Sustainable Energy Technology

The deep-sea aquaculture industry will become one of the important pillars of the future marine economy. However, the application of clean energy in the new scenario needs to be strengthened for platform operation. For this kind of renewable-energy distributed-generation system, an energy storage system is essential. A bidirectional DC–DC converter is essential for distributed power generation systems. It connects a variety of renewable energy sources with energy storage cells. A high-gain bidirectional Cuk circuit with zero ripple is proposed in the paper. It is characterized by a simple structure, zero ripple, low voltage stress of semiconductor power devices, and high voltage gain. A passivity-based control with linear active disturbance rejection is proposed to solve the problems of the large steady-state error. The zero steady-state error, strong robustness, and whole-range stability have been obtained for the proposed control strategy. Finally, a simulation was carried out. A 100 W, 48 V/400 V prototype was built to verify the validity of the theoretical analysis for the proposed circuit. The improved passivity-based control strategy was verified to solve the contradiction between rapidity and overshoot. It can be realized to improve the dynamic performance of the proposed converter and achieve robust control. Full article

Emissions of marine traffic can be lowered by switching to less polluting fuels or by investing in exhaust aftertreatment. Electrostatic precipitation is a widely used method for particle removal but it is not currently used in combination with marine engines. This study presents the particle filtration characteristics of an emission reduction system designed for marine applications and consisting of a scrubber and a Wet Electrostatic Precipitator (WESP) in series. Partial flow of exhaust from a 1.6 MW marine engine, operated with light and heavy fuel oil, was led to the system. Particle concentrations were measured before the system, after the scrubber and after the WESP. Particle removal characteristics were determined for different engine loads. The scrubber alone removed 15–55% of non-volatile particle number, 30–40% of particle mass and 30–40% of black carbon mass depending on engine load, when HFO fuel was used. By studying particle size distributions, scrubber was found also to generate particles seen as an additional mode in 20–40 nm size range. The system combining the scrubber and WESP removed over 98.5% of particles in number, mass and black carbon metrics when HFO fuel was used. With MDO fuel, 96.5% of PN and 99% of black carbon were removed. Full article

The building sector is targeting net-zero emissions through the integration of renewable energy technologies, especially for space cooling and heating applications. In this regard, the use of solar thermal concentrating collectors is of vital importance. The performance of these collectors increases by using an efficient fluid such as a nanofluid due to their high thermal conductivity. This research addresses the preparation, stability analysis, and characterisation of metallic and non-metallic oxide nanofluids and their experimental analysis in a compound parabolic collector (CPC) system. Five different combinations of nanofluids are used with different volumetric concentrations (0.025%, 0.05%, and 0.075%) including multi-wall carbon nanotube with water (MWCNT–H₂O), multi-wall carbon nanotube with ethylene glycol (MWCNT–EG), aluminium oxide with water (Al₂O₃–H₂O), aluminium oxide with ethylene glycol (Al₂O₃–EG), and magnesium oxide with ethylene glycol (MgO–EG). The prepared nanofluids are characterised in terms of thermal conductivity and viscosity. Detailed experimentation is performed to investigate the CPC system integrated with the nanofluids. The results obtained from the detailed characterisation of the MWCNT–H₂O nanofluid showed that the nanofluids have a 37.17% better thermal conductivity than distilled water as a primary fluid, and the MWCNT–EG nanofluid has demonstrated an increase in viscosity by 8.5% compared to ethylene glycol (EG). The experimental analysis revealed that the thermal efficiency of the collector integrated with the MWCNT–H₂O nanofluid is increased by 33% compared to water. Meanwhile, the thermal efficiency of the collector with MWCNT–EG was increased by 24.9% compared to EG. Moreover, a comparative analysis among metallic nanofluids was also performed, i.e., Al₂O₃–H₂O, Al₂O₃–EG, and MgO–EG. In each case, the thermal efficiency of the collector was recorded, which was greater than the base fluid by percentages of 29.4%, 22.29%, and 23.1%, respectively. The efficiency of non-metallic nanofluids is better than metallic nanofluids by 7.7%. From the obtained results, it can be concluded that the CPC system performed best with MWCNT–H₂O compared to any other combination of nanofluids. Full article

Ocean thermal energy is a huge renewable and clean energy. For different applications of the Ocean Thermal Energy Conversion (OTEC) system, new objective functions are proposed and optimal CO₂-based binary zeotropic mixtures for each objective function are discussed. Propane, butane, isobutane, and pentane were selected as the secondary component of the mixture working fluid. Based on each objective function, some parameters of the CO₂-based binary zeotropic mixture power cycle were studied and the optimal working fluids were obtained. The results indicated that the thermal efficiency showed an upwards trend as the evaporating temperature increased from 20 to 23 °C and decreased as the molar fraction of the secondary component of the working fluid increased from 0.01 to 0.05, but the specific volumetric flow showed the opposite trend. The specific net power increased as the evaporating temperature increased, and the net power output had a greater effect on the variations in the specific net power than the molar fraction of the secondary component. When taking thermal efficiency or specific volumetric flow as the objective functions, CO₂/propane was the suitable working fluid under the considered conditions; in the case that specific net power was taken as the objective function, CO₂/butane (0.97/0.03 or 0.96/0.04 molar ratio) or CO₂/isobutane (0.97/0.03, 0.96/0.04, or 0.95/0.05 molar ratio) were suitable under the considered evaporating temperature. Full article

Inductive power transfer (IPT) technology is widely used in autonomous underwater vehicles (AUVs) to achieve safety and flexibility. However, the eddy current loss (ECL) will be generated in the seawater due to the high-frequency alternating current in the transmitter and receiver. An underwater IPT system with a series-none (SN) compensation topology is proposed in this paper to achieve a compact receiver for AUVs and reduce the ECL. The analytical model of the IPT system is built to analyze its transfer performance. The phase difference between the transmitter and receiver current of the SN compensation topology is larger than 90° compared to that of the conventional series-series (SS) topology, which can significantly decrease the magnitude of the electric field caused by coil currents; thus, the eddy current loss is reduced. Moreover, the optimal load resistance of the seawater IPT system is lower than that in the air, and the SN compensation topology has a more compact receiver with no compensation capacitor in the receiving side, which can save the internal space in the AUVs. An experimental prototype based on the SN topology is built, and the experimental results have verified the analysis. Full article

