The development trends of the modern world are such that every year the need for additional sources of electrical energy increases. The reason for this is quite obvious: a gradual process of reorienting many technical sectors, in which its fossil fuels are currently used as fuel, to electricity has already begun. There are many examples: electric arc furnaces, hybrid cars , etc. This is the reason that explains the active construction of power plants around the world.
Each country is interested in the most effective solution. And now there are plenty to choose from: geothermal power plants; atomic; working on fuel oil, coal and gas; hydroelectric power stations; using the energy of the sun and wind. All of them can be conditionally divided into two types: those dependent on fuel supplies (transportation by transport) and others, which are based on natural local sources of electricity. The second are absolutely safe for the environment, which is very important in the modern world.
Among these environmentally friendly solutions, geothermal power plants are of most interest. They have only two significant drawbacks: relatively small installed capacities and the possibility of construction only near existing thermal springs. Consider this type of generating stations in more detail.
It’s not a secret to anyone that in some parts of the globe there are natural sources of water and steam. Usually these are areas near mountain ranges and in places where the thickness of the earth's crust is small. The internal temperature of the Earth is estimated in thousands of degrees. In some cases, water gets into the fracture of the crust, is heated by the heat of the bowels, and breaks up in the form of superheated steam or hot water. Geothermal power plants use the kinetic power of such sources. Obviously, if the steam is directed through the pipes to the turbine, then work will be performed on its rotation. It is enough to connect a classic generating machine and remove electricity from its terminals.
The principle of operation is really very simple. However, there are a number of features due to which such stations differ from one another.
Before the start of construction, geological exploration determines the optimal location for future generating facilities. There is only one condition - proximity to an internal heat source. If there is a developed system of geysers, it remains only to adjust their configuration properly (direct the channel vertically, increasing the speed of steam). In another case, using drilling rigs, one has to go deeper into the bowels of the planet: every 36 meters they give a temperature increase of 1 degree.
Sometimes steam (water) contains a mixture of dissolved gases, quickly destroying the apparatus of the station. In this case, the steam stream undergoes intermediate cleaning. The first geothermal power plants appeared in 1904 and are still operating.
There are two types of work: open and closed loop. When using the first pair, the rotating turbines are released into the atmosphere. The name of the second speaks for itself: the steam rings. Typically, all stations have two underground channels - for supplying media to turbines and pumping back into the bowels. In some countries, a unique solution is used: sewage is pumped into the bowels, replenishing the debit of the aquifer. In this way, it is possible to utilize the water and provide additional steam to the power plant. In addition to steam, water can also be used.
Sometimes an indirect (binary) scheme is used. It creates a circuit of a turbine and looped channels containing liquid with a low boiling point (less than that of water). External hot water of the source evaporates the liquid in the circuit, the vapor pressure of which drives the turbine in motion. In fact, we are talking about a variety of large heat pipe.