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Showing records 4711 to 4735 of 41325. [First] Page: 1 186 187 188 189 190 191 192 193 194 Last
Analysis of the Applicability of the Parabolic Trough Solar Thermal Power Plants in the Locations with a Temperate Climate
Tomasz Janusz Teleszewski, Mirosław Żukowski, Dorota Anna Krawczyk, Antonio Rodero
April 20, 2023 (v1)
Keywords: concentrating solar power systems, parabolic trough collectors, solar gains, solar plants
Currently, intensive work is underway in Poland to increase the share of renewable energy sources in the overall energy balance. Therefore, this paper presents the possibilities of using concentrated solar power in zones with a temperate climate. A simplified model based on the energy balance in the solar collectors considering the main operating parameters of the typical solar power plant was developed. It should be noted here that the model does not take into account issues related to heat accumulation and electricity generation in a Solar Thermal Power Station. The simulation of forced convection inside the solar collector absorber was additionally included in the calculations to improve its accuracy. The model was verified using actual heat measurements at the outlet of the parabolic collector installation at a Solar Thermal Power Station located in the south of Spain. The heat generated by a similar solar collector system in a selected region with a temperate climate, the city of... [more]
Analysis of Small Hydropower Generation Potential: (2) Future Prospect of the Potential under Climate Change
Jaewon Jung, Sungeun Jung, Junhyeong Lee, Myungjin Lee, Hung Soo Kim
April 20, 2023 (v1)
Keywords: climate change scenario, generation potential, hydropower, Renewable and Sustainable Energy
The interest in renewable energy to replace fossil fuel is increasing as the problem caused by climate change has become more severe. In this study, small hydropower (SHP) was evaluated as a resource with high development value because of its high energy density compared to other renewable energy sources. SHP may be an attractive and sustainable power generation environmental perspective because of its potential to be found in small rivers and streams. The power generation potential could be estimated based on the discharge in the river basin. Since the river discharge depends on the climate conditions, the hydropower generation potential changes sensitively according to climate variability. Therefore, it is necessary to analyze the SHP potential in consideration of future climate change. In this study, the future prospect of SHP potential is simulated for the period of 2021 to 2100 considering the climate change in three hydropower plants of Deoksong, Hanseok, and Socheon stations, Ko... [more]
Towards Engineered Hydrochars: Application of Artificial Neural Networks in the Hydrothermal Carbonization of Sewage Sludge
Theodoros N. Kapetanakis, Ioannis O. Vardiambasis, Christos D. Nikolopoulos, Antonios I. Konstantaras, Trinh Kieu Trang, Duy Anh Khuong, Toshiki Tsubota, Ramazan Keyikoglu, Alireza Khataee, Dimitrios Kalderis
April 20, 2023 (v1)
Keywords: artificial neural networks, Biomass, hydrochar, hydrothermal carbonization, Machine Learning, sewage sludge, waste management
Sewage sludge hydrochars (SSHs), which are produced by hydrothermal carbonization (HTC), offer a high calorific value to be applied as a biofuel. However, HTC is a complex processand the properties of the resulting product depend heavily on the process conditions and feedstock composition. In this work, we have applied artificial neural networks (ANNs) to contribute to the production of tailored SSHs for a specific application and with optimum properties. We collected data from the published literature covering the years 2014−2021, which was then fed into different ANN models where the input data (HTC temperature, process time, and the elemental content of hydrochars) were used to predict output parameters (higher heating value, (HHV) and solid yield (%)). The proposed ANN models were successful in accurately predicting both HHV and contents of C and H. While the model NN1 (based on C, H, O content) exhibited HHV predicting performance with R2 = 0.974, another model, NN2, was also able... [more]
