Red mud storage is associated with an increased risk of dam failure and there is an urgent need to address the environmental problem caused by the very fine particle size (average 4.9 µm) of red mud with high alkalinity (pH = 10−12.5) in the alumina industry. The specific objective of this study was to investigate the use of red mud based on the “simulation” integrating the sustainability aspect through the PROMETHEE method. The data source is from a field survey with experts conducted at the research location from the province of West Kalimantan, Indonesia. The results of the study using the PROMETHEE ranking parameter showed that the best optimal industrial cluster sites were Ketapang, followed by Belitung Island, Mempawah, and Teluk Batang, with scores of 0.4167, 0.0476, 0.0, and −0.463, respectively. However, using economic input and environmental output, the efficient frontier showed that Ketapang, Teluk Batang, and Pulau Belitung are efficient sites. Considerably more work will n... [more]

The present work focuses on the quality of char and primary tar produced from fast pyrolysis in N2 and CO2 of lignocellulosic biomasses: walnut shells (lignin-rich), straw (hemicellulose-rich) and pinewood (cellulose-rich). Heat treatments are carried out in a heated strip reactor (HSR) at 1573 and 2073 K for 3 s, with a heating rate of 104 K/s. The equipment allows for quenching the volatiles as soon as they are emitted. Chars are analyzed by thermogravimetric analysis in air. Results are compared with the products obtained from raw lignin, pure cellulose and pure hemicellulose. Cellulose and hemicellulose tars are dominated by anhydrous monosaccharides, which are scarce in straw tar and abundant in walnut shells tar. Polycyclic aromatic hydrocarbons PAHs are present in the primary products, in particular for walnut shells. The most reactive char is the one obtained from straw and the least reactive is the walnut shells char. Severe heat treatment and a CO2 atmosphere generate additio... [more]

The short- and long-term volatility of oil and gas prices has a wide-ranging impact on both parties of petroleum contractual agreements, thus affecting the profitability of the project at any stage. Therefore, the government (first party) and the international oil company (second party) set the parameters of their contracts in a way that reduces the uncertainty. The effect of price fluctuations on economic indicators is investigated in this paper. The Taguchi method is used for the first time to find the best-agreement parameters, which are the “A” and “B” factors, in the standard Libyan agreement. There are four “A” components from “A1” to “A4”, and four “B” components from “B1” to “B4”. The purpose is to reduce the variability in the response variables, which are the company take (the percent of net cash flow for the international company) and average value of the second-party percent share of production (ASPS). The noise factors considered in this paper are oil, liquefied hydrocarbo... [more]

Three vanadium-based catalysts were used to remove high concentrations of nitrogen oxides, and the catalysts’ performance of de-NOx and anti-H2O under the high concentrations of NOx were investigated. The V-Mo-W/TiO2 catalysts were tested under 1500 mL/min gas flow (GHSV = 500 h−1, 2.4% NO2, 4.78% NH3, 13% O2, 4% H2O, 5% CO2) and characterized by BET, SEM, EDS, XRD, XPS, H2-TPR, and NH3-TPD; then, their physical and chemical properties were analyzed. The results showed that under the influence of H2O, the NOx conversion of the V-Mo-W/TiO2 catalysts remained above 97% at 200−280 °C indicating that the catalysts had high catalytic activity and strong water resistance. The analysis of the characterization results showed that the larger specific surface area of the catalyst, the higher acid content, stronger redox ability, and higher V4+ and V3+ content were the reasons for the high NOx conversion. The surface area decreased and the microstructure become smoother after the reaction, which... [more]

At present, the stability study of the flywheel battery system under the influence of road conditions is only limited to the analysis of dynamic characteristics but also lacks effective controller considering road disturbances. In order to solve this defect and further improve the robust performance of vehicular flywheel battery systems under road disturbances, a robust controller considering interference of road surface roughness is proposed. Firstly, on the basis of a brief introduction to flywheel battery system structure, the influence degree of the flywheel by road condition is compared to find the key areas most affected by road disturbance factors. Then the nonlinear dynamic model of the axial suspension system is constructed, and the actual road surface roughness is regarded as the unmodeled dynamics of the external disturbance emphatically. Following, the established unknown system dynamics is approximated by radial basis function (RBF) neural network based on the minimum para... [more]

A proton exchange membrane fuel cell (PEMFC) system requires an adequate hydrogen supply and circulation to achieve its expected performance and operating life. An ejector-based hydrogen circulation system can reduce the operating and maintenance costs, noise, and parasitic power consumption by eliminating the recirculation pump. However, the ejector’s hydrogen entrainment capability, restricted by its geometric parameters and flow control variability, can only operate properly within a relatively narrow range of fuel cell output power. This research introduced the optimal design and operation control methods of a dual-ejector hydrogen supply/circulation system to support the full range of PEMFC system operations. The technique was demonstrated on a 70 kW PEMFC stack with an effective hydrogen entrainment ratio covering 8% to 100% of its output power. The optimal geometry design ensured each ejector covered a specific output power range with maximized entrainment capability. Furthermor... [more]

