Evaporation is the process by which a substance changes from a liquid to a gas. Typically, the evaporation is the result of heating the substance to a certain temperature. Precisely because of the evaporation on Earth is supported by the water cycle, and the evaporator in this case is the Sun. The magnitude of the energy that is consumed for the evaporation process on the planet, is actually very large, although we in everyday life do not notice this.
According to Ozgur Sahina (Ozgur Sahin) and his colleagues from Columbia University, the water that evaporates from all rivers, lakes and dams in the territory of the modern United States (excluding Large lakes) may provide to 2.85 million megawatt-hours of electricity per year. For comparison, this is equivalent to two-thirds of electricity generated in all States in the U.S. for 2015! And this despite the fact that 15 of the 47 States of potential power exceeds the actual energy demand.
The engines of the future: it’s all about the water
The researchers propose to install on freshwater engines that not only produce electricity but also halved the intensity of the evaporation, which in many situations would keep a huge drinking water supplies. However, this technology requires that the body of water is covered with absorbing panels, which is highly undesirable. For a start, however, you need to build himself evaporative engine, but here researchers have demonstrated the power of science and created several miniature, but fully working prototypes of the installation.
Test engines are based on the materials which when dry is compressed — for example, the design involved a tape coated with bacterial spores. Losing water, the spores shrivel and shrink, while reducing tape. Sahin compares the principle of this design with the muscular system, explaining that the microscopic spores can pull the tape with enough large force. To avoid contamination of the soil through repeated soaking and a large number of chemical substances, prototypes adjust their work depending on the changes in the General level of humidity. For example, in one version of the engine “muscle” is located just above the water layer. When the moisture evaporates, rises, then the ribbon, strung on the principle of blinds, deal and create a gap through which in them for air circulation and helps the tape again to dry and to avoid waterlogging.
The advantages and disadvantages of the invention
The scientific community agrees that the potential for this invention is huge. To date, the main problems are in its use. Ken Caldeira from the Carnegie institution for science in Stanford, California, doubts that it is possible to efficiently convert the energy of vaporization into electrical energy. In his opinion, commercial development engines to the extent where their production will be massive and widespread use, is extremely time-consuming task.
The main competitor of the new engines are familiar to all solar panels, since more common for floating solar farms is their location on the reservoirs. However, the evaporator motors can be made of cheap biomaterials that are easier to recycle than solar panels — and this is important.
If the technology can be developed, its use will affect the local climate through changes in the degree of evaporation of water. But it will have some value only if the area of the closed surface is 250 000 km? and more. However, when it comes to such a scale, any power plant, no matter how environmentally friendly it is, will have an impact on the environment. Moreover, in rainy areas where frequent rainfall cause a lot of problems, reduction of the intensity of evaporation of the water will be extremely useful.