To the selection of technology parameters for the use of renewable energy sources on man-made disturbed lands

Renewable energy sources (RES) have become widely used in many developed countries of the world. In the article, the use of RES is considered using the example of wind energy installations (WEI). For industrial scale volumes of electricity produced, wind energy installations of large capacities and designs are used. To choose a rational design of windmills, a classification of windmills of existing designs is provided. Known foreign types of efficient wind generators are considered. Most often, wind energy installations are used in places with a strong wind flow. Wind energy installations with a horizontal axis of rotation are usually used in these areas. For example, information is given on one of the largest wind farms in Ukraine - the Botiivskyi wind farm, which consists of 65 wind energy installations with a horizontal axis of rotation. The practice of using windmills, despite the great benefits of their use, has significant drawbacks. This problem consists in deriving large plots of land for use and having an impact on the surrounding environment. This, in turn, leads to negative consequences for the ecology of these regions. In connection with this, there was a need to use wind energy installations on land plots that have been decommissioned in the conditions of Kryvbas. These include sparsely populated regions, wastelands, and decommissioned plots of land on which the facilities of mining enterprises are located. It has been proven that the placement of WEI with a vertical axis of rotation of medium power on overburden dumps has its own characteristics. For most of the territory of Ukraine, the average wind speed is 3-5 m/s, so the use of wind turbines with a vertical axis of rotation is more appropriate. The starting speed of such wind energy installation is 0.5 m/s, and at a wind speed of 3 m/s, wind energy installations can reach their nominal power. The paper analyzes the possibility of using wind energy installations on man-made disturbed lands, namely on open rock dumps, and recommends their design features. The calculation of the wind energy potential for vertical and horizontal wind energy installations in the conditions of the city of Kryvyi Rih was made. A comparison of the use of vertical and horizontal wind energy installations was made. The effectiveness of the use of wind energy installations with a vertical axis of rotation in the conditions of Kryvbas is shown.

Nuclear installations of various operating principles have become the most widely used for electricity generation.However, the lack of proper safety of their work led to accidents, which negatively affect the ecology of not only regions, but also large areas of different countries.In connection with this, some developed European countries are abandoning the generation of electricity by nuclear power plants and switching to renewable sources of electricity.RES include biomass energy conversion, wind energy, solar energy, small hydropower, solid waste energy, etc. Solar energy (SE) and wind energy (WE) are considered the most promising renewable energy sources.The state energy programs of many countries of Western Europe, the USA and Australia define today as the main task a gradual transition from traditional to alternative energy sourcesrenewable energy sources (RES), both on an industrial scale and in household consumption.SE attracts electricity producers due to its simplicity and lack of moving units.Within the framework of green energy, it takes the first place.It has gained particular popularity among small consumers of household electricity.However, she has a big drawback.Modern technology of manufacturing solar cells can provide a short period of operation without losing its properties to generate electricity.Degradation of the properties before the conversion of solar energy into electrical energy sharply reduces the efficiency of its use.Thus, in 10 years of operation of solar panels, the ability to generate electricity decreases by two times.Thus, the use of wind power plants for electricity generation becomes an alternative to SE. Wind energy installations (WEI) have become especially widespread for industrial consumers.It has become widespread in areas with strong winds in coastal areas of seas and oceans, deserts and lands of low economic value.Wind energy installations with a horizontal axis of rotation are used in these areas.The main disadvantages of wind energy installations with a horizontal axis include: 1. High price of producing a unit of electricity 2. High specific area of wind turbines with a horizontal axis.For a wind energy installations with a capacity of 500 kW under the foundation, including a complete transformer device, an area of 2020 = 400 m 2 is required, for a road with a width of 5 m and a length of 300 m, an area of 1500 m 2 is required.The specific area will be 3,8 m 2 /kW.During the construction of a wind energy installation with a capacity of 50 MW (this capacity is provided by the number of installations of 100 pieces of 500 kW), the area will be equal to 15,7 hectares.The specific area will be 31363,2 m 2 /kW [7].3. Noise from the operation of windmills (table 1) 4. Landscape change, soil erosion. 5. High starting rotation speed of wind energy installations, which makes it impossible to use them in areas with low average annual wind speeds (which is typical for most of the territory of Ukraine) Based on the above, the perspective is the use of wind energy installations in conditions of technogenically changed landscapes in mining regions.At mining enterprises, a significant area is used for waste storage.The problem of using dumps for the placement of wind turbines on them is relevant.It is necessary to determine not only the design of windmills, but also to solve a number of issues related to their location on the dumps of disturbed rocks.

