The thermoregulation of indoor spaces has become a pertinent concern due to rising global temperatures and heat agglomeration. Besides extensive energy consumption in conventional air conditioners, the released heat and greenhouse gases exacerbate cooling requirements. Several regions of the world, such as the Middle East and Eastern Mediterranean countries, are facing temperature rises almost twice as fast as the rest of the world due to rapid urbanization and industrialization, which have far-reaching consequences for the well-being of nearly 400 million people in this region. This study explored the radiative sky cooling (RSC) potential resource map across the Gulf Corporation Council (GCC) region, providing it as a sustainable solution to address the aforementioned challenges. A brief comparison of the daytime, nighttime, seasonal, and annual RSC potential is provided for all six countries within the GCC region. The average annual RSC power is between 116.58 W/m2 and 61.80 W/m2 with an average of 82.60 W/m2. Based on meteorological conditions such as ambient temperature, relative humidity, solar irradiance, cloud cover, and atmospheric transmissivity, the highest RSC power is estimated for Kuwait, with an annual average RSC power of 91.12 W/m2. In comparison, the lowest annual average RSC power of 72.50 W/m2 is found for Oman. Since the climatic conditions within this region remain similar throughout the year, there is not much discrepancy in the average RSC capacity throughout spring, summer, autumn, and winter. Furthermore, the average nighttime RSC power is found to be 92.74 W/m2, which is about 18.47% higher than the daytime average RSC of approximately 67.77 W/m2.

Today, advanced technologies are used for the reliable operation of power systems. In order to access a reliable and practical function in the systems, it is necessary to use precise control systems with higher efficiency in the systems to minimize the problems of the distribution system. Devices that are made on the basis of power electronics have wide applications in power systems today. These devices, which are called FACTS devices, provide the possibility of improving energy transmission with the least investment cost, as well as quick control of power system problems. FACTS devices are placed in series, parallel or series-parallel transmission lines and control the operation of distribution systems in permanent states as well as the dynamic behavior of the system in transient states. FACTS devices are an effective method to solve the problems and limitations of lines. Transmission and replacement networks are used to create new lines in the network. From the point of view of power distribution control, FACTS controllers can be placed anywhere in the transmission line, but the elements are most effectively used when they are placed at the most critical point. Unified Power Flow Controller (UPFC) is one of the most important FACTS devices that can improve parameters. The quality of power used in the power system depends on the effect of this controller in improving the loss reduction, reducing the total harmonic distortion (THD), and removing the clogged lines to their proper location in the power system. This device is capable of all different effective parameters at a time. These parameters usually include voltage, impedance, and phase. This paper uses a new sensitivity analysis index to determine the optimal size and location of the UPFC to improve the power quality parameters of the distribution system. The proposed method is evaluated on the IEEE 14-bus network in the Simulink environment of MATLAB software. Finally, according to the simulation results and the results obtained from the base network, it is determined that using the proposed sensitivity analysis index in UPFC location, losses Network, total harmonic distortions (THD) and eclipses Network lines are much improved. The results indicate that the proposed method has provided a good answer to determine the optimal size and location of UPFC to improve power quality parameters. Using the results of the sensitivity analysis method, the best place to install UPFC in the power grid, mode number 6 between buses 2 and 11 is obtained. and The amount of network power losses after sensitivity analysis, compared to the base network Active losses of about 55% and reactive losses of about 11% deceased, Due to the circular structure of the network, the current passing through the lines is different depending on the amount of load in the bases near that line, and with the presence of UPFC, the network is optimized and the current passing through the lines is also reduced. 4) Percentage of total harmonic distortion (THD) mains voltage before the presence of UPFC is about 27.12%, which after installation in the 6th place with a maximum size has been reduced to about 11.11%.

The electrical power industry has experienced an unprecedented pace of digital transformation as a prevailing economic trend in recent years. This shift towards digitalization has resulted in an increasing interest in the collection of real-time equipment condition data, which provides opportunities for implementing sensor-driven condition-based repair. As a result, there is a growing need for the development of generator maintenance scheduling to consider probabilistic equipment behavior, which requires significant computational efforts. To address this issue, the research proposes the use of a meta-heuristic league championship method (LCM) for generator maintenance scheduling, considering random generation profiles based on generation adequacy criteria. The experimental part of the study compares this approach and its modifications to widely used meta-heuristics, such as differential evolution and particle swarm methods. The identification and demonstration of optimal method settings for the generation maintenance scheduling problem are presented. Subsequently, it is illustrated that employing random league scheduling expedience can reduce the variance of objective function values in resulting plans by over three times, with values of 0.632 MWh and 0.205 MWh for conventional and proposed techniques respectively. In addition, three approaches are compared to assess generation adequacy corresponding to different schedules. The study emphasizes the efficacy of employing the LCM approach in scheduling generator maintenance. Specifically, it showcases that among all the methods examined, the LCM approach exhibits the lowest variance in objective function values, with values of 38.81 and 39.90 MWh for LCM and its closest rival, the modified particle swarm method (MPSM), respectively.