Voltage-Gain Design and Efficiency Optimization of Series/Series-Parallel Inductive Power Transfer System Considering Misalignment Issue
Libin Yang, Ming Zong, Chunlai Li
April 20, 2023 (v1)
Subject: Optimization
Keywords: efficiency optimization, inductive power transfer, misalignment issue, series/series-parallel, voltage-gain
Compensation is key to an inductive power transfer (IPT) system in terms of voltage transfer function and efficiency optimization. Basic compensation is simple, but not suitable, for the achievement of variable load-independent voltage-gains without changing the design of the loosely-coupled transformer (LCT). On the other hand, higher-order compensation circuits enable greater design freedom to achieve variable load-independent voltage-gains while keeping the LCT unchanged, but it requires a variety of compensation components, especially the inductive components, which incur significant copper and core losses. This paper proposes a comprehensive design of the series/series-parallel (S/SP) IPT system. The design methodology for variable load-independent voltage-gains is studied to keep the LCT unchanged and achieve zero phase angle input over the whole load range. Design consideration includes the effect of misalignment issue on the voltage-gain and, thus, a design criteria can be deri... [more]
Unbalanced Voltage Compensation with Optimal Voltage Controlled Regulators and Load Ratio Control Transformer
Akito Nakadomari, Ryuto Shigenobu, Takeyoshi Kato, Narayanan Krishnan, Ashraf Mohamed Hemeida, Hiroshi Takahashi, Tomonobu Senjyu
April 20, 2023 (v1)
Keywords: distribution system, load ratio control transformer, optimal scheduling, step voltage regulator, voltage unbalance
Penetration of equipment such as photovoltaic power generations (PV), heat pump water heaters (HP), and electric vehicles (EV) introduces voltage unbalance issues in distribution systems. Controlling PV and energy storage system (ESS) outputs or coordinated EV charging are investigated for voltage unbalance compensation. However, some issues exist, such as dependency on installed capacity and fairness among consumers. Therefore, the ideal way to mitigate unbalanced voltages is to use grid-side equipment mainly. This paper proposes a voltage unbalance compensation based on optimal tap operation scheduling of three-phase individual controlled step voltage regulators (3ϕSVR) and load ratio control transformer (LRT). In the formulation of the optimization problem, multiple voltage unbalance metrics are comprehensively included. In addition, voltage deviations, network losses, and coordinated tap operations, which are typical issues in distribution systems, are considered. In order to inves... [more]
Design of a Damping Controller Using the SCA Optimization Technique for the Improvement of Small Signal Stability of a Single Machine Connected to an Infinite Bus System
Abdul Waheed Khawaja, Nor Azwan Mohamed Kamari, Muhammad Ammirrul Atiqi Mohd Zainuri
April 20, 2023 (v1)
Keywords: eigenvalues, objective function, power system stability, power system stabilizer parameters, sine cosine algorithm, single machine infinite bus
This paper discusses the use of a stochastic metaheuristic population-based optimization algorithm known as the sine cosine algorithm (SCA) to design the parameters of a power system stabilizer (PSS) for damping electromechanical oscillations in a single machine connected to a large power system. The design of the PSS parameters was formulated as an optimization problem to minimize the objective function value. The SCA was used to obtain the best values of the PSS parameters under the objective function. Simulation was carried out by a linearized power system model. The lead lag controller was used as the PSS structure and the results from that were compared with those obtained by moth flame optimization and evolutionary programming. The results showed that the SCA is more effective than are the other techniques in exploration and exploitation to tune the PSS parameters and enhance the power system stability by damping oscillations in a range of loading conditions.
