Since 2003, Brazil has striven to provide energy access to all, in rural areas, in an effort to economically empower the communities. Unpacking fuel stacking behaviour can shed light onto the speed of transition toward the exclusive use of advanced fuel types. This paper presents findings from surveys that were carried out with 14 non-electrified communities in a rural area of Rio Negro, Amazonas State, Brazil. We identify the fuel choice determinants in these communities using a multinomial logistic regression model and more generally discuss the validity and robustness of such models in the context of statistical validation and evaluation metrics. Specifically for the Amazonas communities considered in this study, the research showed that the fuel choice determinants are the age of household, the number of people at meals each day, the number of meals daily, the community, education of the household head, and the income level of the household. Moreover, given the Brazilian policies r... [more]

During the last few decades, unheated attic spaces (so-called “cold attics”) have been one of the most moisture-problematic spaces in the building practices of Europe and North America. Problems with such spaces are usually associated with condensation, frost formation, and mould growth on the lower surfaces of the roof deck. To solve these problems, a number of qualitative studies were performed. Although these studies revealed many important pieces of information, some of them are seemingly not in accordance with one another. Therefore, there has not yet been presented cold attic design which is suitable (especially moisture-safe) for the whole target region. The aim of this paper is to determine whether such a design can be determined or state the reasons why it is not possible. Based on a review of published studies, 38 cold attic designs were selected for detailed analysis. Their comparative parameters were established, quantified, and compared. The moisture-safeness of each desig... [more]

The sustainable development of the energy sector through the implementation of renewable energy (RE) technology has been a primary concern for the government of Malaysia since the 1990s. Developing RE technology in rural areas is also one of the most important energy strategies. One of the most important requirements for the successful adoption of renewable energy technology is the public acceptance of this technology. This article examines the public acceptance of RE (wind and solar) technologies among rural residents in Mersing, Malaysia. This study is conducted in conjunction with the development of the hybrid wind−solar RE generation system for the Marine Ecosystem Research Centre (EKOMAR), which located in Mersing. To investigate the public acceptance of RE technologies, two surveys were conducted, before and after the installation of the hybrid wind−solar RE generation system. The findings revealed that RE innovations, such as wind and solar energy, were well known among 54.7% an... [more]

Different perovskite materials, such as methylammonium lead triiodide MAPbI3, exhibit many outstanding and desirable properties in solar energy harvesting. In this paper, the enhancement of perovskite solar cells’ both optical and electrical characteristics through adding either gold (Au) or silver (Ag) nanoparticles (NPs) using different simulations was studied. The used plasmonic nanoparticles were found to be able to compensate for the low absorption of MAPbI3 in the visible with optical coupling resonance frequencies close to that spectrum. Optimal diameters of Au and Ag NPs were found and simulated, and their impact on different parameters such as transmission, absorption, reflection, external quantum efficiency (EQE), open circuit voltage, short-circuit current density, fill factor, and most importantly, efficiency of the perovskite solar cell, have been investigated.

The study presents a Life Cycle Assessment (LCA) of Italian electricity scenarios, devised in the Integrated National Energy and Climate Plan (INECP). A fully representative LCA of the national electricity system was carried out, taking into consideration a great number of different power plant typologies for current (2016 and 2017) and future (2030) electricity mixes. The study confirms that LCA can be a powerful tool for supporting energy planning and strategies assessment. Indeed the results put in evidence not only the improvement of the environmental profile from the current to the future mix (the impacts decrease from 2016 to 2030 due to the transition towards renewables, mainly wind and photovoltaic), but also underline the difference between two scenarios at 2030 (being the scenario that includes the strategic objectives of the INECP to 2030 the one showing best environmental profile), providing an evaluation of the effect of different energy policies. For example, in the INECP... [more]

This paper investigates the bottom-hole pressure (BHP) performance of a fractured well with multiple radial fracture wings in a coalbed methane (CBM) reservoir with consideration of stress sensitivity. The fluid flow in the matrix simultaneously considers adsorption−desorption and diffusion, whereas fluid flow in the natural fracture system and the induced fracture network obeys Darcy’s law. The continuous line-source function in the CBM reservoir associated with the discretization method is employed in the Laplace domain. With the aid of Stehfest numerical inversion technology and Gauss elimination, the transient BHP responses are determined and analyzed. It is found that the main flow regimes for the proposed model in the CBM reservoir are as follows: linear flow between adjacent radial fracture wings, pseudo-radial flow in the inner region or Stimulated Reservoir Volume (SRV), and radial flow in outer region (un-stimulated region). The effects of permeability modulus, radius of SRV,... [more]

