Hm, seems to contradict this: https://en.wikipedia.org/wiki/World_energy_consumption
Here I see energy consumption going straight up.
It leaves me wondering if the book (which I admittedly won't be reading; my existing reading list is already long enough) ends up functioning a bit like that satirical paper on smoking and long distance running from 10 years back. In it, the authors "convincingly" argued that marathon runners should all be smokers. The overall structure was a sort of numeric Gish Gallop: the paper focused on a constellation of individual measurements that are plausibly associated with both smoking and long distance running performance, while carefully steering clear of any measurement of smokers' actual athletic performance.