Search Results (113)

As global electricity demand increases and concerns over fossil fuel usage intensify, renewable energy sources have gained significant attention. Solar energy stands out due to its low installation costs and suitability for deployment. However, solar power generation remains difficult to predict because of its dependence on weather conditions and decentralized infrastructure. To address this challenge, this study proposes a flexible hybrid ensemble (FHE) framework that dynamically selects the most appropriate base model based on prediction error patterns. Unlike traditional ensemble methods that aggregate all base model outputs, the FHE employs a meta-model to leverage the strengths of individual models while mitigating their weaknesses. The FHE is evaluated using data from four solar power plants and is benchmarked against several state-of-the-art models and conventional hybrid ensemble techniques. Experimental results demonstrate that the FHE framework achieves superior predictive performance, improving the Mean Absolute Percentage Error by 30% compared to the SVR model. Moreover, the FHE model maintains high accuracy across diverse weather conditions and eliminates the need for preliminary validation of base and ensemble models, streamlining the deployment process. These findings highlight the FHE framework’s potential as a robust and scalable solution for forecasting in small-scale distributed solar power systems. Full article

Distributed renewable energy sources with significant output fluctuations can negatively impact the power grid stability when it is connected to the power grid. Therefore, it is necessary to develop a capacity configuration method that improves the output stability of highly uncertain energy sources such as wind and photovoltaic (PV) power by integrating pumped storage units. In response, this study proposes a capacity configuration method for a cascade small hydropower-pumped storage–wind–PV complementary system. The method utilizes the regulation capacity of cascade small hydropower plants and pumped storage units, in conjunction with the fluctuating characteristics of local distributed wind and PV, to perform power and energy time-series matching and determine the optimal capacity allocation for each type of renewable energy. Furthermore, an optimization and scheduling model for the cascade small hydropower-pumped storage–wind–PV complementary system is constructed to verify the effectiveness of the configuration under multiple scenarios. The results demonstrate that the proposed method reduces system energy deviation, improves the stability of power output and generation efficiency, and enhances the operational stability and economic performance of the system. Full article

A comparison of the net present value, the payback period, and the levelized cost of electricity for three different projects of construction and exploitation of plants for electricity production with the aim of decarbonizing the energy sector is conducted. The first project is the building of a large-scale nuclear power plant with a light-water reactor, the second one is the deployment of several identical small modular reactors, and the third project is based on solar and wind power plants. Given that the sun and wind are intermittent renewable energy sources, it is inevitable to take into account the construction of an energy storage facility in the last project. The results show that the most profitable are the small modular reactors, while the investment into solar and wind power plants is burdened with the necessary electricity storage plant costs. Another drawback of an investment in solar and wind power plants is their shorter exploitation lifetime of 25 years compared to the long-term operation of nuclear power plants of 60 years or even more. Full article

Future power generation plants will be largely based on renewable energy sources such as wind or photovoltaic power. These plants are connected to the grid through power electronic converters, which may present stability problems, specifically in weak grids. Consequently, numerous stabilities studies have been conducted. In these studies, converters work as inverters; however, in power electronic interfaced loads, energy storage systems or High-Voltage Direct Current (HVDC) links, power converters can also function as a rectifier. Stability studies focusing on the rectifier operation have received little attention in previous research. In this paper, the Voltage Source Converter (VSC) stability is analysed for both the inverter and rectifier modes, with particular focus on the influence of the Phase-Locked Loop (PLL) and the current controllers’ bandwidths. Additionally, a Two-Degree-of-Freedom Proportional Integral (2DOF-PI) controller is proposed to expand the stable operating range. The stability study is carried out using a small-signal model validated through PSCAD simulations. The results show that for inverter operations, a slow PLL and fast current controllers yield better performance, whereas for rectifier operation, a fast PLL and slow current controllers are recommended. Finally, a robustness study based on the $H_{\infty }$-norm is carried out to provide some tuning recommendations for the controller parameters, confirming the different behaviour in inverter and rectifier operation. Full article

The energy transition requires substantial financial investments and the adoption of innovative technological solutions. The aim of this paper is to analyze the economic and technological aspects of implementing zero-emission strategies as a key component of the transition toward a carbon-neutral economy. The study assesses the costs, benefits, and challenges of these strategies, with a particular focus on wind farms and nuclear power, including small modular reactors (SMRs). The paper presents an in-depth examination of key examples, including onshore and offshore wind farms, as well as nuclear energy from both large-scale and small modular reactors. It highlights their construction and operating costs, associated benefits, and challenges. The investment required to generate 1 MW of energy varies significantly depending on the technology: onshore wind farms range from $1,300,000 to $2,100,000, offshore wind farms from $3,000,000 to $5,500,000, traditional nuclear power plants from $3,000,000 to $5,000,000, while small modular reactors (SMRs) require between $5,000,000 and $10,000,000 per MW. The discussion underscores the critical role of wind farms in diversifying renewable energy sources while addressing the high capital requirements and technical complexities of nuclear power, including both traditional large-scale reactors and emerging SMRs. By evaluating these energy solutions, the article contributes to a broader understanding of the economic and technological challenges essential for advancing a sustainable energy future. Full article

