4 New Ways to Store Renewable Energy With Water - IEEE Spectrum

If Elon Musk has his way, in the future we'll all be storing renewable electricity inside big banks of lithium-ion batteries.  But let's not forget the energy storage situation today.  In the United States, 97 percent of utility-scale storage in 2014 was in pumped-storage hydroelectric plants, according to research by Oak Ridge National Laboratory, in Tennessee.

In traditional pumped hydro, a dam separates a lower reservoir from an upper reservoir.  When a utility company needs to store energy, the system pumps water from the bottom to the top.  It generates electricity when water flows back down through a turbine.  In 2015, Citibank estimated that the cost of power from pumped hydroelectric was about 5 percent of the cost of grid-scale battery-stored electricity.  The problem is that there are many places that "consume high amounts of power but don't have geological opportunities to build conventional pumped-storage plants," says Jochen Bard, an energy processing technology manager at the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES), in Germany.

In 2017, a number of new pumped-hydro technologies should achieve milestones.  They aim to bring the low cost of the technology to geographies that ordinarily wouldn't allow it. Here are four you might hear about:

The Concrete Bunker
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Compressed-Air Bags
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Energy Island
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Wind Turbines With Water Storage






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