In order to improve the endurance of underwater vehicles and make it possible for the underwater vehicle to inspect long-distance water tunnels, a sliding mode control method based on event triggering is proposed for the depth control of underwater vehicles from the perspective of energy saving. Firstly, the kinematics and dynamics models of underwater vehicle dive surface are established. Secondly, an event-triggered sliding mode controller is designed. According to the Lyapunov function, the stability of the designed controller is proved by theoretical analysis, and Zeno phenomena will not appear in the closed-loop control system. Compared with other controllers, the simulation results show that this controller can effectively realize the depth control of AUV, has strong adaptability and robustness to unmodeled nonlinear dynamics and bounded disturbances, and has the effect of saving computing resources. Full article

The development of electric vehicles plays an important role in the field of energy conservation and emission reduction. It is necessary to improve the thermal performance of battery modules in electric vehicles and reduce the power consumption of the battery thermal management system (BTMS). In this study, the heat transfer and flow resistance performance of liquid cold plates with serpentine channels were numerically investigated and optimized. Flow rate ($$\dot{m}$$), inlet temperature (T_in), and average heat generation (Q) were selected as key operating parameters, while average temperature (T_ave), maximum temperature difference (ΔT_max), and pressure drop (ΔP) were chosen as objective functions. The Response Surface Methodology (RSM) with a face-centered central composite design (CCD) was used to construct regression models. Combined with the multi-objective non-dominated sorting genetic algorithm (NSGA-II), the Pareto-optimal solution was obtained to optimize the operation parameters. The results show that the maximum temperature differences of the cold plate can be controlled within 0.29~3.90 °C, 1.11~15.66 °C, 2.17~31.39 °C, and 3.43~50.92 °C for the discharging rates at 1.0 C, 2.0 C, 3.0 C, and 4.0 C, respectively. The average temperature and maximum temperature difference can be simultaneously optimized by maintaining the pressure drop below 1000 Pa. It is expected that the proposed methods and results can provide theoretical guidance for developing an operational strategy for the BTMS. Full article

The tension legs are the essential parts of the tension legs platform-type (TLP-type) floating offshore wind turbine (FOWT) against the extra buoyancy of FOWT. Therefore, the TLP-type FOWT will face the risk of tension leg failure. However, there are seldom analyses on the hydrodynamic response and tension leg failure performance of FOWT with inclined tension legs. In this paper, a hydrodynamic model was established using three-dimensional hydrodynamic theory and applied in the motion response and tension analyses of FOWT with conventional and new tension leg arrangements on Moses. The influence of draft and tension leg arrangement on the performance of FOWT with inclined tension legs were studied. The optimum draft was the height of the column and lower tensions were obtained for the new tension leg arrangement. Moreover, the tension leg failure performance of FOWT with inclined tension legs was evaluated under different failure conditions. The results illustrated that the FOWT with the new tension leg arrangement can still operate safely after one tension leg fails. Full article

The United States is experiencing a large growth in the solar sector. The U.S. solar power capacity has grown from 0.34 Gigawatts (GW) in 2008 to an estimated 97.2 GW today. However, some states have had difficulty installing large scale solar farms due to concerns regarding geographic location, political climate, or economic factors. Kentucky (KY) is one of the states which is below the national average for solar energy production. However, KY contains a wealth of potential for these types of farms with decent solar irradiation levels and large tracts of unused land for solar farms. For the study, this paper selects three representative areas of KY by using PVWatts and topographical maps which can theoretically produce enough electricity so that KY can meet or exceed the national generation percentage average (2.3% or 2.06 TWh annually in KY’s case). The study analyzes the economic feasibility of solar photovoltaic systems (PV) farms in terms of Cumulative Cash Flow ($) and Payback Time (Year) by using the Cost of Renewable Energy Spreadsheet Tool (CREST). Furthermore, this paper estimates the Average/Median/High output power (kWh) annually for the scenario among three areas in Kentucky, Smithland, Hickman, and Falls of Rough. In this theoretical scenario, an average 2.27 TWh would be generated annually which exceeds the national generation percentage average. Furthermore, by the sixth year, the cumulative cash flow would exceed the breakeven point, proving the feasibility of these solar farms. The annual average power generation estimates for the areas of Smithland, Hickman, and Falls of Rough are 0.3741 TWh, 1.1628 TWh, and 0.731 TWh respectively. The average profit per MWh estimates for the areas of Smithland, Hickman, and Falls of Rough are $11,130.12/MWh, $10,742.46/MWh, and $11,392.01/MWh respectively. According to CREST, the final cumulative cash flow, after the 25-year life span of the panels, would be approximately $624,566,720. Full article

The efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electrical capacitance tomography (ECT) measurements. The two-dimensional images (along the reactor horizontal and vertical planes) of the fluidized bed are obtained from the CPFD simulations at different operating conditions. The CPFD model was developed in a commercial CPFD software Barracuda Virtual Reactor 20.0.1. The bubble behavior and bed fluidization behavior are characterized form the bubble properties: average bubble diameter, bubble rise velocity, and bubble frequency. The bubble properties were determined by processing the extracted images with script developed in MATLAB. The CPFD simulation results are compared with experimental data (obtained from the ECT sensors) and correlations in the literature. The results from the CPFD model and experimental measurement depicted that the average bubble diameter increased with an increase in superficial gas velocities up to $4.2 U_{mf}$ and decreased with a further increase in gas velocities due to the onset of large bubbles (potential slugging regime). The bubble rise velocity increased as it moved from the lower region to the bed surface. The Fourier transform of the transient solid volume fraction illustrated that multiple bubbles pass the plane with varying amplitude and frequency in the range of 1–6 Hz. Further, the bubble frequency increased with an increase in superficial gas velocity up to $2.5U_{mf}$ and decreased with a further increase in gas velocity. The CPFD model and method employed in this work can be useful for studying the influence of bubble properties on conversion efficiency of a gasification reactor operating at high temperatures. Full article

In this paper we propose a modular multilevel converter for a linear generator for a wave energy converter. The coils of this generator are individually controlled to improve energy harvesting performance. This topology involves two stages. The first stage uses a full-bridge to control the harvested current with a reference generated by means of an MPPT method. The second stage uses a half-bridge to control the voltage of the DC-link and the output current. Furthermore, multilevel modular converters allow the generation of a medium DC voltagethat reduces the losses in energy transmission lines from offshore to a coupling common point on the shore. Full article

