Ethereum is planning a switch from Proof of Work (burning CPU/GPU/ASIC cycles to secure the chain), to Delegated (?) Proof of Stake - people lock away some of their ETH holdings, some of those people are random selected to validate a block. They attest which transactions are valid, and put them in a block. If they're judged to be honest/correct they're rewarded with ETH in proportion to their stake. If they're found to have broken the rules their stake is not returned, or only partially returned.

PoS has detractors/claimed flaws, but it is definitely much less energy intensive than PoW.