Chapter I - Energy Needs—Energy Sources

Abstract

This chapter briefly surveys the elements that make up the “energy crisis.” It illustrates various “non-conventional” energy sources proposed for the future: biological, wind, wave and solar. There is a large number of energy sources available on Earth; these sources of energy available to mankind on this planet are commonly divided into two broad categories: energy capital sources—that is, those sources of energy that, once used, cannot be replaced on any time scale less than millions of years; and energy income sources—that is, those sources of energy that are more or less continuously refreshed (by nature or by man assisting nature) and that may be considered to be available, at potentially their current levels of supply, for millions of years. The work discussed in the chapter mainly includes the theory, design and operation of solar cells. In discussing solar energy, the option of using ground-based solar energy collection systems or some type of solar energy collection system that is operated in space must be considered. Solar thermal-electric converters (STECs) and thermoelectric devices, both of which generate electrical energy from sunlight, using heat energy have also been considered as an intermediate step. Both of these systems utilize solar tracking mirror (or lens) optical subsystems for concentrating the relatively weak solar energy.