Breakthrough for superefficient conversion of heat to electricity
Date: Monday, February 11, 2013 @ 11:28:46 GMT
Topic: Science


Via Nextbigfuture.com: Arxiv - Thermionics (electronics for converting heat to electricity) previously had efficiency limitations due to “space current” – build-ups of electrons mutually repelling each other and choking the flow of current – so the new system uses external electric or magnetic fields to get the electrons going in the right direction. The system promises a high fraction of the Carnot Limit can be converted directly into electrical power.

See also: Power from Heat… High-Efficiency Thermoelectronic Converters


...Turning a source of heat – such as concentrated sunlight – into useful power (say, electrical power) is not an easy proposition. There’s a dizzying array of options – thermal engines using different thermodynamic cycles, photovoltaic arrays, thermoelectrics and thermionic conversion. The last was used extensively in early space power generators using small reactors or radioisotope heat sources, but left behind by thermoelectrics and Stirling cycle free-piston systems in more recent work. Now a new approach to “thermionic” conversion, focussing on electrons (thus thermoelectronic), has shown promising behaviour in experiments and out-standing performance in theory.

Highly-Efficient Thermoelectronic Conversion of Solar Energy and Heat into Electric Power

Abstract: Electric power may, in principle, be generated in a highly efficient manner from heat created by focused solar irradiation, chemical combustion, or nuclear decay by means of thermionic energy conversion. As the conversion efficiency of the thermionic process tends to be degraded by electron space charges, the efficiencies of thermionic generators have amounted to only a fraction of those fundamentally possible. We show that this space-charge problem can be resolved by shaping the electric potential distribution of the converter such that the static electron space-charge clouds are transformed into an output current. Although the technical development of practical generators will require further substantial efforts, we conclude that a highly efficient transformation of heat to electric power may well be achieved.







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