When I put together a chart of per capita energy consumption since 1820 for a post back in 2012, there was a strange “flat spot” in the period between 1920 and 1940. When we look at the underlying data, we see that coal production was starting to decline in some of the major coal producing parts of the world at that time. From the point of view of people living at the time, the situation might have looked very much like peak energy consumption, at least on a per capita basis.
~ Gail Tverberg
One of my rules-of-thumb is to thoroughly read everything written my Gail Tverberg.
Years ago, I found a web site called The Oil Drum which was a collecton of superlative thinkers all writing about things related to petroleum. Actually, it still IS a superlative collection, because they’ve left it up as-is to be an archive.