Effects of Impurities on Pre-Doped and Post-Doped Membranes for High Temperature PEM Fuel Cell Stacks
Samuel Simon Araya, Sobi Thomas, Andrej Lotrič, Simon Lennart Sahlin, Vincenzo Liso, Søren Juhl Andreasen
April 20, 2023 (v1)
Subject: Materials
Keywords: diagnosis, distribution of relaxation times, electrochemical impedance spectroscopy, fault, fuel cell, PEM, reformate
In this paper, we experimentally investigated two high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) stacks for their response to the presence of reformate impurities in an anode gas stream. The investigation was aimed at characterizing the effects of reformate impurities at the stack level, including in humidified conditions and identifying fault features for diagnosis purposes. Two HT-PEMFC stacks of 37 cells each with active areas of 165 cm2 were used with one stack containing a pre-doped membrane with a woven gas diffusion layer (GDL) and the other containing a post-doped membrane with non-woven GDL. Polarization curves and galvanostatic electrochemical impedance spectroscopy (EIS) were used for characterization. We found that both N2 dilution and impurities in the anode feed affected mainly the charge transfer losses, especially on the anode side. We also found that humidification alleviated the poisoning effects of the impurities in the stack with pre-doped membra... [more]
Anisotropy of Strength and Elastic Properties of Lower Paleozoic Shales from the Baltic Basin, Poland
Przemyslaw Michal Wilczynski, Andrzej Domonik, Pawel Lukaszewski
April 20, 2023 (v1)
Keywords: anisotropy, Baltic Basin, Poisson’s ratio, shale gas, strength, Young’s modulus
The paper presents the results of laboratory studies on the strength−strain properties of shales representing four siltstone-claystone lithostratigraphic units occurring in the Baltic Basin. Laboratory studies in a triaxial stress state were conducted as single failure tests on cylindrical samples oriented parallel and perpendicular to lamination within the rocks. Mutually perpendicular samples were cut out from the same drill core sections in order to determine mechanical anisotropy. Samples oriented parallel to lamination were characterised by values of the static Young’s modulus twice as high as from samples oriented perpendicular to lamination. Similar variability was observed in the case of maximum differential stress values and Poisson’s ratio. Samples parallel to lamination registered notably lower axial strains, which influenced increased values of Young’s modulus and Poisson’s ratio. The rocks studied are characterised by VTI type (vertical transverse isotropy) internal anisot... [more]
Production of Volatile Fatty Acids in a Semi-Continuous Dark Fermentation of Kitchen Waste: Impact of Organic Loading Rate and Hydraulic Retention Time
Justyna Swiatkiewicz, Radoslaw Slezak, Liliana Krzystek, Stanislaw Ledakowicz
April 20, 2023 (v1)
Subject: Biosystems
Keywords: dark fermentation, metagenomic analysis, mixed microbial cultures, volatile fatty acids
The aim of the study was to evaluate the possibility of using the process of dark fermentation to convert kitchen waste into valuable volatile fatty acids in a semi-continuous process at different values of the organic loading rate (2.5 and 5.0 gVS/(L × d)) and hydraulic retention time (5 and 10 d) using anaerobic mixed microbial consortia. The experiments were performed in a bioreactor of working volume 8L with pH control. The maximum volatile fatty acids yield in a steady state (22.3 g/L) was achieved at the organic loading rate of 5.0 gVS/(L × d) and HRT of 10 days. The main products of dark fermentation were acetic and butyric acids, constituting, respectively, 35.2−47.7% and 24.1−30.0% of all identified volatile fatty acids. Additionally, at the beginning of the fermentation and in a steady-state condition, the microbial population analysis (16S rDNA) of the fermentation mixture with the most effective volatile fatty acids generation has been performed to monitor the DF microflora... [more]
Modelling Aspects in the Simulation of the Diffusive Flame in A Bluff-Body Geometry
Alessandro Di Mauro, Marco Ravetto, Prashant Goel, Mirko Baratta, Daniela Anna Misul, Simone Salvadori, Rainer Rothbauer, Riccardo Gretter
April 20, 2023 (v1)
Keywords: Computational Fluid Dynamics, diffusive flame, gas turbines, pollutant emission modelling, turbulent combustion
Gas turbines are expected to play a key role in the energy production scenario in the future, and the introduction of carbon-free fuels is fundamental for the development of a sustainable energy mix. The development of a reliable numerical model is thus fundamental in order to support the design changes required for the burners. This paper presents the results of a numerical investigation on a turbulent, diffusive, combustion test case, with the purpose of identifying the best compromise between accuracy and computational cost, in the perspective of the model application in real, more complex, geometries. Referring to a test case has two main advantages. First, a rather simple geometry can be considered, still retaining a few peculiar flow features, such as recirculation vortices and shear layers, which are typical of real applications. Second, the experimental setup is much more detailed than in the case of real turbines, allowing a thorough model validation to be performed. In this p... [more]
