In response to the problem of increasing climate change and energy security, investment in renewable energy sources has increased significantly both in Europe and globally. Wind and solar power plants are expected to be the largest contributors to global decarbonization, ranking first and second in projected capacity by 2050. As all power plants have a certain impact on the environment, so do PV power plants, and due to their planned large capacities, it is necessary to assess their impact on the environment. Improving the manufacturing technology of PV system components, increasing the efficiency of solar cells, and using materials that are less harmful to the environment will reduce these impacts. Manufacturing PV system components is a highly energy-intensive process that involves greenhouse gas emissions. As new renewable energy capacity is built, the amount of “green” electricity on the grid increases, reducing CO₂ emissions per kWh consumed. The objective of this paper is to analyze the current status of the environmental impact of PV power plants under these changing conditions in terms of CO₂ emissions, land use, pollutant and noise emissions, and water consumption. The capacity installed to date will reach the end of its lifetime by 2050, which means that the amount of waste associated with it will increase over time. This can have a significant impact on the environment, which is why part of the work is dedicated to this problem. In addition to the available information from the literature, the authors also made their own estimates of land use based on data on newly installed PV power plants and PV modules available on the market. The results of the analysis show that there is enough land both in Europe and worldwide to install the planned capacities of rooftop and ground-mounted PV power plants. CO₂ emissions are at the same level as for concentrated solar power, with a decreasing trend. Pollutant emissions, noise, and water consumption are not major problems compared to other types of power plants. Overall, it can be concluded that the expansion of PV capacity has a very positive impact on the environment.

In response to the problem of increasing climate change and energy security, investment in renewable energy sources has increased significantly both in Europe and globally. Wind and solar power plants are expected to be the largest contributors to global decarbonization, ranking first and second in projected capacity by 2050. Since all power plants have some impact on the environment, this also applies to photovoltaic power plants. Because of the large capacities projected for PV installed capacity, their environmental impacts should be evaluated. The environmental impacts of PV power plants change over time. Improving the manufacturing technology of PV system components, increasing the efficiency of solar cells, and using materials that are less harmful to the environment will reduce these impacts. Manufacturing PV system components is a highly energy-intensive process that involves greenhouse gas emissions. As new renewable energy capacity is built, the amount of "green" electricity on the grid increases, reducing CO2 emissions per kWh consumed. The objective of this paper is to analyze the current status of the environmental impact of PV power plants under these changing conditions in terms of CO2 emissions, land use, pollutant and noise emissions, and water consumption. The capacity installed to date will reach the end of its lifetime by 2050, which means that the amount of waste associated with it will increase over time. This can have a significant impact on the environment, which is why part of the work is dedicated to this problem. In addition to the available information from the literature, in the part related to land use, the authors also made their own estimates based on data on newly installed PV power plants and PV modules available on the market. The results of the analysis show that there is enough land both in Europe and worldwide to install the planned capacities of rooftop and ground-mounted PV power plants. CO2 emissions are at the same level as for concentrated solar power, with a decreasing trend. Pollutant emissions, noise and water consumption are not a major problem compared to other types of power plants. Overall, it can be concluded that the expansion of PV capacity has a very positive impact on the environment.

This Vertical-axis wind turbines (VAWTs) are emerging as promising alternatives to conventional horizontal-axis wind turbines (HAWTs) for renewable energy generation, particularly in urban and offshore environments. Despite increasing interest, a comprehensive evaluation of their technical, economic, and environmental performance remains limited. This review, based on a targeted literature search, critically evaluates and compares the performance, economic viability, environmental impact, technological advancements, and adoption barriers of VAWTs and HAWTs. VAWTs demonstrate lower aerodynamic efficiency (20–35%) and capacity factors (20–35%) compared to HAWTs (efficiency 40–50%, capacity factors 30–45%), yet offer advantages such as omnidirectional wind capture, simpler ground-level maintenance, lower noise emissions, reduced avian impact, and greater feasibility for space-constrained urban settings. Economic analyses indicate that VAWTs typically have higher levelized costs of energy (60–80 EUR/MWh) than HAWTs (40–60 EUR/MWh), although these are partially offset by reduced operational costs. Environmental assessments favor VAWTs in terms of land use, biodiversity impact, and water consumption. Technological progress, including AI-based aerodynamic optimization, hybrid rotor designs, advanced composite materials, and Maglev bearings, has enhanced the competitiveness of VAWTs. The main adoption challenges are lower power output, scalability constraints, and lack of support from policymakers. While HAWTs remain dominant in large-scale wind energy production due to superior aerodynamic performance and economies of scale, VAWTs offer significant benefits for decentralized, urban, and offshore applications where installation flexibility, noise, and environmental considerations are critical. Continued innovation and more policy support could increase VAWT market penetration and contribute to more diversified, sustainable energy portfolios.

The use of heat pumps is increasing worldwide, and knowledge of their properties is becoming more and more important. Although numerous tests regarding heat pumps have been performed, due to the large number of influencing variables, the entire range of input parameters is not covered, and there is no overall picture regarding the range of the coefficient of performance (COP) of heat pumps and their output parameters. This study extends existing research and provides a much more detailed comparison of results for the application of R1234yf and R1234ze(E) refrigerants, including the pressure drop across the evaporator, condenser, and internal heat exchanger (IHX). The appropriate mathematical model for the selected components was defined and verified experimentally. A total of 60 series of measurements were performed at different evaporating and condensing temperatures. The deviation of the numerical simulation results from the experimentally determined results was up to 7.4% for cooling capacity, 8.1% for heating capacity, 7.2% for COP and 6.8% for compressor energy consumption. This study shows that COP increases from 4.77% to 10.73% for R1234ze(E) compared to R1234yf. The use of an IHX in the thermal cycle further increases COP for both refrigerants between 2.61% and 4.99%.

Algal biodiesel is a promising renewable energy source due to its high lipid productivity and environmental benefits compared to conventional diesel fuels. This study presents a SWOT technique (strengths, weaknesses, opportunities, and threats) and an analytical hierarchy process (AHP) to assess the current status and future prospects of algae-based biodiesel production. Data from the last decade on algae production was analysed, highlighting significant technological improvements such as genetic engineering, novel extraction techniques, and integration with circular economy approaches. The results show that algal biodiesel can achieve a lipid content of up to 75% of dry biomass and reduce greenhouse gas emissions by up to 90% compared to fossil diesel. Key strengths include high biomass yield and effective CO₂ sequestration, while challenges include scaling production and reducing capital costs. Opportunities lie in product diversification and policy support, while threats include competition from battery electric vehicles and regulatory barriers. The AHP analysis provides a quantitative framework for prioritising strategies to improve the economic viability and environmental sustainability of algae biodiesel. In the short term (by 2030), algae-based biodiesel is expected to be used mainly as a blend with fossil diesel and to gain traction in niche applications where electric vehicles face competitiveness challenges (marine and heavy road transport). In the long term (by 2050), algae-based biodiesel will play a role in certain sectors that are integrated into the circular economy.

When designing a heat pump evaporator, it is necessary to use correlations that ensure small deviations of the designed and realized process parameters for specific input data. The aim of the work is to propose a suitable mathematical model for the physical process in the tubular evaporator of the heat pump. The applicability of the proposed mathematical model in the design of the heat pump was evaluated by comparing the results obtained from the experimental tests of the tubular evaporator of the heat pump with the numerical results obtained from the application of the proposed mathematical model. For the experimental tests, a tubular evaporator was made and 10 measuring points were set up, where the process parameters were measured (temperature and pressure drop of the working media R134a and water). Theoretical results were obtained by dividing the evaporator into control volumes and solving the corresponding system of equations of the proposed mathematical model using the Runge-Kutta and Adams Moulton predictor-corrector method. As an independent parameter, the water temperature at the inlet to the evaporator was varied in the range of 10 °C to 18 °C. The test results show that the largest deviation of the calculated and measured water temperature is +0.41 °C to −0.58 °C, while the refrigerant temperature is +0.43 °C to + 0.52 °C. The largest deviation of the evaporator thermal capacity based on the calculations and experimental tests is +9.39% to −6.31%. Based on the obtained results, it is possible to recommend the use of the proposed mathematical model for the design of the tubular evaporator of a heat pump.