Of the fossil fuels coal has long been assumed to be the most plentiful, even the most pessimistic forecasters having acknowledged a global lifetime of centuries for known reserves. The determination of the emerging giant economies of China and India and of the USA to fuel themselves through coal-burning seems inevitable if highly risky for the climate. But that depends on coal remaining the cheapest fuel, largely because of the sheer abundance of supplies. A recent commentary on coal (Heinberg, R. & Fridley, D. 2010. The end of cheap coal. Nature, v. 268, p. 367-369) suggests that there is a growing tendency for reserve estimates to decrease as geologists factor in practical restrictions – place, depth, seam thickness and quality – on feasibility under current mining conditions, instead of just looking at known masses of coal. Astonishingly, the end-19th century estimate of five thousand years of US coal supplies dropped to about 400 years by 1974 and is currently judged to be 240 years. China and India look likely to have less than 60 years-worth left. On top of that, the widely publicized turn to carbon capture and storage (CCS)for ‘clean-coal’ future supplies will inevitably drive-up prices of coal-fired energy. The two main factors in this remarkable transformation of ‘King Coal’ are fundamental economic forces in capitalism and the increasing refusal of miners to accept dangerous working conditions. The second is especially the case for China, where most coal is deep-mined; in the late 1990s it saw a drive to close down unsafe mines that caused production to fall, although it has greatly accelerated this century – further driving down coal’s lifetime there. It seems from this analysis that any realistic hope for a CCS-based coal economy, especially in China and India, depends on declining safety and environmental standards in their largely underground mines, which in turn depends on the highly unlikely willingness of their workforces to accept worse conditions.
Earth-logs 
Coal Reserves. I would like to point out that the rapid decrease of coal reserves is almost only caused by the increasingly strict definition of stockmarkets and technical societies of what exactly are “reserves”. As an example, let me cite below the example of the Australian JORC Code.
The true depletion of coal resources is minimal. May I explain?
Mineral resources as opposed to reserves are unknown or little known, or known but not economically recoverable at present conditions. They are Earth’s vast endowment, out of which reserves are defined by investing in exploration and evaluation. The heavy investment required for reserve definition (“assessments and studies” of the Code, typically many hundred thousands to a few billion Dollars for a large mine) explains why dividing mineral reserves by yearly production nearly always results in a “life-time” of 20-40 years. BUT the 20-40 years are NOT the end of the availability of a metal or mineral. They simply mark the length of time for which reserves must be assured in order to support the commitment of funds for a mining investment. Or in other words, reserves are the security for banks providing credits and for investors buying shares in a mining company.
Speculations about the end of certain metals, minerals or energy were always popular – remember the revered Club of Rome’s prediction (ca. 1970) that in the 1990s, the world would run out of many essential mineral resources. When these years arrived, the general public and the media did not even notice that humanity escaped that dire fate although 20 years earlier nobody had any doubt about the imminent catastrophy.
There may be every reason to avoid burning coal, but physical availability is not one of them.
Walter L. Pohl, 5 February 2011
The JORC Code, Australasian Code for Reporting of Identified Mineral Resources and Ore Reserves, was established as a joint initiative of The AusIMM, the Minerals Council of Australia and the Australian Institute of Geoscientists.
Click to access jorc2004print_v2.pdf
Page 10: An ‘Ore (or Coal) Reserve’ is the economically mineable part of a Measured and/or Indicated Mineral Resource… Appropriate assessments and studies have been carried out, and include consideration of and modification by realistically assumed mining, metallurgical, economic, marketing, legal, environmental, social and governmental factors. These assessments demonstrate at the time of reporting that extraction could reasonably be justified.
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