Thermoelectric energy harvesting systems are used to generate electricity from temperature differences. These systems can be employed in autonomous sensor nodes in smart cities to power low-energy devices, such as sensors and wireless communication modules. Here's a basic overview of how electricity is generated in thermoelectric energy harvesting systems:
Seebeck Effect: The key principle behind thermoelectric energy harvesting is the Seebeck effect. This effect states that when a temperature gradient exists between two dissimilar materials, an electric voltage is generated across the junction of the materials. In simple terms, if you have a temperature difference between two points in a thermoelectric device, electricity can be generated.
Thermoelectric Materials: To utilize the Seebeck effect effectively, thermoelectric materials with suitable properties are used. These materials should have a high Seebeck coefficient (thermoelectric sensitivity), low electrical resistivity, and low thermal conductivity. Common materials used for thermoelectric energy harvesting include bismuth telluride, lead telluride, and silicon-germanium alloys.
Thermoelectric Modules: Thermoelectric materials are typically arranged in an array known as a thermoelectric module or thermoelectric generator (TEG). A TEG consists of multiple pairs of n-type and p-type thermoelectric materials connected electrically in series and thermally in parallel.
Temperature Gradient: In the context of smart cities, the temperature gradient can be achieved in various ways. For example, the TEG could be placed in an environment where there is a temperature difference between the top and bottom surface. This temperature difference could be due to natural variations in ambient temperature, exposure to sunlight, or proximity to a heat source (e.g., a motor or electronic component generating heat).
Heat Sink and Heat Source: To enhance the efficiency of the thermoelectric energy