Increasing Energy Costs Research Articles

Energy Efficiency Analysis of Pumping Systems Impacted by the Golden Mussel: A Case Study in the Brazilian Amazon

Pumping systems, especially those used in the water supply sector and in industrial and hydroelectric facilities, are commonly infested by the golden mussel. This causes an increase in maintenance operations (e.g., system shutdowns for cleaning) that can generate an increased energy cost. The geographical expansion of the golden mussel in Latin America presents an economic risk, not only to the ecosystem in general, but also to the energy sector. The imminence of its spread in the Amazon region, one of the main river basins in South America, is cause for concern with regard to the problems that bioinvasion of this species can cause. Given the absence of studies on the loss of energy efficiency in pumping systems impacted by the golden mussel, this study proposes a methodology to estimate the increase in energy consumption and costs of pumping under such bioinfestation. For the standardization of the methodology and development of mathematical calculations (both novel and improved equations), data from the literature (the growth of the golden mussel as a function of infestation time) and an analysis of the dimensions (length and height) of a sample of mussels available in the laboratory were considered. These data were used to calculate the roughness generated by the mussel infestation in the pumping suction and discharger pipe, which was necessary to determine the loss of energy efficiency (load loss, power consumption, and cost of pumping) resulting from the increase in energy consumption for pumping. This methodology was applied to a pumping station representative of the Brazilian Amazon as a case study. The results show an average increase in economic indicators (consumption and cost of pumping) after the system undergoes bioinfestation. This total increase corresponded to 19% and 44% in the first and second years, respectively, achieving a stabilization of the increase in the cost of pumping at 46%, in the 30 months of operation. Our results demonstrate the pioneering nature of the proposal, since these are the first quantitative data on the energy efficiency of pumping systems associated with bioinfestation by the golden mussel. These results can also be used to estimate the increase in costs caused by golden mussel bioinfestation in the raw water pumping systems of other facilities.

The relation of energy cost of walking with gait deviation, asymmetry, and lower limb muscle co-activation in children with cerebral palsy: a retrospective cross-sectional study

BackgroundCompared to typically developing children, children with cerebral palsy (CP) have increased energy expenditure during walking, limiting activity and participation. Insight into whether the also deviating and more asymmetric gait with increased muscle co-activation contributes to this increased energy expenditure is important for clinical decision making. The aim of this study was to investigate the relation between energy cost of walking with gait deviation, asymmetry, and muscle co-activation in children with CP.MethodsForty ambulant children with CP, with Gross Motor Function Classification System (GMFCS) level I (N = 35) and II (N = 5), aged between 5-17y, were tested at one or two occasions with 24 weeks in between, resulting in 71 observations. Gross energy cost (J/kg/m) was measured during a 5-min walk test at self-selected speed. From a 3-dimensional gait analyses, kinematic variables and electromyography were extracted to calculate the gait deviation index (GDI) and co-activation index. The relation between energy cost and GDI, GDI asymmetry, and co-activation index of the lower limb muscles was evaluated through mixed model analyses. Height was included to control for growth-related variation.ResultsGait deviation and height combined explained about 40% of the variance in gross energy cost. No significant contribution was found for gait asymmetry or co-activation index.ConclusionsThis cross-sectional study indicates that increased gait deviation contributes to increased energy cost of walking in children with GMFCS level I and II.

Energy Efficiency Issues in Buildings: Analysis of World Practice

At present, the volume of world energy consumption is continuously and rapidly increasing, which is a consequence of the industrialization process, population growth, increase in energy costs for the extraction of natural resources, etc. Therefore, the importance of solving the problem of energy efficiency is of paramount importance for modern civilization. In this work, there is an analysis of international experience of energy efficient construction. The main directions of energy-efficient development are highlighted. It’s shown that the classical method of heat loss calculations wrongly takes into account the wind effect. The more correct one is required. At the same time, it is worth applying linguistic variables and fuzzy logic, which adequately describe states that are described by verbal statements, and not by numerical values. In conclusion, the most emerging tasks for our Republic are selected: optimal placement of the building on the general plan of the city, incl. maintaining the distance between buildings under the construction and urban-planning regulations; proper heat insulation of the building envelope by the orientation of facades and depending on the climatic parameters of the outside air; air-tightening of building avoiding in- and exfiltration; maximum possible automation of engineering systems up to integration from smart house to smart city level; modernization and optimization of the operation of engineering systems; maximum use of renewable and secondary (such as exhaust air) energy sources; rejection of the classical calculation method of heat loss estimation, which takes into account the effect of wind speed, and to develop a new methodology.