The protection and reclamation of surface waters, particularly lakes, necessitates the implementation of novel approaches that effectively integrate natural biological processes with sophisticated technological solutions. This paper examines the potential of bioremediation techniques utilising artificial aeration systems, with renewable energy sources serving as a viable power source. The objective of the analysis is to enhance the sustainability of the remediation of aquatic ecosystems. A multi-criteria analysis (MCA) was employed to evaluate the performance and environmental impact of the selected methods. Based on the results of the MCA, the SHPP (small hydro power plant) technology achieved the highest score for both lakes, 0.85 and 0.78, respectively, making it the optimal technology. In comparison, wind energy scored around 0.5 and photovoltaic (PV) around 0.6, showing a poorer fit with local conditions. By integrating reclamation with renewable energy applications, this research presents a strategy for developing more resilient and environmentally sound water management strategies. Full article

A national energy crisis has emerged in South Africa due to the country’s increasing energy needs in recent years. The reliance on fossil fuels, especially oil and gas, is unsustainable due to scarcity, emissions, and environmental repercussions. Researchers from all over the world have recently concentrated their efforts on finding carbon-free, renewable, and alternative energy sources and have investigated microbiology and biotechnology as a potential remedy. The usage of microbial electrolytic cells (MECs) and microbial fuel cells (MFCs) is one method for resolving the problem. These technologies are evolving as viable options for hydrogen and bioenergy production. The renewable energy technologies initiative in South Africa, which is regarded as a model for other African countries, has developed in the allocation of over 6000 MW of generation capacity to bidders across several technologies, primarily wind and solar. With a total investment value of R33.7 billion, the Eastern Cape’s renewable energy initiatives have created 18,132 jobs, with the province awarded 16 wind farms and one solar energy farm. Utilizing wastewater as a source of energy in MFCs has been recommended as most treatments, such as activated sludge processes and trickling filter plants, require roughly 1322 kWh per million gallons, whereas MFCs only require a small amount of external power to operate. The cost of wastewater treatment using MFCs for an influent flow of 318 m³ h⁻¹ has been estimated to be only 9% (USD 6.4 million) of the total cost of treatment by a conventional wastewater treatment plant (USD 68.2 million). Currently, approximately 500 billion cubic meters of hydrogen (H₂) are generated worldwide each year, exhibiting a growth rate of 10%. This production primarily comes from natural gas (40%), heavy oils and naphtha (30%), coal (18%), electrolysis (4%), and biomass (1%). The hydrogen produced is utilized in the manufacturing of ammonia (49%), the refining of petroleum (37%), the production of methanol (8%), and in a variety of smaller applications (6%). Considering South Africa’s energy issue, this review article examines the production of wastewater and its impacts on society as a critical issue in the global scenario and as a source of green energy. Full article

With the surge in energy demand worldwide, renewable energy is becoming increasingly important. Solar power, in particular, is positioning itself as a sustainable and environmentally friendly alternative, and is increasingly playing a role not only in large-scale power plants but also in small-scale home power generation systems. However, small-scale power generation systems face challenges in the development of efficient prediction models because of the lack of data and variability in power generation owing to weather conditions. In this study, we propose a novel forecasting framework that combines transfer learning and dynamic time warping (DTW) to address these issues. We present a transfer learning-based prediction system design that can maintain high prediction performance even in data-poor environments. In the process of developing a prediction model suitable for the target domain by utilizing multi-source data, we propose a data similarity evaluation method using DTW, which demonstrates excellent performance with low error rates in the MSE and MAE metrics compared with conventional long short-term memory (LSTM) and Transformer models. This research not only contributes to maximizing the energy efficiency of small-scale PV power generation systems and improving energy independence but also provides a methodology that can maintain high reliability in data-poor environments. Full article

With the transformation of the energy structure, the integration of numerous small-scale, widely distributed renewable energy sources into the power grid has introduced operational safety challenges. To enhance the operational competitiveness, the virtual power plant (VPP) has emerged to aggregate and manage these distributed energy resources (DERs). However, current research on the VPP’s frequency modulation performance and bidding strategy remains insufficient in the joint market of electrical energy and frequency modulation (FM) ancillary services, with inadequate coordination of internally distributed resources. To fully leverage the flexibility of VPPs and incentivize their participation in electricity market operations, this paper investigates game-based bidding strategies and internal distributed resources allocation methods for VPPs in the joint market for electrical energy and frequency ancillary services. Firstly, the regulatory performance indicators of VPPs participating in the joint market and develops the corresponding market-clearing model. Secondly, to address the competition among distributed resources within VPPs, a master-slave game approach is innovatively employed to optimize the VPP’s trading strategies. This method ensures the rational allocation of electricity consumption among distributed energy resources within the VPP and derives the optimized bidding prices and quantities for both the VPP and its internal members. Finally, the case study shows that the proposed trading strategy provides effective bidding strategies for distributed energy resources participating in the joint market for energy and frequency regulation ancillary services. It enhances the regulatory performance of VPPs in the energy-frequency regulation market, ensures the profitability of distributed energy resources, and contributes to the economically stable operation of the market. Full article

This research demonstrates the possibility and expediency of forming local electric energy systems (LEESs) based on renewable sources of energy (RSE) as balancing groups in the electric power system (EPS), which can maintain efficiency and provide power supply to consumers in an autonomous mode. The LEES is a part of the EPS of thermal and nuclear power plants and is considered as a separate balancing group. LEESs are designed in such a way that they can operate autonomously in both normal and extreme conditions in the EPS. The sources of electricity in LEESs are small hydroelectric power plants (SHPPs), photovoltaic power plants (PVPPs), and wind power plants (WPPs), whose electricity generation is unstable due to dependence on natural conditions. Therefore, the structure of a LEES with RSE includes an energy storage system with reserves sufficient to compensate for the unstable generation and balancing of the mode. LEESs can differ significantly in terms of key technical and economic indicators (power supply reliability, power losses, and power quality), and therefore, it is necessary to choose the optimal one. It is not advisable to optimize the quality of power supply in a LEES by individual indicators, as improvement of one indicator may lead to deterioration of another. The functional readiness of a LEES should be assessed by the quality of operation, which depends on reliability, power losses, and power quality. To simplify the task of assessing the quality of operation, which is a vector optimization problem, a method for determining the integral indicator as a number that characterizes the LEES and reflects the compromise between the values of reliability, power losses, and power quality has been developed. The integral indicator of the functioning of complex systems is based on a combination of the theory of Markov processes and the criterion method of similarity theory. The value of the integral indicator of the quality of operation of the LEES allows for comparing different variants of power transmission and distribution systems without determining individual components of technical and economic indicators—reliability, power losses, and power quality. The offered integral indicator of the quality of functioning of a LEES with RSE corresponds to the general requirements for such indicators. It reflects the actual operating conditions; allows for assessing the efficiency, quality, and optimality of power supply systems; and can be easily decomposed into partial indicators. Full article

The Paris Agreement emphasizes the need to reduce greenhouse gas emissions, particularly from coal power. One suggested approach is repowering coal-fired power plants (CPPs) with small modular reactors (SMRs). South Korea plans to retire CPPs in the coming decades and requires alternative options for coal-fired energy. This study presents a scoping analysis comparing variable renewable energy (VRE) sources with SMRs for repowering CPPs in the Korean context. The analysis indicates that SMRs may be a more favorable option than VRE sources, particularly due to their load-following capabilities. In this study, two types of SMRs were investigated: high-temperature gas reactors (HTGRs) and pressurized water reactors (PWRs). HTGRs are suitable to fit the high-temperature operating conditions of steam turbines but require multiple units due to their low volumetric flow rates. PWRs, while matching the volumetric flow rate of existing CPP turbines, require additional thermal energy sources to meet the high-temperature operating conditions of steam turbines. Lastly, an analysis of necessary regulatory and legislative changes in South Korea’s nuclear framework is presented, identifying several key regulatory issues for repowering coal with nuclear energy. Full article

The safety engineering design of hydrogen systems and infrastructure, worker education and training, regulatory compliance, and engagement with other stakeholders are significant to the viability and public acceptance of hydrogen farms. The only way to ensure these are accomplished is for the field of hydrogen safety engineering (HSE) to grow and mature. HSE is described as the application of engineering and scientific principles to protect the environment, property, and human life from the harmful effects of hydrogen-related mishaps and accidents. This paper describes a whole hydrogen farm that produces hydrogen from seawater by alkaline and proton exchange membrane electrolysers, then details how the hydrogen gas will be used: some will be stored for use in a combined-cycle gas turbine, some will be transferred to a liquefaction plant, and the rest will be exported. Moreover, this paper describes the design framework and overview for ensuring hydrogen safety through these processes (production, transport, storage, and utilisation), which include legal requirements for hydrogen safety, safety management systems, and equipment for hydrogen safety. Hydrogen farms are large-scale facilities used to create, store, and distribute hydrogen, which is usually produced by electrolysis using renewable energy sources like wind or solar power. Since hydrogen is a vital energy carrier for industries, transportation, and power generation, these farms are crucial in assisting the global shift to clean energy. A versatile fuel with zero emissions at the point of use, hydrogen is essential for reaching climate objectives and decarbonising industries that are difficult to electrify. Safety is essential in hydrogen farms because hydrogen is extremely flammable, odourless, invisible, and also has a small molecular size, meaning it is prone to leaks, which, if not handled appropriately, might cause fires or explosions. To ensure the safe and dependable functioning of hydrogen production and storage systems, stringent safety procedures are required to safeguard employees, infrastructure, and the surrounding environment from any mishaps. Full article

