Even with clean energy the amount of work put into creating that energy will be still a lot. Nuclear is another topic which we do not like to talk but honestly it is such a power that just one plant could give you enough energy to cover most of the underdeveloped world, I do not remember where I read it but if we had like 200 nuclear plants all over the world then we could have enough energy to cover all energy need ever.

We can move to clean afterwards but nuclear is technically "clean" energy as long as nothing bad happens. The only reason why it is not like is the risk of leakage and something like Chernobyl to happen. With just one nuclear plant we can literally cover ALL bitcoin mining operation electricity requirements and then some (a lot more) which is why if we want free bitcoin transactions we should totally focus on nuclear plants.