Polityka Energetyczna - Energy Policy Journal

This paper assesses the electricity bill savings potential of nationwide demand-side management programs in the residential sector. The analysis provides br oad insights into how time-of-use optimization could bring economic benefits while accelerating the deployment of renewable energy sources. We have built an electricity model with detailed household electricity consumption. Using survey data, we have created a baseline scenario that represents the current appliance usage habits of households in Hungary providing useful information on their shiftable electricity demand. We have then used time-of-use optimization of household appliances that do not affect thermal comfort in order to minimize electricity bills. Assuming different levels of participation in the demand-side management program, we reschedule the use of washing machines, dishwashers and dryers. Load optimization has a peak shaving impact on the total load, ranging from 2.2 to 3.6%. During winter, the potential for peak shaving is around –205 MW, whereas in summer, it is approximately –166 MW. Although solar energy is abundant and cheap during the day in summer, motivating households to shift their load, there is less shiftable load in the late evening hours. Therefore, the peak shaving potential is higher during winter due to the earlier peak. Modelling results from the Hungarian electricity market illustrate that smartening the grid has a bill saving potential of 6.1%, or EUR 700 million in Hungary, assuming that all households are equipped with smart meters. However, half of this reduction can be achieved with only a 25% participation rate.

This research examines an important aspect of technological processes – the process of mixing diesel fuel and biofuel in a specially designed paddle mixer. The main goal is to optimize and improve the quality of the resulting mixture. The use of the FlowVision CFD (Computational Fluid Dynamics) program in this study is of great importance and helps to achieve significant results in the study and optimization of the diesel-biofuel mixing process. In the context of many industrial and technological processes, where efficient mixing of liquids plays an important role, turbulent mixing is of great importance. Optimal mixing not only improves the quality of products, but also ensures the unity of complex reactions and also helps to reduce the time of completion of the process. It is important to emphasize that the research focuses not only on the quantitative aspects of mixing but also on the study of the influence of the geometry of the mixer on the turbulent characteristics of the flow. This can lead to the development of new mixer designs aimed at maximizing the efficiency of the fuel mixing process, which, in turn, will help save resources and reduce emissions of harmful substances into the atmosphere. This research opens up prospects for further developments in the field of fuel blending technologies, which can lead to real improvements in production and sustainability. The discovery of new methods of optimal mixing of liquids in specially designed mixers can determine the future of energy efficiency and reduce the negative impact on the environment.

Solar energy is one of the most important renewable energy sources and it can be exploited to produce electrical energy through photovoltaic (PV) panels. PV panels are affected by several factors, the most important being the panel temperature, which greatly affects the performance and efficiency of the PV. This paper investigates the effect of water-based surface cooling on the PV performance. Techno-economic PV evaluation depending on surface water cooling was examined. The effect of changing the water flow rate on the panel temperature was studied. The proposed system studied the effect of using variable water flow rates (1.25, 5, 7 L/min) on the panel temperature. A 260 W poly-crystalline PV panel combined with a water cooling system was examined experimentally. The PV panel temperature, open circuit voltage, short circuit current and output power were measured before and after cooling at variable flow rates. A PV panel analyzer I-V400 was used to test the panel in order to draw the IV and power curves. It was found that the rate of decrease in panel temperature with time is almost constant for all cases. Increasing the rate of water flow on the panel surface did not affect the rate of its temperature decrease with time. With the proposed surface cooling technique, the panel temperature decreased from 62.4 to 37.6oC. PV output power increased from 182.65 to 214.62W, with an improvement of around 18%. The amount of energy gained as a result of cooling saves around 0.7USD for one panel per year.

Between 2019 and 2023, over one million PV micro-installations were built in Poland. Most of them have the option of settling prosumer discounts: net-metering (80% of energy sent to the grid returns to the user for PV installation power up to 10 kWp and 70% for power between 10 and 50 kWp). Owners of new PV micro-installations (from 2022) are subject to net-billing settlements, which is economically unfavorable due to the coexistence of low energy prices and high productivity of PV panels. This, however, favors efforts to increase self-consumption of energy in prosumer PV micro-installations. Therefore, for the selected PV installation, the use of electricity storage and thermal energy storage (for the purposes of preparing domestic hot water) was analyzed. The calculations were based on data from the installation collected during one year of operation. A calculation methodology for energy distribution for the consumption and storage of electricity and heat was developed, and thus for estimating the value of energy sent to the grid, taking into account the above-mentioned. The use of electrical and thermal energy storage resulted in an increase in the value of self-consumed energy, with the self-consumption coefficient ranging from 30 to over 80%. The self-consumption rate in the first year of operation of the installation (without energy storage) reached 27.1%, and in the second year 30.7%. A 3 kWh electricity storage would increase the selfconsumption rate in the following years to 51 and 57.2%, and for a 6 kWh capacity 58.5 and 64.1%.