Macroeconomic and Uncertainty Shocks’ Effects on Energy Prices: A Comprehensive Literature Review

GDP, monetary variables, corruption, and uncertainty are crucial to energy policy decisions in today’s interrelated world. The global energy crisis, aggravated by rising energy prices, has sparked a thorough analysis of its causes. We demonstrate the significance of categorizing research by influence channels while focusing on their implications for energy policy decisions. We investigate the growing number of studies that use GDP, inflation, central banks’ characteristics, corruption, and uncertainty as critical factors in determining energy policies. Energy prices fluctuate because energy policies shift the supply–demand equilibrium. We categorise the effects and show that GDP, economic policy uncertainty, and, most notably, specific economic conditions and extreme events play a significant role in determining energy prices. We observed that energy consumption, GDP growth, and energy prices have a bidirectional, causal relationship. Still, the literature has not established which causative direction is the most significant. Taxes, interest rates, and corruption also significantly determine energy prices, although the origins of corruption have not been adequately examined. Lastly, uncertainty generally increases energy costs, but this relationship requires additional research in terms of the features of countries, conditions, and, most importantly, the theoretical backgrounds used.

Continuous hydrate-based CO2 separation from H2 + CO2 gas mixture using cyclopentane as co-guest

CO2 separation from H2 + CO2 gas mixture is a necessary technology for a stable supply of blue hydrogen. Among CO2 separation technology, hydrate-based CO2 separation is an environmentally and economically superior technology. Cyclopentane (CP) was selected as guest compound to enable hydrate-based CO2 separation under thermodynamic conditions closer to normal pressure and temperature. Hydrate-based continuous CO2 separation experiments are conducted in the H2 + CO2 + CP + H2O system at 284 K. The results of these experiments showed that mole fraction of H2 in the gas phase reached 0.9 at the steady state in the H2 + CO2 + CP + H2O system after the CO2 was extracted via hydrate formation. At the same time, more H2 was incorporated into the mixed hydrate during this process as the concentration of H2 in the gas phase increases post hydrate formation. Therefore, it was demonstrated that hydrate-based CO2 separation was successful in H2 + CO2 + CP + H2O system at 284 K but there is also increase of energy costs caused by H2 loss. The PXRD results identified H2 + CO2 + CP hydrate as structure II hydrate. Although H2 + CO2 + Tetrahydropyran (THP) hydrate also forms structure II hydrate, more H2 is encapsulated in the H2 + CO2 + CP mixed hydrate than in the H2 + CO2 + THP mixed hydrate. This difference may be caused by the difference in the lattice constants of CP and THP hydrates, which arises from the difference in molecular size of CP and THP, from the differences between the large guest–host interactions, and from differences arising from hydrogen bonding of THP with the host water framework which can decrease the H2 holding capacity. In this study, it was revealed that the molecular diameter of the guest molecules need also to be considered in addition to the phase equilibrium conditions of the hydrates when selecting guest compound of hydrates.

Analysis of Temperature Control Strategy on Energy Consumption in Buildings with Intermittent Occupancy

The increase in energy costs has led researchers and practitioners to investigate the energy consumption of buildings and propose solutions for its improvement. This research aimed at estimating the effect of different temperature control strategies on the energy consumption of a building. This study belongs to the field of research that considers both the structural characteristics and the conditioning systems incorporated into the design or renovation of buildings. The objective was to identify the optimal settings that led to the maximization of energy performance under intermittent occupancy considering the building’s structural and conditioning system characteristics and environmental conditions. To reach this objective, it was necessary to use simulation software that considered all these characteristics simultaneously in a dynamic environment. Specifically, the effect of the geometric and structural characteristics on the thermal profile of the building was investigated by implementing a dynamic hourly regime with temperature fluctuations around an assigned set-point. The study showed that for models with heavy masonry walls, the annual thermal dispersion of the hourly regime was much lower than for the corresponding models with light masonry walls. These results and the related method could be considered by researchers and practitioners for the design and/or renovation of buildings.

