I see PoW more as a stepping stone to bootstrap a crypto currency, and I think it might just go away over time.
Ethereum has done it this way:
First you build a stable blockchain, secured through tremendous amounts of power.
Then, once your system has been widely adopted and people have "skin in the game", you switch to Proof of Stake to minimize power consumption while still maintaining security.
PoS is the better solution, environmentally speaking, but it necessarily depends on there already being value in the system that people can be held accountable with and thus kept honest. But to reach that state, people have to trust your system first, and if you're not an already trusted entity, PoW is one way of achieving that initial phase of trust building.
It's a huge incentive for more power, not for any particular kind of energy. In fact, the value of BTC is actually putting a floor on how efficient it is to close down a fossil-fuel plant.
Ethereum has done it this way: First you build a stable blockchain, secured through tremendous amounts of power. Then, once your system has been widely adopted and people have "skin in the game", you switch to Proof of Stake to minimize power consumption while still maintaining security.
PoS is the better solution, environmentally speaking, but it necessarily depends on there already being value in the system that people can be held accountable with and thus kept honest. But to reach that state, people have to trust your system first, and if you're not an already trusted entity, PoW is one way of achieving that initial phase of trust building.