Solar energy is an excellent source of renewable energy, despite its intermittent nature that can pose a challenge. To meet load demand, a converter is required to integrate the system. The converter acts based on control signals from the controller, which is trained according to the end demand and availability of Sun Irradiance. This paper utilizes the Incremental Conductance (IC) and Perturb and Observe (P&O) algorithms, which are widely accepted in the industry and easy to implement. This study aims to design and compare a Step Voltage (SV) controller and a Step-Duty (SD) Maximum Point Tracking (MPPT) IC controller-based DC to DC boost converter. The paper compares the performance of SV and SD controller-based DC to DC boost converters under different environmental conditions, evaluates the system’s effectiveness by comparing the oscillations in load power for both conditions and discusses the impact of battery charging on the Load. The system performance is tested using MATLAB Simulink/coding, considering the Indian solar radiation intensity (SRI) scenario and temperature variations. Overall, this study provides a comprehensive analysis of the performance of the proposed system, which can contribute to the development and optimization of solar energy systems in various applications. From the comparative analysis of IC SD, SV and P&O SD, SV it is observed the performance of IC SD is superior. The impact of battery charging using IC SD controller on the load and MPPT point is also discussed.

The field of research in this article is small-capacity hydropower conversion plants. The object of the study is the turbines of low-pressure micro hydro power plants ( micro HPP) that convert the energy of velocity head into electrical energy. The purpose of the study is to study the features of the operation of rotary turbines and determine the dependence of the rotational speed on the load and efficiency. The influence of the central gap in the turbine blades on its efficiency was also evaluated. During the research, the results of three-dimensional modeling of three types of hydraulic turbines using the Kompasflow software product and the results of experimental studies obtained on a specially created hydraulic stand were used. Based on the results obtained, it was found that, regardless of the types of turbines under consideration, the rotational speed decreases with increasing load, and there is a certain load interval at which the maximum efficiency is achieved. The presence of a central gap in the turbine blades does not lead to a significant increase in the efficiency of the turbine.

The operations of WPTSs needs to be regulated under both its linear and nonlinear operating behaviors in order to ensure the maximum possible wind power production with lowering costs. This involves developing robust control structures that can stringently handle WPTSs’ sophisticated operation. In efforts to achieve this objective, the previous studies proposed various control strategies that were widely employed for the adjustments of WPTSs’ mechanical components. Herein, this paper pursues a rarely studied electrical-component control approach by implementing IFOC-based MPPT strategy on a RSC of DFIG-based WPTS. The ultimate goal of this study is to maintain the electric power quality by regulating the signal THDs of the system’s rotor alternating current along with mitigating the switching transients. To this end, the performances of conventional PI, and FL-tuned PI (FLPI) controllers, under the system’s both normal voltage rating & low voltage operation—it was assumed to be 10% of normal voltage rating, are set to be evaluated. Furthermore, the overall simulation of a 2 MW power scaled-DFIG system comprising aerodynamic model, electrical system model, control system model, and the controller models was implemented in MATLAB-SIMULINK environment in testing the effectiveness of the proposed approach based on a rated wind speed of 10 m/s. Accordingly, the THD factors of rotor alternating current are resulted to be 9.15% with PI & 8.61% with FLPI under normal voltage operation, and 35.46% with PI & 23.25% with FLPI under low voltage operation. With the recommended baseline of 75%, the FLPI model performance accuracy for the current THD control is found to be 76.75% along with mitigated switching transients, while that of PI is 64.54% without mitigated switching transients in the case of nonlinear operating behavior. Hence, FLPI model has proven to show a superior overall performance.

Waste plastics/pyrolysis oil (WPO) obtained from a batch rotary kiln pyrolysis reactor was collected and stored for 60 months in dark at 10 °C, periodically thoroughly characterized for changes in physical and chemical properties and finally tested as the drop-in fuel for power generating units. Changes during storage were manifested through chain length increase from C5-C33 to C5-C43 and distillation curve shift for 150 °C. The changes were attributed to repolymerization reactions and consequently lowered alkene to alkane ratio, occurring at a slow rate during storage. The drop-in performance of aged WPO was evaluated under a wide range of operating parameters in a compression ignition engine based power generating unit. The results were compared with those obtained with conventional diesel fuel at the same injection and gas path parameters. Emission wise, the trends obtained for aged WPO and diesel were differing in the range of 20%, while more than 50% lower CO emissions could be obtained with WPO in optimized operating points, albeit the order of magnitude higher viscosity of aged WPO. With tailored control strategies and careful guidance of in-cylinder thermodynamic conditions it is possible to exploit the increased alkane content of aged WPO. Results provide a comprehensive basis for further development of control strategies, oriented towards stationary power generation applications with high intermittency, where long and mid-term storage of WPO is expected.

