Water is often essential to mining as well. And part of the lingering issue with capped mines tends to be water infiltration, and run off into local waterways. So we’re often pumping shit around to keep them going/open. Or running water treatment, cisterns, reservoirs etc as part of restoration.
Which means some of them are already set up for pumped storage, many are well suited to it. And pumped storage could be combined with weighted storage as an integrated part of keeping shafts functional to drop weights up and down.
Some may even be suited to primary generation as hydro-eclectic plants, or very close to good sites for it.
Yeah, I agree. Aside from lithium batteries, the company I work for (Convergent E&P) also operates two flywheels. We have two site engineers employed full time just to fix bearings and vacuum pumps on 200 flyhweels at each site, which collectively can store 20MWh at each site. The mechanical storage has an advantage in that it has inertia which is great for system regulation, but otherwise these sites are a beating and I don’t think more of these will ever get built.
In theory a lot of these metals are going to get recovered and recycled; Tesla is working on this one right now. A 90kWh car pack uses 30kg of lithium, so say a 53’ container that starts at 5.5MWh is about 1833 kg of lithium. Some cells use cobalt also, but for stationary batteries we’re mostly moving towards lithium iron phosphate.
The BESS can also smooth out solar at the solar site, which in terms of variability is a good thing for the rest of the power grid. Our projects that are reaching completion now have a DC coupled battery into the same inverter as the solar we’re producing. That’s something no other storage can do right now.
We can deploy a 55MWh battery to smooth around 100MW of solar at about $200/kWh for the BESS itself and about $300 all in for the site - so that site is about $18m for the batteries, and not getting into augmentation that’s on average 85% of that capacity for 20 years. Give or take, we can build a kW of solar for $1. So the BESS that smooths a solar plant is about 1/5 its cost, but a BESS than can really dispatch a solar plant is more, we need at least 4 hours of storage, that’s about equal to the cost of the solar.
Blenheim Gilboa needed the hollowing out of an entire mountain. Taum Sauk, another pump hydro, needed 2.8 million cubic yards of concrete. I know lithium mining isn’t great… Taum Sauk was $45m in 1963, or $410m to build in 2017, but I don’t think that’s including the land costs - which are hundreds of acres. Anyway, that’s a cost of about $0.12/kWh which is only slightly better than current lithium ion, and when you factor in losing an additional 15% of the power you put though it, the pump hydro’s economics for storing renewables quickly die off… the one I worked at barely gets to operate these days.
Other than the fact that battery manufacturers already have their production lines set up to make lithium batteries for the consumer electronics and auto industries, there’s not really any reason that the lithium battery chemistry should be the one we use for stationary, large-scale installations. There are promising alternatives in development that can make use of more common elements:
