More coal gets extracted from the ground each year as measured in tons, but hasn the quality declined so much that net energy content is lower now than 10 years ago?
Powder River coal is lower energy density (sub-bituminous), but it’s sufficiently cheaper to mine that the difference doesn’t matter. Again, this is a purely economic shift from Illinois coal, which is higher energy density (bituminous). This shift has caused endless confusion to analysts unfamiliar with the coal industry (OTOH, people inside the industry understand this).
