*5.1.6 Thermoelectric systems for energy harvesting*

In addition to mechanical energy, a temperature difference is also a very rich source of energy; therefore, often considered a viable option for the development of EH systems. To convert heat into electricity, thermoelectric generators (TEG) use the available temperature differences between two surfaces [35].

Thermoelectric devices for energy production or cooling consist of two types of thermoelectric materialsthermoelements. These are p-type and n-type semiconductors. Thermocouples are electrically connected in series and thermally connected in parallel. The working principle of TEG is shown in **Figure 18**.