With the increase in population and the growing demands of industrialization, carbon emissions across the globe are increasing exponentially. Furthermore, the demand for clean energy from renewable sources (solar, wind, etc.) is growing at an unparalleled rate to fight against the climate change caused by these increased carbon emissions. However, at present, it is very difficult for small-scale industries in urban areas to install solar power systems due to constraints around the operation area and on rooftops. Therefore, these small-scale industries are not able to install any solar plants and, thus, are not able to reduce their carbon emissions. In the context of this problem regarding the generation of cleaner energy and reducing carbon emissions by small-scale industries in urban areas, a model of a rooftop solar photovoltaic tree (SPVT) has been proposed that may be considered by small-scale industries in the place of a conventional rooftop solar photovoltaic (SPV) system. It is also noted that various models of SPVT systems are commercially available on the market, each with their own unique features. However, no new SPVT model has been designed or provided in this paper, which simply presents simulation studies comparing a conventional rooftop SPV system and an SPVT system. The results show that a 9.12 kWp SPVT system can be installed in just 6 Sq.mt, while a 3.8 kWp conventional SPV system requires 40 Sq.mt of rooftop area. Consequently, an SPVT generates around 128% more electricity than a conventional SPV, leading to greater reductions in carbon emissions. Thus, the objective of this study is to identify the most suitable option for small-scale industries in densely populated urban areas to generate electricity and maximize carbon emission reduction. Full article

While South Africa is deemed one of the countries with the highest irradiation levels, it still utilises coal as its primary energy source due to its abundance. Due to the world-wide drive towards carbon neutrality, residential, commercial, agricultural, and industrial consumers are considering small-scale embedded generation systems. The National Rationalised Specifications 097-2-3 document specifies the scale of the embedded generation capacity a consumer is allowed to install. However, specifications do not yet make the required provisions for the addition of energy storage. The effective collective management of the grouped small-scale embedded generation systems could provide a high level of energy security and increase the percentage of renewable energy generation in the total energy mix. Potential challenges come into play when considering the stochastic nature of photovoltaic generation and its effect on the storage capacity and the dispersion in load profiles of the residential units typically present on a low-voltage network. This paper contributes by investigating the utilisation of photovoltaic generation in conjunction with storage as the basis for virtual power plant control, with the aim to safely increase renewable energy penetration and improve energy security, all while remaining within the South African low-voltage regulatory limits. A two-level virtual power plant controller is proposed with the dispersed energy storage units as the primary controllable resources and the dispersed photovoltaic generation as the secondary controllable resources. The objective of the controller is to achieve nodal energy management, energy sharing, and ancillary service provision and finally to increase renewable energy penetration. A representative single-feeder low-voltage network is simulated, and test cases of 50% and 75% renewable energy penetration are investigated as the basis for evaluation. The proposed controller architecture proved to maintain network integrity for both test cases. The adaptability of the controller architecture was also confirmed for a changed feeder topology; in this case, it was a multi-feeder topology. Future work is warranted to inform policy on the allowed levels of renewable energy penetration to be based not only on demand but also on the level of energy storage present in a network. Full article

In order to achieve the goals of carbon neutrality and reduced carbon emissions, China is increasingly focusing on the development and utilization of renewable energy sources. Among these, ocean thermal energy conversion (OTEC) has the advantages of small periodic fluctuations and large potential reserves, making it an important research field. With the development of the “Maritime Silk Road”, the Xisha Islands in the South China Sea will see a growing demand for electricity, providing the potential for OTEC development in this region. Optimal site selection of OTEC power plants is a prerequisite for developing thermal energy provision, affecting both the construction costs and future benefits of the power plants. This study establishes a scientific evaluation model based on the decision-making frameworks of geographic information systems (GISs) and multi-criteria decision-making (MCDM) methods, specifically the analytic hierarchy process (AHP) for assigning weights, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to reclassify the factors, and weighted linear combination (WLC) to compute the suitability index. In addition to commonly considered factors such as temperature difference and marine usage status, this study innovatively incorporates geological conditions and maximum offshore distances of cold seawater based on cost control. The final evaluation identifies three suitable areas for OTEC development near the Xuande Atoll and the Yongle Atoll in the Xisha Sea Area, providing valuable insights for energy developers and policymakers. Full article