The integrity of oil pipelines has received considerable attention. Pipeline leakage accidents cause environmental pollution and casualties. Analysis of accident data in recent years shows that the harbor oil pipeline is prone to natural disasters such as typhoons. The vulnerability analysis of the pipeline was conducted from three perspectives: typhoon grades, windward angles, and operating conditions. The analytic hierarchy is used to build the vulnerability evaluation index system. The vulnerability evaluation score of the pipeline can be calculated by the semi-quantitative method. The results show that the probability of pipeline vulnerability failure increases with the increase of typhoon level, while the change of wind angle has no obvious effect on the pipeline. The full load of the pipeline has a higher evaluation score than that of the empty load, which means the full load is safer. The vulnerability analysis of oil pipelines can effectively improve the safety of pipeline tran... [more]

The dynamic characteristics of pipe piles are of considerable importance for the dynamic foundation design of offshore wind turbines. In this study, we develop an analytical model for the lateral vibration of offshore pipe piles with consideration of the inertia effect and axial loading from the superstructure. A coupled dynamic saturated soil−pile interaction model is established based on Biot’s poroelastic theory and Euler−Bernoulli theory. The potential function, operator decomposition method, variable separation method and matrix transfer method are introduced herein to obtain the lateral force of the inner and outer soil acting on the pile shaft. Then, the analytical solution of the pile dynamic impedance in the frequency domain is derived by employing the soil−pile continuous deformation conditions and the boundary conditions of the pile. The rationality and accuracy of the presented solution have were by comparing its results with those predicted by existing solutions. The influ... [more]

Offshore wind energy has become a hot spot in new-energy development due to its abundant reserves, long power generation time, high unit capacity and low land occupation. In response to the current situation whereby wind energy, and natural and human factors have not been taken into account in the selection of sites for offshore wind-energy-resource development in the traditional “21st Century Maritime Silk Road” region, this paper intends to establish a new risk assessment framework that comprehensively considers the influence of wind resources, the natural environment, and the geopolitical and humanistic environment. The rationality of the new index system and weight determination methods are separately investigated. Some interesting results are obtained by comparing the new framework with traditional frameworks. The results show that the Persian Gulf, the Timor Sea in northern Australia, and the northern part of Sri Lanka in southern India are rich in wind-energy resources and have... [more]

Gas drainage in deep coal seam is a critical issue ensuring the safety of mining and an important measure to obtain gas as a kind of clean available energy. In order to get a better understanding of gas flow and diffusion for gas drainage in deep coal seams, a dual-zone gas flow model, including the drainage damage zone (DDZ) and the non-damaged zone (NDZ), are characterized by different permeability models and anomalous diffusion models to analyze the influence of damage induced by drilling boreholes on gas flow. The permeability model and anomalous diffusion model are verified with experiment and field data. A series of finite-element numerical simulations based on developed models are carried out, indicating that, compared with normal diffusion model, the anomalous diffusion is more accurate and appropriate to field test data. The coal fracture permeability increases rapidly with the distance decreasing from the borehole, and the area of DDZ is increasing significantly with the extr... [more]

New energy technologies are gaining rising importance because of climate change and increasing energy demand, and they show an enormous potential to mitigate environmental issues. With the purpose of maximizing the renewable energy utilization, combined heat and power systems are considered more effective, economical, and ecological. However, renewable energy-based combined heat and power systems are still in the development phase. Hence, this study presents a new methodology to produce combined electricity and heat from wind and solar PV systems to meet the energy demand of small, distributed communities. For this scope, an optimization model is developed to exploit rationally the power generation from renewables and meet the electricity and heating demand of two selected communities. The curtailed energy of solar and wind systems is used to produce heat by a thermal load controller combined with a natural gas boiler. The developed model is also integrated with the grid station for en... [more]

The aim of the research is to assess the potential of agricultural biomass available in European Union countries that can be used for energy purposes. The research took into account the potential of agricultural biomass from: straw from cereal crops, hay from permanent grasslands, natural fertilizers from animal husbandry, cultivation of energy crops on fallow land and waste wood from permanent crops. The study estimated the theoretical potential presenting the energy value of all existing agricultural biomass resources in EU countries and the technical potential taking into account agricultural biomass resources that are not used in agriculture. The research was based on Eurostat data for 2019. The conducted research shows that European Union countries are characterized by a significant potential of agricultural biomass. However, due to the high demand for this resource in agriculture, about 15% of the existing potential can be used for energy purposes. Among the analyzed sources, the... [more]

