The article describes the history of the organization and management of Young researcher’s schools on Renewable Energy, held at the Faculty of Geography of the Lomonosov Moscow State University since 1999 The analysis with the compilation of infographics of the main directions of the topics of reports and the geography of the participants of the scientific Young researcher’s schools "Renewable energy sources" for a 20-year period was carried out.

The most widely presented reports were on solar and wind energy, as well as on economic and ecological problems of renewable energy sources (RES) development. In recent years, new thematic areas have arisen: storage systems, management of energy facilities and networks based on renewable energy sources, the use of GIS technologies. An in-crease in the number of reports on research supported by RFBR is shown. The scientific review of the articles of the participants of the All-Russian Scientific Conference and the XII Young researcher’s schools on RES, held on November 24-25, 2020 in MSU, published in this issue of the journal, is presented.

The article discusses the original designs of solar photovoltaic thermal modules of planar and concentrator design, intended for stationary and mobile power generation. The modeling of the developed modules in the system of finite element analysis is considered, as well as the results of studies of a planar photovoltaic thermal roofing panel and concentrator photovoltaic thermal modules with paraboloid and folding parabolic-cylindrical concentrators. As a thermodynamic converter of solar energy, the Stirling engine is proposed as а part of the photovoltaic thermal concentrator installation, the test results of which are also presented in the article. The developed thermo-photoelectric modules of the planar and concentrator design make it possible to produce autonomous or parallel power supply to consumers. The use of parabolic concentrators, high-voltage matrix photovoltaic converters, as well as a two-component poly-siloxane compound in the designs of thermal photovoltaic modules increases the overall efficiency of solar modules and their service life. In addition to generating electrical and thermal energy, roofing panels also provide the construction and protective function of buildings, and the use of recycled plastic in their basis allows solving problems with its secondary use and reduces the cost of production. Thermal photovoltaic concentrator solar modules with Stirling motors have a significant potential, the electrical efficiency of which can be higher than the electrical efficiency of photovoltaic converters, and the service life would not be less than the service life of photovoltaic converters.

The paper presents thermal and hydraulic analysis of a flat solar collector using CFD-simulation in order to study the influence of the weather conditions (wind velocity) on the collector operation efficiency. Simulation was made with CFD Solidworks Flow Simulation using standard tools of solar radiation simulation and considering the effect of wind. The result obtained is the dependence of the heat carrier temperature difference at the collector inlet and outlet on the operating time for the different values of wind velocity.

Modeling the operation of a flat solar collector was carried out under the influence of solar irradiation in the range from 149 W / m² to 1019 W / m², which corresponds to the minimum and maximum solar radiant heat flux in the city of Moscow. The impact of the wind in the speed range from 0 to 4 m / s, also most typical for Moscow, was considered. With an increase in the wind speed to 4 meters per second, a drop in temperature drop by 26.46% was recorded relative to calm weather. Under the influence of wind, the heat transfer coefficient averaged over the outer surface of the solar collector varied in the range from 5.172 W / m² K to 11.571 W / m² K.

The results obtained show that the presence of wind significantly affects the efficiency of converting solar energy into thermal energy, therefore, when choosing a place for installing a solar collector, it is necessary to take into account not only the angle of incidence of solar radiation, but also the wind rose.

The stochasticity of the wind potential and solar insolation can be taken into account when designing the structure and installing the SC at a specific object. The above research results allow us to assert an increase in efficiency by 812% when performing additional. wind protection measures for flat collectors.

Since the performance of solar power plants is quite variable, the dependence of production on weather conditions significantly increases the need for accurate forecasting. At present, the formation of a new approach to the development of predictive models of the performance of solar power plants based on artificial neural network algorithms is acquiring special relevance. The advantages of artificial neural networks in forecasting, such as the ability to learn and take into account a set of parameters that are not in a functional connection, make it possible to successfully use them in the development of models of the performance of solar power plants. The analysis of existing developments is carried out and promising areas of application of artificial intelligence algorithms in solar energy are determined. To simulate the performance of a solar concentrator module, a two-layer artificial neural network with sigmoid hidden neurons and linear output neurons has been developed. The developed performance model of a solar concentrator module based on an artificial neural network makes it possible, with a significant approximation, to determine the thermal efficiency of a solar module depending on various external conditions and operating parameters.