The Predicted Mean Vote (PMV) has discrepancies in relation to the thermal reality of the environment; thus, adaptive models serve to improve this estimate. In this context, this research aimed to verify the performance of PMV and adaptive models under different conditions in Brazil from an analysis of variance and to further classify individuals into clusters according to their feelings of thermal comfort. Through ASHRAE’s Global II Thermal Comfort Database, users of offices and classrooms in Brasilia, Recife, Maceió, and Florianópolis were investigated. The results of ANOVA showed that the PMV model did not represent the thermal reality of any of the cities investigated, and the cluster analysis showed how most people felt thermally in relation to indoor environments.

With inherent ‘S’ characteristics and the one-tunnel-with-two-units arrangement of the pump-turbine, hydraulic transient changes in the successive start-up process are complex, and the optimal control is difficult. This paper aims to study the dynamic characteristics and successive start-up control strategy optimization of two hydraulic couplings pumped storage units (PSUs) under low-head extreme conditions. Firstly, an accurate model of two hydraulic coupling PSUs’ successive start-up is established. Based on this model, the influence of the interval time of successive start-up on the dynamic characteristics of PSUs is carried out. It is shown that the change of the interval time of the successive start-up (ΔT) of the two PSUs has a significant impact on the dynamic response stability of the low-head start-up. If ΔT is more than 40 s, the hydraulic oscillation and speed fluctuation of the PSUs deteriorate. Secondly, with the different controller parameters for the two PSUs, a novel mu... [more]

The world is facing severe environmental challenges as it heavily relies on a USD 100 trillion fossil-fuel-based economy. Its transition from a fuel-intensive to a material-intensive economy is not well understood. The conventional energy resources are responsible for the excessive generation of Green House Gas (GHG) emissions resulting in increased environmental degradation owing to climate change. The human impact has been cited as highly indisputable in this respect. Pakistan is one of the most climate-vulnerable countries highly suffering from such increased impact of climate change and, thus, has been warned against the excessive use of conventional resources. As such, in the premises of Pakistan, conventional products are being excessively utilized in both power generation and transport sectors. Apart from the electrical power sector, the transport sector is also one of the main contributors to GHG emissions. In this context, the automobile industry has emerged as an environmenta... [more]

Oil/gas is mainly distributed in caves for fractured-vuggy carbonate reservoirs, it is therefore of significance to effectively connect caves for successful carbonate reservoir development. However, the mechanism and controlling factors that influence the connection between fractures and caves still remain unknown. To investigate how hydraulic fracture interacts with natural karst cave, a coupled seepage-stress-damage model for a vuggy carbonate reservoir is established based on statistical damage mechanics theory and finite element method. The accuracy of the proposed model is validated in comparison with experimental results. Some influencing factors, including fluid pressure in the cave, formation parameters, and construction parameters, are fully taken into account. The study results show that, when the fracture deflection degree is small, a hydraulic fracture can indirectly connect with the cave through high permeable damage units. The matrix heterogeneity that influences hydrauli... [more]

The present study compiles a life cycle inventory for Ecuadorian sugarcane-derived ethanol production to quantify its environmental performance and identify the life cycle stages that cause major impacts. The scope of this study encompasses a cradle-to-gate analysis that includes the agriculture, the milling, the distillation, and the co-generation of electricity. This assessment is modeled using the OpenLCA v1.10.3 software. Two functional units (FU) were established in this study: “1 ton of sugarcane at-the-farm-gate” for the agricultural stage and “1 L of ethanol at-the-plant-gate”. A hybrid attributional and consequential life cycle analysis (LCA) approach has been followed. Economic allocation (EA) and system expansion (SE) were used to take co-products into account in the milling and co-generation of electricity stages, respectively. The co-generation stage is analyzed in three different scenarios: (i) average mix displacement scenario where the surplus electricity produced in th... [more]

This paper assesses the primary energy and environmental impacts of a restaurant main course product’s lifecycle, especially focusing on end-of-life (EoL) stage. In the first step, a cradle-to-grave complex life cycle assessment (LCA) model of the product has been set up from the extraction of the required raw materials through the preparation, cooking and use phase to the end-of-life. In the second step, three scenarios (landfilling, incineration, and composting) were compared for the generated food waste in the end-of-life stage given that one of the biggest challenges in waste management is the optimal management of food waste. We calculated eleven environmental impact categories for the examined food product with the help of GaBi 9.0 software. During our research work, the primary energy was examined in each phase. In the third step, a comparison between the traditional and “sous vide” cooking technologies has been created to optimise of the cooking/frying life cycle phase. This pa... [more]