One-Dimensional Model of a Compact DHW Heat Pump with Experimental Validation
F. Aguilar, D. Crespí-Llorens, S. Aledo, P. V. Quiles
April 20, 2023 (v1)
Keywords: domestic hot water, Energy Storage, heat pump, numerical model, stratification
The current work presents a computationally cost-effective numerical model that successfully simulates a heat pump water heater (HPWH) under typical working conditions of dwellings. The model’s main components are a stratified tank and the heat-pump unit. Both systems are coupled, since a good prediction of water temperature is needed to accurately predict the heat-pump performance. Ten thermocouples measured the tank wall temperature. Measurements and simulations were performed under challenging conditions of a heavy stratification. The 190 L tank stratification was successfully modeled employing a 1D model, experimentally adjusted by three tapping cycles, with 6 × 22, 6 × 33, and 3 × 33 L consumptions, covering flowrates of 4 and 6 L/min. Water temperature is obtained with an uncertainty of 2.6 °C while the heat-pump was ON. A black box model has been used to obtain the heat-pump performance out of the external and condenser temperatures. For the analyzed days, the COP estimation pre... [more]
Enhanced Biogas Production by Ligninolytic Strain Enterobacter hormaechei KA3 for Anaerobic Digestion of Corn Straw
Qing Zhang, Jing Zhang, Shuai Zhao, Peizhi Song, Yanli Chen, Pu Liu, Chunlan Mao, Xiangkai Li
April 20, 2023 (v1)
Subject: Biosystems
Keywords: biogas production, Enterobacter hormaechei KA3, gut microbiome, microbial community, microbial lignin degradation
Lignin-feeding insect gut is a natural ligninolytic microbial bank for the sustainable conversion of crop straw to biogas. However, limited studies have been done on highly efficient microbes. Here, an efficient ligninolytic strain Enterobacter hormaechei KA3 was isolated from the gut microbiomes of lignin-feeding Hypomeces squamosus Fabricius, and its effects on lignin degradation and anaerobic digestion were investigated. No research has been reported. Results showed that strain KA3 had better lignin-degrading ability for corn straw with a higher lignin-degrading rate (32.05%) and lignin peroxidase activity (585.2 U/L). Furthermore, the highest cumulative biogas yield (59.19 L/kg-VS) and methane yield (14.76 L/kg-VS) were obtained for KA3 inoculation, which increased by 20% and 31%, respectively, compared to CK. Higher removal rates of COD, TS, and vs. of 41.6%, 43.11%, and 66.59% were also found. Moreover, microbial community diversity increased as digestion time prolonged in TG, an... [more]
Electric Drivetrain Optimization for a Commercial Fleet with Different Degrees of Electrical Machine Commonality
Meng Lu, Gabriel Domingues-Olavarría, Francisco J. Márquez-Fernández, Pontus Fyhr, Mats Alaküla
April 20, 2023 (v1)
Subject: Optimization
Keywords: electric commercial vehicles, electrical machine scaling, fleet optimization, total cost of ownership
At present, the prevalence of electric vehicles is increasing continuously. In particular, there are promising applications for commercial vehicles transferring from conventional to full electric, due to lower operating costs and stricter emission regulations. Thus, cost analysis from the fleet perspective becomes important. The study of cost competitiveness of different drivetrain designs is necessary to evaluate the fleet cost variance for different degrees of electrical machine commonality. This paper presents a methodology to find a preliminary powertrain design that minimizes the Total Cost of Ownership (TCO) for an entire fleet of electric commercial vehicles while fulfilling the performance requirements of each vehicle type. This methodology is based on scalable electric machine models, and particle swarm is used as the main optimization algorithm. The results show that the total cost penalty incurred when sharing the same electrical machine is small, therefore, there is a cost... [more]
Comparative Analysis of Carbon Capture and Storage Finance Gaps and the Social Cost of Carbon
Amanda Harker Steele, Travis Warner, Derek Vikara, Allison Guinan, Peter Balash
April 20, 2023 (v1)
Keywords: carbon capture and storage, economic efficiency, financial gaps, negative externality, social cost of carbon
This paper evaluates how changes in economic market and policy conditions, including the establishment of a per-unit tax on unabated emissions of carbon dioxide (CO2) set equal to estimates of the social cost of carbon (SCC), influence the economics of carbon capture and storage (CCS) for two hypothetical power generation facilities located in the United States. Data are provided from modified versions of models and resources created and managed by the National Energy Technology Laboratory. Changes in economic market and policy conditions are evaluated over a series of scenarios in which differences in the levelized cost of electricity (LCOE) provide estimates of the financial gap necessary to overcome for CCS to be considered the cost-minimizing choice for each power generation facility type considered. Results suggest that for the coal and natural gas power generation facilities considered, a per-unit tax set equal to an SCC exceeding $123 per metric ton of CO2 (/tCO2) emitted (2018... [more]
Transient Fault Detection and Location in Power Distribution Network: A Review of Current Practices and Challenges in Malaysia
Saidatul Habsah Asman, Nur Fadilah Ab Aziz, Ungku Anisa Ungku Amirulddin, Mohd Zainal Abidin Ab Kadir
April 20, 2023 (v1)
Keywords: Fault Detection, fault location, fault-monitoring system, power distribution system, transient fault
An auto-restoration tool to minimize the impact of faults is one of the critical requirements in a power distribution system. A fault-monitoring system is needed for practical remote supervision to identify faults and reduce their impacts, and thus reduce economic losses. An effective fault-monitoring system is beneficial to improve the reliability of a protection system when faults evolve. Therefore, fault monitoring could play an important role in enhancing the safety standards of systems. Among the various fault occurrences, the transient fault is a prominent cause in Malaysia power systems but gains less attention due to its ability of self-clearance, although sometimes it unnecessarily triggers the operation of protection systems. However, the transient fault is an issue that must be addressed based on its effect that can lead to outages and short-circuits if prolonged. In this study, the authors summarize the guidelines and related standards of fault interaction associated with a... [more]
The Correlation of Biodiesel Blends with the Common Rail Diesel Engine’s Performance and Emission Characteristics
Tuan Nghia Nguyen, Nguyen Xuan Khoa, Le Anh Tuan
April 20, 2023 (v1)
Keywords: blended ratio, common rail engine, emission, fish oil, trend changes
The use of biofuel has been researched and announced by scientists to bring benefits in terms of environmental protection. However, studies continue to be conducted to achieve stable results and confirm biofuels as an effective alternative fuel for internal combustion engines. In this study, the fuel used is biodiesel derived from fish oil and conventional diesel fuel. Specifically, the test fuel is conventional diesel mixed with fish oil biodiesel in different ratios, including B0, B10, B20, B30, B40, and B50 (respectively 0%, 10%, 20%, 30% 40%, and 50% biodiesel in the mixture). Research was carried out by both simulation (from B0 to B50) and experiment (from B0 to B30) on a single cylinder common rail diesel engine. Test modes were at 25%, 50%, and 75% load respectively at maximum torque (at 1400 revolutions per minute (rpm)) and minimum fuel consumption (at 2200 rpm). Compared with B0, the average reduction in brake power of the biodiesel decreased relative to the proportion of bio... [more]
Technical and Economic Analysis of the Supercritical Combined Gas-Steam Cycle
Marcin Jamróz, Marian Piwowarski, Paweł Ziemiański, Gabriel Pawlak
April 20, 2023 (v1)
Keywords: combined gas-steam cycles, cost management, economic analysis, efficiency, heat exchange in Heat Recovery Steam Generators (HRSG), managerial decisions
Combined cycle power plants are characterized by high efficiency, now exceeding 60%. The record-breaking power plant listed in the Guinness Book of World Records is the Nishi-Nagoya power plant commissioned in March 2018, located in Japan, and reaching the gross efficiency of 63.08%. Research and development centers, energy companies, and scientific institutions are taking various actions to increase this efficiency. Both the gas turbine and the steam turbine of the combined cycle are modified. The main objective of this paper is to improve the gas-steam cycle efficiency and to reach the efficiency that is higher than in the record-breaking Nishi-Nagoya power plant. To do so, a number of numerical calculations were performed for the cycle design similar to the one used in the Nishi-Nagoya power plant. The paper assumes the use of the same gas turbines as in the reference power plant. The process of recovering heat from exhaust gases had to be organized so that the highest capacity and... [more]
Investigating the Effects of the United States’ Economic Slowdown Related to the COVID-19 Pandemic on Energy Consumption in Other Countries—A Global Vector Autoregressive Model
Sailan Hu, Rongrong Li
April 20, 2023 (v1)
Keywords: COVID-19, energy consumption, GVAR, spillover effects, US economic growth
The COVID-19 pandemic has caused a drop-in economic activity and energy consumption of the United States. This work aims to investigate the spillover effects of the United States’ COVID-19 economic recession on economic growth and energy consumption in other nations using a global vector autoregressive (GVAR) approach and quarterly data between 1990 and 2013 from 41 major countries/regions. On the one hand, the simulation results indicate that the US COVID-19 recession has a negative impact on other countries’ economic growth through trade ties, reducing the economic growth of other countries, especially for countries which have a close trade relationship with the US. In addition, the spillover effects of the US economic recession have different impacts on other countries’ energy consumption. Countries with the closest trade ties to the US are most affected, such as Japan and China. In addition, the impact of the US’ economic shock on energy consumption in developing countries is signi... [more]
