Efficiency in energy may be one thing but the eventual factor will be cost.
In the end, miners will find a new equilibrium between hardware and electricity costs on the one hand, and block rewards on the other hand. If hardware becomes more efficient, they'll buy more hardware and consume more power again. And if they don't do it, someone else will.
The only way to really use less energy, is if the mining hardware is so much more expensive that it takes a larger share of the total costs, which leaves less money to be spend on electricity. But I wouldn't be surprised if most of the energy savings are consumed again by the hardware manufacturer. It's not as if CPU production doesn't consume a lot of energy!
I was thinking about that economical aspect of mining ...
I wonder if mining is a zero-sun game, (like trading) where you just need to beat others miners to stay on step ahead
Regards to the technical electricity consumption I also wondering if there is something regards to parallelism ..
something like ..
"As processor chips become increasingly parallel, an efficient communication substrate is critical for meeting performance and energy targets. In this work, we target the root cause of network energy consumption through techniques that reduce link and router-level switching activity. We specifically focus on memory subsystem traffic, as it comprises the bulk of NoC load in a CMP."
http://ieeexplore.ieee.org/document/5948569/?reload=trueps-> I remember to heard a debate between "makers Vs coders" regards programmers do not know how to parallel
and we used to see memes like ..
CPU Dance
https://www.youtube.com/watch?v=MNhubpzhs-Q