The rapid depletion of fossil fuels, increased electricity consumption, and global environmental concerns have led to shift electricity generation from non-renewable to renewable energy sources. Solar photovoltaic (PV) technology is increasing with significant land requirement. To conserve this valuable land and water evaporation, PV panels are being installed on water bodies such as irrigation canals, lakes and dams. Researchers have found that hybrid power generation systems are more efficient than single power generating system, thus by covering canals with solar panels and harnessing the kinetic energy of flowing water using hydrokinetic turbines (HKT), a massive amount of electricity can be generated. The Hybrid Optimization of Multiple Energy Resources (HOMER) software is used in this study to stimulate and acquire the best results and configuration for a hybrid PV/hydrokinetic system in district Sanghar of Sindh province in Pakistan. Model is designed by covering the 1 km canal surface with PV and the hydrokinetic turbines along with it. The overall potential for 1 km length of canal for both PV/hydrokinetic turbine system is found around 2.8 MW with payback period in 5.7 years and by saving 324.58 million cubic meters of water in terms of evaporation with annual saving in GHG emissions of 416,451.74 kg/yr.

The purpose of this study is to examine optimal solar module investments. Firstly, key determinants of the performance of solar energy investments are evaluated by DEMATEL method with the 2-tuple IVIF sets. Moreover, the cell material alternatives for solar module investments are also ranked. For this purpose, an evaluation has been made by 2-tuple IVIF TOPSIS. The contributions of the paper are performing a priority analysis to understand the most significant factors to increase solar energy projects and creating an original model by the integration of DEMATEL and TOPSIS with the 2-tuple IVIF sets. The findings denote that crystalline silicon is the optimal solar panel module to increase the performance of these projects. In the short term, government subsidies can provide cost advantages to solar energy investors. It is not a very continuous practice to try to increase these projects only with government supports. The costs of solar energy projects should be reduced to solve this problem permanently. Owing to new technological developments, high cost problem of solar energy investments can be handled more successfully.

To ensure reliable and efficient operation of fuel cell systems, it is important to monitor them online. However, placing sensors inside the fuel cell is often challenging, so virtual sensing using an efficient state observer is used in this study. Detecting local internal phenomena, such as reactants’ starvation, membrane dryout/flooding, and nitrogen accumulation, requires knowledge of the spatial distribution of internal states. Lumped-parameter models are not suitable for this, as they use a single variable to describe parameters such as hydrogen concentration. Instead, a high-order distributed-parameter fuel cell model is used to predict the spatial profiles of various internal states. An observer algorithm is employed to correct the predicted quantities using a few measurements taken at the system boundary. This update step only considers dominant dynamics from a reduced model to adjust all system states accordingly, making it computationally efficient and robust. The observer algorithm’s performance was verified against a high-fidelity model through detailed simulations.

This paper proposes a robust control based on the integral backstepping control (IBC) for power quality enhancement of micro-grid-connected photovoltaic (PV) system with battery energy storage systems (BESS), The DC side consists of a PV system and battery storage. As for the AC side, it consists of three phases of a multi-functional two-level voltage source inverter (MVSI) coupled to the electrical grid via an inductive filter, all feeding a non-linear load. The MVSI is controlled by a nonlinear direct power control (DPC) strategy with space vector modulation (SVM) and the proposed IBC technique. Using the proposed IBC technique to control the voltage of the DC link voltage loop, the active/reactive power loops of the grid, the compensation of the harmonic currents of the network, and the injection of the power of the PV battery into the grid, loop of the maximum power point tracking (MPPT) regardless of the random nature of weather changes and guarantees optimal power management system battery storage. Using simulation under the MATLAB environment, the proposed control system was validated and compared to the conventional strategies (proportional–integral controller and backstepping controller) in terms of success, performance, robustness, and efficiency. In addition to its ability to respond under any irradiation distortion and non-linear load unbalance.

