Energy and other resources

It is pointed out that inorganic mineral raw materials, usually called ores, do not form a separate geological class, with a strictly defined limit in quantity. The raw materials are in fact present in continuously variable concentrations and amounts with differing geographical distribution. It is only the richest occurrences which are regarded as resources and exploited. The cone concept of available material is presented, where the amount of material available increases as the work invested is increased, but the profitable ore is represented only by the apex of the cone. In applying this idea to fossil fuels the concept must be modified to a 'pear', since the energy invested in retrieving the fuel must not exceed the energy content of the fuel. Renewable energy sources are also discussed, and it is pointed out that geothermal energy should not be regarded as renewable. It is pointed out, too, that, unless breeder reactors are introduced, the fossil fuel resources will give more energy than uranium, and probably cheaper. (JIW)Ψ