The P–U characteristic curve of the photovoltaic (PV) cell is a single peak curve with only one maximum power point (MPP). However, the fluctuation of the irradiance level and ambient temperature will cause the drift of MPP. In the maximum power point tracking (MPPT) algorithm of PV systems, BP neural network (BPNN) has an unstable learning rate and poor performance, while the genetic algorithm (GA) tends to fall into local optimum. Therefore, a novel PV fuzzy MPPT algorithm based on an adaptive genetic simulated annealing-optimized BP neural network (AGSA-BPNN-FLC) is proposed in this paper. First, the adaptive GA is adopted to generate the corresponding population and increase the population diversity. Second, the simulated annealing (SA) algorithm is applied to the parent and offspring with a higher fitness value to improve the convergence rate of GA, and the optimal weight threshold of BPNN are updated by GA and SA algorithm. Third, the optimized BPNN is employed to predict the MPP voltage of PV cells. Finally, the fuzzy logical control (FLC) is used to eliminate local power oscillation and improve the robustness of the PV system. The proposed algorithm is applied and compared with GA-BPNN, simulated annealing-genetic (SA-GA), particle swarm optimization (PSO), grey wolf optimization (GWO) and FLC algorithm under the condition that both the irradiance and temperature change. Simulation results indicate that the proposed MPPT algorithm is superior to the above-mentioned algorithms with efficiency, steady-state oscillation rate, tracking time and stability accuracy, and they have a good universality and robustness. Full article

Resonance causes extreme stress, acceleration of fatigue, and reduction in lifespan of offshore wind structures. The main factors that cause resonance are environmental loads such as wind and waves, and dynamic loads caused by rotor movement. Estimation of the natural frequency at the design stage is highly uncertain, and natural frequency changes occur due to various factors during long-term operation. Therefore, it is important to ensure structural safety from resonance through a vibration-monitoring system or an additional damper. In this study, the effect of seawater existing inside the substructure on the natural frequency of the structure was dealt with. The natural frequency estimation equation for a fixed offshore wind structure was derived with the “inner fluid simplification assumption”. The finite element modal analysis was performed to verify the principle of Variable Natural Frequency Damper (VNFD), a system that controls the natural frequency of offshore wind structures through a pump, and to find the range of natural frequency control. As a result, interior fluid affects the natural frequency of the wind turbine support structure. Specifically, the variable natural frequency range was very low, at about 0.027% for the monopile model at a depth of 10 m, but increased rapidly to about 3.66% at a depth of 70 m. Furthermore, when estimating the natural frequency of a fixed offshore wind turbine in deep water without consideration of interior fluid, the estimates can be higher than with consideration of it. Full article

The thermophysical properties of a working-fluid play an important role in the process of stirring-heating. The heating process of stirring is accompanied by two processes: the friction between the solid mechanism and the working-fluid and the viscous dissipation of the working liquid. Traditionally, the sensible heat of water-based working-fluids is low, while that of oil-based working-fluids is higher, but the load capacity is relatively low. In order to find a balance between the two, an optimal stirring working-fluid should be selected. In this study, an experimental method was used to study the heating process of 30 kinds of working-fluids. The numerical evaluation model of the effects of thermophysical properties on the comprehensive evaluation index of heat (CEIH) was established by multiple linear regression methods, and a computational fluid dynamics (CFD) tool was used to analyze the heat generation and flow field of different working-fluids in the stirring-heating device. The results show that viscous dissipation is the most important way of stirring-heating. CFD can completely replace the experiment to study the heating effect of stirring. The thermophysical properties of the working-fluid affect the upper circulation and the overall velocity of the double circulation flow. The experimental results and regression model analysis show that specific heat capacity has the greatest effect on the heating effect, but density will also play a positive role in the stirring-heating. Water-based salt solutions such as KCl can achieve a better heating effect, and oil-based working-fluids are not always the best choice. Full article

Hydrogen production from surplus solar electricity as energy storage for export purposes can push towards large-scale application of solar energy in the United Arab Emirates and the Middle East region; this region’s properties of high solar irradiance and vast empty lands provide a good fit for solar technologies such as concentrated solar power and photovoltaics. However, a thorough comparison between the two solar technologies, as well as investigating the infrastructure of the United Arab Emirates for a well-to-ship hydrogen pathway, is yet to be fully carried out. Therefore, in this study we aim to provide a full model for solar hydrogen production and delivery by evaluating the potential of concentrated solar power and photovoltaics in the UAE, then comparing two different pathways for hydrogen delivery based on the location of hydrogen production sites. A Solid Oxide Cell Electrolyzer (SOEC) is used for technical comparison, while the shortest routes for hydrogen transport were analyzed using Geographical Information System (GIS). The results show that CSP technology coupled with SOEC is the most favorable pathway for large-scale hydrogen from solar energy production in the UAE for export purposes. Although PV has a slightly higher electricity potential compared to CSP, around 42 GWh/km² to 41.1 GWh/km², respectively, CSP show the highest productions rates of over 6 megatons of hydrogen when the electrolyzer is placed at the same site as the CSP plant, while PV generates 5.15 megatons when hydrogen is produced at the same site with PV plants; meanwhile, hydrogen from PV and CSP shows similar levels of 4.8 and 4.6 megatons of hydrogen, respectively, when electrolyzers are placed at port sites. Even considering the constraints in the UAE’s infrastructure and suggesting new shorter electrical transmission lines that could save up to 0.1 megatons of hydrogen in the second pathway, production at the same site with CSP is still the most advantageous scenario. Full article

The large amounts of organic waste thrown into the garbage without any productivity, and the increase in the demand for electrical energy worldwide, has led to the search for new eco-friendly ways of generating electricity. Because of this, microbial fuel cells have begun to be used as a technology to generate bioelectricity. The main objective of this research was to generate bioelectricity through banana waste using a low-cost laboratory-scale method, achieving the generation of maximum currents and voltages of 3.71667 ± 0.05304 mA and 1.01 ± 0.017 V, with an optimal pH of 4.023 ± 0.064 and a maximum electrical conductivity of the substrate of 182.333 ± 3.51 µS/cm. The FTIR spectra of the initial and final substrate show a decrease in the peaks belonging to phenolic compounds, alkanes, and alkenes, mainly. The maximum power density was 5736.112 ± 12.62 mW/cm² at a current density of 6.501 A/cm² with a peak voltage of 1006.95 mV. The molecular analysis of the biofilm formed on the anode electrode identified the species Pseudomonas aeruginosa (100%), and Paenalcaligenes suwonensis (99.09%), Klebsiella oxytoca (99.39%) and Raoultella terrigena (99.8%), as the main electricity generators for this type of substrate. This research gives a second use to the fruit with benefits for farmers and companies dedicated to exporting and importing because they can reduce their expenses by using their own waste. Full article