High Precision LSTM Model for Short-Time Load Forecasting in Power Systems
Tomasz Ciechulski, Stanisław Osowski
April 20, 2023 (v1)
Keywords: demand-side management, load forecasting, power systems, prediction systems, recurrent LSTM network
The paper presents the application of recurrent LSTM neural networks for short-time load forecasting in the Polish Power System (PPS) and a small region of a power system in Central Poland. The objective of the present work was to develop an efficient and accurate method of forecasting the 24-h pattern of power load with a 1-h and 24-h horizon. LSTM showed effectiveness in predicting the irregular trends in time series. The final forecast is estimated using an ensemble consisted of five independent predictions. Numerical experiments proved the superiority of the ensemble above single predictor resulting in a reduction of the MAPE the RMSE error by more than 6% in both forecasting tasks.
An Improved Particle Swarm Optimization with Chaotic Inertia Weight and Acceleration Coefficients for Optimal Extraction of PV Models Parameters
Arooj Tariq Kiani, Muhammad Faisal Nadeem, Ali Ahmed, Irfan A. Khan, Hend I. Alkhammash, Intisar Ali Sajjad, Babar Hussain
April 20, 2023 (v1)
Subject: Optimization
Keywords: acceleration coefficients, chaotic and tangent, inertia weight, parameter estimation, solar cell and modules
The efficiency of PV systems can be improved by accurate estimation of PV parameters. Parameter estimation of PV cells and modules is a challenging task as it requires accurate operation of PV cells and modules followed by an optimization tool that estimates their associated parameters. Mostly, population-based optimization tools are utilized for PV parameter estimation problems due to their computational intelligent behavior. However, most of them suffer from premature convergence problems, high computational burden, and often fall into local optimum solution. To mitigate these limitations, this paper presents an improved variant of particle swarm optimization (PSO) aiming to reduce shortcomings offered by conventional PSO for estimation of PV parameters. PSO is improved by introducing two strategies to control inertia weight and acceleration coefficients. At first, a sine chaotic inertia weight strategy is employed to attain an appropriate balance between local and global search. Aft... [more]
Prediction of Air Pressure Change Inside the Chamber of an Oscillating Water Column−Wave Energy Converter Using Machine-Learning in Big Data Platform
Dongwoo Seo, Taesang Huh, Myungil Kim, Jaesoon Hwang, Daeyong Jung
April 20, 2023 (v1)
Keywords: big data platform, HPC cloud, machine-learning, oscillating water column, pressure prediction model, wave energy converter
Wave power is an eco-friendly power generation method. Owing to the highly volatile nature of wave energy, the application of prediction techniques for power generation, failure diagnosis, and operational efficiency plays a key role in the successful operation of wave power plants (WPPs). To this end, we propose the following approaches: (i) deriving the correlation between highly volatile data such as wave height data and sensor data in an oscillating water column (OWC) chamber; (ii) development of an optimal training model capable of accurate prediction of the state of the wave energy converter (WEC) based on the collected sensor data. In this study, we developed a big data analysis system that can utilize the machine learning framework in KNIME (an open analysis platform), and to enable smart operation, we designed a training model using a digital twin of an OWC−WEC that is currently in operation. Using various machine learning models, the pressure of the OWC chamber was predicted,... [more]
Short Term Active Power Load Prediction on A 33/11 kV Substation Using Regression Models
Venkataramana Veeramsetty, Arjun Mohnot, Gaurav Singal, Surender Reddy Salkuti
April 20, 2023 (v1)
Keywords: dimensionality reduction, load forecasting, multiple linear regression, polynomial regression, simple linear regression
Electric power load forecasting is an essential task in the power system restructured environment for successful trading of power in energy exchange and economic operation. In this paper, various regression models have been used to predict the active power load. Model optimization with dimensionality reduction has been done by observing correlation among original input features. Load data has been collected from a 33/11 kV substation near Kakathiya University in Warangal. The regression models with available load data have been trained and tested using Microsoft Azure services. Based on the results analysis it has been observed that the proposed regression models predict the demand on substation with better accuracy.
