Wind Energy Update has an article on Canadian pumped hydro energy storage storing American wind power - American wind to be stored in Canada.

A pair of utilities, Minnesota Power and Manitoba Hydro, have inked a Renewable Optimisation Agreement (ROA) under which electricity from excess wind produced in North Dakota can be stored in Manitoba’s hydro reservoir when loads and prices are low, with the potential for selling that power back onto the huge United States Midwest Independent Transmission System Operator (MISO) market at times when needs are high.

The deal involves the pair building a new 400 mile 500 kV transmission line, with a capacity of 750 megawatts, connecting northeastern Minnesota with Winnipeg, at a cost of $1bn split between the two utilities. ...

The province lies at the centre of a 400,000 square mile watershed that drains from the Rocky Mountains to the west and Lake Superior to the east. The Nelson River drains north to Hudson Bay with an average flow at the sea of 115,000 cubic feet per second - eight times that of the Colorado River.

Manitoba's 1,000 feet of hydro-electric potential remains only half developed and two new hydro projects with associated storage planned for the Nelson River has created the opportunity for further interconnecting the Manitoba battery to MISO.

Think Progress has an article on pumped hydro storage in the US - The Inside Story Of The World’s Biggest ‘Battery’ And The Future Of Renewable Energy.

The largest battery in the world has sat quietly in George Washington National Forest along the Virginia-West Virginia border for nearly 30 years. A five-hour drive from the nation’s capital, it sits in the middle of the Appalachians, tucked behind the Blue Ridge Mountains. ... The Bath County Hydro Pumped Storage Facility is not really a battery in the common sense of the term, but it is the largest pumped storage facility in the world. It stores a lot of energy, which helps 60 million people in 13 states (and DC) served by the regional transmission organization, PJM Interconnection. ...

Europe continues to invest heavily in pumped storage, with skyrocketing renewable output and decent capacity. There are 40 pumped storage facilities in the U.S., and Bath County is one of the youngest, even though it remains the largest in the world. Rocky Mountain Hydroelectric Plant in Georgia is the newest, commissioned in 1995. Development in the U.S. has been slow because the facilities are expensive, hard to site, and hard to build.

Reuters has a report on interest in using Norwegian hydro power for energy storage as part of a north sea supergrid - Norway hydro can aid Europe move to renewables: IEA

The International Energy Agency said Norwegian hydropower could provide the reliable base Europe needs to invest in solar, wind and other renewable energy forms and urged Norway to expand cable links to other countries.

"Norway can help Europe introduce more volatile renewable energy sources into the market by providing a sustainable backup," said Nobuo Tanaka, the agency's executive director, in an interview on Friday at a renewable energy conference. "To have more renewables, we need more interconnectivity." he said.

In particular, Tanaka threw his weight behind a proposal to lay two sea cables between Norway and the UK, which would let the UK draw on Norwegian hydropower when British windmills go still.

Norway's glacier lakes and roaring rivers already provide electricity for almost every household in the country as well as power companies in other Nordic countries and the Netherlands. When hydro capacity is low, Norway imports power from those same countries.

Christian Rynning-Toennesen, the chief executive officer of Statkraft, a state-owned company that operates more than 100 hydropower plants in Norway, called for the country to become the "battery of Europe."

Tanaka said he approved of the image. "Connecting Norwegian hydropower to the bigger European market would be far better than relying on gas for the same purpose," said Tanaka, whose Paris-based agency advises 28 member countries on energy issues.

Norway's minister of petroleum and energy, Terje Riis-Johansen, said he and the UK's minister of energy, Charles Hendry, agreed earlier this week to support an ongoing feasibility study of connecting the two countries by cable. "There is big interest in the UK in building cables from Norway," he told Reuters. "But we are having similar discussions with Germany and other countries. I think Norway's future in Europe is to be a peak producer that always has power stored. If we do that right, it can neutralize the bad aspect of big windmill projects, which is that their production is inconsistent."

The feasibility study of a 700-km dual-cable link between southwestern Norway and eastern England is to be completed within a few months, said Stewart Larque, a spokesman for the UK National Grid. ... The country is nearing completion of a subsea power link to the Netherlands and considering a second one to France. But Larque said the lure of carbon-free power from Norway is great.

The Statkraft CEO said the cost of a cable link, which is not known, would probably be born by its beneficiaries at both ends. "For the British it would cost a lot less than building new power plants as a back-up for wind," said Rynning-Toennesen.

Renewable Energy World reports on more energy storage being added to the European grid - 525-MW Austrian Pumped Storage Plant Opened.

The Kopswerk II pumped storage hydro plant in the Austrian state of Vorarlberg has been officially inaugurated. Capable of feeding up to 525 MW into the grid to serve peak load demand, or absorbing up to 450 MW of surplus energy from the grid, each of the plant's units consists of a Pelton turbine, a motor-generator, a starting converter, and a storage pump.

Kopswerk II uses separate machine sets with separate pumps and turbines rather than reversible pump-turbines and the machine sets are designed to operate with so-called short hydraulic circuits, where the storage pump and the turbine can operate simultaneously.