We will never have an energy surplus, because cheap enough energy will be used for cryptocurrency mining. It's like when we thought that the industrial revolution/productivity boom would lead to a four hour work week.
That's not unique to cryptocurrency mining, there are other things that are rate limited by energy costs as well.
But instead of meeting the demand for those other things, things we need like electric vehicles, we're just going to end up wasting it on cryptocurrency mining and end up right back at square one. I just don't see how Bitcoin is sustainable in it's current form.