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In autumn 2021, the world faced the first round of energy crisis [...]

Ukraine has enough biomass resources for biogas production. However, this energy potential is not used sufficiently. This research is aimed at examining the current experience of commercial biogas systems in the Europe Union and its adaptation for Ukraine. Special attention was paid to economic indicators, such as specific investment costs, production costs (biogas, biomethane, and electricity), and incentives. Using statistical data for the European Union and Ukraine, the biogas potential for Ukraine (based on European experience) was determined. The economic competitiveness of biogas production was evaluated compared to alternatives, such as photovoltaic, wind power, biomass, conventional fuels, and liquid biofuels. The results showed that biogas complexes have higher specific investment costs and produce more expensive electricity. It was highlighted that agricultural residues and industrial waste are sustainable feedstocks for biogas systems. A perspective biogas plant is a plant that is an integrated part of the circular bioeconomy that is based on organic residues. Biomethane production (as a substitution for vehicle fuel) combined with capture and utilization of carbon dioxide is a more profitable pathway. Awareness and perception of the importance of biogas are key factors for the development of the biogas industry. To develop an effective strategy for the biogas industry, it is necessary to create a positive image in order to raise awareness and knowledge of biogas technologies.

This article concerns the method of material consumption assessment of the cylinder-piston group of diesel engines in the biodiesel environment. The obtained experimental dependences of the wear coefficients on the example of the tribounit cylinder liner and the piston ring can be used to forecast the resource use during operation under specific conditions of the engine and the environment as a whole. The article systematizes the types of biofuels, depending on the type of raw materials from which they were made, taking into account the process and application. The physical and chemical aspects of the catalysts used for biofuels were indicated. The applied experimental methods for tribological wear of the piston-cylinder pair were analyzed. B70 biodiesel was used in the research, i.e., 70% mineral diesel oil and 30% methyl esters of rapeseed oil. Experimental tribotechnical studies of the influence of biofuels on the behavior of various materials have shown that when using this type of fuel, it is necessary to replace the materials from which some parts of the cylinder-piston group are made. To solve this problem, research has been carried out on a specially designed friction machine. The novelty in the article concerns the association, based on the literature, of hydrogen consumption causing material wear in friction contacts. The mechanism of the interaction of various construction materials during such friction has been disclosed.

The article deals with the study on the efficiency of units for porous ammonium nitrate production. The ways which increase the effective implementation of energy resources are determined by including the ejector recycling module, heat and mass exchangers that utilize principles of regenerative indirect evaporative cooling, and the sub-atmospheric inverse Brayton cycle. Mixed exergy analysis evaluates all flows of the system contour as those of the same value. The target parameter for determining the efficiency of both systems is the ratio of the unit’s productivity to the exergy expenditures to produce the unit mass of the product. As a result, it is found that the mentioned devices and units enable to increase the efficiency of the basic scheme by 87%.

The Ukrainian renewable energy sector has demonstrated a significant increase in its renewable power capacity, especially for solar and wind power plants. Decommissioning the end-of-life equipment in Ukraine has not yet taken place, but it is only a matter of time. With this in mind, this paper assesses the quantities and the market values of the materials that could potentially be recovered from used solar and wind power plants, and it estimates the impact of their decommissioning on employment in Ukraine. It has been estimated that approximately 8.9 GW of solar power plants, and 3.6 GW of wind power plants, will be decommissioned from 2044 to 2059, and that the cost of the raw materials recovered could reach EUR 421.4 million and EUR 124.6 million in 2021 prices, respectively, compared to the decommissioning costs of EUR 240.1 million and EUR 49.1 million, respectively. Decommissioning renewable power plants will require the creation of new jobs, including 11.6 thousand in the solar industry, and 2.8 thousand in the wind sector. It is essential to amend the legislation in Ukraine, particularly Directive 2012/19/EU, to introduce the principle of the extended producer responsibility to ensure the efficient recycling of renewable power plant end-of-life equipment in Ukraine in the future.

The use of fossil fuels (methane, oil, etc.) is undergoing an unprecedented crisis now. There is the urgent need to search for alternative energy sources. A wide range of degraded organic materials can be effectively used to provide energy together with environmental protection. Soapstock is a hazardous waste containing a high concentration of toxic organic compounds of man-made origin (fatty acids, surfactants, dyes, etc.). To prevent environmental contamination such substances require an effective treatment approach. The goal of the study was to isolate the adapted-to-fatty-acids methanogenic microbiome and investigate the patterns of sodium acetate and soapstock degradation with simultaneous biomethane synthesis. The effectiveness of the degradation of sodium acetate and soapstock by non-adapted and adapted microbiomes was evaluated by decreasing the concentration of dissolved organic compounds. The effectiveness of the fermentation process was determined by the biogas (mixture of CH4 and CO2) yield. The most effective degradation occurred in the variant with sodium acetate and adapted methanogens and amounted to 77.9%. In other variants, the patterns and the efficiency of purification were similar ranging from 60.6 to 68.0%. The biomethane was mostly synthesized by adapted methanogens on the soapstock and sodium acetate as substrates. Thus, the CH4 yield was 368.4 L/kg of dissolved organic compounds or 127.5 L/kg of soapstock. The results of this study demonstrated the potential of methanogenic microorganisms in the biodegradation of soapstock with simultaneous biogas synthesis. The results can serve as a basis to reduce the reliance on fossil fuels by generating biomethane via the fermentation of toxic organics.

This study describes a life cycle assessment (LCA) of a fourth generation (4G) nuclear power plant. A high temperature helium cooled reactor and gas turbine technology with modular helium reactor (GT-MHR) is used in this study as an example. This is currently one the safest design of a nuclear power plant. The study also takes into account impact of accidents and incidents (AI) which happened around the world at nuclear power generation facilities. The adopted method for the study is a hybrid LCA analysis. The analysis of each phase of the life cycle was done on the basis of process chain analysis (PCA). Where detailed data were not available, the Input/Output (I/O) databases was employed. The obtained results show that greenhouse gases (GHG) emissions and energy intensity per unit of electricity production are relatively low. In fact, these are even lower than emissions from a number of renewable energy sources. The results show considerably different greenhouse gases (GHG) emissions and energy intensity per unit of electricity production when effects of AI are taken into account.