  We study the linear and nonlinear thermovoltage of a quantum dot with
effective attractive electron-electron interaction and weak, energy-dependent
tunnel-coupling to electronic contacts. Remarkably, we find that the
thermovoltage shows signatures of repulsive interaction which can be
rationalized. These thermovoltage characteristics are robust against large
potential and temperature differences well into the nonlinear regime, which we
expect can be demonstrated in current state-of-the-art experiments.
Furthermore, under nonlinear operation, we find extended regions of large power
production at efficiencies on the order of the Curzon-Ahlborn bound interrupted
only by a characteristic sharp dip.
