Business & Industry
Dec 1, 2016
ENERGY FROM RAINDROPS
Solar energy is one of the global solutions and bets to produce electricity with low environmental impact. However, this method still faces some obstacles, such as low production on cloudy or rainy days. A scenario that is about to change, thanks to the research of a Chinese scientists group who have been developing a technique able to produce electricity from the rain.
As it is known, photovoltaic solar panels allow the production of electric energy through solar energy, thus enabling, for example, a home to be autonomous and independent of traditional electricity networks. The main disadvantage was the dependence of the weather conditions, that is, the existence of sun, since in the rainy and windy days it is not yet possible to obtain a good performance of the photovoltaic panel, making it necessary to use energy storage systems.
A reality that will change very soon by the hands of a team of scientists from Quindao, China, led by Qunweu Tang, Wang Xiaopeng, Peishi Yang and Benlin He, who developed a photovoltaic plate with capacity to produce energy, not only from the sun's rays, but also from the raindrops, being efficient independent of the climatic conditions. The system works thanks to a layer of graphene incorporated to the surface of the plates. The material is used to coat the solar cells, but it is also an excellent conductor of electricity. According with these scientists, «all that is needed to realize this idea is a layer of graphene with an atom of thickness, so that many electrons can move along the surface». On the contrary to the already existing ones in the market, these solar panels have a single sheet of graphene. In practice, when water falls on the surface (plates), graphene binds electrons with positive ions, a phenomenon called the "acid-base Lewis interaction".
Considering that rainwater is not pure, that is, it contains elements such as ammonium, calcium, and sodium, it turns into ions, making graphene and water an excellent combination for energy production. In turn, the water adheres to the graphene, forming a double layer with the electrons of graphene. It is the fact that the difference between the layers is so strong that it makes possible the energy production. Scientifically, when water falls on the surface, it creates what is called a "pseudo-condenser" (unbalanced charge points where electrons are sent from one side to the other). «The unbalanced load is just a potential difference, which means that researchers can use the process to capture energy», explain the scientists involved in the study.
These solar cells can be stimulated either through sunlight, in good weather, or through raindrops, on bad weather days, achieving an ideal energy conversion efficiency of 6.5 percent. A value that is, however, greatly reduced when compared to other solar panel technologies that are typically around 20 percent energy efficiency.
Over the last few years, companies and engineers have been focused on improving the efficiency of solar panels and their storage capacities, but have never focused on finding a solution to produce power in adverse weather conditions. So, if the idea behind this study materializes, this technology will revolutionize the solar panel market by making it possible to produce energy regardless of the weather.
A new hope for undeveloped and sunless countries
Good news for an industry that can see its market expanded, as this infrastructure will allow homes and other buildings located in countries where the sun is a rarity, to have access to a greener energy production method, similar to the countries where the sun is abundant. In addition, it will be possible to improve the performance of solar panels by reducing the need to use energy storage systems.
For curiosity, it is in Pampanga, Philippines, that we find the world largest roof covered with solar panels, where 2.9 megawatts of energy are generated. In contrast, there are 1.3 million of people in the world without electricity access, and for whom, common objects such as a lamp, a refrigerator or a television are scarce. Myanmar, Uganda and India are some of the countries where electricity is scarce, and where the use of solar panels has lit up the lives of many people and families.
Portugal, for instance, is a country that benefits from sunshine, therefore, the concern with this new technology is smaller, even so, the actual system presents, besides the environmental advantage, significant savings, in the order of 75 percent of the expenses, a number that can increase during the summer or even the whole year through the implementation of this new technique.