With the hot topic of “Carbon Neutrality”, energy efficiency and saving practices such as reducing fuel consumption, vigorously advocating new energy power and modern rail are now becoming the main research topics of energy conversion technologies. Supercapacitors, with their ability of higher power density, fast charging, and instantaneous high current output, have become an indispensable energy storage element in modern traction systems for modern rail. This proposal introduced wireless power transfer technologies by using LC series resonant technology for charging the supercapacitors. To match the voltage and current level of the supercapacitor, a four-switch buck-boost converter was applied on the secondary side of the load-matching converter. To regulate the wireless transfer power and charging power of the supercapacitor, the active modulation control method was introduced on both the primary and secondary sides of the transfer system. On the primary side, the power is controlled... [more]

This field study evaluated the building performance of a nearly zero-energy office building near Brussels, Belgium, located in the temperate climatic zone. The building’s thermal comfort and energy parameters were monitored from May 2018 to April 2019. The time-integrated thermal discomfort, primary energy use, and greenhouse gas emissions from the building were then analyzed using the monitored data. The case study evaluated the HVAC system performance with an air-cooled chiller with water cooling coils and a water boiler with water heating coils. The findings indicated an indoor overheating degree of 0.05 °C and an indoor overcooling degree of 0 °C for the observed period. The building’s primary cooling energy use was found to be 37.54 kWhPE/m2.a and primary heating energy use was found to be 46.08 kWhPE/m2.a for the monitored period. The cooling and heating greenhouse gas emissions were 10.14 kg.CO2e/m2.a and 8.34 kg.CO2e/m2.a, respectively. The observed data also indicated that the... [more]

In this article, a resonant converter based on a series-parallel self-adjusting rectifier structure is proposed. By changing the driving signal of the switch, the converter has four working modes: full-bridge structure frequency modulation control, full-bridge structure phase-shift control, half-bridge structure frequency modulation control and half-bridge structure phase-shift control. The newly proposed resonant converter retains the soft switching characteristics of the LLC resonant converter and the mode switching can be completed only through software control without adding additional switches. Different modes correspond to different gain ranges. By changing the control strategy of the modes, the newly proposed converter can meet the design requirements of wide output. Finally, an experimental prototype with an input voltage of 25 V and an output voltage of 9 V to 35 V is built. The experimental results prove the correctness of the wide output characteristics of the converter prop... [more]

Knowledge of the distinctive frequencies and amplitudes of broken rotor bar (BRB) faults in the induction motor (IM) is essential for most fault diagnosis methods. Fast Fourier transform (FFT) is widely applied to diagnose the faults within BRBs. However, this method does not provide satisfactory results if it is applied directly to the stator current signal at low slip because a high-resolution spectrum is required to separate the different components of the frequency. To address this problem, this paper proposes an efficient method based on a Hilbert fast Fourier transform (HFFT) approach, which is used to extract the envelope from the stator current using the Hilbert transform (HT) at low slip. Then, the stator current envelope is analyzed using the fast Fourier transform (FFT) to obtain the amplitude and frequency of the particular harmonic. These data were recently collected and selected as BRB fault features and were employed as adaptive neuro-fuzzy inference system (ANFIS) input... [more]

An external thermal high-temperature continuous feed moving bed tubular reactor was used for the gasification of high moisture content lignite (30.41 wt.%) under CO2 and an auto-generated steam atmosphere. The objectives of this study are to illustrate the synergistic gasification characteristics of high moisture content lignite and CO2 in the tubular reactor; CO2 and auto-generated steam (steam released from the lignite) were used as gasification agents for lignite gasification. The effects of temperature and CO2 flow rate were also investigated. Experimental results showed that when the gasification temperature increased from 800 °C to 1000 °C, the H2 yield also increased from 8.45 mol kg−1 to 17.86 mol kg−1. This may indicate that the H2O-CO2 gasification of semi-coke was enhanced with the rise in temperature. At 900 °C, the gas yield increased with the increase in CO2 flow rate, while the yield of char and liquid product showed an opposite trend. The lower heating value of the H2-r... [more]

In recent years, due to the rise in energy prices and the impact of COVID-19, energy shortages have led to unsafe power supply environments. High emissions industries which account for more than 58% of the carbon emissions of Guangdong Province have played an important role in achieving the carbon peak goal, alleviating social energy shortage and promoting economic growth. Controlling high emissions industries will help to adjust the industrial structure and increase renewable energy investment. Therefore, it is necessary to comprehensively evaluate the policies of energy security and the investments of high emission industries. This paper builds the ICEEH-GD (comprehensive assessment model of climate, economy, environment and health of Guangdong Province) model, designs the Energy Security scenario (ES), the Restrict High Carbon Emission Sector scenario (RHS) and the Comprehensive Policy scenario (CP), and studies the impact of limiting high emissions industries and renewable energy p... [more]