Concentrated solar power is an alternative renewable energy technology that converts solar energy into electrical energy by using a solar concentrator and a solar receiver. Computational fluid dynamics have been used to numerically design concentrated solar power. This is a powerful numerical analysis approach that is widely used in energy and environmental engineering applications. In this paper, we review previous work on the applications of computational fluid dynamics in the design of concentrated solar power technology. We performed a bibliometric analysis of journal articles relevant to applications to analyze the current trend of utilization of computational fluid dynamics in these technologies. Then, we conducted a comprehensive analysis focused on the design of solar dish technology using computational fluid dynamics. Furthermore, we reviewed in detail the optical modeling of solar concentrators and solar receivers. Of the 83 retrieved publications from Scopus database, 80 were journal articles, and only three were review papers. Among these 80 journal articles, only 54 were relevant to this study, and 23 were relevant to solar dish technology. The documents were analyzed according to their number of citations, journal sources, and keyword evolution and network map. The information presented in this paper is useful to further recognize the contributions of computational fluid dynamics to the development of concentrated solar power, particularly to solar dish technology. In addition, we also discuss the challenges and future research directions to make solar energy a more sustainable source of renewable energy. Full article

Currently, most cotton textile waste is sent to landfill. However, due to the use of synthetic additives and the chemical treatment of cotton fibers, cotton textile waste is difficult to biodegrade. Cotton textile waste can also be subjected to material recycling, or to incineration/gasification to produce energy. Here, we present the optimization of acid hydrolysis of cotton yarn fibers for glucose efficiency. The cotton yarn hydrolysates showed great potential for replacing simple sugar solutions in fermentation media. The highest glucose concentration was obtained in the hydrolysates of cotton yarn hydrolyzed in a 2% solution of sulfuric acid or phosphoric acid at 140–160 °C for 2 h. After 2 h of hydrolysis at 140 °C with 2% H₃PO₄, the concentration of glucose in the cotton yarn hydrolysate (13.19 g/L) increased fivefold compared with cotton yarn treated under the same conditions with H₂SO₄ (2.65 g/L). The structural modifications in the solid residues after acid hydrolysis were analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), attenuated total reflectance Fourier-transform infrared spectroscopy (FTIR-ATR), and Raman spectroscopy. The SEM images, IR spectra, and Raman spectra revealed that the most significant changes in the morphology of the fibers occurred when the process was carried out at high temperatures (≥140 °C). Better growth of the yeast strains Saccharomyces cerevisiae Ethanol Red and Saccharomyces cerevisiae Tokay ŁOCK0204 was observed in the medium containing phosphoric acid hydrolysate. The maximum methane yield of 278 dm³/kgVS and the maximum hydrogen yield of 42 dm/kgVS were reported for cotton yarn waste after pretreatment with H₃PO₄. This might have been linked to the beneficial effect of phosphorus, which is a key nutrient for anaerobic digestion. The proposed hydrolysis method does not generate fermentation inhibitors. Full article

Extensive research on the production of energy and valuable materials from plastic waste using pyrolysis has been widely conducted during recent years. Succeeding in demonstrating the sustainability of this technology economically and technologically at an industrial scale is a great challenge. In most cases, crude pyrolysis products cannot be used directly for several reasons, including the presence of contaminants. This is confirmed by recent studies, using advanced characterization techniques such as two-dimensional gas chromatography. Thus, to overcome these limitations, post-treatment methods, such as dechlorination, distillation, catalytic upgrading and hydroprocessing, are required. Moreover, the integration of pyrolysis units into conventional refineries is only possible if the waste plastic is pre-treated, which involves sorting, washing and dehalogenation. The different studies examined in this review showed that the distillation of plastic pyrolysis oil allows the control of the carbon distribution of different fractions. The hydroprocessing of pyrolytic oil gives promising results in terms of reducing contaminants, such as chlorine, by one order of magnitude. Recent developments in plastic waste and pyrolysis product characterization methods are also reported in this review. The application of pyrolysis for energy generation or added-value material production determines the economic sustainability of the process. Full article

Producing ice using adsorption systems can represent a sustainable solution and meet the recent global environmental regulations as they use natural refrigerants and can be driven by solar energy. However, the beds used in these systems still have low thermal and adsorption characteristics. This study investigates numerically the use of an emerging aluminum foamed bed packed with advanced Maxsorb adsorbent in a two-bed adsorption system and reports cases of performance improvements compared to the classical finned-tube based system used to produce ice. A comprehensive 2-D transient pressure distribution model for the two beds was developed and validated. The model considers the temporal and spatial variations of the two beds’ parameters, while the effect of the thermal mass and heat transfer effectiveness of the condenser and evaporator components are imitated at the boundary conditions for bed openings using two zero-dimensional models. The results show the interrelated effects of varying the cycle times from 400 s to 1200 s with 2, 5, and 10 mm foam thicknesses/fin heights on the overall performance of both systems. The Al-foam based system demonstrated the performance superiority at a 2 mm foam thickness with maximum ice production of 49 kg_ice/kg_ads in 8 h, an increase of 26.6% over the counterpart finned-tube based system at a 400 s cycle time. The best COP of 0.366 was attained at a 5 mm foam thickness and 1200 s with an increase of 26.7%. The effective uptake of the Al-foam based system was reduced dramatically at a 10 mm foam thickness, which deteriorated the system performance. Full article

A computational study on thermal stability was conducted the first time, combining the modified quasi-chemical model, the Antoine equation, and the adiabatic flash evaporation calculation principle to design a method to calculate the system pressure-temperature (P-T) phase diagram of binary chloride molten salts. The evaporation temperature of the molten salt obtained by analyzing the P-T phase diagram of the eutectic molten salt clearly defined the upper limit of the optimal operating temperature of the mixed molten salt. The results indicated that the upper-temperature limits of NaCl-KCl, NaCl-CaCl₂, KCl-CaCl₂, NaCl-MgCl₂, and KCl-MgCl₂ are determined to be 1141 K, 1151 K, 1176 K, 1086 K, and 1068 K. The maximum working temperature was measured experimentally using a thermogravimetric analysis (TGA), and the relative error between the calculation and experiment was calculated. The maximum error between the calculated and experimental values of the maximum operating temperature was 6.02%, while the minimum was 1.29%, demonstrating the method’s high accuracy. Combined with the lowest eutectic temperature and the upper-temperature limits of binary chloride molten salts, the stable operating temperature ranges of NaCl-KCl, NaCl-CaCl₂, KCl-CaCl₂, NaCl-MgCl₂, and KCl-MgCl₂ are 891~1141 K, 750~1151 K, 874~1176 K, 732~1086 K, and 696~1086 K. Full article

Over the last few years, new materials have been developed which a priori, appear to improve passive energy efficiency in buildings. This article focuses on chromogenic devices that allow changing their optical properties in a reversible manner through some external stimulus. The covering of the envelopes may have different textures or colors, which determine the amount of solar radiation absorbed by the material compared to the incident radiation. In buildings with a high percentage of roof relative to façade, the surface finish plays an interesting role in the energy demand. In the present work, the influence of the application of thermochromic materials to the roofs of commercial buildings is analyzed. It has been demonstrated that the application of a thermochromic surface finish can produce savings of annual energy demand between 1% and 12% in kilowatt-hours and kilograms of CO₂ and they become more significant for construction solutions with higher transmittances values. Then, the impact of applying a thermochromic finish per day is analyzed and which transition temperature range will be the most optimal to the highest energy performance is discussed. At the same time, an assessment is made of the optimal cost; although economic investment is not currently amortized, it is a good resource for reducing energy demand in buildings. Full article

At present, primary power generation depends on non-renewable energy resources, which will become extinct. Solar is the best option in renewable energy sources to achieve clean and green power extraction. Solar PV transforms light energy into electrical energy. However, the output power of solar PV changes with solar insolation. It is also affected by environmental factors and the shading effect. One of the key factors that can reduce the PV system output power is partial shading condition (PSC). The reduction in power output not only depends on shaded region but also depends on pattern of shading and physical position of shaded modules in the array. Due to PSCs, mismatch losses are induced between the shaded modules which can cause several peaks in the output power-voltage (P-V) characteristic. This article describes the non-symmetrical reconfiguration technique and compares it with the primary total cross tied connection. The performance of non-symmetrical reconfiguration techniques is evaluated and compared in terms of global maximum power (GMP), voltage and currents at GMP, open and short circuit voltage and currents, mismatch power loss (MPL), fill factor, efficiency, and number of local maximum power peaks (LMPPs) on a 9 × 9 PV array. Full article

In this study, the structural changes of alkali lignin induced by ozonation were investigated, and the effect of ozone-treated alkali lignin and its mechanism on Avicel enzymatic hydrolysis was examined. The physicochemical properties of alkali lignin were analyzed by FTIR, ¹H-¹³C HSQC NMR, and GPC. It was revealed that ozone pretreatment increased the content of carboxyl and/or aldehyde groups and the negative zeta potential of alkali lignin, which enhanced the electrostatic repulsion between alkali lignin and cellulase; The S/G ratio was reduced, indicating the hydrophobic interaction was diminished. The Langmuir adsorption isotherm showed that the cellulase binding strength of ozone pretreated alkali lignin (OL-pH3, OL-pH7, and OL-pH12 were 16.67, 13.87, and 44.05 mL/g, respectively) was significantly lower than that of alkali lignin (161.29 mL/g). The 72 h hydrolysis yields of Avicel added with OL-pH3, OL-pH7, and OL-pH12 were 55.4%, 58.6%, and 54.9% respectively, which were 2.6–6.3% higher than that of Avicel added with AL (52.3%). This research aimed to reduce the non-productive adsorption between cellulase and lignin by investigating the structural changes of lignin caused by ozone treatment. For the first time, we discovered that ozone-treated alkali lignin has a further promotion effect on the enzymatic digestion of cellulose, providing a green and feasible pretreatment process for the enzymatic hydrolysis of lignocellulose and aiding in the more efficient utilization of biomass. Full article

The use of fossil fuels to generate energy is often associated with serious negative effects on the environment. The greenhouse gas emissions resulting from burning these fuels destroy the ozone layer and lead to global warming. As a strategic approach to the solution of this problem, calls for research and development, as well as the implementation of technologies associated with renewable energy sources within the European Union (EU), have intensified in recent years. One of the keys to a successful outcome from this intensified effort is to identify the challenges associated with the transfer of both intellectual property and technology rights in the renewable energy sector within the EU. The present paper contributes towards this direction. Firstly, data from the literature were used to identify contemporary trends within the European Union with regards to technology transfer and intellectual property within the sector of renewable energy. Then, a statistical analysis utilising an ordinary least squares (OLS) model was conducted to establish a correlation between renewable energy innovations (research and development) and the level of investment associated with renewable energy technologies. Finally, this correlation, along with the associated challenges, was then critically explored for four of the most popular renewable energy sources (namely solar energy, biomass, wind energy, and marine renewable energy), and conclusions are reported. Full article

In response to the objective of fully attaining carbon neutrality by 2060, people from all walks of life are pursuing low-carbon transformation. Due to the high water cut in the middle and late phases of development, the oilfield’s energy consumption will be quite high, and the rise in energy consumption will lead to an increase in carbon emission at the same time. As a result, the traditional energy model is incapable of meeting the energy consumption requirement of high water cut oilfields in their middle and later phases of development. The present wind hydrogen coupling energy system was researched and coupled with the classic dispersed oilfield energy system to produce energy for the oilfields in this study. This study compares four future energy system models to existing ones, computes the energy cost and net present value of an oilfield in Northwest China, and proposes a set of economic evaluation tools for oilfield energy systems. The study’s findings indicate that scenario four provides the most economic and environmental benefits. This scenario effectively addresses the issue of high energy consumption associated with aging oilfields at this point, significantly reduces carbon emissions, absorbs renewable energy locally, and reduces the burden on the power grid system. Finally, sensitivity analysis is utilized to determine the effect of wind speed, electricity cost, and oilfield gas output on the system’s economic performance. The results indicate that the system developed in this study can be applied to other oilfields. Full article

The countries of the Gulf Cooperation Council (GCC)—Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates—hold almost 30% of the world’s total proven oil reserves and around 20% of its total proven natural gas reserves. They are also endowed with a high abundance of renewable energy resources such as solar and wind. Yet, the GCC’s primary energy consumption is still dominated by fossil fuels, and the share of renewable energy still does not exceed 1%. Drawing on secondary data, including journal articles, governmental and companies’ websites, and reports and newspaper articles, this paper assesses the reasons behind their underutilization of renewable energy resources. Whereas technical and economic feasibility issues had been identified as the main barriers to slow the uptake of renewable energy technologies in the GCC, this paper uncovered that various additional factors have remarkably influenced such delays. High hydrocarbon subsidies, low electricity tariff structure, fragmented energy policy, the absence of dedicated renewable energy regulator and regulatory framework, and a highly controlled power market are major barriers to renewable energy adoption in the GCC. The paper concludes with policy options to inform scaling up the adoption of renewable energy in the GCC. Full article

