  Thermal-electric conversion is crucial for smart energy control and
harvesting, such as thermal sensing and waste heat recovering. So far, people
are aware of two main ways of direct thermal-electric conversion, Seebeck and
pyroelectric effects, each with different working mechanisms, conditions and
limitations. Here, we report the concept of "Geometric Thermoelectric Pump", as
the third way of thermal-electric conversion beyond Seebeck and pyroelectric
effects. In contrast to Seebeck effect that requires spatial temperature
difference, Geometric Thermoelectric Pump converts the time-dependent ambient
temperature fluctuation into electricity. Moreover, Geometric Thermoelectric
Pump does not require polar materials but applies to general conducting
systems, thus is also distinct from pyroelectric effect. We demonstrate that
Geometric Thermoelectric Pump results from the temperature-fluctuation-induced
charge redistribution, which has a deep connection to the topological geometric
phase in non-Hermitian dynamics, as a consequence of the fundamental
nonequilibrium thermodynamic geometry. The findings advance our understanding
of geometric phase induced multiple-physics-coupled pump effect and provide new
means of thermal-electric energy harvesting.
