Worldwide energy demand is increasing exponentially, presenting significant challenges for existing power generation systems to meet this demand. Enhancing energy efficiency has become critical for reducing consumption and addressing the ongoing environmental crisis. Consequently, there is a need for smart control systems that optimize system costs and improve efficiency. Because of the introduction of smart grids, customers can now participate in demand-side management and integrate renewable energy sources (RESs). Electricity consumption during peak hours often leads to increased grid demand and higher costs. However, the integration of RESs enables consumers to operate appliances during peak hours, thereby reducing reliance on grid power. Therefore, residential load management seeks to reduce power peaks and electrical energy costs. In home energy management systems (HEMS), appliance scheduling is crucial because it continually monitors appliance usage, ensuring that energy supply and demand are balanced. This research aims to optimize power usage by reducing peak loads and electricity costs through the integration of RESs, such as solar or photovoltaic (PV) systems, while considering grid limitations, PV capacity, appliance ON/OFF schedules, and time-of-use tariffs. A genetic algorithm (GA) based optimization technique was employed to evaluate the performance of a HEMS and validated with particle swarm optimization (PSO) technique under identical initial conditions for each appliance and their corresponding energy pricing over different periods. The results show that GA achieved a 48% cost reduction compared to PSO, with significant peak load reduction and improved energy optimization when integrated with PV systems. GA also demonstrated better appliance scheduling, with appliances in the “ON” state for 82% of the time, compared to 52% with PSO.
Production of electric energy or power. Powerplants. Central stations, Renewable energy sources
Srayyih Mustafa S., Al-Gbory M. M., Khanjar Ebtesam F.
et al.
The attention of developed countries is turning to utilizing renewable energy sources, especially after the fossil fuel crises and environmental pollution caused by power plants, Solar cells are considered one of the main sources of energy in smart cities, which are especially focused on the roofs of houses and the unused area that provide a continuous source of energy and reduce polluting emissions to the atmosphere, solar energy is a more today’s efficient renewable resource, especially in areas with high solar energy. Solar cells turn solar energy into a source of electricity for domestic and industrial use. In this study we used using geographic information systems (GIS) and remote sensing to potentially appropriate locations for solar power plants in the holy city of Karbala, Iraq, which makes religious tourism in this city the most distinctive because it is a significant religious hub that draws many visitors from both inside and outside of Iraq. Despite other historical, cultural, heritage, and tourist attractions in the province. After determining the necessary criteria and collecting their data via the satellite images of Landsat 8 for the year 2022 and analyzing them by ArcGIS, the ideal land for the installation of solar cells was chosen using the Multi-Criteria Decision-Making Process (MCDA) and the Analytical Hierarchy Process (AHP). The results showed that the areas that are suitable and very suitable are (15.41%), equivalent to (775.76607 Km2) of the total area of Karbala governorate (5033 Km2). As a result, this model is suitable for setting the parameters chosen to choose the most promising sites in Karbala governorate that can achieve the research objectives, this study helps urban planners, designers and investors to implement and develop solar power plants within the governorate.
Between 51% and 72% of a bituminous roofing membrane used for structural waterproofing consists of organic material, predominantly bitumen—a derivative of crude oil refining—highlighting the strong dependence of this product on fossil resources. Considering that several tonnes of these membranes must be replaced every 30 to 50 years, substantial potential exists for emission reduction through the establishment of circular material systems. This study investigates this potential by analysing 26 Environmental Product Declarations (EPDs) and life cycle datasets from across Europe covering the period from 2007 to 2023. To ensure comparability, all data were normalised to a declared unit of 1 kg of roofing membrane. The reinforcement layers were categorised into glass and polyester & glass composites, and their differences were examined using Welch’s <i>t</i>-tests. Correlative analyses and linear as well as multiple regression models were then applied to explore relationships between environmental indicators and the shares of organic and mineral mass fractions. The findings reveal that renewable energy sources, although currently representing only a small share of total production energy, provide a major lever for reducing nearly all environmental impact categories. The type of reinforcement layer was also found to influence the demand for fossil resources, both materially and energetically. For most environmental indicators, only multiple regression models can explain at least 30% of the variance based on the proportions of organic and mineral inputs. Overall, the study underscores the crucial importance of high-quality, transparently documented product data for accurately assessing the sustainability of building products. It further demonstrates that substituting fossil energy carriers with renewable sources and optimising material efficiency can substantially reduce environmental burdens, provided that methodological consistency and clarity of indicator definitions are maintained.