Plastic products are widely used due to their superior performance, but there are still limitations in the current methods and technologies for recycling and processing of waste plastics, resulting in a huge wasting of resources and environmental pollution. The element composition of waste plastics determines its great gasification potential. In this paper, three different waste plastic gasification processes are designed in a process simulator based on the conventional Integrated Gasification Combined Cycle (IGCC) system to achieve waste conversion and utilization as well as carbon capture. Design 1 is based on the cryogenic air separation (CAS) process to obtain oxygen, which is sent to the gasifier together with steam and pretreated waste plastics. The synthesis gas is purified and synthesized into methanol, and the residual gas is passed to the gas turbine and steam turbine to achieve multiple production of heat, electricity, and methanol. Design 2 uses a Vacuum Pressure Swing Adsorption (VPSA) process to produce oxygen, which reduces the energy consumption by 56.3% compared to Design 1. Design 3 adds a calcium-looping (CaL) reaction coupled with a steam conversion reaction to produce high-purity hydrogen as a product, while capturing the generated CO₂ to improve the conversion rate of the reaction. Full article

To meet the increased demand of hydroelectric power generation, a novel drag-based Savonius turbine with the characteristics of a simpler fabrication process and good starting characteristics is designed, fabricated, and analyzed. The newly designed turbine is suitable to be installed in rivers, irrigation channels, ocean currents, etc., for small-scale hydroelectric power generation. In the present study, experiments are carried out to investigate the influence of the design parameters of this turbine on its power performance in order to improve its efficiency, including blade arc angles (180°, 135°), blade placement angles (0°, ±22.5°), and the number of blades (2, 3, 6, and 8). Further, three-dimensional CFD simulations are performed with Re = $6.72\times {10}^5$, matching the experimental conditions, in order to study the changes in the flow field and the rotation characteristics of the turbine. The research results indicate that a six-bladed turbine with a blade arc angle of 135° and a blade placement angle of 0° has higher torque and better power performance, which makes it the most suitable design when also considering cost. Furthermore, it was found that an increase in the number of turbine blades contributes to improving the performance of the turbine. The maximum power coefficient is 0.099 at a tip speed ratio of 0.34. Full article

The utilization of new and renewable energy sources explicitly based on biomass needs to be increased to reduce dependence on fossil fuels. One of the potential biomasses of plantation waste in Indonesia that can be utilized is oil palm plantation waste in the form of fronds and trunks that are converted with multi-stage downdraft gasification technology. This study aimed to conduct a technical analysis, economic analysis, investment risk analysis, social analysis, and an environmental impact assessment of power plants fueled by oil palm plantation waste. The method used was the upscaling of a prototype of a 10 kW power plant to 100 kW. The results showed that it was technically and economically feasible to apply. The economic indicators were a positive NPV of USD 48.846 with an IRR of 9.72% and a B/C ratio of 1.16. The risk analysis predicted a probability of an NPV 49.94% above the base case. The study of the social aspects suggested that the construction of power plants has a positive impact in the form of increased community income and the growth of new economic sectors that utilize electricity as a primary source. An analysis of the environmental effects is critical so that the impacts can be minimized. Overall, the construction of small-scale power plants in oil palm plantations is worth considering as long as it is carried out following the applicable regulations. Full article

Low-grade renewable energy possesses large reserves and a wide distribution in the environment, but it is far from fully exploited due to the high cost–income ratio when using traditional convertors. A fluid-induced-vibration-based flow energy convertor with a low-cost bent plate as an oscillator is proposed to achieve better energy converting performance for low-grade flow energy conversion. The energy extraction performance and dynamic response of the bent plate are assessed numerically. The results demonstrate that the prescribed single-DOF (degree of freedom) bent plate can reach the maximum efficiency of 29.6% and power coefficient of 2.36 at the relative plunging amplitude of 3.5, while the double-DOF bent plate achieves a maximum efficiency of 37.3% and power coefficient of 1.42 at a smaller amplitude of 1.4. It is discovered that the adoption of pitching motion can help to control the variation pattern of the effective AOA (angle of attack), while the camber of the bent plate also regulates the effective AOA from the geometrical respect. The FIV-based single-DOF convertor can achieve an energy converting efficiency of 29.3% and approach the ideal sinusoidal motion trajectory closely, indicating that the optimal active motion mode can be realized by the passive motion mode with the appropriate choice of the dynamic parameters. Full article

Wind energy is an alternative source of clean energy to address the growing energy demand and provide pollution-free electricity. With the rapid development of urban areas, high wind energy resources such as high-rise building rooftops are excellent locations for urban wind turbine installation. One of the practical and simple urban wind turbines is the Savonius design. It has a simple design, easy to maintain, and is very affordable. This work focuses on the design evaluation of a Savonius wind turbine (SWT) by varying the rotor diameter, rotor height, and twist angle for urban applications. A transient computational fluid dynamics (CFD) approach is applied to assess the various design treatments using a space-filling design of experiments. To address the spaces in the hypercube statistical design, a sphere packing design method was adopted which suited the evaluation of computational simulations results such as that of the CFD. The Gaussian stochastic process model was applied to establish the trend of the parametric performance of the optimized SWT design through the model fitting. The results have shown that optimized SWT performs well with its self-starting capability compared to the traditional Savonius design. In addition, the optimized SWT has shown a better peak power coefficient compared with the results of previous works on the design of SWT. Full article

The progressive use of renewable energy sources to ensure a continuous and abundant energy supply is the significant target towards a sustainable and secure energy system. Previously, the countries that had relied on fossil fuel as a dominating energy source are now endorsing energy system transition towards renewable energy sources. In this study, a comparative assessment of the energy problems of South Asian countries is summarized. Nevertheless, there are many similarities and differences in the electricity supply system of these countries. Long-term planning for renewable energy development is suggested for a diverse population and dispersed geographical location considering all the significant challenges. However, appropriate schemes are imperative for integrating significant renewable energy sources. This study introduces a foresight plan of the electricity model according to the demand and supply balance for extensive technical analysis. The EnergyPLAN modeling tool was employed to work out a more ambitious VRE integration scenario than the official plans. The reference model was validated according to legitimate and authentic data, and then, the technically most feasible renewable energy-based alternate scenario was built. The additional grid integration cost of variable renewable energy was quantitatively investigated for comprehensive power system modeling for a real-time economic analysis. The results may be adapted and support developing more sustainable power generation serving 1787 million in South Asian countries. Full article