A Study on the Interdependence in Sustainable Mobility Tools and Home Energy Equipment Choices

Energy consumption in transportation and households are the main two sections of energy consumption in Europe. To cope with the challenges raised by energy security, sustainability, and pollution, great efforts have been made to encourage the transition from fossil fuel vehicles to electric vehicles and car sharing. In terms of households, home renewable energy equipment such as heat pumps and solar panels are promising solutions. To accelerate the diffusion of these promising and environmentally friendly technologies, an abundance of studies has investigated the factors that impact the adoption of them. Most of the existing literature considered the choice behavior of vehicle types and choice behavior of energy equipment to be exogenous to other. Charging electric vehicles at home will lead to an increase in home energy costs. It is important to understand to what extent a household’s decision to purchase new mobility tools or energy equipment is affected by the other. This paper, therefore, attempts to investigate the correlation between the choice of home energy equipment and the choice of new mobility tools. An inverted sequence stated preference experiment was designed and conducted in the Netherlands to examine the interdependence of mobility tools choice and home energy equipment choice. Two logit models were presented to investigate how the choice of mobility tools and energy equipment impact each other. Results indicate that the promoting effect between electric vehicles and solar panels is bidirectional, while the promoting effect between electric vehicles and heat pumps is unidirectional.

Evaluation of the Biomass Energy Production Potential in Agricultural Holdings in Relation to Their Size. Case Study for COP Farms in Romania

Biomass energy production is a priority for the global economy in terms of ensuring the premises for sustainable development. The current context, determined by increases in energy costs, involves the identification of applicable and eco-intensive measures by which the use of biomass in productive activities will reduce the level of pollution and, implicitly, global warming. Progress of the bioeconomy is intercorrelated with the dimension of agriculture, which is the major provider of biomass for food, feed, and other bio-based industries. The agricultural sector in the last decades is characterized by an increase in energy production and consumption, with direct consequences on the environment. Biomass is for Romania, a renewable energy source, particularly valuable, both in terms of potential and in terms of future use, through complementarity with the sustainable development programs of the state that aim to develop the capacity of production and the creation of well-being. This research aims to estimate the energy efficiency of three types of COP farms (which cultivate cereals, oilseeds, and protein crops) of different physical sizes, and the analysis of the potential energy generated by energetical cultures, with emphasis on biomass energy. The energy balance at the farm level remains a very important method to determine the efficiency of agricultural systems and for the assessment of potential energy from biomass. With this study, we emphasize the need to support a more sustainable demand for biomass and to make the bioeconomy market more competitive.

Energy-Optimal Coverage Motion Trajectory Generation for Industrial Machines*

Coverage motion of industrial machines are widely used for manufacturing tasks such as milling, polishing, laser cutting, and inspection. Motion smoothness of industrial machines under their kinematic limits are crucial in coverage motion to increase the production efficiency and accuracy. Motion trajectory optimization for typical computer numerical control (CNC) machines plays an important role in achieving smooth motion. In addition, with the current increase in energy costs and environmental concerns, there is a great need to reduce energy consumption by industrial machines which are extensively used in manufacturing industries. This study presents an energy optimization approach for coverage motion of industrial machines, which simultaneously integrates trajectory generation and geometric path optimization. The trajectory along a linear segment is described by the modified S-curve profile with harmonic motion employed for smooth jerk continuity to enhance the motion accuracy. An energy consumption model of the feed drive system is used to achieve energy-optimal. A genetic algorithm is applied for the optimization. Experimental validation of the simulation results is carried out using a two-axis feed drive system. Simulation and experimental results shows that the energy saving of the feed drive system is achieved under machine kinematic limits ensuring smooth motion.

