Before human race built solar cells to turn light source into electricity and maybe even before plants stored it as chemical energy , rocks were doing the same thing . The first examples of raw but non - biological changeover of light to electrical energy have been found , and it seems it is actually common , taking place on surface covering of rock find in Taiwanese deserts . The process may even play an important part in making the Earth inhabitable .
Many desert rocks have slender coatings of iron and atomic number 25 . While examine samples from the Gobi desert under lustrous light , Professor Anhuai Luof Peking University get galvanizing currents on the surface , but only in the vicinity of sediment of these alloy . The weaker the light , the less current , demonstrating the coating are turning the photons into moving negatron . The coating are also quite stable , so generation probably survive all daytime .
However , do n’t imagine you could charge your phone off rocks if trapped in the desert with a flat battery . The current are tiny , Lu reports inProceedings of the National Academy of Sciences , even when the careen are exposed to luminousness several times more powerful than the Sun .
Less than 1/10,000th of the photons in the sunlight are convert to moving electrons by the manganese - rich coatings , and those heavy in iron alone do even worse . That equate with commercial-grade solar cells , which get close to 100 percentage at the correct wavelengths .
On the other handwriting , if these varnishes insure much of the 35 million straight kilometers ( 13 million square Admiralty mile ) of deserts worldwide , this could make accumulative effects strong . world may have no style to harness this resource , but photoelectrotrophic bacteria are a unlike affair . Other researchers have stimulated the growth of certain bacteria using minerals that convert sunshine to electrical energy .
There ’s always a promise find like this could take the search for better solar panels down new and expert paths . That may be a vain hope grant the modest efficiency , but the findings may have other uses . Some of the bacteria Lu thinks are fertilise off these current make carbon copy dioxide from the air and turn it to acetate , although we do n’t yet know if this represents a major atomic number 6 sink .
Lu bump that manganese absorption in these facing can be 100 time those in the body of the rock , but only on the surfaces exposed to sun . experimentation evidence manganese - rich coatings rise quickly under impregnable visible or ultraviolet light , but slowly , if at all , in shade . There could , therefore , be a cycle per second where sunshine stimulates manganese - rich varnish , which then increase Energy Department product . These manganese - rich coatings have sufficient chemic potency to convert body of water to oxygen , although again we do n’t know how globally significant this is .