Statement of the problem
Make a selection of the structure of the wind turbine and its parameters in the conditions of location on dumps of disturbed rocks for the conditions of Ukraine, namely the Kryvyi Rih Basin.

Solving the problem
To choose a rational structure of windmills, consider the classification of windmills of existing structures.
Types and kinds of wind generators (WG).Classification of WG is carried out according to various signs.First of all, they are divided into:  horizontal -the axis of rotation is located horizontally, the devices have a higher efficiency of operation, but they require accurate orientation in the direction of the wind and they start working at a sufficiently high starting wind speed of 3,5-4,5 m/s;  vertical -these generators rotate around a vertical axis, so the direction of the air flow is not important for them, and the starting speed is 0,5 m/s, which is more appropriate for the conditions of the Dnipropetrovsk region, because the wind speed here rarely reaches 3,5-4,5 m/s.
According to the type of design, WG are divided into: In addition, there is a division according to the structure of the blades:  hard blades (made of metal);  sailing (made of soft materials or fabric stretched over a frame).
According to their purpose, they are divided into: It should be taken into account that the classification of WG is quite conditional, because new types of structures are constantly appearing.The process of development of wind energy is constantly growing, so there cannot be a final classification yet.When choosing WG, the main parameters of interest to the consumer are:  WG power.This indicator allows you to estimate the cost of the received energy and decide how much this device covers electricity needs;  cost of WG;  repairability, features of operation and maintenance of the device;  conditions of location (need for natural resources -land, water, air);  environmental friendliness (impact on people, animals, vegetation, etc.).
The first WG was installed in the late 70s of the 19th century in the USA.It produced 1.2 kW of electricity, successfully serving its owner for over 20 years.Today, there are two main types of WG with a horizontal axis of rotation and with a vertical one.But there are other well-known foreign types of WG, the most interesting of which are the following [1].Typhoon turbine.Developed by the Japanese Atsushi Shimitsu, WG uses the powerful energy of typhoons, which are often encountered by the people of Japan.According to Shimitsu's calculations, the energy of one typhoon is enough to provide electricity to the entire population of the country for 50 years.This installation can withstand the most powerful gusts of wind due to the comprehensive vertical axis.Tests of a scaled-down prototype of the system were successful, so the inventor is looking for investors who could build a full-scale generator.Hybrid WG.In 2018, the German energy company Max Bögl Wind AG and the American GE Renewable Energy installed the world's first wind-hydro turbines in the Swabian-Franconian Forest (Germany).The four 13.6 MW units are located on a hill, as the plant needs to be on high ground for efficient operation.In the absence of wind, hydro turbines are involved in the work, thanks to which the process of energy production becomes continuous.Aerostat wind generator (AWG).Most WG are firmly fixed to foundations on land or the seabed, but there are exceptions.Pera's flying wind turbine was launched in Fairbanks, Alaska in 2014.The OJSC system was created by a startup with Altaeros Energies.A cylindrical turbine filled with helium can float at an altitude of 300 m and collect energy 5-8 times more powerful wind gusts than on the ground.In 18 months, the installation produced enough energy to supply more than 10 homes.In addition, OJSC can distribute Wi-Fi and mobile signals, as well as collect weather data.Safe generators.Vortex Bladeless units are specifically bladeless to protect passing birds that are often victims of WG.The shape of the turbine resembles thin columns, due to which they can be installed at a close distance from each other.Vortex collects the energy of vortices in the air flow.The developers assure that the production of such units is 53% cheaper, and operating costs are reduced by 80%.INVELOX wind pipe from SheerWind.The innovative installation produces 600 times more energy than conventional windmills.The system picks up the wind at the surface of the earth, and then drives it through a funnel inside the generator.Thus, the speed of air movement increases.The installation can generate energy even in light winds, and the lack of blades does not harm wildlife.The construction of such an installation is also cheaper than the construction of a classic WG.Catching Wind Power.Bird lover Raymond Green developed the Catching Wind Power system in 2012.Equipped with the likeness of megaphones, generators pick up the wind, twist it in funnels, and then compress it.There are no moving parts on the outside, so the windmills are completely safe for birds and bats flying by.WG can be scaled and used both for industrial enterprises and for ordinary households.Based on the above, it can be seen that there are still few industrial developments today.Basically, they are represented by foreign models, which are focused mostly on high performance, which entails high prices, and thus puts a serious barrier between them and consumers.At the same time, this situation stimulates the growth of independent developments, many of which are able to significantly change the situation around wind energy as a whole.These developments serve to create an opportunity to provide electricity to a small area -a private home, or some production process, and therefore they are a cheaper option with completely different conditions of use.In Ukraine, WG with a horizontal axis of rotation are used on an industrial scale, for example, the largest in Ukraine -the Botiyiv wind power station (WPS), which is located near the village of Primorskyi Posad, Melitopol district, Zaporizhzhia region.It was launched in 2012.The installed capacity of the station is 200 MW, a total of 65 units have been launched.The average annual generation is expected at the level of 686 million kWh of electricity annually.In 2014, the