Thermal energy harvesting: thermomagnetic versus thermoelectric generator

We compare the efficiency and the power density of thermoelectric and thermomagnetic generators at maximum power. The performances of thermomagnetic generator are computed using an equation of state, either extrapolated from experimental data for 2nd order transition or deduced using a phenomenological Landau model on measured data for 1st order transition. The performances of thermoelectric generator are computed using the Onsager model. Moreover, the heat exchange in finite time is estimated using a simple model of thermal conductance. According to the results, thermomagnetic generator is more efficient and have slightly higher power density than thermoelectric for temperature difference lower than 10 K. Therefore low grade heat thermal energy harvesting could consider thermomagnetic generator.