With the gradual increase in load demand due to population and economic growth, integrating renewable energy sources (RES) into the grid represents a solution for meeting load demand. However, integrating RES might change the power system type from radial to non-radial, where the current can flow forward and backward. Consequently, power system analysis methods must be updated. The impact on power systems includes changes in the load flow affecting the voltage level, equipment sizing, operating modes, and power system protection. Conventional power system protection methods must be updated, as RES integration will change the power flow results and the short circuit levels in the power system. With an RES contribution to short circuit, existing settings might experience missed coordination which will result in unnecessary tripping. This paper considers the impact of integrating renewable energy sources into power system protection on overcurrent time delay settings. A new method to upgr... [more]

Among the numerous renewable energy resources, the main advantage of water energy is that it utilizes the current of the streams and rivers regardless of the given time of the day or season. The main purpose of this study was to create a low capacity, floating hydropower plant that is suitable for shallow and even narrow water bodies. The device was designed to create electric energy while floating on the water’s surface; therefore, it can be used not only in natural streams but also in drainage channels and wastewater treatment plants. The prototype was tested under real circumstances to identify the impacts of various settings on the energy efficiency. Measurements were conducted in Veszprém, Hungary on the Brook Séd. The average depth of the riverbed was 36 cm. Based on the field measurements, optimal efficiency was achieved by using six paddles. On the other hand, much lower efficiency was achieved when low (two or three) or high numbers (12 or 15) of paddles were used. A design fr... [more]

A battery management system (BMS) is an important link between on-board power battery and electric vehicles. The BMS is used to collect, process, and store important information during the operation of a battery pack in real time. Due to the wide application of lithium-ion batteries in electric vehicles, the correct estimation of the state of charge (SOC) of lithium-ion batteries (LIBS) is of great importance in the battery management system. The SOC is used to reflect the remaining capacity of the battery, which is directly related to the efficiency of the power output and management of energy. In this paper, a new long short-term memory network with attention mechanism combined with Kalman filter is proposed to estimate the SOC of the Li-ion battery in the BMS. Several different dynamic driving plans are used for training and testing under different temperatures and initial errors, and the results show that the method is highly reliable for estimating the SOC of the Li-ion battery. T... [more]

The solar module output power is the power generated by all individual cells in their specific electrical circuit configuration, multiplied by the cell-to-module power ratio. The cell-to-module power ratio thus reflects the sum of the losses and gains produced by the structure of the module. The biggest process change in module design during the last few years was the introduction of half cells. Another important trend is the use of bifacial cells to build bifacial modules. These two trends increase parts of the module that correspond to the intercell gaps, and the light does not meet the cell in its path. This part of the radiation is therefore not used efficiently. Scientific efforts focus on the texturing surface of covering glass and cells, and the introduction of narrower ribbons and encapsulation materials with improved UV performance, etc. The concept of a diffusor that actively redirects light from the intercell space into the cell was proposed in the past, in the form of a mic... [more]

A good turbine casing cooling design should control the thermal stress and maintain a reasonable tip clearance between the turbine blade and the casing. Since the turbine inlet temperature has been increased yearly, the influence of thermal radiation on the temperature of a turbine casing has become more significant. Therefore, the heat transfer characteristics of a turbine casing considering the radiation effect need to be precisely predicted. In this study, a theoretical model is established for describing the heat transfer characteristics of a turbofan casing, and the model’s effectiveness is verified by comparing the numerical and experimental results. Based on the validated model, the effects of single changes of the wall temperature, cooling air temperature, Reynolds number, and surface emissivity on the heat transfer of the casing are discussed. The results show that the increment of cooling air temperature and surface emissivity leads to the enhancement of the average radiative... [more]

The recovery of oil from a reservoir can be accomplished with various methods, one of the most commonly applied types being waterflooding. A common theory used to describe immiscible displacement is the Buckley−Leverett theory. A brand new type of micromodel, generated and fabricated by using a micro-computer tomography (μCT) image stack of a real sandstone core, was used to conduct immiscible displacement experiments. Critical logging data were recorded, and a high-resolution camera took pictures of the displacement process. In an image processing tool (MATLAB), an algorithm was developed to evaluate the pictures of the experiment and to examine the changes in the saturations of the displacing and the displaced fluid. The main objective of the displacement experiment was to validate the new microchip in two-phase displacement experiments and to assess the feasibility of the image processing algorithm. This was performed by comparing the results of the experimental to the analytical so... [more]

