On 15 September 2022, Ethereum transitioned its consensus mechanism from proof-of-work (PoW) to proof-of-stake (PoS) in an upgrade process known as "the Merge". Consequently, Ethereum's energy consumption rate was reduced by about 99.95%, translating to an estimated 110 TWh of annual energy savings (110 billion kilowatt-hours). The upgrade requires no actions from Ethereum's users. During the Merge, Ethereum's proof-of-work mining mechanism was replaced with the Beacon Chain, a proof-of-stake blockchain network secured by validators staking ether.
