Prospects for the application of a small wind power device with a vertical axis in the Jizzakh region

. In recent years, renewable energy sources, especially wind energy, have been widely used around the world. Big projects are being implemented in Uzbekistan for the development of wind energy in the next decade. Large wind power plants are being built in different regions of the country such as Navoi, Bukhara, and Karakalpakstan. In these wind power plants, horizontal type wind energy devices are mainly used for the production of electricity. Horizontal-axis wind energy devices are used not only in the production of large capacities, but also in providing local consumers with small capacities. However, the share of electricity generation or supply of local consumers with the help of small vertical axis wind energy devices is much smaller. In this article, analyzing the potential of wind energy in Jizzakh region, the prospects of using small vertical wind energy devices are theoretically researched.


Introduction
The population of the Earth is increasing from year to year, and the amount of electricity consumed by them is also increasing [1][2][3].To meet the ever-increasing energy consumption, extensive use of renewable energy sources in addition to existing fuels is the need of the hour [4][5][6].The source of energy of the world since 1970 and its trained until 2040 is shown in Fig. 1.It can be observed that oil, gas, and coal were the main source of energy for the last five decades and similar trend is projected for the coming decades [7][8][9][10].
Annual renewable capacity additions are forecast to increase continuously over the forecast period, reaching a record 460 GW in 2027 in the main case, 60% higher than last year's growth [11][12][13][14][15].At the end of the forecast period, solar PV and wind provide the vast majority of global renewable capacity additions in 2027, accounting for nearly 95% as technologyspecific challenges and limited policy support hamper faster expansion of hydropower, bioenergy, geothermal, CSP and ocean technologies Fig. 2. Wind is a readily available renewable free and sustainable energy source [16][17][18].In every single day around the world, the wind energy is seized and converted using wind turbines into electricity [19][20].Wind energy is one of the best renewable energy which can potentially substitute the fossil fuels with no gas emission and water consumption, and in little land space [21][22][23].The increase in demand for energy resources on a global scale has given a great impetus to the development of wind energy.
An estimated 102 gigawatts (GW) of wind power capacity was installed globally in 2021 -including more than 83 GW onshore and almost 19 GW offshore.Total additions were up around 7% relative to 2020 to the highest level to date, with annual offshore installations almost three times their previous high.By year's end, total global wind power capacity rose 13.5% over 2020 to surpass 845 GW (791 GW onshore and the rest offshore) [24][25].Wind power capacity in operation around the world contributed an estimated 7% of total electricity generation in 2021 fig 3. 93.6 GW of new wind power capacity was added worldwide in 2021, only 1.8% lower than the 2020 record, bringing the total installed wind capacity to 837 GW, a growth of 12.4% compared to last year [26][27][28].Although new installations in the onshore wind market dropped to 72.5 GW last year, it was still the second highest year in history.The offshore wind market had a record year with more than 21 GW grid connected, three times more than the previous year, making 2021 the highest year ever Fig. 4. [29][30].
The top five global markets for new installations in 2022 were: China, USA, Brazil, Germany and Sweden.Overall, they accounted for 71% of global installs last year, down 3.7% from 2021 [31][32][33].This was primarily because the world's two largest markets, China and the US, lost a combined market share of 5% year-over-year, the second year in a row that both countries lost market share [34][35].Given the fact that water sources in the Central Asian region are declining, it is important to accelerate the use of alternative energy.Uzbekistan has the opportunity to use wind energy, but previously this renewable energy sector was not among the priority areas for the development of local energy.At the beginning of the 21st century, national and foreign experts summarized previously known information, conducted a new series of observations necessary to assess the local and regional environmental situation, the risks associated with the movement of air masses (about 90 meteorological stations operate on the territory of the country, which provided the results of systematic observations for 1994 -2004 and other periods, mainly at altitudes up to 10 m).As a result, in the mid-2000s, the gross potential was estimated at 2.2 million toe. per year, technical -0.4 million toe. per year (five times less), and economic -as "Insignificant".Below in the figure 5. one of the variants of the wind map of the Republic of Uzbekistan is shown.Its analysis allows a general idea of the nature of the distribution of wind energy potential within the territory of the country.Promising development areas include the Navoi region and sites located in the Republic of Karakalpakstan near remote settlements and the small industrial zone "Muynak" (created in 2017 on the territory of the former "Muynak fish cannery" and the largest in Central Asia).From a technical point of view, according to the recommendations of the researchers, the most optimal solution is the use of wind turbines with a capacity of 3 MW and a rotor diameter of 100 m. specific capital investments in the creation of 1 MW of wind power capacity were estimated at 1 million US dollars (comparable to the same indicator for thermal power plants), the cost of wind power was approximately 5.5 q/kWh.In the Republic of Uzbekistan, in cooperation with international financial institutions, feasibility studies have been carried out in the field of widespread use of

Materials analysis of wind potential of the region
Uzbekistan, double landlocked country with no coastal area, consists of 25% mountainous valleys and 75% desert covered oasis.Therefore the average yearly wind speed on the whole territory of the country is estimated between 2-2.5 m/sec, which indicates a nonpromising future for wind power engineering in Uzbekistan, especially for wind turbines of middle and high power.Consequently the wind energy potential in Uzbekistan is relatively less exploitable in comparison with the solar and hydropower potential (Table1).Even in the provinces with areasonable potential wind resource is very seasonal and it is necessary to study the coincidence between peak wind months and the electricity demands.

