The pump storage is not a mystery project.
It is a matter of economics, the power companies have a high cash
outlay in their equipment, remember electricity has to be produced
as you use it.
When the load varies equipment has to be cycled to follow it.
The large, base loaded plants are not designed for that.
So the power company maintains the load by pumping
water up to a reservoir on the off hours. When the load picks up in the
morning, when the toasters are plugged in, then they run the water from
the reservoir backwards through the pump using it as a turbine and run
the motor as a generator.
See http://www.tva.gov/orgs/hydro/what.htm
the plant illustrated is the TVA Raccoon Mountain Pumped-Storage
facility on the Tennessee River.
The cost as I remember was about 50% efficient, as a conventional steam
generating plant is about 33% efficient it can be a good economic
mix for a large utility.
Jim