Energy is essential to achieving economic growth, yet the production of energy results in the emission of carbon dioxide, the primary factor in the deterioration of the environment and the acceleration of climate change. In this sense, the diversity of energy sources can contribute to achieving both environmentally sustainable development. This study investigates the relationship between energy diversification and economic growth in Nordic nations by employing a unique measure of energy diversity. The Nonlinear Panel Autoregressive Distributed Lag (NPARDL) approach is utilized in the research, and it looks at data from 1998 through 2018. According to our results, these nations experience favorable economic growth when there is an increase in the long-term diversity of their energy sources. However, in the near term, they have seen negative economic development due to the diversification of their energy sources. According to these findings, energy diversification benefits Nordic economi... [more]

The deactivation of catalysts and their regeneration are two very important challenges that need to be addressed for many industrial processes. The most quoted reasons for the deterioration of dimethyl ether synthesis (DME) concern the sintering and the hydrothermal leaching of copper particles, their migration to acid sites, the partial formation of copper and zinc hydroxycarbonates, the formation of carbon deposits, and surface contamination with undesirable compounds present in syngas. This review summarises recent findings in the field of DME catalyst deactivation and regeneration. The most-used catalysts, their modifications, along with a comparison of the basic parameters, deactivation approaches, and regeneration methods are presented.

The main problem of fluid sampling during well testing of reservoirs with near-critical fluids (gas condensate and volatile oil) is due to the fact that even a small pressure drawdown usually leads to the formation of a two-phase mixture in the bottom hole area, and it is almost impossible to take representative samples with downhole samplers or a formation tester. Sampling via test-separator and the current non-separation methods are also imperfect. An alternative method—MIKS (Multiphase IsoKinetic Sampling)—of gas condensate well testing was proposed, which is based on emulsifying a multiphase flow to particles of about 1−10 μm. Thereby MIKS would eliminate the problem of particle slippage in a homogeneous flow and enables high-quality sampling directly from the flowmeter line. The initial formation fluid is characterized by the maximum value of the condensate-gas ratio (CGR). Therefore, first, the well effluent would be adjusted to the mode with the maximum CGR using a choke manifol... [more]

Turbulent swirl flow, which exists in numerous turbomachinery systems, is the focus of this paper. It consumes a significant amount of energy, so it is a subject of investigation for many researchers. It is even more present in ventilation systems, as numerous axial fans are still installed without guide vanes. The experimental investigation of the turbulent swirl flow behind an axial fan in a pipe, installed in a test rig with a free inlet and ducted outlet, as defined in the international standard ISO 5801, is presented in this paper. Moreover, in this paper, the axially restricted case is studied. A designed axial fan generates a Rankine vortex with a complex structure, and research on the vortex turbulence structure and dynamics is presented. On the basis of the HSS PIV (high-speed stereo particle image velocimetry), measurement results are calculated using invariant maps. All states of turbulence anisotropy are thoroughly analyzed by applying the invariant theory on HSS PIV result... [more]

Mineral oil has long been used as an adequate coolant and dielectric medium in power transformer design. However, it is flammable and environmentally risky as it may be leaked or spilled. Therefore, ester fluids, which have been increasingly used in the last two decades, look promising as an ideal dielectric option. This research aims to better understand how using ester fluid insulation in power transformers impacts their physical and electrical dimensions, including their load-losses, impedance, masses, and equipment dimensions. Three case studies were carried out in a Portuguese electrical equipment manufacturer’s facility, with varying electrical parameters and physical properties of the mineral oil and ester-filled power transformers. The main results enhanced the known good electrical behavior of ester fluids, namely creating a lower electric field around winding wedges, yet the use of ester fluids led to higher load-losses, larger masses, additional radiators and, consequently,... [more]

The rate of technological progress is an important metric used for predicting the energy consumption and greenhouse gas emissions of future light-duty fleets. A trade-off between efficiency and performance is essential due to its implications on fuel consumption and efficiency improvement. These values are not directly available in the Brazilian fleet. Hence, this is the main gap in knowledge that has to be overcome. Tendencies in all relevant parameters were also unknown, and we have traced them as well, established on several publications data and models. We estimate the three indicators mentioned above for the Brazilian fleet from 1990 to 2020. Although the rate of technological progress was lower in Brazil than that in developed countries, it has increased from 0.39% to 0.61% to 1.7% to 1.9% in subsequent decades. Performance improvements offset approximately 31% to 39% of these efficiency gains. Moreover, the vehicle market is shifting toward larger vehicles, thus offsetting some... [more]