STRENGTHENING AND RESTORATION OF THE GEOMETRIC PARAMETERS OF WOOD-CUTTING SAWS USING THE METHOD OF PLASMA DEPOSITION OF WEAR-RESISTANT ALLOYS

The article covers the issues related to wear and blunting of the teeth of wood-cutting tools, which leads to the loss of the tool's cutting capacity, a decrease in the productivity of the wood sawing process, the quality of lumber and blanks, and an increase in energy costs. It is shown that the process of wear of a wood-cutting tool is a rather complex complex of interrelated phenomena. The types of wear of the tool are given and it is indicated that the degree of wear of the cutting part of the saw teeth and the nature of the change in their microgeometry depends on a number of factors. Methods of increasing the wear resistance of wood-cutting saws are considered. It is shown that the method of strengthening saw teeth by surfacing wear-resistant alloys is the most promising. The purpose of the research is to increase the wear resistance and efficiency of the use of saws due to their strengthening by the method of plasma application of wear-resistant alloys. The method of experimental research with a circular saw of a special design is presented, the geometric parameters of the experimental samples of the tool are determined. Saws with inserted teeth made of P6M5, 8X6НФT, 9ХФ steels, cast hard alloy ВЗКР and hard metal-ceramic alloy ВK15 were studied. The analysis of the obtained results showed that the dulling intensity is the lowest with the use of the ВЗКР alloy. Wear-resistant ВЗКР alloy can be welded using various methods on automated equipment, provides high wear resistance of the tool and is cheaper than metal-ceramic hard alloys. The characteristics of the equipment for surfacing wear-resistant alloys on saw teeth and the technology of their strengthening are given. Tests of saws with teeth strengthened by ВЗКР alloy deposited in production conditions showed high wear resistance of saws, increased productivity of the sawing process, reduction of roughness of processing surfaces, and reduction of saw dust consumption in the sawing process.

Current challenges in agricultural supply chains: an empirical assessment based on expert perspectives

The food industry is an essential sector of any country, and it should ensure the continuous supply of food to consumers. Currently, more and more companies are turning to international trade to meet the demands of their markets and at the same time ensure the profitability of their own business. This market transformation has resulted in food supply chains evolving from simple regional supply to a complex network supply that is highly vulnerable and unstable, due to the inhomogeneity of supply chain actors, especially in times of crisis. This vulnerability is related to numerous challenges and associated consequences. This study examines the impact of the current crises on the food supply chain, as well as the strategies adopted by supply chain actors to ensure the stability and sustainability of their businesses. For this purpose, a qualitative analysis was undertaken, based on 17 expert interviews with representatives of the entire supply chain, ranging from seed producers to retailers and including agricultural cooperatives, consulting companies, food networks. The results revealed that the combined effects of the Ukraine-Russia conflict, the COVID-19 pandemic, and customer behavior have had a significant impact on the food supply chain, such as a pronounced shortage of raw materials, supply shortages, price volatility and increased energy costs. The causal consequence of this is unrestrained market volatility which ultimately results in planning uncertainties for the companies involved; at the same time, supply chain actors are responding by implementing strategies to address these challenges. Strategies include the discovery of new markets and target groups, renewable energy sources and the consolidation of strategic suppliers, as well as the relocation of operations from abroad to the domestic market. The results of the study explain recent experience and serve as a starting point for further research that can help better understand and predict future crises.

Airports and environmental sustainability: A review

This paper examines the energy and environmental context of the design and operation of airports and air transport in general in the direction of achieving sustainability and cooperation with modern sustainable trends. At the same time, the importance of this design is highlighted, and all the latest developments on individual issues (e.g., impact management, policies, benchmarking, modeling) are recorded. In parallel, apart from the theoretical approach, an analysis of the main environmental and energy achievements of different airports in Greece and abroad is made, which highlights, among others, the dynamics and the priority of these issues in the field of aviation. The need for a more extensive study of this sector is dictated by the reduction of energy reserves, increased energy costs, climate change, new energy regulations, and fines, increased passenger numbers, increased flights and airports, and the need for new airports. Therefore, knowing the benefits and impacts of a transition from simple economic growth to sustainable growth in the economy and the environment is essential. The circle is about society, the economy, and the environment and is repeated.

