Concerning my remark that H2 can be made during off-peak times, Bernard
Cleyet said the French use gravitational PE to store energy during off
peak times.
Yes, we do this in the US also. I do not know how many places do this,
but one place is Grand Coulee Dam in the state of Washington. It's
worth the tour if you are ever in the area. There is also a good
website for it.
Yes, the generators and pumps are the same. Off-peak, some generators
are used as pumps to pump water to a higher reservoir. That water can
then be used for irrigation, domestic water supply, or it can go back
through the generator/pumps to make electricity during peak demand.
The problem is that this method of off-peak energy storage is only
feasible at a limited number of sites. It takes lots of water and the
right geography. Storage of energy as H2 takes much less water and no
particular geography (assuming the availability of some water).
Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Bluffton College
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu