Thermoelectric energy harvesting is a process that converts heat energy into electricity using the Seebeck effect, which is based on the principle that when a temperature gradient exists between two different materials, a voltage is generated. This technology is used to power wireless communication devices and other low-power electronics.
The basic components of a thermoelectric energy harvesting system for wireless communication devices include:
Thermoelectric Generator (TEG): The heart of the system is the thermoelectric generator, also known as a thermoelectric module. It consists of semiconductor materials (often bismuth telluride-based) with a high Seebeck coefficient. The TEG is composed of two distinct sides: a hot side and a cold side.
Heat Source: A heat source is required to maintain the temperature difference between the hot and cold sides of the TEG. This heat can be obtained from various sources, such as body heat, ambient temperature differences, or waste heat from other devices or systems.
Heat Sink: The heat sink serves as the cold side of the TEG. It helps dissipate the heat absorbed by the hot side, maintaining the temperature gradient.
The working principle of the thermoelectric energy harvesting system is as follows:
Heat Absorption: The hot side of the thermoelectric generator is exposed to the heat source, absorbing thermal energy.
Temperature Gradient: As the hot side absorbs heat, it becomes hotter than the cold side (heat sink), creating a temperature gradient across the TEG.
Voltage Generation: Due to the temperature gradient, a potential difference (voltage) is created across the TEG, based on the Seebeck effect. This voltage drives an electric current through an external load (e.g., a resistor).
Power Generation: The electric current flowing through the external load represents the electrical power generated by the TEG. This power can be used to directly power the wireless communication device or charge a battery for later use.
Thermoelectric energy harvesting systems are particularly useful in applications where there are small temperature differences, and they can generate electricity in a reliable and sustainable manner. However, the efficiency of thermoelectric energy harvesting systems is typically lower than other energy harvesting methods, like solar or kinetic energy harvesting, so they are best suited for low-power devices and situations where other forms of energy harvesting are not feasible.