The reserves of fossil fuels are analysed and some of the methods being developed to improve the energy yield from existing reserves are looked at, including enhanced oil recovery and magnetohydrodynamics. Other sources of energy not relying on fossil fuels are considered. Some could be tapped immediately or with some straightforward development, e.g. nuclear fission, solar, tidal and wave power. A proposed 2MW French prototype solar power station under construction in the Pyrenees is described. Future large-scale production of power by deep gasification of coal and by nuclear fusion are discussed and their role as potential replacements for coal, gas and oil are considered.Based on a lecture to the Beds and Herts Section on 11th May 1978.