How? mining new coins doesn't cost energy, preventing double-spends does. Premining wouldn't make any difference
Proof of stake or some other non proof of work consensus mechanism could reduce the energy usage
[1] https://blog.ethereum.org/2016/12/04/ethereum-research-updat...
Cardano Solana Polkadot Tron Avalanche
Ethereum is also on a roadmap to migrate to proof of stake
Oh wait, most mining operations are in the millions of dollars range, nevermind the fact that 84% of all BTC is held by .3% of addresses with > 100 BTC...
Both PoW and PoS have centralisation, but PoS vastly increases this centralisation, does it at a far faster rate, and "locks it in" (there is no feasible way to overcome the most powerful node in PoS, this is not the case thankfully in PoW)