Modelling the effects of the pyrethroid insecticide cypermethrin on the life cycle of the soil dwelling annelid Enchytraeus crypticus, an original experimental design to calibrate a DEB-TKTD model

The Dynamic Energy Budget theory (DEB) enables ecotoxicologists to model the effects of chemical stressors on organism life cycles through the coupling of toxicokinetic-toxicodynamic (TK-TD) models. While good progress has been made in the application of DEB-TKTD models for aquatic organisms, applications for soil fauna are scarce, due to the lack of dedicated experimental designs suitable for collecting the required time series effect data. Enchytraeids (Annelida: Clitellata) are model organisms in soil ecology and ecotoxicology. They are recognised as indicators of biological activity in soil, and chemical stress in terrestrial ecosystems. Despite this, the application of DEB-TKTD models to investigate the impact of chemicals has not yet been tested on this family. Here we assessed the impact of the pyrethroid insecticide cypermethrin on the life cycle of Enchytraeus crypticus. We developed an original experimental design to collect the data required for the calibration of a DEB-TKTD model for this species. E. crypticus presented a slow initial growth phase that has been successfully simulated with the addition of a size-dependent food limitation for juveniles in the DEB model. The DEB-TKTD model simulations successfully agreed with the data for all endpoints and treatments over time. The highlighted physiological mode of action (pMoA) for cypermethrin was an increase of the growth energy cost. The threshold for effects on survival was estimated at 73.14 mg kg− 1, and the threshold for effects on energy budget (i.e., sublethal effects) at 19.21 mg kg− 1. This study demonstrates that DEB-TKTD models can be successfully applied to E. crypticus as a representative soil species, and may improve the ecological risk assessment for terrestrial ecosystems, and our mechanistic understanding of chemical effects on non-target species.

Water-energy-food-environment nexus in action: Global review of precepts and practice

Abstract Using water-energy-food-environment (WEFE) nexus as the prism, this review explores evolution of groundwater governance in Iran, Saudi Arabia, Mexico, China, Bangladesh and India – which together account for two-thirds of the global groundwater-irrigated area. Global discourse has blamed widespread water scarcity squarely on supply-side policymaking and advocated a broader template of water governance instruments. Integrated Water Resources Management (IWRM) presented just such a template – with pricing, participation, rights and entitlements, laws, regulations, and river basin organizations – as additional water governance tools. However, the IWRM template faced disillusionment and pushback in many emerging economies. WEFE nexus, the new paradigm, prioritizes system-level optima over sectoral maxima by harnessing synergies and optimizing trade-offs between food, water, energy, soil, and eco-system sustainability within planetary boundaries. Realizing this vision presents a complex challenge in groundwater governance. Global groundwater economy comprises three sub-economies: (a) diesel-powered unregulated, as in Nepal terai, eastern India, Bangladesh, Pakistan Punjab and Sind, and much of Sub-Saharan Africa, where use-specific energy subsidies are impractical; (b) electricity-powered regulated, as in North America and Europe, where tubewells are authorized, metered and subject to consumption-linked energy charges; and (c) electricity-powered unregulated, as in geographies covered by our review – barring China, Bengal and Bangladesh – where unmeasured electricity subsidies have created a bloated groundwater economy. This last sub-economy represents the heartland of global groundwater malgovernance, least equipped to meet the sustainability challenge. It has an estimated 300 million horsepower of grid-connected electric pumps that are either unauthorized and/or unmetered and/or use free or heavily subsidized or pilfered power for irrigating 50–52 million hectares, nearly half of global groundwater-irrigated area. In (a) and (b), groundwater scarcity inspires water-energy saving behavior via increased energy cost of pumping. In sub-economy (c), users are immune to energy costs and impervious to groundwater depletion. Here, the WEFE nexus has remained blind to the irrigation realpolitik that catalyzes or constrains policy action. We explore why the political costs of rationalizing subsidies are prohibitive and exemplify how a smart transition from fossil to solar energy for pumping may offer an opportunity to turn the perverse WEFE nexus into a virtuous one.

