Nighttime power generation and energy storage

We demonstrate >100 mW/m 2 power generation at nighttime, which represents a significant advancement in the quest of using radiative cooling to generate electricity. Radiative-cooling-based nighttime power generation has been analyzed in Raman et al., 2019; Assawaworrarit et al., 2022; Chen et al., 2016.

At night, as the sunlight is absent, to provide power, one needs another source of energy from the ambient environment. Technologies such as wind (Holmes et al., 2004) and radio-frequency harvesting (Yeatman, 2004; Ajmal et al., 2014) have been proposed and tested.

While there have been several theoretical proposals and experimental demonstrations of energy harvesting from the radiative cooling of a PV cell at night, the achieved power density is very low.

The spike in power density just after midnight is likely due to the thermal storage effect, which can lead to higher-than-expected power density when the ambient temperature drops. Requests for further information, resources, and reagents should be directed to and will be fulfilled by the lead contact, Shanhui Fan ([email protected]).

A previous study 30 has calculated the theoretical power density—the useful power that can be generated per unit area used to emit radiation—that can be harvested by radiative cooling from the earth's surface at ∼300 K under a realistic atmospheric model to be ∼6,000 mW/m 2.

The coldness of the universe is a thermodynamic resource that has largely remained untapped for renewable energy generation. Recently, a growing interest in this area has led to a number of studies with the aim to realize the potential of tapping this vast resource for energy generation.