Why do we need overhead power lines again? Distribute the generation of electricity (solar, fuel cell, wind) and connect it all via underground wiring.
Underground is harder, you have to dig up land every time you want to fix or replace something, this can be mitigated but it still isn't that great. More importantly in urban areas digging up land is really hard (sidewalks, roads, residences, buildings, water pipes, sewage systems...), not to mention the politics!