Coal and Other Fuels
Global data on coal reserves are squishier than for petroleum, also not not known for precision. Peak coal seems most immanent in China, which burns twice as much as the U.S. but has less than half the reserves. Rough estimates are that Chinese coal production will peak by 2020. China began net importing of coal in 2009.
The energy content of coal varies widely. Anthracite packs five times the energy density of low grade lignite. Since the richest coal is mined first, estimators figure that the global energy yield from coal may come within 20 years. After that we’ll mine more and more tons to get less heat because its overall energy yield (EROEI) will decline.
This assumes coal burning unimpeded by tighter limits on CO2 or impurities dumped in the air. If additional cleaning of the CO2 or air pollutants is mandated, energy yields will drop even faster.
Hydrofracking natural gas is now boosting American gas production, but peering into the future of gas as well as coal envisions issues of collateral damage and social protest when working difficult reserves. Recent public outcries are from mountaintop coal mining, alleged contamination of water by hydrofracking, and deep sea well blowouts.
The harder sources are to tap (lower energy yields), the more likely that people will protest disruption because it covers a wider swath and a denser population affects more people who can scream NIMBY.
The effects of slow degradation of EROEI are suggested by a graph.