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In this paper, a novel Model Predictive Control (MPC) technique for multi-satellite formation flying geometry acquisition and maintenance in high-drag environment is presented. The proposed MPC relies on a linearized and convexified quasi-nonsingular Relative Orbital Elements (ROE) model based on state transition matrices propagation, allowing to include the effect of perturbations in the prediction to optimize fuel efficiency and tracking accuracy. The formation is controlled with respect to a non-decaying orbiting point to perform absolute and relative station keeping simultaneously. For this purpose, a new dedicated plant matrix to include drag effects on ROE in the propagation is derived and validated with respect to numerical results. In all simulations, the satellites are assumed to be equipped with a single low-thrust propulsion unit, therefore, specific constraints are included in the controller to obtain a feasible solution in a real operational scenario. Moreover, a collision avoidance constraint is added in case of close proximity operations exploiting a linear mapping between the set of ROE and cartesian coordinates expressed in the Local-Vertical-Local-Horizontal (LVLH) reference frame. The controller response is simulated in several realistic mission contexts with a high-fidelity orbital propagator and the results are validated for fuel efficiency by comparing them to similar approaches available in literature and to optimal solutions obtained respectively with a direct single shooting algorithm and with a closed-form impulsive formulation. [ABSTRACT FROM AUTHOR]

This paper explores the feasibility of utilizing lead-free multilayer piezo stacks, particularly focusing on Zr-doped 0.95(Bi 0. 5 Na 0.5)TiO 3 -0.05(BaTiO 3) piezoceramics, for energy harvesting. Various lead-free BNT-BT disk samples with different Zr concentrations undergo structural, microstructural, and electrical characterizations. The results illustrate that Zr-doping improves piezoelectric constitutive parameters, notably at a 2.0 mol% concentration. Electromechanical tests were conducted on multilayer piezo stacks, involving variations in electric load, mechanical load, frequency, and number of stacked disks. These tests demonstrate the ability of the multilayer transducer to produce up to 1.5 V (peak) under particular conditions: a 250 Hz frequency, a 10 N mechanical load, and an open circuit electric load, utilizing a stack comprising 5 disks. Employing an analytical mathematical model, an effective d 33 e f f of the system is determined, yielding values ranging from 588 to 625 pC/N for a stack composed of 5 disks. These findings highlight the considerable potential of lead-free multilayer piezo stacks in energy harvesting applications, offering crucial insights for the development of sustainable and eco-friendly energy solutions. [ABSTRACT FROM AUTHOR]

Closed-form models are important because they offer more design insights, require less computing time and prevent convergence problems in modeling compliant mechanisms. However, most of the available closed-form models, e.g., beam constraint models, are only appropriate for beam flexures within the intermediate deflection range. In this paper, a method for developing closed-form models based on the chained beam constraint model through the combined use of strain energy and Castigliano's first theorem is proposed. A closed-form model for beam flexures with a large prediction range is derived using this method. By modeling simple beams and compliant mechanisms using the proposed closed-form model, it is shown that the model has a significantly broader prediction range than the beam constraint model and is more efficient than the chained beam constraint model. The large prediction range and high efficiency of the proposed closed-form model make it potentially useful for optimizing compliant mechanisms. • A method to develop closed-form models for beam flexures is proposed. • A closed-form model for CBCM with 3 discretized elements is obtained. • Closed-form load-displacement relations for beam flexures are obtained. • The proposed molded is demonstrated to reduce the computational time. [ABSTRACT FROM AUTHOR]