Low carbon and renewable energy sources (RESs) are fast becoming a key sustainable instrument in meeting the global growth of electricity demand while curbing carbon emissions. For example, the gradual displacement of fossil-fuelled vehicles with electrically driven counterparts will inevitably increase both the power grid baseload and peak demand. In many developed countries, the electrification process of the transport sector has already started in tandem with the installation of multi-GW renewable energy capacity, particularly wind and solar, huge investment in power storage technology, and end-user energy demand management. The expansion of the Electric Vehicle (EV) market presents a new opportunity to create a cleaner and transformative new energy carrier. For instance, a managed EV battery charging and discharging profile in conjunction with the national grid, known as the Vehicle-to-Grid system (V2G), is projected to be an important mechanism in reducing the impact of renewable energy intermittency. This paper presents an extensive literature review of the current status of EVs and allied interface technology with the power grid. The main findings and statistical details are drawn from up-to-date publications highlighting the latest technological advancements, limitations, and potential future market development. The authors believe that electric vehicle technology will bring huge technological innovation to the energy market where the vehicle will serve both as a means of transport and a dynamic energy vector interfacing with the grid (V2G), buildings (V2B), and others (V2X). Full article

The results show that Wood Chips of Acacia Nilotica trees available in Sudan lands can be successfully used in the gasification process and, on the same basis, as a bio-renewable energy resource. Simulation models were used to characterize the air gasification process integrated with a Regenerative Gas Turbine Unit. The results revealed that at a moisture content of 12%, gasification temperature of 1500 K, pressure of 20 bar, and air-like gasification medium, the biomass gasifier’s flow rate is higher at higher syngas rates. The results verified that there is an optimum ER for each syngas rate, in which the slow growth of the ER revealed the maximum gasifier biomass flow rate. For ER growth at lower levels, the specific fuel consumption (SFC) of the RGT Unit declines sharply from the maximum value reached at 0.27 kg/kW·h at an ER of 5% to the minimum value reached at 0.80 kg/kW·h at an ER of 25% for the lowest gasification temperature of 1000 K. Moreover, ER growths at low levels have a significant effect on the RGT plant’s performance, leading to increased RGT thermal efficiency. The increase in the biomass moisture content led to a sharp decrease in the RGT thermal efficiency. The RGT thermal efficiency remains high at higher gasification pressure. The results revealed that the syngas lower heating value remains high at lower produced syngas rates. At the optimum ER, the H₂ mole fraction depicted a value of 1.25%, 0.85% of CO, and 10.50% of CH₄ for a lower heating value of 38 MJ/kg syngas. It is shown that the gasification air entered into the gasifier decreases amid the increase in the biomass moisture content. At different syngas rates (3–10 kg/s) and optimum ER, the results predicted that the Wood Chip biomass flow rates decrease when the gasifier efficiency increases. The simulation model revealed that ER growths at lower levels have a significant effect on increasing the power of the RGT plant. Full article

The Froude-scaled offshore floating wind turbine model is inevitably affected by the Reynolds number effect, making the model unable to correctly reproduce the thrust performance of the reference wind turbine (RWT). To solve this problem, an Xfoil-AirfoilPrep-Matlab (XAM) system and a wide tip speed ratio search method (WTSM) are proposed to design a wide tip speed ratio (TSR) thrust-match model blade. The XAM system is utilized to select the best airfoil for WTSM by calculating the lift and drag coefficients of several airfoils. The WTSM is utilized to optimize the blade chord and twist. It formalizes the blade chord and twist by polynomials and then optimizes the polynomial coefficients. The thrust coefficients construct the optimization object at different TSRs. For validating the effect of the redesigned blade, the thrust performance is compared to that of the RWT blade. In addition, the thrust performance of redesigned blade at different pitch angles is also calculated and compared to those of the RWT blade. Results show that the thrust performance of redesigned blade matches well with that of the RWT blade at 0 pitch angle, and it can also match the variations of that of the RWT blade at the other pitch angles well. Full article

Air-to-water heat pumps (HPs) are widely installed in new buildings; however, they face performance degradation with high temperature emission systems, which is typical of existing buildings, or during domestic hot water (DHW) production. Hybrid systems (HSs), composed by air-to-water HPs and gas-fired boilers, can mitigate these issues by increasing the overall system efficiency. HS performance is strictly dependent on the configuration and control management of the system itself. Moreover, the building and heating plant also have a strong influence. This study presents an overview of the application of HSs that considers both space heating (SH) and DHW production, by comparing the primary energy (PE) consumption obtained by dynamic simulations. Different climates, building typologies, and DHW withdrawal profiles are used to extend the results’ validity. Additionally, several HS control strategies were implemented and compared. The results show a PE savings ranging from 5% to 22% depending on the control strategy and the external parameters applied in the simulation. The comparison of the control strategies shows that the most efficient strategies are the ones maximizing heat pump utilization. The dependence of PE savings of HS on COP values is highlighted, and a correlation is presented to provide designers with guidance on the applicability of HSs. Full article

The global energy sector is aiming to rapidly transform energy systems into those less dependent on fossil fuels to reduce their harmful effects on the climate. Although ground source heat pump (GSHP) systems are more efficient than conventional air-source heat pump (ASHP) systems, the high initial investment cost, particularly for a vertical closed-loop type ground heat exchanger (GHX), makes it difficult to incorporate them into small buildings. This paper proposes a low-depth modular GHX for reducing cost and improving the workability of GSHPs. A modular GHX is a cubical structure comprising tubes and buried using an excavator at a depth 4 m below the ground surface. This GHX is manufactured at a factory, carried by a small truck, and then installed by a small lift or a backhoe such that it can be installed in small buildings or narrow spaces at low depths underground. In this research, the performance and feasibility analyses of modular and vertical GHXs were conducted via a real-scale experiment. The results demonstrate that the modular GHX influences the workability of GSHPs by 91% during the heating period and 70% during the cooling period. In contrast to the conventional HVAC, the modular and vertical GHXs could recover the initial investment costs in 4 years and 10 years, respectively. Full article

A fully resolved (FR) NREL 5 MW turbine model is employed in two unsteady Reynolds-averaged Navier–Stokes (URANS) simulations (one with and one without the turbine tower) of a periodic atmospheric boundary layer (ABL) to study the performance of an infinitely large wind farm. The results show that the power reduction due to the tower drag is about 5% under the assumption that the driving force of the ABL is unchanged. Two additional simulations using an actuator disc (AD) model are also conducted. The AD and FR results show nearly identical tower-induced reductions of the wind speed above the wind farm, supporting the argument that the AD model is sufficient to predict the wind farm blockage effect. We also investigate the feasibility of performing delayed-detached-eddy simulations (DDES) using the same FR turbine model and periodic domain setup. The results show complex turbulent flow characteristics within the farm, such as the interaction of large-scale hairpin-like vortices with smaller-scale blade-tip vortices. The computational cost of the DDES required for a given number of rotor revolutions is found to be similar to the corresponding URANS simulation, but the sampling period required to obtain meaningful time-averaged results seems much longer due to the existence of long-timescale fluctuations. Full article

