• Energy Research

Calculations are made and energy parameters are compared for the actual operation data of three network photovoltaic power plants built in Russia by JSC Solar Systems. As the initial data for the calculations, the daily amounts of solar radiation and ambient temperature taken from the databases of NASA POWER, Meteonorm, and ERA5 have been used. The calculations have been carried out using a TRNSYS simulation environment, a specialized PVSyst engineering software package, and a HOMER Pro software package. In addition, we have used calculations based on a simplified technique including a linearized dependence of the photovoltaic module power on insolation and temperature implemented by means of Microsoft Excel. In all cases, we considered the efficiency of the network inverter depending on the transmitted power and the operating parameters of the module depending on the temperature. The results using each method have shown a good agreement with the actual output of photovoltaic power plants for the considered time periods. The best coincidence was observed for the case of TRNSYS, although the results vary depending on the source of the initial climatic data. Based on a simplified technique, an analysis performed concerning the output sensitivity with respect to the inverter efficiency factor and with respect to the temperature dependence of the power of photovoltaic modules showing that the method taking into account the ambient temperature makes a considerable contribution to the error of the results. The calculation results demonstrate that one could use engineering methods with a linear approximation of the photovoltaic module power depending on insolation and temperature in order to estimate the output of network power plants; however, of great importance is choosing the initial climatic data.

Hydrothermal liquefaction of different microalgae samples ( Arthrospira platensis cultivated by our research group) – fresh (directly after harvesting), dried and frozen – have been performed. In hydrothermal liquefaction process, the samples were heated up to 300°C for 30 min and kept at a constant temperature for 60 min. Then dichloromethane was added to the samples to extract the oil fraction. The products obtained after aqueous and dichloromethane solutions evaporation are referred to as water soluble organics and bio-oil correspondingly. The experiments on hydrothermal liquefaction of microalgae pre-treated in different ways were conducted for three independent harvest samples. The average values of bio-oil yield in the experiments with fresh, dried and frozen microalgae were equal to 44.07%, 39.97% and 39.65%, respectively. The average yields of water soluble organics were equal to 19.34%, 29.00% and 21.43% respectively. In all the experiments, the highest yield of bio-oil was reached for fresh microalgae. From this point of view, direct hydrothermal liquefaction processing of fresh microalgae seems to be more preferable that further enhances the advantage of hydrothermal liquefaction in comparison with other biomass-to-biofuel conversion methods.

The Republic of Kazakhstan has significant deposits of fossil fuels and is one of the largest energy producers among the countries of Central Asia. At the same time, The Republic of Kazakhstan is one of the richest countries of the world in terms of renewable resources, evaluated to over 1000 billion kWh/year. The application of therenewable energy sources (RES), both on a large scale and at the level of a single household, ensures the transformation of the energy system to a “green state”. However, these initiatives should be substantiated by relevant supportive information to promote transformation of the country's economy to a qualitative ecological state.The paper covers developed multi-criteria decision-making system (MCDM) and software tools for processing of spatial heterogeneous data which could be applied for evaluation of the RES potential.The developed system serves to evaluate the potential of usable RES as it allows the assessment of a territory of the country in terms of installing photovoltaic and wind generators.A feature of the proposed MCDM is the use of an analytical hierarchical process (AHP) in combination with the Bayesian approach, which allows obtaining two complementary assessments of the territory areas. The method allows a rough estimate in an event of lack of data.The verification performed based on the available data on the installed solar and wind power stations shows that the system gives a relatively small root-mean-square error within 15%.

The paper presents the results of an experimental study of the efficiency of the integrated controllers of PWM and MPPT PV/batteries, which are part of an autonomous photovoltaic power plant. The dependences of the efficiency on the hourly sums of solar radiation are represented, which can be used to calculate the productivity of autonomous photovoltaic systems with an hourly integration step. The operational features of the controllers during low-level periods of solar radiation are considered.

This work is devoted to the wave energy in the Caspian Sea analysis for the period from 1979 to 2020. Wave energy calculations were performed using the WAVEWATCH III wave model on an irregular grid with a step of up to 900 m in the coastal zone. Results are obtained on the spatial variability of the wave energy flux and its seasonal variability. The maximum values of the energy flux are about 5 kW/m of the wave front and appear in the central part of the Caspian Sea. Availability of wave energy of 1 kW/m in the central part of the Caspian Sea is 50-55%, in the northern part – no more than 20%, and in the southern part – 30-45%. The seasonal variability of the energy flux analysis for three points located in different parts of the sea has been carried out. Seasonal changes in the energy flow are most pronounced in the central part of the sea: in the summer months, the energy flow is 2-5 kW/m, and in winter it increases to 7-10 kW/m. The maximum average monthly flow of wave energy was 18.5 kW/m of the wave front.

Scientific, educational, cultural and educational network Journal

Abstract The problem of hydrogen production using renewable energy sources in the world and in Russia is considered. Preliminary estimates of possible volumes of hydrogen production and of carbon dioxide emission reducing in the coastal regions of the North and East of Russia using wind power plants have been carried out. Based on the calculations of the wind characteristics variability over a 30-year period for the Sakhalin Peninsula, an analysis of possible interannual and within-year variability of the capacity factor was accomplish. Estimates of the prospects for reducing of CO2 emissions due to the potential for green hydrogen production using wind power plants energy as an alternative to fuel power plants in regions of Russia are completed.

Presents the results of the cereals waste energy potential assessment for the municipalities of the Krasnodar region. The gross and technical potential of cereals waste (straw), calculated according to the author’s methodology and correlated with the needs in thermal energy for the population of the studied region. The obtained results show a significant amount of technical heat potential for many municipalities of the region. The spatial distribution obtained with the help of geoinformation technologies makes it possible to determine the most promising areas for the use of cereals waste for the thermal energy production. Also assessed the prospects for replacing traditional fuels such as coal, diesel fuel, natural gas and heating oil with straw energy. The possible environmental effect from the replacement of hydrocarbon fuel for the municipal districts of the Krasnodar region was calculated.