[bobthepanda]

IIRC there are actually starting to be wind, solar and pumped hydro sited at former coal mines and plants because they already have transmission capacity. (In the case of pumped hydro, a coal mine can also act as a big hole with an elevation difference to drive a turbine.)

[syllablehq]

There's lots of exciting progress happening with underground mechanical storage like this. It's so interesting that the U.S. DOE has been studying underground pumped hydro since at least the 1980.(https://www.osti.gov/servlets/purl/6517343)

Today: - Hydrostor just signed a near $1 Billion contract to build their first underground facility in California using advanced compressed air with water to help efficiency. See also: Green Gravity, Gravitricity, Terrament, Renewell, RheEnergise, and more.

[kuchenbecker]

My comment is less about storage and more about the physics of the Grid (not an expert though so fact check me) It's largely one giant multitenant pool of both capacity and consumption with Voltage being the indicator.

Variable load sources often change transmission requirements on existing lines because there can be power draw increase between A and B where previous there was less generation at A.