• Novel damped conformable fractional accumulation method. • Prediction of energy related series with the uncertainties. • Design of damped conformable fractional grey bernoulli model. • Improved prediction accuracy, robustness and applicability. • Prediction of world coal consumption and production in 2025–2026. Energy resources, such as oil, coal are important to people's life and the development of the economy. Predicting the energy consumption and production with uncertainties can help the government and policymakers make the reasonable energy strategy and give constructive guidance. In this paper, a novel damped conformable fractional accumulation operator with two parameters are proposed to have control of both accumulation generation and new information involvement. The new accumulation can be adjusted from linear approximation to high order accumulation. A structure adaptive grey Bernoulli model based on proposed accumulation method is established, with the parameters optimized by particle swarm optimization algorithm. For testifying the effectiveness and the robustness of the model, two validation cases and two application cases are used to build the prediction model of diverse series with unexpected trends or fluctuations in energy fields. Compared with other existing fractional grey models and non-grey models, the proposed model has best prediction accuracy, better model stability and greatly improved applicability. The global coal consumption by industry is predicted as 30.85×106 TJ in 2025 and 30.81×106 TJ in 2026. The world coal production could be 182.93–187.73 exajoules in 2025 and 180.85–182.16 exajoules in 2026. [ABSTRACT FROM AUTHOR]

The demand for eco-products due to the exigency of friendly and environmental production could affect the employment of the firms. This paper tests whether product and process eco-innovations boost employment in Spain differentiating by the environmental goals (material and energy efficiency and environment responsiveness), by the level of qualification of the workers, and by the dirtiness of the industries. We apply a Green Harrison model, using the Technological Innovation Panel (PITEC) for Spain from 2008 to 2016. Results show a positive relationship between all types of product eco-innovations and employment, while the influence of process eco-innovations on employment depends on the environmental goals, the level of skills, and the industry. Specifically, distinguishing by industry there is a labour-saving effect in clean industries and a labour-friendly effect for low-skilled employment in dirty industries. [ABSTRACT FROM AUTHOR]

• A distribution dynamics approach is employed to examine the converge of TFEE across Chinese PAA level cities. • The findings show a clear convergence in TFEE. • Convergence comes more from efficiency drops in high TFEE cities than from efficiency gains in low TFEE cities. • The environmental protection polices in key cities improved energy efficiency. • Large-sized cities show better performance in energy efficiency than small- and medium-sized cities. Improving energy efficiency is considered the most direct route to reducing carbon emissions on a massive scale. To examine the long-run trend of China's energy efficiency, this paper employs a distribution dynamics approach to analyze the convergence of total-factor energy efficiency (TFEE) across 286 Chinese cities between 2002 and 2014. The result suggests the existence of convergence, which comes more from the efficiency declines in the high TFEE cities rather than the efficiency gains in the low TFEE cities. Despite the fact that a few cities have performed well in energy efficiency, the majority of cities have converged to a low-efficiency point. Further analyses show that the inefficiency was attributed to inefficient energy use in small- and medium-sized cities. Our analysis provides strong scientific support for China's ongoing energy conservation and environmental protection policies. [ABSTRACT FROM AUTHOR]

The measures needed to limit global warming pose a particular challenge to current fossil fuel exporters, who must not only decarbonise their local energy systems, but also compensate for the expected decline in fossil fuel revenues. One possibility is seen in the export of green hydrogen. Using Algeria as a case study, this paper analyses how different levels of ambition in hydrogen exports, energy efficiency and fuel switching affect the cost-optimal expansion of the power sector for a given overall emissions reduction path. Despite falling costs for photovoltaics and wind turbines, the results indicate that in countries with very low natural gas prices, such as Algeria, a fully renewable electricity system by 2050 is unlikely without appropriate policy measures. The expansion of renewable energy should therefore start early, given the high annual growth rates required, which will be reinforced by additional green hydrogen exports. In parallel, energy efficiency is a key factor as it directly mitigates CO2 emissions from fossil fuels and reduces domestic electricity demand, which could instead be used for hydrogen production. Integrating electrolysers into the power system could potentially help to reduce specific costs through load shifting. Overall, it seems advisable to analyse hydrogen exports together with local decarbonisation in order to better understand their interactions and to reduce emissions as efficiently as possible. These results and the methodology could be transferred to other countries that want to become green hydrogen exporters in the future and are therefore a useful addition for researchers and policy makers. • The required strong capacity expansion for PV and wind is challenging, but feasible. • "Energy efficiency first" benefits both the local energy transition and H2 exports. • Fully renewable power systems require a suitable political framework. • Higher hydrogen exports might help to reduce the specific power system cost. • Fossil capacity expansion must be stopped to avoid lock-ins and higher future costs. [ABSTRACT FROM AUTHOR]

