[SideburnsOfDoom]

> Cooling the stations is not an engineering challenge. Installing and operating huge chillers is a solved problem.

Not correct in context. You cannot successfully chill air without having a place to vent the resulting waste heat.

Where, in deep tube lines, to vent the waste heat, is _not_ a solved problem. It _is_ an unsolved engineering challenge.

The heat has been accumulating there for decades.

As detailed here

https://en.wikipedia.org/wiki/London_Underground_cooling

https://news.ycombinator.com/item?id=38364027

https://news.ycombinator.com/item?id=38363476

[NegativeLatency]

At a certain point it seems like there'd be enough stored energy to justify some heat pumps for nearby building heating.

[SideburnsOfDoom]

If that was easy, it would have happened already

https://news.ycombinator.com/item?id=38367176