Why not install heat pumps that line the tunnels and actually pay down the debt? Air conditioning the trains is hilarious to me. You could run these units when

Why not install heat pumps that line the tunnels and actually pay down the debt? Air conditioning the trains is hilarious to me. You could run these units whenever there is an excess of renewable generation on the grid. It's kind of like a battery. Clearly we can store a lot of energy down there for a really long time.