A Study of Radiative Cooling with Thermoelectric for Power Generation in the Tropics

Radiative cooling (RC) is an intriguing cooling technology that operates without external energy sources. It works by emitting thermal radiation into outer space, utilizing a long-wave infrared window with a wavelength range of 8 µm to 13 µm. This passive cooling system cools the surrounding area by allowing thermal radiation to escape from the Earth's surface. A thermoelectric generator (TEG) converts thermal energy into electrical energy using the Seebeck effect. By applying a constant heat flux and temperature difference, TEG can continuously generate power for up to 24 hours. Combining a radiative cooling material with a TEG creates the necessary temperature gradient and continuous heat flux for electricity generation. In this work, a TEG system with various radiative cooling coatings was developed and evaluated. The coatings studied included barium sulfate (BaSO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>) and silicon dioxide (SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>). The TEG system with different coating layers demonstrated varying radiative cooling effects. With a double-layer coating, the system was able to generate a daytime maximum voltage of 128 mV and a continuous nighttime voltage of 27 mV. These values translated to 1.5 µW power generated, based on an actual high-load resistor in the circuit. Theoretical calculations indicated that the system has the highest power generation of 22.54 mW and 352.30 mW/m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. These findings underscore the potential of the TEG system with a double-layer radiative cooling coating as passive power generation throughout the day.