Protection of the natural environment is a key activity driving development in the transport discipline today. The use of simulators to train civil aviation pilots provides an excellent opportunity to maintain the balance between efficiency and limit the negative impact of transport on the environment. Therefore, we decided to determine the impact of selected simulations of air operations on energy consumption. The aim of the research was to determine the energy consumption of the flight simulator depending on the type of flight operation and configuration used. We also decided to compare the obtained result with the energy consumption of an aircraft of a similar class, performing a similar aviation operation and other means of transport. In order to obtain the results, a research plan was proposed consisting of 12 scenarios differing in the simulated aircraft model, weather conditions and the use of the simulator motion platform. In each of the scenarios, energy consumption was measured, taking into account the individual components of the simulator. The research showed that the use of a flight simulator has a much smaller negative impact on the natural environment than flying in a traditional plane. Use of a motion platform indicated a change in energy consumption of approximately 40% (in general, flight simulator configuration can change energy consumption by up to 50%). The deterioration of weather conditions during the simulation caused an increase in energy consumption of 14% when motion was disabled and 18% when motion was enabled. Energy consumption in the initial stages of pilot training can be reduced by 97% by using flight simulators compared to aircraft training. Full article

Wind power’s increasing penetration into the electricity grid poses several challenges for power system operators, primarily due to variability and unpredictability. Highly accurate wind predictions are needed to address this concern. Therefore, the performance of hybrid forecasting approaches combining autoregressive integrated moving average (ARIMA), machine learning models (SVR, RF), wavelet transform (WT), and Kalman filter (KF) techniques is essential to examine. Comparing the proposed hybrid methods with available state-of-the-art algorithms shows that the proposed approach provides more accurate prediction results. The best model is a hybrid of KF-WT-ML with an average R2 score of $0.99967$ and RMSE of $0.03874$, followed by ARIMA-WT-ML with an average R2 of $0.99796$ and RMSE of $0.05863$ over different datasets. Moreover, the KF-WT-ML model evaluated on different terrains, including offshore and hilly regions, reveals that the proposed KF based hybrid provides accurate wind speed forecasts for both onshore and offshore wind data. Full article

Lowering the condensing temperature of the Refrigeration and Air-conditioning (RAC) system has been proven to effectively increase the system’s Coefficient of Performance (COP). This paper revolves around evaluating the energy-saving generated by applying a Thermal Diode Tank (TDT) in the RAC systems. The TDT is a novel invention, which is an insulated water tank equipped with gravity heat pipes. If the TDT was placed outdoors overnight, its inside water would theoretically be at the minimum ambient temperature of the previous night. When the TDT water is used to cool the condenser of RAC systems that operate during the daytime, a higher COP of this TDT assisted RAC (TDT-RAC) system could be achieved compared with the baseline system. In this study, a steady-state performance simulation model for TDT-RAC cycles has been developed. The model reveals that the COP of the TDT-RAC cycle can be improved by 10~59% over the baseline cycle depending on the compressor types. The TDT-RAC cycle with a variable speed compressor can save more energy than that with a fixed speed compressor. In addition, TDT-RAC cycles can save more energy with a higher day/night ambient temperature difference. There is a threshold tank size for a given TDT-RAC cycle to save energy, and the energy-saving can be improved by enlarging the tank size. A desk-top case study based on real weather data for Adelaide in January 2021 shows that 9~40% energy could be saved by TDT-RAC systems every summer day on average. Full article

The Republic of Djibouti has untapped potential in terms of renewable energy resources, such as geothermal, wind, and solar energy. This study examines the economic feasibility of green hydrogen production by water electrolysis using wind and geothermal energy resources in the Asal–Ghoubbet Rift (AG Rift), Republic of Djibouti. It is the first study in Africa that compares the cost per kg of green hydrogen produced by wind and geothermal energy from a single site. The unit cost of electricity produced by the wind turbine (0.042 $/kWh) is more competitive than that of a dry steam geothermal plant (0.086 $/kWh). The cost of producing hydrogen with a suitable electrolyzer powered by wind energy ranges from $0.672/kg H₂ to $1.063/kg H₂, while that produced by the high-temperature electrolyzer (HTE) powered by geothermal energy ranges from $3.31/kg H₂ to $4.78/kg H₂. Thus, the AG Rift area can produce electricity and green hydrogen at low-cost using wind energy compared to geothermal energy. The amount of carbon dioxide (CO₂) emissions reduced by using a “Yinhe GX113-2.5MW” wind turbine and a single flash geothermal power plant instead of fuel-oil generators is 2061.6 tons CO₂/MW/year and 2184.8 tons CO₂/MW/year, respectively. Full article

The demand for liquefied natural gas (LNG) as an energy commodity is increasing, although its respective supply chain is subjected to risks, uncertainties, and disturbances. An analysis of experiences from the global LNG supply chain highlights many of these risks. As such, there is an incumbent need to develop resilient LNG supply chains. In this study, the risks associated with the LNG supply chain are categorized into four dimensions: Political and regulatory, safety and security, environmental effects, and reliability of new technologies. A SWOT method is then implemented to identify strengths, weaknesses, opportunities, and threats within the LNG supply chain, where the LNG supply chain of Qatar is considered as a case study. Relevant strategies are then recommended using a SWOT matrix to maximize strengths and opportunities, while avoiding or minimizing weaknesses and threats within the LNG supply chain. Finally, major parameters to be considered to develop a resilient LNG management model are listed based on the level of priority from LNG producer and receiver perspectives. Thus, as part of creating a robust LNG supply chain, decision-makers and stakeholders are urged to use the learnings from the SWOT analysis and experiences from LNG supply chain management. Full article

In the paper, we report our research on the improvement of thermal efficiency of refrigerated trailers by modification of their wall structure by placing a layer of phase change material inside them. The research was carried out in the field of transport, meeting the requirements of all classes provided for in the ATP agreement for refrigerated trailers. As part of the research, we formulated a numerical model of the proposed design of the refrigerator walls, which was subsequently validated by comparing the modeling results with the results of experimental tests carried out on a test bench designed specifically for this purpose. Based on the validated simulation conditions, we formulated the numerical model of a full-scale refrigerated semi-trailer, which was numerically tested under the conditions specified in the ATP Agreement. The results proved that adding a 6 mm layer of the SP-24 phase change material in each of the walls of the cold store allows the temperature inside the trailer to be kept below −20 °C for a period of 24 h without the need to supply cold from the outside during operation. The passive refrigerated semi-trailer system implemented in this manner with 6 mm PCM layer allows for a reduction in primary energy consumption by up to 86% in a period of 22 h. The mentioned percentage did not take into account the efficiency of the cooling system of the phase change material. Full article