By L. David Roper
One often reads and hears statements: “The United States has 250 years supply of coal,” “United States oil independence is no longer a joke” and “Shale gas could supply 100 years of consumption for the United States.”
I have done detailed depletion analyses of coal, crude oil and natural gas extraction for the United States and the world that clearly show that those optimistic statements are false. The results of the analyses can be seen at roperld.com/science/minerals/FossilFuelsDepletion.htm.
To be accurate about extraction of a fossil fuel from the Earth in the future, one must use a mathematical function that rises quickly, usually exponentially, then levels off to a peak and then falls, usually exponentially, either slower or faster than it rose. This is called a depletion curve. Until one does such a math analysis, one cannot make reasonable and valid statements about the future of extraction of a fossil fuel.
Roper is professor emeritus of physics at Virginia Tech. He lives in Blacksburg.