It has been shown that a reduction in the shunt resistance can lead to solar module degradation over time, resulting ultimately in module failure. This paper reports how the effects of reduced shunt resistance on the current–voltage (I-V) characteristics of a PV cell can be used to identify degradation before it becomes critical. Five commercial polycrystalline solar cell samples had their shunt resistance artificially lowered before measuring their I-V characteristics. Analyses of the effect of lowered shunt resistance on maximum power output (Pmax), short-circuit current (ISC), open-circuit voltage (VOC) and fill factor were conducted. Reduction in shunt resistance was correlated with the cells’ electrical parameters to determine the critical shunt resistance where degradation becomes catastrophic. Linear models were developed relating reduction in shunt resistance to the solar cell’s Pmax and VOC. These relationships are proposed as strong predictors and observers of shunt resistance degradation and are suitable for implementation in online monitoring systems for operational PV modules.

Experimental data from a Direct Ethanol Fuel Cell (DEFC) provides a general perspective about its performance; nevertheless, it does not provide information about the cell’s physical characteristics nor information to improve its performance. On the other hand, numerical simulation can be used to test the cell’s design and boost its performance but requires a set of physical parameters. In this proposal, we introduce a novel modification to an empirical model for a Direct Methanol Fuel Cell to make it suitable for DEFC simulations at different temperatures by a new semi-empirical mathematical model. In addition, we introduce temperature-depending parametric forms of several terms to reduce the number of possible parameters to estimate from the DEFC. Then, we combined the models with an estimation of distribution algorithm to find the numerical simulation that best reproduces the experimental polarization curve. The method is validated by estimating the parameters to reproduce the experimental data at different temperatures reported in the literature, and with data obtained in an in-house open-cathode DEFC, recorded at a scan rate of 10 mVs−1, using as fuel CH3CH2OH 1 M at 25 °C and 60 °C. From the estimation results at temperature set T1→=(T1a,T1c) ∘C, the same parameters are used for a simulation at T2→=(T2a,T2c) ∘C, demonstrating that it reproduces the two experimental polarization curves. Hence, the models and methods presented here can be used to reduce physical experimentation and to test different designs and operation settings.

This paper considers the impact of adding PCM/fin slab on thermal performance and power consumption of an ordinary one-door refrigerator/freezer. The PCM box with different materials is attached to the bottom surface of evaporator. Water with melting temperature of 0 °C is used as a phase change material. To study the effect of enhancing heat conduction through the PCM domain, placing fin with different geometrical configurations in PCM slab is investigated too. The results indicate that the presence of PCM- slab under the surface of the evaporator helps to decrease the cabin temperature due to the potential of PCM in absorbing and releasing cold energy. Also the results show that copper is more appropriate for PCM slab material due to its higher thermal conductivity. Furthermore, distributing the fins in PCM slab helps to narrow down the temperature fluctuations of cabin and decrease the power consumption.

Adopting suitable energy policies that consider the existence of main obstacles could make the development of solar energy systems much smoother. Several obstacles have been placed in the way of solar energy development in Pakistan, which has prevented its growth from reaching a satisfactory level. In order to tackle these issues, it is necessary first to recognize the obstacles that stand in the way of implementing solar energy. So, this research aims to find and rank the obstacles to the expansion of solar power in Pakistan using a novel spherical fuzzy analytical hierarchy process. The results revealed that the economic obstacles category (21.46%) ranks highest among major categories. In contrast, the overall global ranking of sub-obstacles showed that budget constraints (4.68%), lack of access to credit/capital (4.52%), political instability (4.51%), high investment risk and operation cost (4.42%), and partnership issues (4.37%) are the more critical five sub-obstacles than the rest of the twenty-one obstacles within different categories. In addition, recommendations are made for the elimination of the obstacles. The current study has policy implications for policymakers, researchers, and practitioners involved in the solar sector in the country. Furthermore, it may help develop strategies for the smooth deployment of solar energy in Pakistan.

This paper applies sign restrictions to identify oil structural shocks by imposing nonzero restrictions on the short-term price elasticity of oil supply. With the help of oil inventory data, flow supply, flow demand and speculative demand shocks in the global oil market are identified. Then, the impact of different kinds of oil price shocks on fluctuations of the U.S. and Chinese stock markets is examined and some insights from the perspective of frequency domain are provided. We observe that the U.S. and Chinese stock markets are extensively influenced by the three types of oil structural shocks. In particular, oil price shocks induced by speculation can significantly affect the performance of stock markets in both countries. Under the frequency domain, we notice that the flow demand shock is the most important driver of the variance in U.S. and Chinese stock returns and volatility, particularly at low and business cycle frequencies. Meanwhile, we note that short-term fluctuations in Chinese stock market returns and volatility are more vulnerable to speculative demand shocks. These analysis results are not only useful for policymakers to take targeted measures to deal with the impact of oil price shocks on the stock market, but also useful for investors to adjust their stock portfolios to achieve excess returns.

