Power discharged underground? are the poles have battery slots on them? or Substations ONLY that require batteries to generate power.
or Steam Tanks to be fed to underground Broilers or Turbines. or to keep burner tech relevant underneath. Hopefully the Pollution doesn't migrate to the main map.

pollution does migrate to top.
Underground power transfer station transfer power between surfaces to to middle(connected accumulators)
Battery cell can be used to jumpstart areas, so for lower levels may be a case of transporting fluid and jumpstarting the base.

so poles from top can connect to poles underneath? has Accumulators have battery slots in them?

Underground power transfer station act like connected poles from one surface to other