Table 1.
Jizzakh region is located in the central region of Uzbekistan.The region borders on the Republic of Kazakhstan in the north and northeast, Syrdarya region in the east, the Republic of Tajikistan in the east and southeast, Samarkand region in the south and southwest.and Navoi region in the west.Air currents that affect the climate of the region are predominantly northwestern and southwestern air currents.The northwesterly air flow comes from the north from the western part of Russia and Kazakhstan and is 34.5 days a year.The south-west air flow also has a great influence on the climate of the region and is 63.2 days a year.Fig. 7. shows the direction of the north-western air flow entering the territory of the Jizzakh region [7][8][9].Around the world, horizontal wind turbines are mainly used in the production of large-scale electricity from wind energy.It is also possible to use a horizontal type wind power device to supply electricity to household consumers.When using a horizontal type wind power device, it is necessary to take into account the speed, direction and frequency of the wind.The use of horizontal wind turbines in areas where the direction and speed of the wind changes is technically and economically inefficient.In regions with variable wind direction and speed, it is effective to use vertical wind power devices.The advantages and disadvantages of vertical wind energy devices can be listed as follows: VAWT advantages -No yaw mechanisms is needed.
-VAWTs have lower wind startup speeds than HAWTs.-VAWTs may be built at locations where taller structures are prohibited.
Despite the existence of different constructions vertical type wind energy devices, they can be divided into two large groups: Savonius vertical wind turbines and Darrius vertical wind turbines.Savonius turbines working on the aerodynamic drag principle and excellent in areas of turbulent wind and can self-start at low wind speed.Darrieus turbines were operating on the principle of lift.The efficiency of Savonius type wind turbines is lower than that of Darrius type wind turbines.According to Betz's law, the efficiency of the Savonius turbine is up to 20%, and the efficiency of the Darrius wind turbine is up to 40%.

Discussion and results
Unlike other energy sources, wind energy efficiency is high.Therefore, the theoretical and technical potential of wind energy is taken into account when using wind energy potential.The theoretical potential of wind energy is determined by the following expression: here, ρ is air density, kg/m 3 ; T = 8760 hours during the year; S -area surface, m 2 ; v -i multi-year wind speed in the range; t -I approximate wind speed in the range.
Technical potential of wind energy: here,  -the average power of the wind turbine and it is expressed as follows: here, ɳ efficiency index of VAWT here,  -wind energy utilization factor; ɳ -mechanical efficiency of the wind turbine; ɳ -electrical efficiency of the wind turbine.
The amount of electricity produced by a wind turbine: Useful power of the wind turbine: Flow-specific power,  0,5   v In the production of electricity from wind energy, the working range of wind speed is used.This working range should not exceed 25 m/s.This speed is equal to 9 points on Beaufort's 12-point scale.Wind turbines generally operate between 3 and force 10 on the Beaufort scale and the rated capacity is commonly defined at forces 6/7 depending upon the wind turbine type Table 2.

Table 2.
Fig. 9. based on the data presented in the annual average wind speed at a height of h=10 m is in the range of 8-10 m/s, 5 points on the Beaufort scale, the annual average wind speed at h=50 m is 10-12 m/s , corresponds to 6 points on the Beaufort scale.The 6point scale, calculated according to the Beaufort scale, corresponds to Dostlik, Mirzachol and Sh.Rashidov districts of Jizzakh region.[9][10][11][12] based on the information presented in the sources, the use of vertical wind power plants in Dostlik, Mirzachol, and Sh.Rashidov districts are considered more effective compared to other regions.The use of H-type turbines, which are modern modifications of the Darrieus wind turbine, is efficient compared to the Savonius-type vertical wind power plant.We will analyze some types of modern H-type vertical wind energy devices produced by different companies and their technical characteristics for regions with high wind potential.Companies that produce vertical small power wind energy devices offer wind energy devices with different capacities and characteristics.In particular, Aeolos company (Great Britain) Aeolos -V5 (1), UGE (USA) UGE Vision AIR 5(2), KESSLER (Germany) Kessler SPINWIND(3), Tianjin Galaxy Tech Co., Ltd (China) JX -H3 and JX -H5(4), Hi-VAWT ( Taiwan) DS-3000(5), Royall Products LLC (USA) WindSpire 5 kW, United Solar Technologies (Russia) Sokol Air Vertikal-5kW(6) models are among them (Fig. 12).Table 3. below shows the technical parameters of the vertical H-type wind energy devices named above [16][17][18][19][20].Analyzing the VAWT models presented in Table 3, it is possible to make sure that the models capable of operating at the smallest initial wind speed are Aeolos V5 (1.5 m/s) and Sokol Air Vertikal (2 m/s).The nominal speed of these models is 10 m/s (Aeolos V5) and 7.5 m/s (Sokol Air Vertikal).Compared with other VAWT models, these models are an optimal solution for using the wind potential of Dostlik, Mirzachol and Sh.Rashidov districts at a height of h=10 m.At a height of h=50 m, in addition to Aeolos V5 (1.5 m/s) and Sokol Air Vertical models, UGE Vision Air 5 and Kessler SPINWIND vertical wind energy devices can be a good solution for the above three districts.If we take into account that the wind potential in these districts is high and the annual average wind speed is up to 12.25 m/s, then DS-3000, JX-H3, and JX-H5 models can also be used for electricity generation.But for Dostlik, Mirzachol and Sh.Rashidov districts, Aeolos V5, and Sokol Air Vertical wind energy devices are the optimal options for electricity production using wind energy at heights of h=10 and h=50 m.Firstly, the starting speed of these models is small (1.5 and 2 m/s), and secondly, their nominal speed is equal to or less than the annual average wind speed at h=10 m and h=50 m.