Although firms' expectations on future price dynamics are key for monetary policy, we still lack information on the expected effect of the transition to a net-zero economy on future prices. This paper fills this gap in the literature using survey data collected in the first quarter of 2022 on Italian firms' expectations of the impact of the Fit-for-55 - the package established by the EU to achieve its climate targets - on the prices of the goods and services they purchase. First, it documents that almost half of the sample expects that the Fit-for-55 plan will increase their input costs over the short and medium term, while the rest foresee no effect on prices. Then, it shows that firms extrapolate their private experience of high energy prices and shortages in raw materials when forming their expectations. These are salient events that are likely to be recalled relative to the others stored in memory when forming expectatons. In contrast, aggregate information such as energy, oil, and gas prices do not enter the expectations formation process. Finally, a propensity score analysis shows that the expected price impact of the green transition shapes firms' pricing and investment choices such that firms expecting the transition to raise the prices of the inputs they will purchase in the medium term increase (or intend to increase) their selling prices more than the others and are more likely to invest in improving their energy efficiency. [ABSTRACT FROM AUTHOR]

This paper looks into the crucial macroeconomic feedback mechanisms emerging from the interplay among the goods market, the labor market, the financial sector, and monetary policy, particularly in the context of transitioning towards a climate-neutral economy. The investment decisions of firms, pivotal in this interaction, can trigger feedback loops with potentially destabilizing effects, underscoring the critical role of investment within the complex interplay of market and sector dynamics in the macroeconomy. Governmental intervention is highlighted as a key factor in steering the green transition while preserving economic stability. A carbon tax on fossil fuel consumption is proposed as a primary tool for facilitating this green transition. Our investigation employs a disequilibrium model of monetary growth, a la Keynes-Metzler-Goodwin (KMG), incorporating a portfolio perspective across three asset markets - money, bonds, and stocks. This framework allows for an in-depth analysis of how a carbon tax influences real production, inflation, and inequality during the transition. Our findings indicate that imposing a carbon tax on production does not markedly disrupt economic stability, as long as the carbon pricing and its growth rate remain within low bounds. [ABSTRACT FROM AUTHOR]

• A novel forced-air ice slurry wet precooling system is proposed and built. • The precooling experiments with tomatoes as cooling subject are carried out. • There is an optimal value of precooling uniformity with the increase of wind speed. • Weight loss and energy consumption are lower than those in traditional precooling. • The overall precooling effect is excellent when wind speed is 1.5–2.5 m/s. Aiming at the problems of low humidity and high dry consumption in the present forced-air precooling room, the combination of the ice slurry wet cooling system with the forced-air precooling was proposed, and a novel forced-air ice slurry wet precooling test platform was designed and built. The purpose of this paper is to experimentally study the effects of wind speeds on the performance of ice slurry wet precooling system by taking tomatoes as precooling objects, including precooling rate, precooling uniformity, precooling energy consumption and weight loss ratio of tomatoes. Also, the results are compared with those of other similar studies such as traditional forced-air precooling system. The results show that with the increase of wind speed, the precooling rate increases, the required precooling time is shortened, and the temperature variation coefficient of tomatoes decreases first and then increased, that is, the precooling uniformity becomes better and then worse. When the wind speed is 2.5 m/s, the overall precooling uniformity is the best. The precooling energy consumption decreases first and then increases, and is relatively low when the wind speed is between 1.5 m/s and 2.5 m/s (lowest at 2.5 m/s), which is lower than that of traditional forced-air system. With the increase of wind speed, the weight loss of tomatoes decreases first and then fluctuates slightly, and the weight loss ratio is about 0.1 %, which is much lower than that of tomatoes in the traditional forced-air precooling system. Overall, the maximum wind speed is not recommended to exceed 2.5 m/s for the precooling system studied in this work. The results can provide references for the further research and development of forced-air precooling technology. [ABSTRACT FROM AUTHOR]

