The Making Of A Pumped Hydro Water Battery In Switzerland – With Video

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The Nant de Drace pumped hydro facility, with a capacity to store 20 GWh of electricity, is now in operation high in the Swiss Alps near the border with France. For nearly 200 years, during the period we call the Industrial Revolution, we humans have been taking advantage of the energy stored in fossil fuels such as coal, oil, and gas to power our civilization. Those fuels resulted from the decomposition of trillions upon trillions of plants and animals — organisms that relied on sunlight for their existence.

When we burn them today, we release energy that has been sequestered for millions of years. That extra energy gets added to the solar energy that our planet receives from the sun every day. We humans have figured out a way of releasing millions of years of stored energy in less than two centuries and then wonder why our activity is disrupting the natural rhythms of the Earth. Well, duh, people!

Many wonder why publications like CleanTechnica are such gloomsters, always nattering on about climate change leading to an overheating planet that will no longer be able to support human life. They think we are making this stuff up just to garner some extra clicks on the internet. In truth, we are like canaries in the coal mine — harbingers of a calamity that will befall us all if we continue to act as though we are the masters of the Earth, when in fact it is the other way around.

Renewable Is A Matter Of Opinion

Coal, oil, and gas are renewable, if we are willing to wait millions of years for them. But if we want clean energy that does not disrupt the delicate balance of nature, we have no choice but to discover new ways of harvesting the nearly infinite power of the sun. Solar panels and wind turbines do precisely that. The problem is, they are intermittent whereas the society we have constructed demands instantaneous access to energy — particularly electricity — every second of every day. That means we need to figure out ways of storing some of that solar and wind power.

There are dozens of ways of doing that. We can make batteries to store some of that energy. We can fill train cars with rocks and haul them up mountains so they can generate electricity as they glide back down. We can pile massive concrete blocks on top of each other and use them to turn generators as they are lowered. Or we can fill large reservoirs with water when electricity is abundant and cheap so the water can flow downhill later, spinning giant electrical turbines as it goes.

Pumped Hydro 14 Years In The Making

That is precisely what a consortium led by electricity producer Alpiq and Swiss Federal Railways have done. After more than 14 years, the Nant de Drance pumped hydro installation is complete and in operation. “The output is more than 80% — for every kilowatt-hour of electricity used to pump the water upstream, 0.8 is fed into the grid,” explains Alain Sauthier, chief engineer and director of the Nant de Drance facility. “The electric storage capacity of the reservoir surpasses that of 400,000 electric car batteries.”

“In the future, it will be increasingly necessary to store large amounts of electricity, as renewable sources gradually replace nuclear and fossil energy,” Sauthier says. He adds that solar and wind power are volatile resources that do not necessarily generate electricity when it is needed, which is why systems such as this are so important. They can store energy and help keep the entire European electrical grid stable.

According to Swiss Info, since the project began more than 14 years ago, 18 kilometers of tunnels have been cut into the Valais Alps between the Emosson reservoir, an artificial lake built high in 1955, and the Vieux Emosson reservoir to the south. The Emosson has a capacity of 25 million cubic meters (about 6.5 trillion gallons). Here’s a time lapse video that shows the construction process.

Heavy vehicles used those tunnels to bring in all the material and equipment needed to complete the project, from prefabricated buildings with offices to ball valves weighing over 100 tons. The engine room at the heart of the system is 200 meters long, 32 meters wide, and 52 meters high — tall enough for the Eiffel Tower to fit inside. With a capacity of 900 megawatts, Nant de Drance is one of the most powerful generating plants in Europe.

Sauthier is especially proud of the 6 pumps/turbines, which are almost unique in the world in terms of their sheer size and the technology used. “In less than ten minutes, we can reverse the direction of rotation of the turbines and switch from electricity production to storage. Such flexibility is key in order to react promptly to the needs of the electricity grid and adapt electricity generation and consumption. Otherwise, you risk a collapse of the grid and blackout, as happened in Texas at the beginning of the year.”

pumped hydro turbine

Image credit: Nant de Drance / Sébastien Moret

Managing Demand In A Time Of War

The Nant de Drance facility has come online just in time to help Europe cope with the challenge of keeping the lights on without access to natural gas from Russia. Switzerland is planning a number of steps to lower the demand for electricity this winter. First the government will request voluntary conservation steps, then it plans to curb non-essential uses like illuminating shop windows, using mobile heaters, or other uses of nighttime lighting.

It is also asking people to curb the use of electricity to recharge their electric cars. If necessary, it could order as many as 30,000 companies to save up to 30% of their electricity usage and ask people to defer charging their electric cars. It is estimated that those three steps could cut power demand by up to 30%. As a last resort, the government could shut down parts of the electrical grid.

“You have to imagine this as a puzzle. Individual segments would be removed for four hours, then turned back on while others are removed. Some parts of the network — the pieces of the puzzle — would have no power for four hours, then have power again for four or eight hours again depending on the situation,” Michael Frank, director of the VSE association of Swiss electricity companies, tells Reuters.

616,000 Pumped Hydro Sites

According to Matthew Stocks of the Australian National University, there are 616,000 sites around the world where closed circuit pumped hydro facilities could be built. Building just 1% of them could solve all problems associated with the storage of intermittent energies based solely on geographical considerations, he says.

That is the ideal. The reality is that pumped hydro installations are typically located some distance from the places where most electricity is needed. That means there needs to be a high voltage transmission line linking them to population and commercial centers. Those links are quite expensive to construct and getting permission to connect them to the larger electrical grid can be a challenge.

According to the Washington Post, there are at least 930 gigawatts of clean energy capacity and 420 gigawatts of storage waiting to be built in America today. Many of those pending renewable energy and battery storage products can’t get connected to the electrical grid, so they aren’t getting built fast enough. “It’s a huge problem,” David Gahl, executive director of the Solar and Storage Industries Institute, says. “If we don’t make changes, we’re not going to meet state and federal targets for climate change.”

The Takeaway

All energy storage has advantages and disadvantages. Pumped hydro cannot provide the frequency and voltage stabilization services of a lithium-ion battery, but it can store energy for months or even years, something no ordinary battery can do, not even the ultra long lasting iron-air batteries from Form Energy. A conventional battery storage facility can be completed in a matter of months. Pumped hydro often takes more than a decade to bring online.

The genius of energy storage is in knowing which technology works best for each individual use case. Certainly there is a place in the arsenal of energy storage techniques for pumped hydro, and the Nant de Drace facility is already proving its worth, thanks to the vision of people who started thinking about building it almost two decades ago.


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