All-day thermoelectric power generation beyond 1 W m⁻² regime via radiative heat exchange with space and water-based heat storage

While the Sun is a potent energy source, the ultra-cold space has excellent potential for nighttime power generation because of its accessibility at night. Herein, we propose and demonstrate an effective approach that enables all-day energy harvesting using water-based heat storage and radiative thermal emitters across thermometric devices. We experimentally demonstrate all-day power generation with a peak power density of 1.51 W m−2 at daytime and 0.32 W m−2 at nighttime, surpassing the previous experimental records by nearly an order of magnitude. We further develop a theoretical model to validate and predict the power generation performance of the tested system. In addition, we show that the thermoelectric power generation can be enhanced with further optimization. This work opens opportunities to develop scalable, efficient all-day power generation based on thermoelectric devices.