Thermoelectric generators (TEGs) are devices that generate electricity through the direct conversion of heat energy into electrical energy using the Seebeck effect. The Seebeck effect is a phenomenon in which a temperature difference between two dissimilar materials creates a voltage potential across them, leading to the generation of an electric current.
In remote power applications, TEGs are often used to generate electricity in situations where there is a heat source available, but connecting to a conventional power grid is not feasible. Here's how electricity is generated in thermoelectric generators for remote power applications:
Heat Source: TEGs require a heat source to function. This heat source can be derived from various remote power applications, such as waste heat from industrial processes, exhaust gases from engines, solar radiation, geothermal heat, or even biomass combustion.
Thermoelectric Materials: TEGs are constructed using semiconductor materials that have a high thermoelectric efficiency, which is characterized by a high Seebeck coefficient and low thermal conductivity. Bismuth telluride and lead telluride compounds are commonly used in TEGs due to their favorable thermoelectric properties.
Heat Sink: To maintain a temperature gradient and allow the Seebeck effect to occur, the opposite side of the TEG is connected to a heat sink or a cooling system. The heat sink absorbs heat from the cold side, ensuring a continuous temperature difference between the hot and cold sides of the TEG.
Thermocouples: The TEG is made up of multiple thermocouples connected in series or parallel. A thermocouple consists of two dissimilar semiconductor materials, with one side exposed to the heat source and the other side connected to the heat sink. The temperature difference between the hot and cold sides creates a voltage potential across the thermocouple.
Electrical Load: The voltage generated by the thermocouples is typically low, so multiple thermocouples are connected in series to increase the output voltage. The electric current generated by the TEG is then passed through an electrical load, such as resistors, to convert the thermal energy into usable electrical power.
Power Management: In remote power applications, it is essential to regulate and manage the generated electricity efficiently. Power management systems, including voltage regulators and battery banks, may be used to ensure a stable power supply to the end-user or store excess energy for later use.
Thermoelectric generators are often chosen for remote power applications due to their simplicity, reliability, and ability to generate electricity from waste heat or other readily available heat sources, reducing the need for fuel-based power generation in remote areas. However, their efficiency is generally lower compared to conventional power generation methods, and they are most effective in low to medium power applications.