Increasing energy prices and market volatilities force energy intensive industries to implement energy management systems in order to ensure competitiveness. In this paper, we focus on the strategic level of energy management, specifically, on the analysis of the internal and external conditions that form the basis for strategic development. For this, we selected the case of the Austrian paper and pulp industry. We applied a hybrid method by combining an analysis of strengths, weaknesses, opportunities and threats with an analytic hierarchy process which was based on a survey of expert opinion. The results show that cost-related factors predominate. According to our analysis, the four most important factors are all directly linked to energy costs, energy efficiency, and the energy market. Experts pay little attention to environmental issues or to energy market volatilities. Apart from that, the combination of an analysis of strengths, weaknesses, opportunities and threats with an analytic hierarchy process promises to be a valuable tool for strategic energy management. This is especially true for energy intensive companies and/or sectors, since it enables decision makers to take strategic decisions based on a systematic understanding of the main issues. [ABSTRACT FROM AUTHOR]

The development of large energy systems based on renewable energy sources is accompanied by an increase in the input capacities of large grid storages. Taking into account the vector for decarbonization and maneuverability, the use of hydrogen as a fuel in the cycle of a diabatic compressed air energy storage (CAES) is a promising scientific and technical direction. This paper analyzes the key performance indicators of a compressed air energy storage in the presence and absence of thermal energy recovery within the cycle. In addition, an assessment was made of the prospects for the use of a methane-hydrogen mixture in gas turbines. At the end of the paper, a calculation of the process of plasma pyrolysis of methane is given as one of the possible methods for the production of hydrogen for use in energy purposes. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cell (SOFC) is regarded as a promising energy conversion device because of its advantages such as high efficiency and fuel flexibility. With the advent of aviation electrification era, SOFC has been gradually studied as aviation power system. However, the high temperature operation and temperature gradient of SOFC bring challenges to practical application. Nowadays SOFC systems often use excessive air as coolant to reduce the temperature gradient of SOFC, which leads to the increases of the fuel consumption and reduction of the power generation efficiency. In order to maintain a lower temperature gradient with less air, a supercritical fuel cooled SOFC scheme is proposed in this paper. By establishing a one-dimensional model of conventional air-cooled fuel cell and fuel cell with fuel cooling channel. Through calculating the fuel cell temperature gradient under different working conditions, the results show that when the excess air coefficient (EAC) is 3, the temperature gradient of air-cooled SOFC reaches 22.7K/cm, while the temperature gradient of SOFC with fuel channel decreases to 8.35K/cm. Therefore, the SOFC with fuel channel can effectively reduce the use of air, reduce parasitic power consumption and improve the efficiency of the system while maintaining a lower temperature gradient. • A supercritical fuel cooled SOFC scheme is proposed in this paper. • When the excess air coefficient is 3, the temperature gradient of fuel cell with fuel channel decreases to 8.35K/cm. • The fuel cell system with fuel channel can effectively reduce the use of air. • The SOFC scheme of fuel cooling can improve the electrochemical performance of SOFC. [ABSTRACT FROM AUTHOR]

In the context of renewable energy systems, microgrids (MG) are a solution to enhance the reliability of power systems. In the last few years, there has been a growing use of energy storage systems (ESSs), such as hydrogen and battery storage systems, because of their environmentally-friendly nature as power converter devices. However, their short lifespan represents a major challenge to their commercialization on a large scale. To address this issue, the control strategy proposed in this paper includes cost functions that consider the degradation of both hydrogen devices and batteries. Moreover, the proposed controller uses scenarios to reflect the stochastic nature of renewable energy resources (RESs) and load demand. The objective of this paper is to integrate a stochastic model predictive control (SMPC) strategy for an economical/environmental MG coupled with hydrogen and battery ESSs, which interacts with the main grid and external consumers. The system's participation in the electricity market is also managed. Numerical analyses are conducted using RESs profiles, and spot prices of solar panels and wind farms in Abu Dhabi, UAE, to demonstrate the effectiveness of the proposed controller in the presence of uncertainties. Based on the results, the developed control has been proven to effectively manage the integrated system by meeting overall constraints and energy demands, while also reducing the operational cost of hydrogen devices and extending battery lifetime. • Implementation of an SMPC strategy based on a scenario-based approach. • Reduction of operation and maintenance costs and integration of uncertainties. • Minimization of the overall operational costs and maximization the profits. • Reduction of complexity and computational time. • Implementation of a unique control architecture to manage a microgrid in different modes. [ABSTRACT FROM AUTHOR]