Geomechanical and multiphase flow characteristics are essential in recovering oil from naturally fractured rocks during hydrocarbon production because of changes in pore pressure and tension within the rock. It is a well-established fact that the geomechanical and multiphase flow characteristics of fractured rocks are interdependent on each other. Evaluation of these characteristics, for hydrocarbons displaced by water in fractured rocks under external stress loading, is severely lacking in published literature. This study aims to develop a novel numerical framework for a fully coupled model of fractured rocks, taking into consideration the pore pressure and porous media discontinuity at the fracture-matrix interface, along with an expanded Darcy's equation. The fully coupled Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) model developed in this study is shown to accurately predict geomechanical and multiphase flow behaviour at the fracture-matrix interface. The results show that as external stress loading on the fractured rock increases, the porosity and permeability of the rock matrix decrease, capillary pressure at the fracture-matrix interface decreases, and the relative permeability curves shift to the right, indicating a water-soaked fracture-matrix interface. The findings of this study can be used to develop innovative strategies for enhanced oil recovery from fractured rocks.
Olexandr Shavolkin, Iryna Shvedchykova, Michal Kolcun
et al.
Improvement of the principles of the implementation of a hybrid solar-wind system equipped with a battery for self-consumption of a local object, with the control of power consumed from the grid, is considered. The aim is to increase the degree of energy use from renewable energy sources for consumption while limiting the degree of battery discharge, taking into account deviations in the load schedule and generation of energy sources relative to the calculated (forecast) values. The possibility of compensating for deviations in the load schedule and renewable energy sources generation relative to the calculated (forecast) values is shown when electricity consumption decreases and the degree of energy use increases. Compliance of the schedule of the battery state of charge with the calculated schedule is achieved by correcting the consumption of active power according to the deviation of the state of charge with a given discreteness of time. The algorithm of the control was improved by taking into account the measured value of the load power with an increase in the degree of energy use. Also, the use of correction allows you to limit the depth of discharge of the battery at the accepted value. A mathematical 24 h model of energy processes was developed, taking into account the error in estimating the state of charge. The results of the modeling using archival data on renewable sources generation confirm that the proposed solutions are effective. For the considered application with average monthly generation in February, the correction allows reducing electricity consumption by 16–21% and payment costs at three tariffs by 24–27%.
Anthropogenetic environmental deterioration and climate change caused by energy production and consumption pose a significant threat to the future of humanity. Renewable, environmentally friendly, and cost-effective energy sources are becoming increasingly important for addressing future energy demands. Mechanical power is the most common type of external energy that can be converted into useful electric power. Because of its strong electromechanical coupling ability, the piezoelectric mechanism is a far more successful technique for converting mechanics energy to electrical energy when compared to electrostatic, electromagnetic, and triboelectric transduction systems. Currently, the scientific community has maintained a strong interest in piezoelectric micro-power generators because of their great potential for powering a sensor unit in the distributed network nodes. A national network usually has a large mass of sensor units distributed in each city, and a self-powered sensor network is eagerly required. This paper presents a comprehensive review of the development of piezoelectric micro-power generators. The fundamentals of piezoelectric energy conversion, including operational modes and working mechanisms, are introduced. Current research progress in piezoelectric materials including zinc oxide, ceramics, single crystals, organics, composite, bio-inspired and foam materials are reviewed. Piezoelectric energy harvesting at the nano- and microscales, and its applications in a variety of fields such as wind, liquid flow, body movement, implantable and sensing devices are discussed. Finally, the future development of multi-field coupled, hybrid piezoelectric micropower generators and their potential applications are discussed.
The current focus on renewable energy sources and the circular economy favors the thermal conversion of low-quality fuels, such as biomass and waste. However, the main limitation of their usability in the power sector is the risk of slagging, fouling, ash deposition, and high-temperature corrosion. These problems may be avoided or significantly mitigated by the application of aluminosilicate clay minerals as fuel additives. In this paper, the three most commonly occurring aluminosilicates are reviewed: kaolin, halloysite, and bentonite. Their application has been proven to minimize combustion-related problems by bonding alkalis in high-melting compounds, thus increasing ash melting temperatures, reducing ash deposition tendencies, and decreasing the particulate matter emission. Due to excellent sorption properties, aluminosilicates are also expected to fix heavy metals in ash and therefore decrease their emissions into the atmosphere. The application of aluminosilicates as fuel additives may be a key factor that increases the attractiveness of biomass and other low-quality fuels for the power sector.
