Instead of absorbing light from the Sun and transforming it into electricity like your typical solar panel, a new radiative cooling technology developed by researchers at Stanford University works in reverse.
Even though there’s no incoming heat for solar panels to capture at night, there is still outgoing heat that can be used for energy. By pointing a warm solar panel at the cooling sky at night, this outgoing heat starts to radiate outwards as invisible infrared light. This is radiative cooling could be used as a cheap nighttime lighting source in cities if we were to tap into its potential.
Using a thermodynamic model of a thermoelectric power generator, Stanford University researchers have worked out a rooftop proof-of-concept that, in theory, can generate 2.2 watts per square meter (10.7 sq ft) without the need for an external energy source. The researchers are working to develop high-performance, sustainable lighting generation that can provide everyone – including those in developing and rural areas – access to reliable and sustainable low-cost lighting energy sources. A modular energy source could also power off-grid sensors used in a variety of applications and be used to convert waste heat from automobiles into usable power.