Which is meaningless unless you believe that energy efficiency has only happened in the 2008-2018 period, which is not true. I happened to be working in the coal industry for most of that time and the decline isn't because people are using 40% less energy. It has nothing to do with increased efficiency. It has to do with:
1) Political action.
2) Alternative energy sources getting more competitive. Particularly natural gas, renewables and US shale oil.
You're arguing that use-of-energy efficiency can cause a decline in coal production. That is wrong; if you use energy more efficiently I'll mine more coal - I've met the people who make that sort of decision. Coal is declining for other reasons - mainly that alternative sources are getting cheaper (which is not using energy more efficiently).
I did not say that greater efficiency in coal use was the cause of US coal's decline. My last post was contra to:
Take a look at US coal production [0]. There is no evidence there that energy use from coal will decrease with improved technology.
There is ample evidence that improved technology is driving declines in American coal use/production. The combined cycle gas turbine made it possible to extract more electricity from a megajoule (thermal) of natural gas than a megajoule of coal. Hydraulic fracturing made natural gas cheap in the US. Improved technologies and economies of scale made wind and solar electricity more efficient and cheaper. These are all electricity production technologies. They are what what I had in mind with my up-thread Alice and Bob example. US electricity production is getting more efficient (more electricity per ton of material inputs consumed); Bob believes that any efficiency increase must be more-than-offset by increased electricity consumption, and exclaims "Jevons Paradox!" before even reviewing the numbers.
1) Political action.
2) Alternative energy sources getting more competitive. Particularly natural gas, renewables and US shale oil.
You're arguing that use-of-energy efficiency can cause a decline in coal production. That is wrong; if you use energy more efficiently I'll mine more coal - I've met the people who make that sort of decision. Coal is declining for other reasons - mainly that alternative sources are getting cheaper (which is not using energy more efficiently).