Dimitrios Drosos, Grigorios L. Kyriakopoulos, Stamatios Ntanos
et al.
Global economic growth is accompanied by increased energy demand, thus conventional fuels such as coal, oil and gas, which are the primary energy sources, are gradually being depleted. At the same time, the combustion of conventional fuel for energy production causes serious adverse effects on the environment and contributes to climate change due to the emitted greenhouse gases. For the above reasons, most of the developed and developing countries especially during the last decades, have introduced various incentives for the greater penetration of renewable energy sources (RES) in all sectors of the economy. Concerning the building sector, several measures have been adopted, including the promotion of energy efficiency and energy saving. A significant proportion of the building stock are the school buildings where students and teachers spend a significant proportion of their daily time. Teachers' attitudes and views, especially the school unit managers concerning the use of RES in schools, are important in the effort to rationalize and control energy use. This study was conducted through a structured questionnaire applied to a sample of 510 school managers in Greece's primary and secondary education. The school unit managerial role for the case of Greek schools is performed by the school principal who has both administrative and educational duties. Statistical analysis included the application of Friedman's test and hypothesis test on questions concerning school manager environmental perceptions and energy-saving habits. According to the results, Greek school managers have a high degree of environmental sensitivity, since 97.6 % agreed or strongly agreed that the main concern should focus on energy saving. Furthermore, 71% of the respondent reported to have good knowledge on solar energy, followed by 64% on wind energy while only 34% are knowledgeable on biomass. Almost all the respondents (99%) agreed that it is important to provide more RES-orientated education through the taught curricula. Concerning energy saving behaviour, around 90% reported that they switch off the lights when leaving the classroom and they close the windows when the air-condition is operating. Hypothesis tests revealed a relationship between the school managers' ecological beliefs, the energy saving habits in the school environment, and the recognition of the importance of environmental education. Conclusions highlighted the need to intensify environmental education programs in the school environment concerning RES in schools. This will lead to a higher level of environmental awareness of both teachers and students and therefore to a more dynamic behaviour towards the effort to “greenify” the school environment.
The inertial energy of generators in a power system plays an essential role in maintaining the transient stability in response to the strike of short-circuit faults. Integration of large quantities of renewable energy resources, such as wind and solar energy, and the reduction in the number of conventional generators can lead to the reduction of the overall system inertia of the power system and may result in their vulnerability to faults. To enable a higher integration of renewable energy and to ensure a reliable operation of the power system, it is imperative that the impact of transient stability criteria be incorporated into Unit Commitment algorithms. This thesis proposes to incorporate an inertia based transient stability constraint in a unit commitment formulation. Algorithm to estimate parameters for the proposed transient stability constraint is developed and presented. A transient stability constrained unit commitment (TSUC) is formulated as a mixed integer linear programming (MILP) model. The effectiveness of proposed method is successfully tested on a 9-bus power system and results are discussed
The steady-state activity of zeolite 4A and 5A has been investigated experimentally for nitrous oxide and other emission gases in highly oxidizing conditions, typical for lean-burn engine exhaust. Zeolite has been characterized by XRD and FTIR. The CAD model is designed which shows the layout and basic mounting points of the catalytic converter on the Kirloskar TVI engine. Zeolite 4A and 5A substrate has been made using simple molding techniques, further heating it in an electric heater at 650°C for 6 hours. Several fuels such as plastic pyrolysis oil and diesel oil have been used to investigate the effect of NO on zeolite 4A and 5A substrate. The NO conversion has been found to be decreased by 40% using plastic pyrolysis oil. The zeolite powder has been added with 8% of bentonite clay and 5% of carboxymethyl cellulose powder, and 34% distilled water was stirred constantly to form like molding sand. The applied torque was monitored during stirring, signifying even mixing. The mixture has been kept in the prearranged mold design, and uniform pressure has been applied to guarantee no air holes in the shape. The hole pattern has been made using SOLIDWORKS and has been printed to get reliable openings (10 mm) with the assistance of wooden bars; the prearranged mold has been dried for 92 h in the immediate daylight; thereafter, dry pipes have been taken out from the mold. The subsequent form has been kept in the furnace at first at 150°C. Carboxymethyl cellulose is utilized as a fastener which assists with shaping the mold since it has great binding properties. Significant NOx reduction of 45~50% using zeolite 5A and 27~30% using zeolite 4A mold structure with diesel fuel was observed. Reduction of 35~40% using zeolite 5A and 13~16% using zeolite 4A mold structure with PPO+diesel fuel was observed.
