A Review on Thermoelectric Generators: Progress and Applications

Abstract

A thermoelectric effect is a physical phenomenon consisting of the direct conversion of heat into electrical energy (Seebeck effect) or inversely from electrical current into heat (Peltier effect) without moving mechanical parts. The low efficiency of thermoelectric devices has limited their applications to certain areas, such as refrigeration, heat recovery, power generation and renewable energy. However, for specific applications like space probes, laboratory equipment and medical applications, where cost and efficiency are not as important as availability, reliability and predictability, thermoelectricity offers noteworthy potential. The challenge of making thermoelectricity a future leader in waste heat recovery and renewable energy is intensified by the integration of nanotechnology. In this review, state-of-the-art thermoelectric generators, applications and recent progress are reported. Fundamental knowledge of the thermoelectric effect, basic laws, and parameters affecting the efficiency of conventional and new thermoelectric materials are discussed. The applications of thermoelectricity are grouped into three main domains. The first group deals with the use of heat emitted from a radioisotope to supply electricity to various devices. In this group, space exploration was the only application for which thermoelectricity was successful. In the second group, a natural heat source could prove useful for producing electricity, but as thermoelectricity is still at an initial phase because of low conversion efficiency, applications are still at laboratory level. The third group is progressing at a high speed, mainly because the investigations are funded by governments and/or car manufacturers, with the final aim of reducing vehicle fuel consumption and ultimately mitigating the effect of greenhouse gas emissions.

Doping Effect on Cu2Se Thermoelectric Performance: A Review

“…From Equation (1), ZT has a strong relationship with temperature T, thus, according to the optimum operating temperature, the thermoelectric materials are divided into three groups, which are: low temperature ( ) TE materials: Bi 2 Te 3 series; mid temperature ( ) TE materials represented by PbTe series; high temperature (>900 ) TE materials which are represented by SiGe series. These series of materials have already achieved high figure of merit (ZT) values, and are applied in some certain field [ 12 , 13 , 14 , 15 , 16 ]. For instance, SiGe and PbTe series of TE materials, using radioisotope as heat source, have been used in space domains.…”

Solid-state Thermoelectric Characteristics of NiII, FeII, CoII, and CuII Borohydrides

“…In other words, the thermal energy transport in these materials is basically phononic rather than electronic where κtotal ≈ κlat. In this respect, amorphous/ glassy semiconductors, as seen in our case, exhibit low κ as compared with crystalline semiconductors [55,56]. Furthermore, the multi-center clustering and nano-sized MT-BHs allow phonons scattering and thus suppress κlat in these semiconductors.…”

“…However, the thermal heat transfer in TE semiconductors involves multi-transport pathways comprised of an electronic component due to charge carrier migration (e -& h + ) and phonon scattering due to lattice dynamics [4,55]. Thus, κtotal comprises two main contributions, an electronic (κel) and lattice (κlat) where κel is influenced by charge carrier concentration, mobility, their ratio, bipolar interactions, and scattering mechanisms similar to σ while κlat is generally influenced by lattice vibration, Equation 12 [4,55,56]. Fortunately, κel can be approximated from the σ values using Wiedemann-Franz law (κel = L σ T) where L is the Lorenz number (2.44 × 10 −8 WΩK −2 ).…”

“…Fortunately, κel can be approximated from the σ values using Wiedemann-Franz law (κel = L σ T) where L is the Lorenz number (2.44 × 10 −8 WΩK −2 ). Although this law is best applied to metal, it is widely employed for semiconductors [4,55]. The calculated κel data in Table 4 demonstrates that the κtotal = κel + κlat (12)…”

Testing of proposed design of stove-powered thermoelectric generator using natural and forced air cooling

“…The use of new TE materials with a large ZT (figure of merit expressing the efficiency of TE materials) can revolutionise applications of TE devices in various fields. 5,7,9,12 The dimensionless parameter ZT is as follows:…”