Still on the developers stand point,
I’ve come to understand that mining of Bitcoin have had a shift as per level of sophistication. From a time when all that was needed was just a device, a desktop was okay for the task and now, they’ve got sophisticated devices designed for the sole purpose of coming up with these calculations for block reward and confirmation of transactions. This is largely due to the design by Satoshi Nakamoto as per difficulty level and block reward after the halving.
It would be contributed by the competition as opposed to protocol design. Difficulty only rose when more miners with more resources entered the market. The market could've stayed in the CPU mining era, but GPUs, FPGAs and ASICs are just better. This is just a product of capitalism.
With the fact that, these devices are the ones using up these energy, wouldn’t it make more sense for the company behind these devices design it in such a way that, it’s able to use less energy or perhaps have some backup energy source to switch to remotely, creating a time out for conventional energy source like the fossil fuel.
Why would any miner want to buy a miner which performs less efficiently? There is no way to reduce energy without reducing hashrate, assuming each of them are performing at optimal efficiency. In addition, it is impossible for anyone to dictate what the miners should do.