Global Coal Supplies: It Might Be Worse Than Anyone Thinks - Scitizen: "A new study on global coal supplies suggests a worldwide peak in production from existing fields in 2011.
Claims that the world has 200 to 400 years of coal left at current rates of consumption have blinded policymakers and the public. The claims are based on two questionable notions: 1) That official coal reserve estimates are accurate and 2) that the world will experience no growth in the rate of consumption of coal over the period cited.
In a new study published in the international journal Energy researchers Tadeusz W. Patzek and Gregory D. Croft suggest that actual historical coal production is a better indicator of the future trend of worldwide coal output than stated reserves which are notoriously unreliable. They note, for example, that the state of Illinois, despite its rank as second in reserves in the United States, has seen its production decline by half over the last 20 years. In the meantime Illinois' estimated recoverable reserves have actually increased from 32 billion tons to 34 billion tons between 1987 and 2006.
They mention the work of David Rutledge at the California Institute of Technology who has detailed the sharp downward revisions in the official reserve estimates in recent decades and who believes ultimate production will fall far short of the current reserve estimates. The trajectory for reserves, Rutledge shows, has largely been down as planners include constraints both technical and practical such as coal in seams too thin to mine economically or the presence of a large city over a shallow coalfield. Rutledge also applies Hubbert Linearization to the production data to obtain a truly startling picture of ultimate future recoveries: 50 percent less than current forecasts..."