reservoirs on impermeable ground in mountainous country that’s safe from large earthquakes. They also require pumps, tunnels, large-diameter pipes, high-voltage transmission lines, and more.

Around 2005, materials scientist Igor Shvets of Trinity College Dublin realized that nature had provided the coast of western Ireland with exactly the right conditions to combine large-scale wind energy and pumped hydro energy storage. Ireland’s wind is abundant and strong enough, particularly in the west, to supply as much energy as half of Iraq’s annual oil production. As for storing that energy, some 60 large, sparsely populated, glacial valleys lined with impermeable schist and basalt dotted 600 kilometers of the western Irish coast, and these valleys sit just above a steep drop-off to the ocean. All this means that on the coast of western Ireland, “90% of what you need for energy storage is already made for you by nature,” Shvets says.

Assuming they get the necessary permissions from Ireland’s government,, Shvets’s company, Natural Hydro Energy, plans within 5 years to dam five of those valleys, build large wind farms, and use wind energy to pump seawater from the ocean, creating lakes roughly 2 kilometers long and 2 kilometers across. And if they get the necessary permissions from the United Kingdom’s government, the company plans to lay high-voltage direct-current cable across Ireland and under the Irish Sea to supply power to the that country. Shvets and his colleagues have spent 3 years so far on detailed technical, economic, and environmental studies of potential valleys, and they’re in the process of raising €1.6 billion to finance the effort. And the facilities, and wind energy more generally, “could make a huge contribution to economic improvement in Ireland,” Shvets says.

Shvets’s proposal is technically feasible, says Robert Schainker, a senior technical executive at the Electric Power Research Institute in Palo Alto, California, but the prospects of the ambitious storage project, like those of other large energy installations, depend more on its economic viability. If the economics work, he concludes, “combining wind and large-scale pumped hydro is a very good idea.”

Full coverage of AAAS 2012