> This would mean that we need reservoirs to be much larger than equivalent chemical batteries.
Yes we know. It is still cheaper on a cost-per-kwh basis than batteries, by a significant margin.
> I would love to see an analysis of whether it is feasible to build enough such large scale reservoirs (and how many we would need) to store an order one fraction of the daily energy needs. (at city/country/world levels)
No it is not, there are not enough suitable sites in most places in the world to make this work for world levels. That said, it is entirely up in the air if there would be enough mineable lithium to make batteries for similar amounts of storage.
Efficient electrical energy storage at scale is currently unsolved.
Yes we know. It is still cheaper on a cost-per-kwh basis than batteries, by a significant margin.
> I would love to see an analysis of whether it is feasible to build enough such large scale reservoirs (and how many we would need) to store an order one fraction of the daily energy needs. (at city/country/world levels)
No it is not, there are not enough suitable sites in most places in the world to make this work for world levels. That said, it is entirely up in the air if there would be enough mineable lithium to make batteries for similar amounts of storage.
Efficient electrical energy storage at scale is currently unsolved.