Renewable energy sources (RESs) are generally connected to the grid through power electronic interfaces, which generate electrical power instantaneously with little inertia. With the increasing penetration of RESs, the grid will gradually develop into a low inertia and underdamped power system, which results in serious grid frequency stabilization problems. The virtual synchronous generator (VSG) is an emerging technology that mimics the operation characteristics of traditional synchronous generators (SGs). Virtual inertia and damping are therefore introduced, which help to stabilize grid frequency. This paper gives a comprehensive overview of the VSG. The basic operation principle of VSG is introduced and analyzed in depth. The key issues related to VSG are summarized and discussed, including hardware configuration, software control strategies, energy supporting methods, and typical applications.
Renewable energy generation is no more an alternative rather it becomes a choice for the power generation to meet the upcoming energy demand. Considering the non- renewable energy unavailability, as well as, the environmental impact, renewable energy should be the first choice. Most of the power generation in Bangladesh comes from nonrenewable energy and a noticeable amount of energy is imported from abroad. As a developing country, it is not cost-efficient and never ensures energy security. To ensure long-term energy security, it is time to shift power generation from nonrenewable to renewable energy generation. This paper presents an approximate calculation for the renewable power generating plant cost and returning year. The cost calculation is done in the context of Bangladesh.
Generating electricity using Renewable Energy Sources (RES) is taking over more and more shares in the global market of energy production. This results from global energy policy which is closely related to the reduction of greenhouse gas emission and environmental pollution as well as to reducing consumption of fossil fuels. The constantly increasing number of producers of electricity from RES, such as Hydroelectric Power Plants and Small Hydroelectric Power Plants, gives an impulse for carrying out work on the development and improvement of their operation. It forces continuous work on development of technical diagnostics methods which allow to detect faults at an early stage and even, using properly designed systems, to prevent them or minimize their effects. The main task of the diagnostics and control systems is to identify any symptoms of inaccurate device operation. Next, to modify the algorithm so that the device is introduced to the area of correct operation. Detecting a defect at its initial phase gives opportunities to plan and prepare for the repair of the device. Using appropriate diagnostic methods helps to minimize the costs of major repairs and overhauls of machines and maintain the work efficiency at the desired level. This article presents selected diagnostic methods used in Hydropower Plants.
Presently, electric power systems based on microgrids are reaching an important position in different locations around the world. The multiple distributed generation technologies employed in modern microgrids allow a joint operation of renewable and non-renewable energy sources with many types of loads. Nonetheless, induction motor (IM) type dynamic loads represent one of the most critical factors that make microgrid systems vulnerable to scenarios that could trigger voltage instability. This paper proposes the incorporation of FACTS (flexible ac transmission system) devices to improve the dynamic voltage stability of microgrids with high dynamic load penetration. The work focuses on the impact of including a DSTATCOM (distribution static compensator) in a microgrid with high IM type dynamic load penetration when a fault occurs that causes the microgrid isolation. Various case studies are analyzed using the CIGRÉ microgrid test system. The results show the improvements in the voltage stability of the microgrid with the coordination of distributed generation technologies and the DSTATCOM.
Control engineering systems. Automatic machinery (General)
Vedik Basetti, Shriram S. Rangarajan, Chandan Kumar Shiva
et al.
Load flow analysis is an essential tool for the reliable planning and operation of interconnected power systems. The constant increase in power demand, apart from the increased intermittency in power generation due to renewable energy sources without proportionate augmentation in transmission system infrastructure, has driven the power systems to function nearer to their limits. Though the power flow (PF) solution may exist in such circumstances, the traditional Newton–Raphson based PF techniques may fail due to computational difficulties owing to the singularity of the Jacobian Matrix during critical conditions and faces difficulties in solving ill-conditioned systems. To address these problems and to assess the impact of large-scale photovoltaic generator (PVG) integration in power systems on power flow studies, a derivative-free quasi-oppositional heap-based optimization (HBO) (QOHBO) technique is proposed in the present paper. In the proposed approach, the concept of quasi-oppositional learning is applied to HBO to enhance the convergence speed. The efficacy and effectiveness of the proposed QOHBO-PF technique are verified by applying it to the standard IEEE and ill-conditioned systems. The robustness of the algorithm is validated under the maximum loadability limits and high R/X ratios, comparing the results with other well-known methods suggested in the literature. The results thus obtained show that the proposed QOHBO-PF technique has less computation time, further enhancement of reliability in the presence of PVG, and has the ability to provide multiple PF solutions that can be utilized for voltage stability analysis.