Research on the technical and economic aspects of organic Rankine cycle (ORC) systems is of great relevance, showing potential for reducing environmental impacts and improving resource efficiency, which becomes critical in the context of the rapid global transformation towards sustainable and energy-efficient solutions. The purpose of this study was to investigate the existing systems in the field of ORC systems, including the technical and economic aspects of their application in small-scale power units. The study employed the statistical method, comparative method, and analysis. The study highlighted the key aspects of the application of ORC technology in small-scale power units. Substantial attention was given to economic analyses to identify factors affecting the competitiveness of technology in the field of small-scale energy projects. An economic study found high unit costs to be the main obstacle to the widespread adoption of the ORC in small-scale energy applications. This study also presented a technical review of the techniques for selecting the expander and working fluid. The analysis of these aspects revealed the main parameters affecting the efficiency and cost of the system. Optimization of the ORC to reduce unit cost was highlighted as a priority area for development, facilitating faster payback and widespread adoption of the technology. The role of the expander in the system and reducing the cost of high-speed power generators were also considered prominent factors for improving economic efficiency. The obtained findings may represent a valuable framework, enabling cost reduction in small-scale ORC systems and promoting the development of clean and economically competitive small-scale energy solutions.

The study examines the factors and risks that affect the operational safety of energy infrastructure. Economic and technical diagnostics were performed, and the causes of equipment (turbine generator) failures were identified in order to develop effective approaches to managing the technical diagnostics of critical energy equipment and ensuring energy efficiency and safety of energy processes. This study presents a methodology for analyzing heat transfer in the stator winding core of turbine generators at South Ukrainian and Khmelnytsky NPPs, which allows us to gain insight into the temperature distribution and suggest ways to optimize thermal processes. The proposed approach facilitates the assessment of the temperature regime, identification of overheating risks and formulation of emergency measures. The results of the analysis of Khmelnytskyi NPP (Unit 2) and South Ukrainian NPP (Unit 1) showed that at Khmelnytskyi NPP the heat transfer parameters are within the permissible values for all rods, and at South Ukrainian NPP, the heat transfer parameter in rods 13 and 23 is 0 W, which requires immediate intervention to ensure the safety of further operation. This approach allows for timely response to power unit failures, ensuring safety and efficient management of power equipment operation and ensuring the continuous stable operation of the energy infrastructure with maximum efficiency. Further research will focus on the development of methods for predicting the stable operation of the power system based on preliminary technical assessments and thermal and mechanical analysis, which will allow for making science-based decisions on the stability of NPP equipment.

Energy scarcity in the world and the pollutants resulting from excessive use of energy lead to an increase in global warming. There is a need to search for sustainable alternatives that use less energy to reduce environmental problems as well as alternatives to the use of Freon, which is harmful to the environment, one of the most dangerous pollutants, and increases the ozone hole. The current research aims to investigate the performance of thermoelectric refrigerators with different operating conditions. A portable thermoelectric refrigerator was developed for those living in remote areas of Egypt off the electrical grid (e.g., deserts). The designed refrigerator is based on the Peltier effect using Peltier units. The refrigerator is designed, manufactured, and experimentally tested. Several variables were studied in fast cooling systems for different conditions to minimize time, decrease the cooling temperature, and increase the coefficient of performance (COP) by the response surface methodology (RSM) model. The results reveal that the obtained maximum COP was 77.3%, at 4 V and 1.006 with a difference in cooling temperature (ΔT) of 8°C. The highest ΔT was 26.4°C at 10 V, 9.149 A, 91.49 W and COP 11.2%. The optimum condition was cooling temperature 12.7°C, COP 51.4% at 4 V, 3.445 A by using 4 Peltier, according to Response surface methodology (RSM) includes optimization procedures for the settings of factorial variables by design expert 13, such that maximum ΔT was 20.3°C and maximum COP 49.576% with 4 volts, 4 no. of Peltier and current 3.601 A in the value range. The results reveal that the obtained determination coefficient for ΔT and the COP adjusted R2 and R3 values 0.9286 and 0.9603 respectively.

