How does a temperature difference produce direct current in a thermoelectric power generator?

A thermoelectric power generator converts heat directly into electricity through the Seebeck effect. This process relies on a temperature differential ($\Delta T$) maintained between a heat source and a heat sink, which are connected by legs made of p-type and n-type semiconductor materials.12

When this temperature difference is applied, it generates a voltage ($V_{\alpha }$) across the device terminals, defined by the equation $V_{\alpha }=\alpha \Delta T$, where $\alpha$ represents the Seebeck coefficient. When an electrical load is connected to these terminals, this voltage drives a direct current through the circuit.12

The efficiency of this conversion is influenced by the material's properties—specifically its Seebeck coefficient, electrical resistivity, and thermal conductivity—as well as the geometric design of the semiconductor legs. Because there is no intermediate energy conversion process, such as the use of a turbine or steam, this is classified as direct power conversion.12