Current Status and Perspectives of Carbon Capture and Storage

As climate change progresses rapidly, unprecedented weather and natural changes are occurring. After carbon dioxide was identified as the main culprit of global warming and climate change, at the UN General Assembly in 2015, 195 countries signed the Paris Agreement to set greenhouse gas emission reduction targets. However, some countries are either withdrawing from the Paris Agreement or failing to implement it due to their own economic reasons. Reducing the use of fossil fuels increases energy costs. In this context, carbon capture and storage technology (CCS) is emerging as an alternative. In this review, the outline of CCS technology is explained, and the advantages and disadvantages of each technology, the status of CCS technology, and commercialization cases are investigated and analyzed. In addition, for an in-depth analysis of the CCS technology itself, the following issues were analyzed in depth during the research and analysis process: 1) Efficiency of CCS technology, 2) Comparison of carbon capture and storage capacity between CCS technology and vegetation, 3) Stability of carbon storage through CCS technology. Finally, the policy for carbon capture and storage technology and the development direction of this technology were presented.

Design and economic analysis of high-pressure proton exchange membrane electrolysis for renewable energy storage

The proton exchange membrane (PEM) electrolysis with a high-pressure cathode can help avoid the utilization of a hydrogen compressor and improve the efficiency of hydrogen transmission. The economic analysis of the entire process from hydrogen production to transportation was conducted in this study, and the advantages of high-pressure PEM electrolysis were proved. The economic analysis has also illustrated the influence of the cathode pressure and membrane thickness involved in PEM electrolysis on the energy consumption and capital expenditure of the electrolyzer from the perspectives of hydrogen permeability, ohmic impedance, and structural design. Although the output pressure of hydrogen is increased several tens of times, the proper structure and unchanged thickness of the membrane can help satisfy the strength and safety requirements of the electrolyzer simultaneously. In addition, the energy consumption and cost increase associated with the high-pressure electrolyzer can be limited to an acceptable range. The impact of the renewable energy scale on the decision and selection for PEM or ALK is also analyzed; PEM has an advantage over ALK in large-scale renewable energy hydrogen production scenarios because of its own wider upper and lower load limits compared to those of ALK.

ИНТЕНСИФИКАЦИЯ ПРОЦЕССА СМЕСЕОБРАЗОВАНИЯ КОРМОВЫХ СМЕСЕЙ

The quality and reliability of the technological process of preparing feed mixtures has a significant role both on the properties of the manufactured product and on the productivity of animals. The use of standard mixer designs, as a rule, does not ensure the quality of mixtures, economy, efficiency and leads to an increase in energy costs for the implementation of the technological process. Despite the presence of a wide variety in mixer designs, the need for new mixer developments remains an urgent problem associated with the constant increase in requirements for the uniformity of feed mixtures. When preparing combined feeds of own production, the degree of uniformity should be 90...95%. The study of the mixing process was carried out for a two-shaft bladed mixer of continuous operation. During the research, three variants of the operation of the paddle mixer were considered, differing from each other in the number and size of the blades. The greatest intensity of mixing was in a mixer with smaller blades, but at the same time the segregation period was more than 50%. In all variants, 30...50% of the time is spent on convective mixing. High-quality mixing will be ensured by increasing the number of force impacts of the blades in the elementary mixing zones, which determine the total length of the continuous mixer. A new theoretical dependence of the mixing kinetics in a continuous-action paddle mixer is obtained. The formula shows that increasing the uniformity of the finished feed mixture can be achieved by controlling the mixing process and improving the working bodies of mixers. The efficiency of the mixing process is ensured first by creating a preliminary value of the homogeneity of the mixture Θ0, outside the mixing chamber, and then by varying the mixer parameters to ensure the required quality of the feed mixture. The obtained dependence is the basis for a new method of gravitational mixing and a device for its implementation.

A Comprehensive Predictive-Learning Framework for Optimal Scheduling and Control of Smart Home Appliances Based on User and Appliance Classification.

