

The production of coal is directly related to the energy demand that is related to economic production. Another reason for the increase in coal production is an increase in the population. My two daughters are certainly using lots of electricity. Cold winters and hot summers are also important components in the overall coal demand. However, climate concerns and changing economics of cheap natural gas and increasingly cheaper renewable energy (initially wind and in the future solar) are having greater contributions and many older coal power plants (coal-fired utilities) are closing thus reducing the U.S. demand for coal. Some of the coal-plants generating electricity have also switched over to natural gas.

You should now be able to explain why this production (mining) of coal looks this way. The coal production typically rises due to economic growth, perhaps hot summers or cold winters. The dips are slow economic growth, mild summers/winters, with the overall decline being related to fuel switching to cheap natural gas for electricity generation and increasing renewables.
I expect most of you are familiar with coal, as most will have Pennsylvania ties. You are probably well aware that the number of mines and the number of coal miners has been dramatically reduced in the last 20 years. There are many good reasons for closing a mine: the coal might have been mined out, flooded, safety issues, switching to cleaner coal (lower sulfur coal) due to environmental regulations, and of course or cost issues. Cheap natural gas is the latest challenge along with increasingly stringent environmental regulations for coal mining and coal use.
We also tend to mine more of the lower Sulfur coal much of which is in Wyoming in the Powder River deposit, which has a significant impact on this region (we have higher sulfur coals) and where our coal comes from. Thus, due to environmental pressure (sulfur emissions), and changing economics (cheap shale gas) many coal mines have closed in Appalachia with significant losses of employment.

