In article
,
Jim Wilkins wrote:

On Jan 14, 1:00*am, Andy Asberry wrote:

Maybe I didn't explain this well. There is NO storage. They are
pumping it in one end of a pipe and putting the generator on the other
end. Power used and power generated is at the same time. Stop the
pump/stops the generator....
Maybe they figure the pipe is a transmission line. Possibly it is
cheaper than hanging wires.

Maybe cheaper than acquiring a new right-of-way for a power line.
jw

Seems like ordinary, garden-variety, load balancing to me. Overbuild
for anticipated loads. During the times your load is minimal use some of
your capacity, while the generators are lightly loaded, to pump the
water to the source.

Next day, when the load is highest drop the water back through the
penstocks to ramp up the other generators.

Power is cheap in the wee hours, especially if you're your own customer,
and loads are light. Then you use the "banked" water to pick up the load
during the day when demand is high and you can charge more.

You have to keep a crew on duty all night anyway. Why not let them do
something useful and cost effective?