Chapter 4 - The Energy Conversion Processes

Abstract

This chapter focuses on several processes related to energy conversion. Man is capable of performing a number of energy conversion processes by means of various devices that can be classified according to the type of construction used, according to the underlying physical or chemical principle, or according to the forms of energy appearing before and after the action of the device. Conversion of radiant energy (light quanta) into electrical energy can be achieved with the use of semiconductor materials, for which the electron excitation caused by impinging light quanta has a strong, enhancing effect on the conductivity. Electrochemical energy conversion is the direct conversion of chemical energy into electrical power or vice versa. A device that converts chemical energy into electric energy is called a fuel cell. Conversion of solar energy to heat requires a light-absorbing material—a collector—that can distribute the absorbed radiant energy over internal degrees of freedom associated with kinetic energy of motion at the molecular level. Conversion of solar radiation into electric energy can also be achieved either in two steps: by converting radiation to heat, and then heat into electricity, or alternatively, by direct conversion of radiation into electricity, using the photovoltaic conversion scheme. Moreover, conversion of wind energy into linear motion of a body has been utilized extensively, particularly for transportation across water surfaces.