This is fascinating. So they are essentially harvesting the gravitational potential energy of the iron ore at altitude to charge the batteries (and then some) for the cargoless return trip. Outstanding.
https://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_...
> ... catastrophic failure of a triangular section of the reservoir wall and the release of 1 billion US gallons (3,800,000 m3) of water in 12 minutes. The sudden release sent a 20-foot (6.1 m) crest of water down the East Fork of the Black River.
> A broad swath of dense forest was washed away and scoured to bedrock by the escaping flow.
A tidbit that will be interesting to any programmer or engineer: one of the causes of the failure was that the high-water gauges were moved to above the height of the dam wall because someone was annoyed by false positives.
This is exactly the feeling I had when visiting the Seneca Pumped Storage Generating Station that I mentioned in one of my other comments that I just posted before seeing your post. Truly awe inspiring. (Links provided in my other comment). Do go visit one of these!
Hydro power storage is fantastic but needs truly ridiculous amounts of water and height deltas to make sense.
I got 450 kWh? Maybe you meant 1/2 MWh
A kitchen tap provides like what, 0.2 liters per second?
3.8Mg * G * 50m ~ 1700M Joules which is about 500kWh.
Energy is force times distance. You need to know more than just pressure to calculate energy.
(A bicycle tire at 120psi has a lot less energy than a truck tire at 90psi.)
there isn't much energy in a water tower. and that water is already doing work, pressurizing the water system.
And you have to maintain water in the tower in order to keep the water distribution system pressurized.