Microalgae biomass is one of the most promising sources of renewable biofuels. The fuel produced from microalgae is called "third-generation biofuels". This type of biomass is not the main raw material for food and is usually grown in areas unsuitable for crop production. The productivity of microalgae (per unit area used for cultivation) with biomass and fats (lipids) is ten times higher than the corresponding yield of terrestrial biomass. In recent years, hydro thermal technologies have attracted increasing attention as promising ways to process microalgae biomass into biofuels. However, the most attractive technology is hydrothermal liquefaction (HTL) of microalgae to produce liquid biofuels (bio-oil) as the target product. One of the main advantages of GTS technology is that not only lipids, but also carbohydrates and proteins contribute to the yield of bio-oil, which increases the overall yield of the product. In this paper, an experimental study of the hydrothermal liquefaction (HTL) process of microalgae biomass Arthrospira platensis was performed to obtain mass data on the yield of products and further study of the products of this process using thermogravimetric analysis and calorimetry, with the determination of the effect of process parameters on the yield and quality of products.

The article considers the design features and operating modes of KVM-4.0D hot water boilers, analyzes their technical, economic and environmental indicators when changing the heat output in the range from 0.32 to 1.15 of the nominal value. The fractional composition of fuels, ash and slag has been investigated. Durability of the pellets have been tested as well as its change when the granules pass through the fuel supply system. The content of combustible substances in ash and slag and the effect of underburning of combustible substances in various fractions of combustion residues on the carbon loss have been determined. Thermal analysis of wood pellets was carried out. The components of the heat balance have been determined. Recommendations for further improving the energy and environmental performance of hot water boilers are proposed, which create the basis for improving the designs of heat-generating plants operating on wood pellets. After constructive revision associated with the installation of an additional line for recirculation of exhaust flue gases under the grate, the KVm-4,0D boilers ensured efficient combustion of wood pellets with technical, economic and environmental indicators exceeding those of Austrian hot water boilers of the same capacity. Considering that the focal residues of these boilers contain a significant amount of CaO and a large amount of fine particles less than 45 microns in size, these dust particles have an increased health hazard for the boiler house operator. To maintain high technical, economic and environmental performance of the boilers, it is necessary to ensure periodic monitoring of the density of all elements of the gas path and the ash removal system, as well as regular cleaning of industrial premises. The studies carried out have shown that these boilers are not recommended for long-term use in operating modes with low load, since such modes are accompanied by increased values of carbon monoxide emission, and, consequently, heat losses with chemical incompleteness of combustion due to high air excess ratios.

It is proposed to use, on the basis of the experience of developed European countries and the United States, the cofiring technology in boilers of small and medium power. A comparison of the prospects for using traditional coal with solid fuel compositions from local types of fuel and organic waste (biomass) is considered. The results of experimental studies on the change in ash content, volatiles yield depending on the amount of biomass in the total balance of solid fuels during their co-combustion are shown. Calculations of the required amount of fuel for combustion in a boiler house with a capacity of 400,000 Gcal / year have been carried out. The high yield of volatiles and the relatively low ash content, as well as the availability compared to coal in terms of supply from the mining site to the consumer, make peat and sawdust a promising fuel for small and medium-sized boiler houses in areas with low gasification. At the same time, peat and sawdust can be used as an additional fuel to the main one, and the main one during monocombustion. In addition, the conversion of boiler houses from coal to peat or sawdust does not always require reconstruction and significant investments, the size of which can be estimated for each specific boiler house, and in some cases such a transfer can be completely non-investment. Peat and sawdust can be considered as an additional resource in solving the problem of finding affordable energy raw materials.

