How do you get the idea that we have any of that technology? Brains are nothing like computers and we have almost no technology that is like biology. There is no reason to be sure that we can just scale down the existing tech to arrive at something as efficient. Maybe we can. But if not then developing a system that‘s more like chemistry could take 50 years or 100 or more.
But humans are able to exercise a ton of thinking with remarkably low energy levels a day. And the calories of energy humans consume are also used primarily for physical mechanisms like movement, breathing, etc. so the energy requirements for pure thought is even less.
Why should improved AGIs in the future consume any more energy? Besides, AGIs across the world can communicate with each other. So once one AI computes something theoretically it should never need to do it again. It can tap into the answer saved by some different AI at some point in the recent past further reducing energy needs.
I really don’t see why AI energy consumption should be too high.