Direct Energy Conversion Devices

A thermoelectric generator (TEG), also called a Seebeck generator, is a solid state device that converts heat (driven by temperature differences) directly into electrical energy through a phenomenon called the Seebeck effect (a form of thermoelectric effect).

A thermionic converter consists of a hot electrode which thermionically emits electrons over a potential energy barrier to a cooler electrode, producing a useful electric power output.

A magnetohydrodynamic generator (MHD generator) is a magnetohydrodynamic converter that transforms thermal energy and kinetic energy directly into electricity.

The Johnson thermoelectric energy converter (JTEC), also known as the Johnson thermo-electrochemical converter, is a solid-state heat engine that utilizes the electrochemical oxidation and reduction of hydrogen within a two-cell thermal cycle to approximate the thermodynamic Ericsson cycle.

A radioisotope thermoelectric generator (RTG, RITEG), or radioisotope power system (RPS), is a type of nuclear battery that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity by the Seebeck effect.

Thermophotovoltaic (TPV) energy conversion is a direct conversion process from heat to electricity via photons.

A betavoltaic device (betavoltaic cell or betavoltaic battery) is a type of nuclear battery that generates electric current from beta particles (electrons or positrons) emitted from a radioactive source, using semiconductor junctions.