The global trend of decarbonization of the economy can have a significant impact on the main exporters of the Republic, since the use of coal generation significantly increases the carbon intensity of manufactured products, and the widely discussed introduction of cross-border carbon regulation by the EU countries will potentially reduce the competitiveness of energy-intensive products of Kazakhstani producers in the European market. More than 80% of the country's electricity is generated by coal-fired thermal power plants. The development of renewable energy can serve as one of the directions for achieving the goals of reducing greenhouse gas emissions both at the country level and for large industrial producers. Renewable energy installations are characterized not only by a lower environmental load, but also by design flexibility. Currently, studies devoted to the regional analysis of the territory from the point of view of the applicability of renewable energy are especially relevant. The current study will present an attempt to analyze the energy supply potential of the regions of Kazakhstan based on fossil fuel and renewable energy plants (solar and wind power plants). The use of spatial analysis tools made it possible to take into account the factors contributing and limiting the construction of wind and solar stations, as well as to calculate the territories available for design in the regions of Kazakhstan. The estimates of the potential average annual specific productivity of typical solar and wind power plants allowed us to conclude that wind energy is more competitive than solar (WPP - from 63 to 342 MWh / year / km², SPP - from 41 to 68 MWh / year / km²). As a result of the study, energy-deficient regions were identified: Akmola, Turkestan and Kostanai, where the development of renewable energy is most promising. The study carried out a comparative analysis of the present value of generated energy at renewable energy stations with the value of tariffs of energy supplying organizations in the regions of Kazakhstan. According to the calculation results, the present value varies from 5.7 to 7.9 rubles / kWh for SPP and 0.8-2.6 rubles / kWh for wind power plants.

In the vast majority of cases, hydraulic ash and slag removal systems are used for conveying ash and slag at the coal-fired thermal power plants (TPPs) in Russia. Such technical solutions related to the evacuation of slag from boilers and transportation of fly ash after electrostatic precipitators have been replicated since the Soviet times. Hydraulic ash and slag removal systems cause significant damage to the natural environment in the area of coal-fired TPPs location. It should be noted, that the average age of TPPs is about 45-50 years. The inter-repair period and reliable operation of pipelines of TPP ash and slag removal systems significantly depend on abrasive wear, which is one of the main problems when transporting fine bulk materials like ash and slag. Abrasive wear or erosion in pipelines leads to a decrease in the reliability of the entire wet ash removal system; there is a need for the unplanned downtime caused by fistulas in pipelines, resulting in the release of ash and slag slurry into the environment. In addition, the thinning of the c'u'u pipeline wall thickness leads to the increase in the diameter of pipes, which, in turn, leads to deterioration in the eco- au'a nomic efficiency of transporting the ash and slag slurry.

The article deals with the problem of abrasive wear of slurry pipelines of TPP ash and slag removal systems. Based on the research results, the main measures for extending the service life of straight and shaped sections of pipelines of TPP wet ash and slag removal systems are described. In order to reduce the intensity of abrasive wear, it is possible to apply regime measures that do not require investment in the reconstruction of existing hydrotransport installations. These measures include: turning the straight horizontal and inclined sections of pipelines around their axis; transporting the slurry with optimal parameters. In addition to the mentioned group of measures, constructive measures are considered that require investment in the reconstruction of hydrotransport installations to varying degrees, such as: optimizing the shape of curvilinear sections of pipelines; performing sections of hydrodynamic flow stabilization at the entrance and exit of the curvilinear (shaped) sections of pipelines, taking into account the zone of maximum wear; anti-abrasive inserts in the shaped sections of pipelines; stone-cast products; pipes with an aluminum-thermal coating. The maximum effectiveness of implementing anti-abrasive recommendations is achieved by combining regime and constructive measures.

