Solar power is one of the best sources of renewable energy resources, that are within reach of human race. Virtually inexhaustible and with an almost omnipotent level of availability, sunlight seems to be the perfect resource for humans to tap into. However, as with every good thing, sunlight goes out at night and when there are clouds around. What then? Well, scientists may have figured a way around the problem.
The solution to the problem may lie in Graphene, a material we have been hearing about quite a lot lately, and the good old rain. Scientists are attempting to create an all weather cell, that could use either the sun or the rains, to create electricity.
The electricity generating Graphene sheets are based on the fact that rainwater is not just completely pure, electrically neutral, water. In reality, it contains a whole bunch of various salts that can be split up into positive and negative ions. Apparently, a team from the Ocean University of China in Qingdao thinks that such an event is not too far off (via ScienceAlert).
Graphene, for those who are unaware of it, is an allotrope of the form of a two-dimensional, atomic-scale, honey-comb lattice with one atom forms each vertex. The unique structure of the material gives it a bunch of special properties, including superb strength, extremely high heat and electricity conduction efficiency and it is also very nearly transparent.
What scientists have been doing with this carbon allotrope, that some have taken to calling the wonder material, is pretty interesting. They are basically adding a layer of graphene to an extremely thin-film solar cell called a dye-sensitised solar cell. The whole setup is then put upon a transparent backing of indium tin oxide and plastic.
The solar cell thus produced shows definite promise in generating electricity in all weathers. By using slightly salty water as a substitute for rain, hundreds of microvolts of electricity has been generated at a 6.53 percent solar-to-electric conversion efficiency ratio.
So yes, we have a solar cell that is capable of generating electricity under fair weather or foul, in a manner of speaking. Albeit, the apparatus hasn’t been properly tested in the open yet.
So hows the magic happening? Actually, salty water contains a whole lot of positive ions of elements like sodium, potassium etc. These positively charged ions bind to the ultra-thin layer of graphene and form a double layer with the electrons that are already present over there. Now you have two layers, with a substantial potential difference between them. This difference is what actually generates the electric current.
So the tests are promising. But there is still a long way to go before we can say yay to the concept of graphene based solar cells. Before implementing them on a wide scale, researchers are going to have to figure out ways to ensure that the rainwater, which has varying capacity of ions, is able to generate a current worth using it storing.
Another problem will be to deal with the myriad of ions found in rainwater. It is, after all, not created in laboratories under strictly monitored conditions.
However, the concept shows promise and if successful, has the potential to take care of one of the biggest issues that have kept the human race from successfully harnessing the energy from the sun to fulfil our needs.
The study has been published in the journal Angewandte Chemie.