The choice of a particular PV technology for best performance is sometimes based upon a single factor or single operating condition. However, many parameters have functionalities that oppose each under actual operating conditions. In this paper, the comparisons of different PV module technologies under moderate environmental conditions (Tropical Climate Zone, Belo Horizonte, Brazil) are explored based upon the two competing parameters of soiling-layer spectral effects and panel operating temperature. Specifically, low-bandgap PV technologies (e.g., Si or Cu(In,Ga)(SSe)2) are reported to have performances less affected by the absorption of incoming sunlight than higher-bandgap absorbers (e.g., a-Si:H or CdTe). However, the opposite is true for operating temperatures, with higher bandgaps having advantages under higher-temperature operating conditions. We present a simple comparative soiling-temperature model with experimental collaborative data to address the following question: What is... [more]

The motions of power sources in industrial applications were always provided by electromechanical systems, which use around 70% of the gross energy consumption of industrialized economies [...]

Renewable energy sources have become necessary for long-term energy sustainability due to the increased demand for electric cars and worrisome rises in carbon dioxide emissions from traditional energy sources. Furthermore, transportation is one of the sectors that uses the most energy on the planet, accounting for 24% of overall consumption. Fossil fuels are still the dominant energy source for balancing global demand/supply dynamics. Supporting laws and regulations have enhanced the first phase of environmentally friendly energy-resource consumption. This has spurred the development of new solutions that cut greenhouse-gas emissions and reduce the air pollution produced by internal combustion engines that are fuelled by fossil fuels. Wind energy is one of the clean energy sources that may be utilised for this purpose. Wind energy has been used to power electric-car-charging infrastructure, generally in a hybrid mode with another renewable source. This research examines the possibility... [more]

Stand-alone DC microgrids have multiple distributed generation (DG) sources that meet the required demand (load) by using droop control to achieve load (current) sharing between the DGs. The use of droop control leads to a voltage drop at the DC bus. This paper presents a distributed secondary control scheme to simultaneously ensure current sharing between the DGs and regulate the DC bus voltage. The proposed control scheme eliminates the voltage deviation and ensures balanced current sharing by combining the voltage and current errors in the designed secondary control loop. A new flight-based artificial bee colony optimization algorithm is proposed. This selects the parameters of the distributed secondary control scheme to achieve the objectives of the proposed controller. A state−space model of the DC microgrid is developed by using eigenvalue observation to test the impacts of the proposed optimized distributed secondary controller on the stability of the DC microgrid system. A real... [more]

The widespread popularity of renewable and sustainable sources of energy such as solar and wind calls for the integration of renewable energy sources into electrical power grids for sustainable development. Microgrids minimize power quality issues in the main grid by linking with an active filter and furnishing reactive power compensation, harmonic mitigation, and load balancing at the point of common coupling. The reliability issues faced by standalone DC microgrids can be managed by interlinking microgrids with a power grid. An artificial intelligence-based Icosϕ control algorithm for power sharing and power quality improvement in smart microgrid systems is proposed here to render grid-integrated power systems more intelligent. The proposed controller considers various uncertainties caused by load variations, state of charge of the battery of microgrids, and power tariff based on the availability of power in microgrids. This paper presents a detailed analysis of the integration of wi... [more]

High precision short-term photovoltaic (PV) power prediction can reduce the damage associated with large-scale photovoltaic grid-connection to the power system. In this paper, a combination deep learning forecasting method based on variational mode decomposition (VMD), a fast correlation-based filter (FCBF) and bidirectional long short-term memory (BiLSTM) network is developed to minimize PV power forecasting error. In this model, VMD is used to extract the trend feature of PV power, then FCBF is adopted to select the optimal input-set to reduce the forecasting error caused by the redundant feature. Finally, the input-set is put into the BiLSTM network for training and testing. The performance of this model is tested by a case study using the public data-set provided by a PV station in Australia. Comparisons with common short-term PV power forecasting models are also presented. The results show that under the processing of trend feature extraction and feature selection, the proposed me... [more]

The availability of near-real-time data on energy performance is opening new opportunities to optimize buildings’ energy efficiency and flexibility capabilities and to support the decision-making and planning process of building retrofitting infrastructure investment. Existing tools can support retrofitting design and energy performance contracting. However, there are well-recognized shortcomings of these tools related to their usability, complexity, and ability to perform calculations based on the real-time energy performance of buildings. To address this gap, the advanced retrofitting decision support tool is developed and presented in this study. The strengths of our solution rely on easy usability, accuracy, and transparency of results. The automatic collection of real-time building energy consumption data gathered from the building management systems, combined with data analytics techniques, ensures ease of use and quickness of calculation. These results support step-by-step think... [more]