Updated perspective on the potential for thermionic conversion to meet 21st Century energy needs

Thermionic conversion is unique amongst power conversion approaches in its ability to generate power efficiently with high temperature heat rejection. This feature has made thermionics an attractive choice for space power systems; and it has substantial potential for terrestrial advanced energy conversion, if certain recently identified technological developments are realized in a low cost manner. Thermionic energy converters are well suited to a modular approach. Thermionics is a passive system without moving parts. Recently it has been shown that close spaced thermionic converters can achieve the performance goals necessary to meet attractive new terrestrial power applications. The paper addresses the progress in this regard and describes approaches for engineering practical closed spaced converters for large scale applications. Clearly the potential for thermionic energy conversion is great. Every effort must now be made to use this technology to help solve the world's energy problems. Investments in the manufacturing infrastructure necessary to make thermionic energy conversion cost effective are needed to reach this goal.