The heating processes of private residential buildings demand substantial fuel and energy resources and contribute to global warming, necessitating the transition to energy-efficient and eco- -friendly heating. This study aims to develop a methodological approach for selecting cost-optimal strategies for household heating systems by assessing the environmental impacts and cost-effectiveness of available options of fossil fuels and renewable energy used in the residential sector during a heating season while ensuring homes’ greening and energy efficiency. The research extends the existing methodology by considering climatic zones and their ambient air temperature fluctuations during a heating season, household energy efficiency, various energy carriers used for heating, household running and capital costs for heating, multi-zone electricity tariffs, and prospects of heating automation, aiding policymakers in shaping residential heating choices. Tested on a typical Ukrainian household, the approach contributes to sectoral policy improvement by creating energy-efficient and decarbonization strategies for housing stock, with potential application in other countries. The results show that the most cost-optimal options for heating in Ukraine are firewood and natural gas use under the current energy policy. Based on the findings, the study suggests recommendations within Ukraine’s regional context and carbon neutrality goals. They provide a transition to renewables (wood pellets and heat pumps) by developing a market infrastructure for servicing boiler equipment and logistics for biofuel supply, state economic support to local boiler equipment manufacturers, and partial reimbursement of investments in pellet boilers and heat pumps for households, electricity tariff adjustments, etc.

In Poland, the main fossil fuel for electricity generation is thermal coal. In most countries of the EU, natural gas is used as a fuel. The aim of the article was to compare the competitiveness of electricity generation from thermal coal and natural gas, taking into account the costs incurred by power generators related to the purchase of fuel and the required CO2 emission allowances. The calculations were carried out for the years 2022–2023, a period of very high volatility of energy carrier prices on international markets. Fossil fuels generated 31% of electricity in the EU in 2023, and 71% in Poland. In 2022, thermal coal prices were high and highly volatile, with maximum daily fluctuations reaching USD 104/ton, well above previous historical values. The main factor causing coal prices to be so high in Europe was the extremely high gas prices resulting from Russia’s invasion of Ukraine. Natural gas prices quoted in August 2022 reached EUR 350/kWh. CDS (Clean Dark Spread) simulations were carried out to assess the competitiveness of thermal coal generation relative to natural gas. In 2022, the cost of power generation from natural gas was higher than coal by an average of EUR 121/MWh. The situation was different in 2023. The dynamic fall in natural gas prices (TTF exchange) caused the costs of generating electricity from these two fuels to equalize. This comparison shows what price fluctuations energy carriers and energy producers have to be prepared for. Such large price fluctuations are most influenced by political factors. The question can be raised as to whether betting on gas as a transitional fuel for a country with a large coal production is the right thing to do.

The amount of potential generation of the energy fraction in the municipal waste was analysed based on the generation index for this fraction (Klojzy-Karczmarczyk and Staszczak 2017) and based on the generation and morphological composition of municipal waste in the analysed national waste management plans. Those morphological fractions, which are characterised by a high calorific value, frequently above 12 MJ/kg (waste plastic, waste paper and cardboard, waste textiles and clothes, waste wood, multi-material waste), were considered the energy fractions. The estimated weighted average of the energy fraction in the total stream of municipal waste generated on a national scale is 29.8% (an index of energy fraction). The generation of the energy fraction based on the figures forecast in the planning documents in the years 2014–2019 ranged between 3.3 and 4.0 million Mg. Instead, the mass of the energy fraction generated under actual conditions ranged between 3.2 and 4.0 million Mg. The analysis has shown definitely smaller real generation with respect to the forecast figures for the years 2014–2016. A reverse trend has been observed in consecutive years. Considering the morphological composition, the obtained values of the potential generation are close to the figures provided based on the adopted generation index. In the years 2014–2015, the averaged mass of energy fraction in the total stream of municipal waste amounted to 3.3 million Mg per year, while its averaged mass in the stream of unsorted waste was 2.9 million Mg. In the years 2016–2022, the averaged mass of energy fraction in the total stream of municipal waste amounted to 3.8 million Mg per year, while in the stream of unsorted waste this value reached approx. 2.9 million Mg.