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.