Energy consumption is increasing daily, and with that comes a continuous increase in energy costs. Predicting future energy consumption and building an effective energy management system for smart homes has become essential for many industrialists to solve the problem of energy wastage. Machine learning has shown significant outcomes in the field of energy management systems. This paper presents a comprehensive predictive-learning based framework for smart home energy management systems. We propose five modules: classification, prediction, optimization, scheduling, and controllers. In the classification module, we classify the category of users and appliances by using k-means clustering and support vector machine based classification. We predict the future energy consumption and energy cost for each user category using long-term memory in the prediction module. We define objective functions for optimization and use grey wolf optimization and particle swarm optimization for scheduling appliances. For each case, we give priority to user preferences and indoor and outdoor environmental conditions. We define control rules to control the usage of appliances according to the schedule while prioritizing user preferences and minimizing energy consumption and cost. We perform experiments to evaluate the performance of our proposed methodology, and the results show that our proposed approach significantly reduces energy cost while providing an optimized solution for energy consumption that prioritizes user preferences and considers both indoor and outdoor environmental factors.

A voltage control strategy to improve the cycling stability of organic electrode materials: The case of para-dinitrobenzene

Small-molecule organic cathode materials (SMOCMs) with high energy density are promising for various energy storage devices including rechargeable lithium batteries, but it is a huge challenge to simultaneously satisfy the demand of cycling stability. Herein, by taking nitro-based para-dinitrobenzene (pDNB) as an example, we propose a simple but effective voltage control strategy to improve the cycling stability, without energy density decrease or cost increase of the system as for many other complicated solutions. The highly reversible two-electron redox reaction of pDNB provides it full utilization of the theoretical capacity (319 mAh g−1) and high discharge plateau at 2.65 V vs Li+/Li, and thus an outstanding energy density of 850 Wh kg−1. Different voltage windows of 1.8/2.4–3.4/3.8 V are applied to test the cycling performance, and 2.4–3.8 V is selected as the optimized one endowing a high capacity retention of 86 % after 100 cycles (as a contrast, only 8 % within 1.8–3.4 V). Various electrochemical analyses and ex-situ characterization methods reveale that the influence is not in the depth of discharge/charge, but in the dissolution–redepostion behavior of active material and thus the electrode structure evolution. This work provides not only a novel strategy to improve the cycling stability of SMOCMs, but also a new perspective to understand the capacity fading mechanism of them.

Modelling and Simulation Hydrodynamics Processes in Liquefied Natural Gas Transportation Systems

Global natural gas resources are growing and are increasingly geographically diverse. A Floating Storage and Regasification Unit (FSRU) is one of the most commonly used vessel types in the global ship fleet due to the possibility of storage, reloading to another ship, and regasifying it for re-injection into the natural gas grid. It is important to control system parameters for reliable technological processes such as tank hydrostatic pressure, vapor pressure, LNG density, LNG temperature, and phase changes between liquid and gas states. Additionally, pressure monitoring is important to control during transit in port and bunkering to prevent the pressure in the tanks from exceeding the tank design pressure. In this research study, a comprehensive hydrodynamic model for an LNG storage tank in a real-life regasification terminal (Floating Storage and Regasification Unit, LNG Terminal of Klaipeda City, Lithuania), operating in transportation mode to the regasification unit, was created. For this research, LNG is investigated as a compressible liquid and the speed of sound in LNG is evaluated. A complex mathematical model of the system allows the analysis of high-speed hydrodynamic and dynamic processes at cryogenic temperature (110 K) and evaluates the geometric parameters (tank geometry, electric motors and pumps, pipe geometric parameters, and roughness of internal surfaces) and the characteristics of pumps and electric motors. The complex mathematical model of the system was implemented using Fortran programing language and MATLAB R28a. It determined the parameters (pressure, velocity, liquid level of LNG in the tanks, electric motor angular velocity, torques, hydraulic energy losses, etc.) of the system during its start-up mode (until 5 s). It was found that hydraulic energy losses in all pipes contain 1.7% of the whole system power (the total power of the electric motors is 3132 kW). In case of increasing energy costs, this model could be used to control energy losses during the operation of the FSRU in various technological modes.