You have been confused by unclear reporting. The way the Ethereum blockchain works has been altered.
The old method was "proof of work" where you needed to expend a lot of computing power (and thus electricity) to add transactions to the Ethereum blockchain, and got rewarded for that with new "coins".
The new method is "proof of stake" when you need to show that you have a bunch of the right kind of coins already, and someone with a stake is "randomly" selected to add transactions to the Ethereum blockchain. I put the scare quotes around "randomly" because it seems to me that the large centralised Ethereum operators might be able to cheat.
Wasting a lot of energy was absolutely necessary to make the old Ethereum blockchain work. That wastage is no longer required for that particular blockchain. The wastage is still required for every other proof-of-work blockchain. Expect to see blockchain promotors claiming that since Ethereum transitioned, blockchains are no longer wasting energy. This is false: Bitcoin is wasting just as much as before.