In the era of energy transition, climate and topography characteristics make wind energy a promising renewable energy source in South Korea. Following the successful operations of onshore wind power generation, the South Korean government has implemented the 3020 renewable energy implementation plan with a target of establishing 12GW offshore wind farms by 2030. Considering financial and time constraints, it is important to determine the most suitable locations to enable renewable energy farms to achieve the proposed targets for renewable energy production. Although several studies conducted in South Korea have assessed the economic feasibility of potential wind farm sites using the discounted cash-flow method, this method involves some limitations regarding incorporating the value of flexibility and uncertainty factors in the site evaluation process. Thus, this study utilized a real options approach – the Geske compound option model – in a system dynamics framework to evaluate potential sites for offshore wind farms on the mid-west coast of South Korea. Using the developed potential site evaluation model, this study obtained different results from the reference study, which conducted cost-benefit analyses of the same areas. The results of this study demonstrate the importance of flexibility value and uncertainty factors in the site evaluation process. This study also estimates the environmental mitigation of each potential site concerning carbon emission reduction for offshore wind farms.

The COVID-19 pandemic has caused huge health and economic damages. Various protective face masks, such as single-use, cotton, and the most widespread FFP2 or KN95 masks, are used to prevent the spread of this virus. However, these face masks are usually packaged in plastic packaging, which increases the amount of plastic waste. Plastic gloves are also often used in the connection of the pandemic. All this leads to a large production of protective equipment, but their use contributes to the increase of this type of waste, which presents a new challenge in waste management. This article investigates a complete element analysis of these mentioned materials and observes potential harmful substances. Further, pellets, as a potential fuel for combustion or pyrolysis purposes, were produced with the content of 5% and 10% of face masks. FFP2 were firstly separated from ear straps and wires, then disintegrated, added to spruce sawdust, and compressed into pellets. A series of experiments were realized and aimed at elemental, thermogravimetric, and calorific value analyses of produced pellets. Based on the results, it can be concluded that the presence of face masks FFP2 in pellets increases the content of carbon, hydrogen, and nitrogen, volatile matter, and calorific values, but decreases the content of fixed carbon. According to elemental analysis of produced pellets, no significant amounts of harmful elements were found.

The energy supply of healthcare facilities is of great importance under different circumstances. In this study, supplying the energy of a clinic using maximum renewable resources under normal and crisis conditions is examined. This paper is novel in that it designs an energy system specifically for times of crisis. The proposed clinic is located in two different regions in Iran. This paper considers a solar panel, wind turbine, battery, inverter, and controller for electricity generation from renewable resources, a steam boiler for heating needs, and a diesel generator as a backup system. Scenarios, including changes in the type of controller and the price of different parts, were examined. In the optimal scenario, where the clinic is in normal conditions in terms of patient acceptance, the net present cost and cost of energy were estimated to be $2.57 million and 0.0606 $/kWh for Rasht, and $3.09 million and 0.0732 $/kWh for Shiraz, respectively. In a new scenario, in a critical time of the COVID-19 outbreak, the net present cost and cost of energy were calculated to be $4.29 million and 0.0608$/kWh for Rasht, and $5.31 million and 0.0755 $/kWh for Shiraz, respectively. Also the clinic will generate an annual income of $0.12 million by selling excess energy produced in this scenario during normal conditions.

Direct methanol fuel cell (DMFC) is a device which converts chemical potential energy into electrical energy through the electrochemical reaction that involves oxidation of methanol. This study investigates the underlying voltage loss mechanism and determines how a change in process conditions will affects the resulting voltage loss, through the development of a one-dimensional mathematical DMFC model in software (MATLAB). The one-dimensional mathematical model has adopted a modelling approach that is simple and relatively easy to be constructed, thus providing a method for simple yet accurate estimation of the DMFC voltage loss curve. The study is conducting in three stages, which include the construction of preliminary model, model parameter fitting and model simulation. Based on the developed DMFC model, the polarization curve of a DMFC are dividing into three regions, including activation polarization-controlled region, ohmic drop controlled region and concentration polarization-controlled region. In each of these regions, one of the voltage loss mechanisms is the dominant mechanism that causes the greatest voltage loss. Voltage loss from all three mechanisms are finding to be reduced at higher temperature. The simulated DMFC can operate at a maximum power density of 0.15 W/cm2, with a voltage efficiency of 33.9%. This model operates at temperature of 343K and uses 2M methanol concentration.