Conclusion
This study provides information on the potential of wind energy in the world and in Uzbekistan, as well as on the projects launched to develop wind energy in the country.The data obtained from international databases, the wind energy potential of Jizzakh region was analyzed.Based on the conducted theoretical studies, it was determined that 3 out of 11 districts of the region have a high wind energy potential compared to other districts.The possibilities of using a verticaltype wind energy device for these districts were considered.As a result, it was theoretically analyzed that the use of Aeolos -V5, and Sokol Air Vertical wind energy devices in the production of electricity using the potential of wind energy in these districts is the optimal solution.

Fig. 5 .
Fig.5.Uzbekistan: Wind Speed Hazard Distribution Map.The first wind turbine with a capacity of 170 kW and a cost of more than 2 million US dollars was built in 2010 near the Charvak reservoir.Design documentation was prepared by Hydroproject OJSC, equipment was supplied by Doojin Co. (The Republic of Korea).The second (experimental, but the first large on the scale of Central Asia) Chinese-made wind

Fig. 6 .
Fig.6.Wind map of Uzbekistan by Intec-GOPA and Geo-NET wind energy and the "Concept of Electricity Supply of the Republic of Uzbekistan for 2020-2030" has been developed.One of the main goals is the construction of wind power plants with a capacity of 3000 MW by 2030 in the republic.Today, several projects on the construction of SPPs have been launched in Uzbekistan.Including: Based on an agreement signed on April 1, 2021, Masdar Clean Energy of the United Arab Emirates and the Ministry of Energy of the Republic of Uzbekistan reached an agreement on the construction of a 500 MW wind farm in the city of Tomdi district of the Navoi region.With a project cost of $600 million, the wind farm will generate 1.8 billion kWh of electricity per year at full capacity.Two more large projects are being implemented by ACWA Power Company of Saudi Arabia, and one of these projects, according to the contract signed between ACWA Power Company and the Ministry of Energy on January 23, 2021, provides for the construction of two wind power plants with a total capacity of 1 GW in Gijduvon and Peshkun districts of Bukhara region.The second project with the participation of this company is based on the agreement signed between the Ministry of Energy and ACWA Power (Saudi Arabia) on December 23, 2022 with the financial support of the European Bank for Reconstruction and Development, and works on the construction of another wind power plant with a capacity of 1500 MW in Beruni and Karauzyak regions of Karakalpakstan.When this wind farm is operational, it will produce 350 million kWh of electricity per year.On March 28, 2023, a memorandum of understanding was signed between China's CNEEC (China National Electric Engineering Company), China Huadian Overseas Investments, SANY Renewable Energy and the Ministry of Energy to study the possibilities of building wind power plants with a capacity of up to 1000 MW in Jizzakh region.According to this memorandum, 1 billion US dollars will be directly invested in the implementation of the project[4-6].

Fig. 7 .
Fig.7.The direction of the north-west air flow Based on the data obtained from the Global Wind Atlas international database, the wind energy density is high in Sh.Rashidov, Dostlik and Mirzachol districts of Jizzakh region at heights of h=10 and h=50 m, while it is low in Zamin and Zafarabad districts, fig.8.

Fig. 8 .
Fig. 8.It can be seen from the data that the wind potential in Dostlik, Mirzachol and Sh.Rashidov districts of Jizzakh region is higher than the rest of the districts.This will expand the possibilities of using vertical axis wind wind turbine in these districts.Based on the data obtained from the NASA POWER international geographic database and the MERRA-2 satellite, the annual average wind speed in the Jizzakh region at a height of h=10 m for different districts in 2019 is 9.02 -10, 56 m/s, in 2020 7.94 -9.96 m/s and in 2021 it took values in the range of 8.42-9.8m/s.The annual average wind speed at h=50 m was 11.26 m/s to 12.25 m/s in 2019, 9.5 m/s to 11.05 m/s in 2020, and 2021 and it was from 10.3 m/s to 11.66 m/s Fig.9.[10-12].