  A theoretical study of the thermoelectric current and energy harvesting in an
interacting double quantum dot system, connected to reservoirs held at
different chemical potentials and temperatures is presented. Using a
rate-equation approach, the current is evaluated for different energetic
configurations of the double quantum dot. We discuss in detail the
current-temperature gradient relations (the thermoelectric analog to
current-voltage relations), and demonstrate that, due to interactions, the
current is non-monotonically dependent on thermal bias. This
interaction-induced non-monotonicity influences the possibility of harvesting
thermal energy from the double-quantum dot, and it is shown that in some
configurations, energy cannot be harvested at all. We analyze the conditions
under which energy can indeed be harvested and converted to useful electrical
power, and the optimal conditions for thermoelectric energy conversion.
