Since the beginning of the Industrial Revolution, the question of the future of energy supplies has been of interest. In 1865, William Stanley Jevons published "The Coal Question" in which he saw that the reserves of coal were being depleted and that oil was an ineffective replacement. In 1914, U.S. Bureau of Mines stated that the total production was . In 1956, Geophysicist M. King Hubbert deduces that U.S. oil production would peak between 1965 and 1970 and that oil production will peak "within half a century" on the basis of 1956 data. In 1989, predicted peak by Colin Campbell In 2004, OPEC estimated, with substantial investments, it would nearly double oil output by 2025