There is fundamentally no way to reduce bitcoin or blockchain energy consumption, it is the very thing which enables decentralized trustless transactions and the quality required implies a minimum power use. Everything else uses authority in one way or another, and is vulnerable in ways btc is not.

Reducing energy use for environmental reasons is ridiculous, the sun gives plenty of power and we have fissile materials to last for many millennia. The problem isn't power use, its power production, which requires global enforcement of carbon emission laws.