Oil as a General Fuel
B y any measure we can apply, the world is now becoming rapidly more dependent on oil and natural gas, the petroleum fuels. During the sixties, for the first time in history, man will begin to get more heat and mechanical energy from petroleum than from any other fuel. Before 1970, petroleum may be supplying more of the world's supplies of commercial energy than all other fuels put together. For something approaching a century, in these senses, coal has been the world's dominant fuel; but now the balance is tipping over.
These are broad statements; but it is only broadly that any statement about the quantities of energy consumed right across the world can pretend to be true, and historically the perspectives are even more blurred. For large parts of the world no figures exist, reliable or unreliable; and where any figures do exist, they vary enormously in scope and quality. Fortunately for this kind of figuring, most of the areas for which statistics are entirely lacking are places where people use little fuel or at least buy practically none, relying mainly on wood and farm wastes. Statisticians generally find it convenient to exclude these fuels from their figuring as 'non-commercial'. They are still burned in huge quantities: as recently as 1875, for example, three-quarters of the fuel consumed in the United States is reckoned to have been wood, and today some guesses would still put the contribution of such fuels to total energy consumption in the world as high as a sixth.
But under the heading of 'commercial energy', then, the statisticians rank only the fuels supplied for sale in response to a defined market demand -- coal and other solid fuels such as lignite; petroleum, liquid and in the form of gas; hydro-electricity; and nuclear electricity, though production of this new 'primary fuel' is so far too miniscule to show at all on any graph of world supplies. During 1961, the world appears to have burned, either as raw fuel or in secondary forms, the equivalent of about 4,550 million tons of coal. Of this total, coal and lignite