[en] Although it is quite certain that all our efforts should aim at developing all possible energy sources, it is equally true that fossil and nuclear fuels - and to a lesser extent hydroelectric power - are the sole options of importance open to mankind for the rest of this century and perhaps even after that. This does not, of course, preclude the possibility, in highly specific local situations, of resorting to solar energy or using biomass, but it will not be possible, on a global scale, for these energy forms to play a major part in the world's energy balance during this century. Within the context of each country, whether one that is already highly industrialised or one still developing, the implementation of an energy plan should enable it to gain a better idea of future needs and to determine the technical options that will best meet those requirements, bearing in mind the natural constraints imposed by the country's resources, industrial infrastructure, available manpower and, it goes without saying, financial capacity