station generated 652 million kWh of electricity.The station provides electricity to the south of the Zaporizhzhia region, and until 2014 -also part of the Crimea [2].The site for the construction of the wind power station was chosen based on wind monitoring based on three-year observations.The average wind speed at the Boivska wind farm site is 7.3-7.7 m/s at a height of 70 m.These figures are typical for the territory of the Azov coast, but in general, for most of the territory of Ukraine, the average wind speed is 3-6 m/s in summer.in winter, the winds are stronger -5-8 m/s, therefore, for most of the country, the use of WG with a horizontal axis of rotation is impossible.The starting wind speed for WG with a horizontal axis of rotation is 3,5-4,5 m/s, and the nominal one is 8-12 m/s.Windmills with a vertical axis of location of the power shaft.Thus, it is advisable to consider another type of WG -with a vertical axis of rotation.The starting speed of such WG is 0.5 m/s, and with a wind speed of 3 m/s, the WG can reach its nominal power.Currently, the most promising for use are WG with a vertical axis of rotation, in which the windmill is held by magnetic levitation (the property of magnets to repel each other) and seems to hang in the air.Due to the use of this modern technology, the friction of the support bearing of the windmill has been reduced to almost zero, the vibration is so small that it can be neglected, and the noise is almost imperceptible to the human ear.And most importantly, it allows you to use this type of WG at wind speeds of 3-6 m/s.There are also a number of positive features of using WG based on magnetic levitation, namely:  low starting wind speed;  rotation does not depend on the direction of the wind;  the system does not require maintenance (the generator uses only one bearing for the stability of the wind wing with a 500-fold safety margin);  noise load within 20 dB, no magnetic radiation and vibration;  there is no need to use additional system startup devices;  the system is absolutely safe for birds, bees and the environment;  does not require a sanitary protection zone and can be installed as close as possible to residential and industrial buildings;  the system works stably in aggressive environments: sharp temperature drops, strong gusts of wind, can withstand even a hurricane wind;  the possibility of installation without harming landscape views.
From an ecological point of view, in addition to the obvious advantages of using WG, such as: no emissions and discharges, safety for animals and birds, low noise level, etc., it becomes essential that for their location it is possible and expedient to use land plots that have been decommissioned for destination, i.e. man-made disturbed lands.These include sparsely populated regions, wastelands, and decommissioned plots of land on which the facilities of mining enterprises are located.For example, it is appropriate for the territories of Kryvbas, where there are many vacant territories disturbed by mining operations.Wind speed is the most important element in the design and use of wind energy installations.In general, with an average annual wind speed of more than 4 m/s at a height of 10 m (at this height, anemometers are installed at weather stations), wind energy installations can be used effectively.For wind energy installations that are connected to power grids, the acceptable minimum speed is 6 m/s.The main rule is that the possible power produced by wind energy installation is proportional to the cube of the wind speed and the square of the rotor diameter.This means that when the wind speed is doubled, the possible power increases by 8 times.Even a small increase in wind speed leads to a significant increase in power.If the wind speed is determined by the place where the wind energy installation is installed, then the diameter of its rotor is a structural element, the size of which depends on many calculation parameters.Most often, a reversible problem is solved: the design capacity of the wind turbine is set, and the required diameter at a certain calculated speed is then determined.The formula for wind energy installation (P), kW, looks as follows [4]. г і  р -efficiency coefficients of the generator (≈0.95) and the reducer (≈0.9);С рthe coefficient of wind use, which depends on the profile of the blades and other mode parameters, the largest value of which is 0.593, reaching the value of the coefficient -0.4-0.45;π=3.14.
As it is known, with an increase in height, the wind potential also increases in relation to the indicator at the level of the 10-meter mark: at a height of 30 mby 1.5 times, at a height of 60 mby 2 times, at a height of 100 mby 2.5 times.Based on this, overburden dumps are promising for the installation of WG.
The average annual wind speed v at the installation height h of the wind turbine is determined by the well-known formula [3]: ) where v 10 is the standard wind speed measured at a height of 10 m above the ground; ba parameter that varies depending on the closed area, time of day, season; for open terrain b = 0.14.
Average wind speeds vary significantly during the day, month and season.According to this, daily, monthly, seasonal and annual course of wind speed are distinguished.The annual course of the wind is a seasonal change in average wind speeds.The daily course of the wind is a change in the average wind speed during the day.It is most clearly visible in the summer and is less evident in the winter.In the summer, the wind speed during daytime hours is on average 1.5-2.0m/s higher than at night.In the conditions of a decrease in the general level of wind intensity in the summer, the daily maximum of wind speeds is favorable for the effective use of wind energy, since it is during the daytime hours that, as a rule, there is an increased demand for energy by consumers.
Let's consider the prospects of installing WG for the conditions of Kryvbas.To do this, we calculate the WE potential of the city Kryvyi Rih.The weather archive for a day, a period of 30 minutes from the website Meteopost for the year 2021 was used for the calculation [5].The growth factors of the average wind speed with height are presented in Table 2 (calculated according to formula (2)) [6].The calculation results are given in Tables 3-5.