Buildings are responsible for around 30 to 40% of the energy demand and greenhouse gas (GHG) emissions in European countries. Building stock energy models (BSEMs) are an established method to assess the energy demand and environmental impact of building stocks. Spatial analysis of building stock energy demand has so far been limited to cases where detailed, building specific data is available. This paper introduces two approaches of using synthetic building stock energy modelling (SBSEM) to model spatially distributed synthetic building stocks based on aggregate data. The two approaches build on different types of data that are implemented and validated for two separate case studies in Ireland and Austria. The results demonstrate the feasibility of both approaches to accurately reproduce the spatial distribution of the building stocks of the two cases. Furthermore, the results demonstrate that by using a SBSEM approach, a spatial analysis for building stock energy demand can be carried... [more]

A rapid transition toward a decarbonized economy is underway, following the Paris Agreement and the International Maritime Organization 2030 decarbonization goals. However, due to the high cost of the rapid transition to eco-friendly energy and the geopolitical conflict in eastern Europe, liquefied natural gas (LNG), which emits less carbon than other fossil fuels, is gaining popularity. As the spot market grows due to increased LNG demand, the usage of period extension options in time charter (T/C) contracts is increasing; however, these options are generally provided free of charge in practice, without economic evaluation; this is because some shipowners want to make their time charter contracts more attractive to the more credible charterers. Essentially, the reason for why this option has not been evaluated is because there is no reliable evaluation model currently used in practice. That is, research on the evaluation model for the T/C extension option has been insufficient. Theref... [more]

Sustainable construction is a comprehensive process of balancing the natural and built environment by applying sustainable development concepts. The golden triangle in the construction of time, cost, and quality should also assess risks from a sustainable perspective and investigate the environmental dimensions of the project. However, proper risk assessment for green sustainability is challenging, resulting in project management conducted under uncertain conditions. This study proposes a procedure based on Monte Carlo Simulations to improve the assessment of critical risk factors associated with construction activities. The AHP method was applied to rank environmental impact indicators, and the EMV approach was used to calculate the effects of the expected outcomes. The current study shows that air, water, and land pollution, water consumption, and solid waste are the most critical indicators. The results indicate that the equipment breakdown significantly impacted the duration of (an... [more]

This paper proposes a smart system for managing the operations of grid-connected charging stations for electric vehicles (EV) that use photovoltaic (PV) sources. This system consists of a mobile application for EV drivers to make charging reservations, an algorithm to optimize the charging schedule, and a remote execution module of charging operations based on the open charge point protocol (OCPP). The optimal charging schedule was obtained by solving a binary integer programming problem. The merits of our solution are illustrated by simulating different charging demand scenarios.

A hybrid short-term wind power prediction model based on data decomposition and combined deep neural network is proposed with the inclusion of the characteristics of fluctuation and randomness of nonlinear signals, such as wind speed and wind power. Firstly, the variational mode decomposition (VMD) is used to decompose the wind speed and wind power sequences in the input data to reduce the noise in the original signal. Secondly, the decomposed wind speed and wind power sub-sequences are reconstructed into new data sets with other related features as the input of the combined deep neural network, and the input data are further studied for the implied features by convolutional neural network (CNN), which should be passed into the long and short-term memory neural network (LSTM) as input for prediction. At the same time, the improved particle swarm optimization algorithm (IPSO) is adopted to optimize the parameters of each prediction model. By superimposing each predicted sub-sequence, th... [more]

In this paper, a blockchain-enabled energy trading method is proposed to deal with the inefficiency and security issues in energy trading for electric vehicles in smart grids. It includes the design of a smart contract and the excitation mechanism of energy sharing. The credit points of each vehicle as a node are considered in the design of the smart contract, which is used to supervise the process of energy trading. A strategy to estimate the credit points of each node and describe the excitation mechanism is illustrated. The connection between the credit points and the probability that a node would be accepted for energy trading has been established. To control the energy trading access, a double auction method is used to choose the part of the nodes participating in energy trading. Only selected nodes with winning bids can supply or request energy from the blockchain-based platform. Then it reaches the conclusion that the higher the credit points they have, the more trading initiati... [more]

The presented work contains the comparison of a different photovoltaic system approach, in terms of monthly energy production profiles, with detailed user needs profiles. Two types of investors were taken into account—a company where the yearly energy consumption exceeded 50 MWh and a standard household where the yearly energy consumption was around 6 MWh. Moreover, two different scenarios were considered; the first one was focused on the maximization of the energy production during a year by choosing optimal azimuth and tilt angles, whereas the second PV system was based on the East−West azimuth angles, which usually enables one to have better energy self-consumption, which leads to sustainable energy usage. Energy production profiles, along with users’ energy needs profiles, were analyzed in terms of sustainability, investment payback time, and energy loss in the face of the new Polish Renewable Energy Law. Recent changes in the Renewable Energy Law in Poland, which came into force o... [more]