The article examines the impact of renewable energy sources development on increasing the energy security level of the country, energy security risks and threats. The main hypothesis of the study is the presence of renewable energy influence on energy security level of the Republic of Belarus. In the course of the study, the existing indicators of energy security, formed in the Concept of Energy Security of the Republic of Belarus, and the existing methodology for assessing the energy security level in the country were considered. Information on the installed capacity of power plants based on renewable energy sources in the country and the energy they generate was collected; factors that accelerated the development of the most popular areas of renewable energy in the country have been identified. On the basis of the existing indicators of energy security, an integral indicator was developed and calculated. The calculation results indicate a gradual increase in the level of energy security of the Republic of Belarus in the period from 2010 to 2018. The main hypothesis was tested using the correlation analysis. Based on the previously calculated values, a correlation matrix was built and the values of the correlation coefficients were determined. Correlation analysis showed the presence of a strong positive relationship between the installed capacity and energy production from renewable sources, on the one hand, and the integral indicator of energy security and its individual blocks, on the other hand. Renewable energy sources have the greatest impact on such blocks of energy security as energy independence, energy efficiency of final consumption of fuel and energy resources and economic sustainability of the fuel and energy complex. The statistical significance of the correlation coefficients was checked using the Student's t-test and showed the high significance of the results obtained. Based on the results of the study, it can be concluded that the development of renewable energy sources has a significant positive impact on the level of energy security of the country and, accordingly, the possibility of reducing the risks and threats to which the energy industry is exposed through the development of renewable energy. The work may be of interest to scientists and teachers, specialists, graduate students and students in the field of energy.

Over the past half century, there has been a steady increase in the share of electricity generated by renewable energy sources. For the regions of the Russian Federation, in the economy of which agriculture plays a significant role, it is important to use crop waste for the purpose of their further processing and use as a source for electricity generation. In a number of articles, the analysis of resources at the regional level is carried out only on the basis of statistical data summarized by administrative divisions. In this paper, a methodology based on the use of remote sensing data of the earth is considered, which allows localizing the source of energy resources (fields of grain crops). The technique was implemented for the Ryazan region. The selection of the contours of agricultural fields is based on the multitemporal satellite images of Landsat-8 and Sentinel-2, which depict agricultural fields at different stages of the growing season. Since most types of grain crops are characterized only by the course of vegetation development, which is accompanied by a change in spectral characteristics, it is possible to separate grain from other types of agricultural crops. On the basis of well-known formulas, the energy potential of individual fields was calculated. Agricultural enterprises of animal husbandry in the region were chosen as places where concentration and processing of grain crops wastes is possible. Based on the road graph of the Ryazan region, the Location-Allocation problem was solved. As a result, on the basis of the shortest distance along the road network, the belonging of each field to a certain processing point was determined. This problem was solved for 3 cases: 100, 50 and 10 processing enterprises. The results showed how much the difference is between the energy potential calculated on the basis of administrative statistics and the energy potential calculated using remote sensing data and network analysis.

The current upward trend in electricity demand determines the need to explore and apply alternative methods of generating electricity. At the same time, with an increase in the unit capacity and the share of renewable generation in the total installed capacity, studies aimed at a systematic study of the influence of the implemented facility on the parameters of the operating mode of the electric power system acquire relevance. A number of optimization tasks aimed at determining the optimal location and size of the generation units being implemented in terms of reducing power losses and maintaining an appropriate voltage level in the nodes of the power system can be noted here. Within the framework of this article, a variant of solving the indicated optimization problem for a typical 15-node IEEE scheme is presented by means of a software calculation using the bubble sorting method. On the way to achieve this goal, the following tasks were solved: an objective function was formed, which serves as an indicator of the optimality of the location and size of the generation units; limiting criteria are defined, such as voltage tolerance; the software implementation of the algorithm for calculating flows and power losses using the bubble sorting method has been carried out. The results of the work of the program code for two scenarios, in particular installation of one renewable generation unit with a different range of possible capacities, are presented and compared with the data obtained in the MATLAB / Simulink software.