For a year 17370
Table 5 shows that for the conditions of Kryvyi Rih, the use of vertical wind turbines is more effective, and it has been proven that their efficiency increases rapidly with altitude, and electricity generation begins at lower wind speeds.In addition to the height of the wind energy installation, the shape of the selected wind turbine, in particular its blades, plays an important role in increasing efficiency [8].There are different ways of controlling the position of rotating WEI blades, depending on the tasks, which include stabilization of a given frequency of rotation of the wind wheel by turning the blades relative to their axis or by turning the blades relative to the axis of rotation of the wind wheel.Management is carried out with the help of centralized or other regulators on the frequency of rotation of the windmill.Thus, there is a design of a windmill with adaptive control of the position of the blades, which consist of separate sections, each of which rotates freely on an axis, which allows them to self-install and be in a state of aerodynamic equilibrium due to the action of the force of the wind, the force of resistance to rotation from the oncoming air flow and the load on wind turbine shaft.Windwheels with multi-section adaptive blades change their integral profile at the slightest change in wind speed or useful load on the wind turbine shaft, providing you with maximum power.This allows you to use them in a wide range of wind speeds, including low ones, which are widespread in the territory of Ukraine.Another effective type of wind energy installation with a vertical axis of rotation is the helical rotor (or Horlov rotor), which was invented by Alexander Horlov, a professor at Northeastern University in Boston (USA) in 2001.This design of the wind engine is a type of Darier rotor.It has blades twisted around the axis of the rotor.At the same time, the coefficient of wind energy utilization increases to 0.4.The torque becomes constant regardless of the position of the blades relative to the direction of the wind, and self-starting at idle is quite regularly observed at wind speeds of 3 m/s and higher.The optimal mode of operation of these wind engines is achieved with the number of blades from 3 to 5 units.Increasing the number of rotor blades by more than 5, as a rule, leads to a decrease in speed and a decrease in the coefficient of wind energy utilization [9].Due to the twisting of the blades, the rotation of the rotor is more uniform, which significantly reduces the dynamic loads on the support nodes, which increases their service life.The only drawback is that twisted blades complicate the production technology, which, in turn, increases their cost.

Conclusions
The use of RES, in particular WEI, is currently a very promising direction of energy development in Ukraine.The prospect exists not only in areas with high wind speeds, but also throughout the territory of Ukraine.Everything depends on the design of wind energy installations and their location.It has been proven that it is expedient to use WEI with a vertical axis of rotation.Which begin their work at low wind speeds, and for their placement you can use man-made disturbed lands, which for a number of reasons are not subject to reclamation and further use for agricultural purposes.As an illustrative example, the calculation of the wind energy potential for vertical and horizontal WEI in the conditions of the city Kryvyi Rih was made.From the calculation, it can be seen that the use of vertical WEI is more effective and that their efficiency increases with height, therefore it is advisable to install them on rock dumps.

Table 1 .
[4]se of wind energy installations with a horizontal axis of rotation of small and medium power at the base of the mast[4]

Table 2 .
Growth factors of average wind speed with height

Table 3 .
Number of windy days with different wind speeds in the city Kryvyi Rih in 2021 on

Table 4 .
Calculation of the average annual wind speed at a height of 20-100 m for the conditions of

Table 5 .
Calculation of the wind energy potential for vertical and horizontal wind energy installations in the conditions of the city Kryvyi Rih for 2021