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ENERGY is an important basis for the affluent and stable society. The increased growth in all aspects of human life demanding huge energy. Importantly, the irresponsible and rapid increase in the world’s population made the situation so worse, providing electricity to everyone is really a big challenge. Despite many other energy resources, fossil fuels were the major energy resources for many decades and even at present, they are the main sources. However, the utilization of solar energy, wind energy, etc has made some contribution to decreasing the use of fossil fuels. Still, the energy demand is increasing day by day due to the fast growth of population and technological developments. Another issue is the low efficiency of the energy converting devices, which is also a major drawback. As a result, close to two-thirds of the energy produced is lost in the form of waste heat. Several such examples where energy is being wasted are industrial processes, automotive exhaust, home heating, etc. They generate an enormous amount of waste heat on a daily basis. So, possible solutions for such problems can also be indirectly beneficial to the entire energy spectrum. There is a huge interest in the scientific community to find a cost-effective technique to recover this waste heat so that it can help in reducing energy-related issues.
ENERGY is an important basis for the affluent and stable society. The increased growth in all aspects of human life demanding huge energy. Importantly, the irresponsible and rapid increase in the world’s population made the situation so worse, providing electricity to everyone is really a big challenge. Despite many other energy resources, fossil fuels were the major energy resources for many decades and even at present, they are the main sources. However, the utilization of solar energy, wind energy, etc has made some contribution to decreasing the use of fossil fuels. Still, the energy demand is increasing day by day due to the fast growth of population and technological developments. Another issue is the low efficiency of the energy converting devices, which is also a major drawback. As a result, close to two-thirds of the energy produced is lost in the form of waste heat. Several such examples where energy is being wasted are industrial processes, automotive exhaust, home heating, etc. They generate an enormous amount of waste heat on a daily basis. So, possible solutions for such problems can also be indirectly beneficial to the entire energy spectrum. There is a huge interest in the scientific community to find a cost-effective technique to recover this waste heat so that it can help in reducing energy-related issues.
Thermoelectric energy conversion can significantly contribute to the recovery of this waste heat which is an interesting technology that directly converts the thermal energy into useful electrical energy. Thermoelectric materials are used for the task in the form of thermoelectric generators.
- Easy maintenance: Thermoelectric generators work without any moving parts so they are virtually maintenance-free.
- Environment-friendly: Thermoelectric generators are eco-friendly as there is no release of any toxic gases during the working of the devices.
- Compact: The overall thermoelectric system is much smaller and lighter than a comparable mechanical system.
- Work in aerospace: They can be used in any orientation and in zero gravity environments. Thus they are popular in many aerospace applications.
- High Reliability: Thermoelectric modules exhibit very high reliability due to their solid-state construction.
- Remote Area Application: They are very useful in remote areas where there are no conventional energy sources are available.
To take advantage of these generators, the efficiency of the generators is a very crucial factor.
Wiedemann-Franz Law says, higher the electrical conductivity higher is the thermal conductivity!
It is observed that the semiconductors are quite suitable for the applications as they possess a high thermoelectric power factor (the product of the terms in the numerator in ZT expression). Also, the thermal conductivity of the semiconductors is very low as compared to the metals.
There are mainly two major drawbacks that the thermoelectric conversion technology is facing;
- A low thermoelectric conversion efficiency
- Unavailability of cost-effective, earth-abundant material to make thermoelectric generators
Bi2Te3, PbTe, and alloys of these compounds have been used in the applications extensively. However, the use of these compounds is limited for several reasons…
- the toxicity of the heavy elements Pb and Te
- the scarcity
- difficulty in processing
- expensive raw elements
