Power Generation Through Radiative Cooling

Renewable energy is essential to achieve the goal of ‘carbon emission peak’ and ‘carbon neutrality’.Recently,outer space,which sits at a temperature of-270 ℃,has drawn significant attention.Harvesting electricity from outer space using the radiative cooling technology and thermoelectric generators provides a new carbonless solution to alleviate the conflict between the energy supply and demand.In this thesis,a theoretical framework is developed to predict the limit of the output power density based upon the radiative cooling technology and thermoelectric generators.Using dimensionless analysis,the optimization of multiple variables,e.g.,the ratio of external and internal resistance,the non-radiative heat transfer coefficient and the geometries of the thermoelectric generator,is conducted.With a thermoelectric figure of merit of ZT= 6,the output electrical power density can be improved to 9.0 W/m,which represents a 309 %increase as compared to the previous design.The dependence of the electrical power output on the resistance and radiative cooling area is verified using experiments.Two major conclusions are worth noting.First,the device reaches its maximum output power when the load resistance is greater than the internal resistance of the thermoelectric generator,different from the conventional impedance-matching condition.Second,the output power increases while the output power density decreases with the increase of the radiative cooling area.