This Dutch Innovation May Solve The Energy Storage Problem
http://oilprice.com/Energy/Energy-General/This-Dutch-Innovation-May-Solve-The-Energy-Storage-Problem.html
I was half expecting to read a story about manufacturing giant flywheels . . . I wasn't too far off.
The energy return on investment for this boondoggle (hey, that word even sounds Dutch!) would be atrocious, especially the part where they have to lower a huge honking pump/generator and install it in blazing heat (apparently the Millenial kiddies doing the "engineering" on this think it will be nice and cool like a root cellar.
Far more efficient use of resources would be hydrolysis and fuel cell recombiners
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/electrol.html (http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/electrol.html)