The Impact of Low-Resource Periods on the Reliability of Wind Power Systems for Rural Electrification in Africa
Hanieh Seyedhashemi, Benoît Hingray, Christophe Lavaysse, Théo Chamarande
April 20, 2023 (v1)
Keywords: adequacy, demand flexibility, low wind power, rural electrification, wind power potential
Decentralized electricity systems based on variable renewable energy (VRE) sources such as wind power can provide affordable, dependable, and modern energy in a manner consistent with the Paris Agreement. Such sources are, however, sensitive to extreme values of climatic factors—an issue that may jeopardize power system reliability. As a resource-rich region with a high proportion of rural population without access to electricity, Africa has been of wide interest in studies on VRE-based electricity generation. Nevertheless, there is still a major gap in our continent-scale understanding of the wind power potential and its variability at different time scales, as well as the influence of low-wind-resource periods in Africa. Using ERA5 hourly estimates of wind speed, the present study investigated the adequacy and temporal variability of local wind power potential across Africa over the 2000−2017 period. The results indicated that design requirements of wind power systems are, on average... [more]
Assessing the Link between Vessel Size and Maritime Supply Chain Sustainable Performance
Dariusz Bernacki
April 20, 2023 (v1)
Keywords: dry bulk and container shipping, economies of scale, energy savings, maritime supply chain
This study determines the relationship between the increase in size of dry bulk carriers and container ships and the changes in sustainable shipping performance. It measures the elasticities of shipping costs for bulk carriers and container ships. Using regression, it derives the functions of the daily and unit costs of shipping with respect to the size of dry bulk carriers and container ships. The estimated daily and unit cost elasticities and cost models reveal significant but diversified impacts of vessel size on dry bulk and container shipping cost and its components, other operating capital, and fuel costs. Findings: Dry bulk carriers and containership size mean elasticities of daily operating costs estimates respectively: total operating costs 0.291 and 0.552, other operating cost (labor cost included) 0.238 and 0.328, capital costs 0.329 and 0.765, fuel costs 0.289 and 0.462; dry bulker and container ship unit shipping mean elasticity respectively: full operating costs (−0.751)... [more]
Analysis of Small Hydropower Generation Potential: (1) Estimation of the Potential in Ungaged Basins
Sungeun Jung, Younghye Bae, Jongsung Kim, Hongjun Joo, Hung Soo Kim, Jaewon Jung
April 20, 2023 (v1)
Keywords: blending technique, generation potential, hydropower, modified-TPM
Small hydropower (SHP) plants are advantageous as they have a short construction period and can be easily maintained. They also have a higher energy density than other alternative energy sources as environmentally-friendly energy sources. In general, hydropower potential is estimated based on the discharge in the river basin, and the discharge can be obtained from the stage station in the gaged basin. However, if there is no station (i.e., ungaged basin) or no sufficient discharge data, the discharge should be estimated based on rainfall data. The flow duration characteristic model is the most widely used method for the estimation of mean annual discharge because of its simplicity and it consists of rainfall, basin area, and runoff coefficient. Due to the characteristics of hydroelectric power depending on the discharge, there is a limit to guaranteeing the accuracy of estimating the generated power with only one method of the flow duration characteristic model. Therefore, this st... [more]
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