Solar energy is an excellent source of renewable power but the biggest caveat in harnessing it is varied weather conditions and hence, it cannot be kept going all round the clock. Converting solar energy into electrical energy utilizes the principle of optoelectronics, by means of large-scale photodiodes. These devices are made of a semiconductor material that turns light particles or photons coming from the Sun, into electricity by exciting electrons in a material such as Silicon.
However, not all regions of Earth receive the same amount of sunlight and for solar energy to be a dependable source of power, it would have to work 24/7. Of course, there’s a stark difference between the frigid temperatures of the space and the temperate atmosphere of Earth, and scientists have come to believe that this difference can be leveraged to generate electricity.
In an experiment, Stanford University engineers Wei Li and Shanhui Fan along with University of California Los Angeles and materials scientist Aaswath Raman developed a device that produces a voltage by channelling the day’s residual warmth into cooling air. What the trio basically did is that they flipped the photovoltaic on its head by squeezing electricity from the glow of heat radiating out of the planet’s surface warmed by the Sun.
Hence, the photodiodes work ‘backwards,’ as photons, in the form of infrared radiation, leave the system, and a small amount of energy is produced in that process. This is what researchers call the ‘negative radiation effect’.
But we’re not talking about massive amounts of power, The experiment could only produce 64 nanowatts per square metre (10.8 square feet) of power, which is only a trickle. In theory, if the right materials and conditions are put together, scientists speculate that four watts per square metre could be produced.
This is a fantastic starting point, if you consider the prototype that it is. Even in its earliest form, it could be helpful for keeping low-power devices and machines running at night, for example your hearing aid or laser pointer. The complete study is published in Joules.