simple math
100e * 80j =8000
140e * 30j=3600
so we are using less energy than last year by more then 50%
It's not quite
that simple. Such a calculation would only be true if all miners upgraded all their mining rigs every time a new model was released, which is obviously not the case. The majority of mining is not done on the most latest tech, and most miners will continue to run their older models until they are no longer profitable.
However, for the time being, the principle holds true - miners are become more efficient faster than the hashrate is increasing, so over time, electricity requirement is decreasing rather than increasing. How long this will continue to be true for is impossible to say, as it depends both on the advancement of ASICs as well as the changing hashrate. However, even if electricity requirements do start increasing, over the next decade or so I would expect the carbon footprint of bitcoin to continue to decrease as the minority of miners who are not yet using renewable sources make the switch.
