With a steep increase in population across the planet, electric power shortage has become a significant issue. Solar energy has now been accepted as a widespread process to generate electricity. The US department of energy has stated that half of the sunlight that strikes the earth in 30 minutes is enough to satisfy the energy demand of the whole world for a year. Thus, eighteen days of sunshine contains the equivalent amount of energy that the coal, natural gas & oil reserves of the planet have. The solar cells function by absorbing the sunlight and using heat energy to generate electrical power. The drawback of this type of system is that it can work only in the day time in the presence of sunlight. Over the day-night cycle to balance the power grid, the idea of electricity production at night with the assistance of solar cells is really fascinating.
Jeremy Munday, an engineering professor at the University of California, Davis, has developed a prototype called “anti-solar” cells that work in reverse to that of normal solar cells. The principle of cooling houses with this phenomenon has been prevalent for centuries. Electricity can be generated at night by radiating heat to space by utilizing the temperature difference between earth and space and make use of the night sky as a heat sink. The system can perform its function by utilizing the waste heat from industries. Hence, carbon neutrality could also be achieved.
This system can generate one-fourth of the power produced by the conventional solar cells during the daylight hours, i.e. around 50 watts per square meter. Solar cells cannot work solely during the day but these “thermoradiative cells” technology can produce energy 24/7 which is the real benefit of the system. The physics is totally the same, the difference lies in the material used to perform this reverse function.
Jeremy’s paper “Nighttime Photovoltaic Cells: Electrical Power Generation by Optically Coupling with Deep Space” discusses in detail an overview of the operation performed by the system by radiating heat during night hours to generate power.
In past years, many attempts have been made to produce power with the principle of temperature difference. The patent “CN208158485U” titled “Utilize temperature difference power generation devices that solar photovoltaic power generation waste heat and wind -force heated” disclosed a structure having a circular truncated body having outer thermal oil layer and inner semiconductor temperature difference power generation layer to maintain power generation at night. The device uses wind as well as solar energy at the same time by the utilization of waste heat produced by the photovoltaic power generation for generating power with the difference in temperature. In a nutshell, we can say that this concept of generating electricity with temperature difference phenomenon at night by using “anti-solar” cells can be really advantageous in fighting the power shortage problem. Researchers are working to increase the output and performance of the system and we expect a practical implementation very soon.