In the present study, the thermal performance of an electronic equipment cooling system is investigated. The heat sink used in the current cooling system consists of a porous channel with a rectangular cross-section that is assumed to be connected directly to the hot surface of an electronic device. In this modeling, a fully developed flow assumption is used. The Darcy−Brinkman model was used to determine the fluid flow field. Since using the local thermal equilibrium (LTE) model may provide results affected by the error in metal foams, in the present research, an attempt has first been made to examine the validity range of this model. The local thermal non-equilibrium (LTNE) model taking into account the viscous dissipation effect was then used to determine the temperature field. To validate the numerical solution, the computed results were compared with other studies, and an acceptable agreement was observed. Analysis of the temperature field shows that if the fluid−solid-phase therm... [more]

In this paper, we seek to find a balanced structure of energy sources that can simultaneously achieve two essential goals: (i) the environmental (degradation) goal and (ii) the economic (growth) goal. This study combines quantitative and qualitative methods to estimate and then rank each of the energy sources (including coal, gas, oil, hydropower, and renewable energy) to achieve the above two goals. This paper uses the weighted scoring method, the most popular method in multi-criteria decision-making techniques, to combine the rankings using five energy sources and two goals from panel data of 28 countries from Organization for Economic Co-operation and Development (OECD) countries for the period 1980−2017. Techniques for estimating the mean group long-run effect, including fully modified ordinary least squares (FMOLS) and dynamic ordinary least squares (DOLS), are used. The empirical findings of this paper reveal that, in the long term, in achieving both environmental goals and econo... [more]

Biohydrogen production from organic solid waste has shown particular advantages over other methods owing to the combination of waste reduction and bioenergy production. In this study, biohydrogen production from the co-digestion of cattle manure and food waste was optimized in a mesophilic semi-continuous process. To maximize hydrogen production, the effects of the mixing ratio (the proportion of food waste in the substrate), substrate concentration, and hydraulic retention time (HRT) on the co-digestion were systematically analyzed using a Box−Behnken design. The results showed that strong interactive effects existed between the three factors, and they had a direct effect on the responses. Hydrogen was primarily produced via the butyrate pathway, which was accompanied by the competing heterolactic fermentation pathway. Propionate and valerate produced from lipids and proteins, respectively, were obtained along with butyrate. The optimal process parameters included a mixing ratio of 47... [more]

Manta Ray Foraging Optimization Algorithm (MRFO) is a new bio-inspired, meta-heuristic algorithm. MRFO algorithm has been used for the first time to optimize a multi-objective problem. The best size and location of distributed generations (DG) units have been determined to optimize three different objective functions. Minimization of active power loss, minimization of voltage deviation, and maximization of voltage stability index has been achieved through optimizing DG units under different power factor values, unity, 0.95, 0.866, and optimum value. MRFO has been applied to optimize DGs integrated with two well-known radial distribution power systems: IEEE 33-bus and 69-bus systems. The simulation results have been compared to different optimization algorithms in different cases. The results provide clear evidence of the superiority of MRFO that defind before (Manta Ray Foraging Optimization Algorithm. Quasi-Oppositional Differential Evolution Lévy Flights Algorithm (QODELFA), Stochast... [more]

The limitation of fossil fuel uses and GHG (greenhouse gases) emissions reduction are two of the main objectives of the European energy policy and global agreements that aim to contain climate changes. To this end, the building sector, responsible for important energy consumption rates, requires a significant improvement of its energetic performance, an obtainable increase of its energy efficiency and the use of renewable sources. Within this framework, in this study, we analysed the economic feasibility of a stand-alone photovoltaic (PV) plant, dimensioned in two configurations with decreasing autonomy. Their Net Present Value at the end of their life span was compared with that of the same plant in both grid-connected and storage-on-grid configurations, as well as being compared with a grid connection without PV. The analysis confirms that currently, for short distances from the grid, the most suitable PV configuration is the grid-connected one, but also that the additional use of a... [more]

This paper discusses three methods of modulation for a single-phase isolated matrix converter. The matrix converter is combined with a transformer integration to perform power decoupling control in order to reduce the number of component and capacitor volumes. Due to the reason of (i) Alternating current (AC/AC) direct conversion and (ii) transformer integration, obtaining a clean sinusoidal grid current waveform in the modulation of matrix converter (MC) is important. Three methods of modulation are compared in terms of control complexity, quality waveform, and inductive-capacitive-inductive (LCL) filter sizing. The principal control of each method is described. Finally, a prototype was tested to verify the validity and the effectiveness of grid current control and power decoupling in the spoken circuit structure.

According to the International Energy Agency (IEA)’s forecast, China will fully electrify its railway system by 2050. However, the development of electrified railways is limited in the weak areas of China’s power grid. To surpass these limitations, we turn our attention to new railway energy sources, among which the most suitable is photovoltaic power generation. To evaluate the feasibility of integrating railway systems and photovoltaic power generation in China, this paper analyzes the geographical conditions and railway layout of China, gives a potential method for evaluating railway asset energy transformation measures and asset energy transformations that are suitable for China’s national conditions, and proposes an application of railway system energy transformation on this basis. Then, this method is used to evaluate the potential of a substation section of the Lanxin high-speed railway in China for reference. The results show that the green energy potential and scheduling poten... [more]

The electrification of the mobility and heating sectors will significantly change the electrical behavior of households in the future. To investigate this behavior, it is important to include the heating and mobility sectors in load profile models. Existing models do not sufficiently consider these sectors. Therefore, this work aims to develop an integrated, consistent model for the electrical and thermal load of private households and their mobility behavior. The model needs to generate regionally distinct profiles depending on the building, household and resident type and should be valid for Germany. Based on a bottom-up approach, a model consisting of four components is developed. In an activity model based on a modified Markov chain process, persons are assigned to activities. The activities are then allocated to devices in the electrical and thermal models. A mobility model assigns distances to the journey activities. The results of the simulation to validate the model shows an av... [more]

In this paper, organic phase change materials are modeled and studied both numerically and computationally. The results are compared with those of other research available in the international literature. Regardless of their heat storing capacity, the low heat conductivity of PCMs constitutes a significant obstacle to the further advancement of technologies pertaining to latent heat energy storage, as it hampers the immediate response of systems both at heat storage and at heat recovery. In this work, two types of nanoparticles are used as enhancing media, and the calculations are repeated in terms of melting front and stored energy enhancement. The results show that a 6.5% value for the melt percentage enhancement and a 5.5% value for the heat stored enhancement are exhibited when copper nanoparticles are utilized.

The concept of techno-economic pathways is used to investigate the potential implementation of CO2 abatement measures over time towards zero-emission steelmaking in Sweden. The following mitigation measures are investigated and combined in three pathways: top gas recycling blast furnace (TGRBF); carbon capture and storage (CCS); substitution of pulverized coal injection (PCI) with biomass; hydrogen direct reduction of iron ore (H-DR); and electric arc furnace (EAF), where fossil fuels are replaced with biomass. The results show that CCS in combination with biomass substitution in the blast furnace and a replacement primary steel production plant with EAF with biomass (Pathway 1) yield CO2 emission reductions of 83% in 2045 compared to CO2 emissions with current steel process configurations. Electrification of the primary steel production in terms of H-DR/EAF process (Pathway 2), could result in almost fossil-free steel production, and Sweden could achieve a 10% reduction in total CO2 e... [more]

A liquid-solid circulating fluidized bed (LSCFB) helps to overcome the shortcomings of conventional fluidized beds by using a particle separation and return system as an integral part of the overall reactor configuration. Batch adsorption experiments were carried out for the removal of phenol from a synthetically prepared solution using fresh activated-carbon-coated glass beads. The morphological features and surface chemistry of the adsorbent were analyzed via SEM and FTIR techniques. The adsorbent dosage, contact time and temperature were varied along with solution pH to assess their effects on the adsorbent performance for phenol removal. Isotherm modeling showed that the phenol removal using the activated-carbon glass beads followed the Langmuir model. Effectively, it was observed at an adsorbent loading of 2.5 g/150 mL of feed volume and a contact time of 3 h produced an 80% efficiency in the batch study. Furthermore, on scaling it up to the column, the desired 98% phenol-removal... [more]

In this paper, we present a new control technique for sustaining dynamic voltage stability by effective reactive power control and coordination of distributed energy resources (DERs) in microgrids. The proposed control technique is based on model-free control (MFC), which has shown successful operation and improved performance in different domains and applications. This paper presents its first use in the voltage stability of a microgrid setting employing multiple synchronous generator (SG)-based and power electronic (PE)-based DERs. MFC is a computationally efficient, data-driven control technique that does not require modelling of the different components and disturbances in the power system. It is utilized as an online controller to achieve the dynamic voltage stability of a microgrid system under different disturbances and fault conditions. A 21-bus microgrid system fed by multiple DERs is considered as a case study and the overall dynamic voltage stability is investigated using ti... [more]

In this paper, we examine the energy efficiency performance of the Belt and Road Initiative (BRI) countries using a newly developed panel data stochastic frontier model that allows for estimation of both persistent and transient efficiency while controlling for random country effects and noise. By this, we contribute to the energy economic literature by providing a complete picture of the level of persistent, transient, and total energy efficiency estimates from a cross country perspective for a panel of 48 BRI countries during the period 1990−2015. Adding that there is little evidence to support energy efficiency convergence in the energy economic literature, we went further to check whether energy efficiency converges in the BRI countries. The results show that (1) persistent efficiencies are much lower than transient efficiencies, suggesting that the energy problem in the BRI countries is more of a structural issue; (2) while energy efficiency varies widely across the countries, hig... [more]

The effect of ventilation bars on the porosity of a sinter bed charged on a sinter machine was investigated. The behavior of the sinter feed was calculated by discrete element method (DEM) simulation. By taking into account the adhesion force, the sinter feed in the wet state was represented and the simulation parameters were determined to reproduce the experimental values of the angle of repose. The porosity of the sinter bed was calculated, and the mechanism of the formation of the packing structure and the cause of the distribution of porosity in each region were clarified. As a result, it is shown that in the case of shear flow, the higher the powder pressure during flow, the higher the porosity.

In this research, the cyclic mechanical behavior of two heat storage sandy soils is experimentally studied using a cyclic thermo-mechanical triaxial device. The results of the tests, which were performed under controlled temperature conditions between 20 and 60 °C, show a significant dependence of the mechanical response of the sandy soils with the amplitude of the cyclic loading and medium temperature. The mechanical performance and accumulation of plastic strains of the soils with an increasing number of loading cycles are discussed in view of the intrinsic soil behavior.

Predictive maintenance in the permanent magnet synchronous motor (PMSM) is of paramount importance due to its usage in electric vehicles and other applications. Recently various deep learning techniques are applied for fault detection and identification (FDI). However, it is very hard to optimally train the deeper networks like convolutional neural network (CNN) on a relatively fewer and non-uniform experimental data of electric machines. This paper presents a deep learning-based FDI for the irreversible-demagnetization fault (IDF) and bearing fault (BF) using a new transfer learning-based pre-trained visual geometry group (VGG). A variant of ImageNet pre-trained VGG network with 16 layers is used for the classification. The vibration and the stator current signals are selected for the feature extraction using the VGG-16 network for reliable detection of faults. A confluence of vibration and current signals-based signal-to-image conversion approach is also introduced for exploiting the... [more]

There is a significant interaction between wind and earthquakes for large-scaled wind turbines due to an aeroelastic effect. This study evaluates the accuracy of an uncoupled method extensively utilized to analyze the seismic response of wind turbines at the operational state. Initially, the oscillation of the blade for the National Renewable Energy Laboratory (NREL) 5 MW wind turbine excited by wind and wind-earthquake combination, respectively, is compared using the fully coupled method to verify the assumption in this uncoupled method. Subsequently, the influence of ground motions on the aerodynamic loadings of the rotor is discussed to evaluate the interaction between wind and earthquake loads. In addition, the accuracy of the uncoupled method is assessed by comparing the analysis results of the coupled and uncoupled methods, where different mean wind speed and equivalent aerodynamic damping ratio are considered. The results indicate that the oscillation velocity of blades and thru... [more]

Energy theft refers to the intentional and illegal usage of electricity by various means. A number of studies have been conducted on energy theft detection in the advanced metering infrastructure using machine learning methods. However, applying machine learning for energy theft detection has a problem in that it is difficult to obtain enough electricity theft data to train a machine learning model. In this paper, we propose a method based on anomaly pattern detection to detect electricity theft in data streams generated from smart meters. The proposed method requires only normal energy consumption data to train the model. Previous usage records of customers being monitored are not needed for energy theft detection. This characteristic makes the proposed method applicable in real situations. Experiments were conducted using real smart meter data and artificial attack data, including the preprocessing of daily consumption vectors by standard normalization, the construction of an outlier... [more]

The frozen phenomenon is unfavorable for the direct air-cooled condensers (DACCs) in a very cold area. The effect of crosswind on frozen phenomena in DACCs at the representative 2 × 350 MW thermal power units was investigated numerically. Results showed that when the crosswind velocity was 4 m·s−1, the number of frozen air-cooled units reached a maximum of six. The increase of vortex range in the air-cooled unit was one of the important reasons to restrain the formation of frozen phenomena at a crosswind velocity from 4 m·s−1 to 12 m·s−1. The frozen phenomena in the DACC disappeared when the crosswind velocity was 12 m·s−1. As the crosswind velocity continued to increase to 28 m·s−1, the frozen region mainly appeared at the position of column 1 row 4, where the airflow rate was the maximum and the inlet air temperature was the minimum among all air-cooled units. This phenomenon occurred because there existed a relatively high-pressure zone near the inlet of each frozen air-cooled unit.... [more]