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.
Reminds me of this dam operation around here that pumps water up to a mountain top reservoir during the day when power is cheap and then lets it go at night when it can generate and sell the electricity for more money. I was always in awe of the lake size battery they created.
> ... 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.
Taum Sauk is unusual in that the dam fully surrounds the upper reservoir (i.e. the lake was made from scratch), although certainly all types of dam can fail.
Pumped hydro is one of the cheapest ways to store electricity iff you have the topography available to create the uphill lake and plenty of water available to compensate for evaporation.
> I was always in awe of the lake size battery they created.
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!
So in an hour that's 36000L of water pumped up into the hypotheticals 1 million gallon tank. Right on the three orders of magnitude short that a previous commenter pointed out.
Right, but that's about maintaining pressure and supply when everyone wants a shower at the same time in the morning, not about harvesting the energy of it all flowing downhill.