André Quites Ordovás Santos, Adriel Rodrigues da Silva, Jorge Javier Gimenez Ledesma
et al.
With the current worsening of climate change-associated risks, the transition to low-carbon energy sources has become a global priority. In this context, the advances in the implementation of smart grids, which, in addition to greater efficiency and resilience, also allow greater penetration of renewable distributed energy resources, are becoming increasingly important. However, the necessary investments will be colossal. Many specialists see the process of opening up the electric energy markets as essential to boosting these new technologies. Greater decentralization of the decision-making process can potentially promote greater scalability. However, not all liberalization reforms have led to good results. Several researchers have been evaluating experiences in different countries. Brazil, a country with continental dimensions and peculiar characteristics, already counts with a mostly renewable electric energy generation mix. In recent decades, however, it has become increasingly dependent on fossil fuel sources. Brazil has been conducting a process of opening the electric energy market since the 1990s. This process has faced a series of barriers. This article presents a critical bibliographic review of the Brazilian Power System history and its ongoing opening process, its possible successes and errors, as well as its perspectives and challenges.
Biogas is one of the promising futuristic renewable energy sources with enormous market potential. However, the presence of CO2 lowers down the calorific value of biogas. Hence, various biogas upgradation technologies are under intense investigation to increase the methane content to the desired level. This study reports on enhancing methane content in biogas through CO2 sequestration into acetic acid via microbial electrosynthesis (MES) process. The previously enriched mixed chemolithoautotrophic microbial culture dominated by Acetobacterium spp. used CO2 present in the biogas as the sole carbon source. After establishing a stable performing biocathode at a fixed cathodic potential of −1 V (vs. Ag/AgCl) through batch mode operation, biogas was fed continuously at different feed rates, viz., 0.5, 0.3, and 0.2 ml/min to the cathode chamber. The highest feed rate of 0.5 ml/min was least effective both for methane content increment (from 61 ± 3% to 86 ± 2%) and acetic acid titer (1.5 ± 0.5 g/L; 0.107 ± 0.02 g/L/d.). In comparison, the lowest flow rate of 0.2 ml/min was the most effective for the intended process (methane upgradation from 62 ± 7% to 93 ± 3% and acetic acid titer 3.4 ± 0.6 g/L produced at 0.24 ± 0.04 g/L/d rate). Both acetic acid bioproduction and biogas upgradation occurred best at an Ecell of 3.3 ± 0.35 V at the low feed rate. A maximum of 84 ± 7%, 57 ± 10% and 29 ± 2% coulombic, carbon and energetic efficiencies, respectively, were achieved in acetic acid. Cyclic voltammograms of biocathodes revealed the decrease in hydrogen evolution potential and increased bioelectrocatalysis, thereby suggesting the contribution of microbes in the process. Acetobacterium, which is known for CO2 fixation, was found to be the dominant microbial genus in biogas fed reactors. The demonstrated approach not only offers the advantage of obtaining two products, one in the bulk phase and the other in the off-gas, it also validates the applicability of the bioelectrochemical biogas upgradation technology.
Dominika Čeryová, Tatiana Bullová, Izabela Adamičková
et al.
Greening the economy requires green innovations, and innovations require investments. Most countries of the world are still relying on conventional (fossil-based) sources of energy. The transition toward green or renewable energy sources is an effective and innovative way to meet ever-increasing demand as a result of the rising population. Another reason for innovations in the field of green energy is the need to mitigate climate change and avoid pollution, especially in developing countries. The monitored investments into renewable energy sources are usually public. Therefore, this paper aims to determine whether the selected countries of the world produced renewable energy efficiently, considering the investments made by public financial institutions and installed electricity capacity for renewable energy sources, for the period 2013–2017 (for a deeper analysis, the year 2017 was chosen). For this purpose, the Stochastic Frontier Analysis model in the logarithmic form of the Cobb-Douglas production function is used, which helps to judge the competitiveness of countries based on effectively transforming the inputs into outputs. Results suggest that the effect of the first variable “installed electricity capacity” on electricity generation was highly statistically significant, and the impact of the second variable “public investments” was characterized as statistically insignificant. The monitored countries were divided into 10 groups according to the different range of estimated output-oriented technical efficiency from 0.00 to 1.00. Most countries should increase the renewable electricity generation approximately by 40-49%, given the level of inputs (16 countries of 6th group with estimated output-oriented technical efficiency 0.51-0.60) for the year 2017.