Daytime subambient radiative cooling is a most promising alternative to electricity-free building cooling. However, optical performance degradation arising from surface contamination and inevitable parasitic heat gain still pose unprecedented challenges to cool building at subambient temperatures. This paper proposed a superhydrophobic cellulose aerogel cooler (SHB-CAC) as building envelope by integrating self-cleaning capacity, passive daytime radiative cooling and thermal insulation to reduce environmental heat gain. The SHB-CAC demonstrates high solar reflectance (93%) and long-wave infrared emittance (91%), accomplishing a temperature drop of 8.5 °C lower than the ambient under sunlight of 800 W/m2 in the outdoor experiment. Notably, the SHB-CAC possesses low thermal conductivity (28 mW/(m∙K)) that suppresses parasitic heat gain from warmer surrounding and reduces cooling energy consumption. The self-cleaning property resulting from superhydrophobicity protects SHB-CAC from water wetting and dust contamination but also maintains its good surface radiation capacities under different humidity environment. A building energy simulation was conducted and results showed that 43.4% of cooling energy on average could be saved compared to the building baseline consumption, if SHB-CAC was widely used in China, indicating that the strategy of optical and thermal conductivity management of cooler has the potential to reduce the energy consumption of buildings. [Display omitted] • Waste paper is converted into aerogel cooler for building cooling. • High R solar and ε IR , thermal insulation, and self-clean are achieved in one design. • The aerogel achieves a high sub-ambient temperature drop of ∼8.5 °C on daytime. • The aerogel shows that 43.4% of cooling energy could be saved. [ABSTRACT FROM AUTHOR]

Under the dual pressure of energy consumption and environmental pollution, mankind hopes to develop clean and renewable alternative energy, and the rapid development of fuel cells meets people's demand for energy-efficient power systems. The emergence of portable micro energy systems represented by microfluidic fuel cells, such as paper-based microfluidic fuel cells, has greatly enriched the means of medical detection to better cope with the threat of disease transmission. In this work, the numerical simulation method is innovatively introduced to study the paper-based microfluidic fuel cells. Both transient and steady-state modes are employed to demonstrate the whole operation process of the paper-based microfluidic fuel cell. In addition, the different structural parameters, including electrode spacing, the distance between electrode and inlet, channel thickness, and electrode length, are also investigated their influence mechanisms on cell performance. Results show that the increase of most structural parameters decreases cell output power in different degrees. Even on the premise that increasing channel thickness has a positive impact on the output power, the fuel utilization still shows a downward trend. These conclusions provide theoretical support and reference for future optimization work and accelerate the development of microfluidic fuel cells. • Numerical simulation is employed to study paper-based microfluidic fuel cell. • The effects of structure parameters on cell performance are discussed. • Through fuel concentration distribution to reveal cell performance mechanism. • Fuel utilization is used to evaluate energy efficiency. [ABSTRACT FROM AUTHOR]

To reduce energy use and achieve a low carbon production in pulp and paper industry (PPI), it is essential to improve energy efficiency in pulp and paper production. In this study, the energy savings from the PPI were estimated based on a techno-economic analysis by EAGER tool for PPI at the factory level. The structure and implement procedure were introduced initially. Two typical pulp and paper mills from China were determined to estimate the impact of selected energy efficiency technologies (EETs) on energy savings as the cases in the base year. One Factory (A) only produced paper products (i.e. corrugated paper and Kraft linerboard) while the other Factory (B) also produced market pulp besides sack paper. In totally 22 selected EETs were applied to assess their saving potential in Factory A, and 29 measures were applied in Factory B. The results show that 2290 TJ and 1179 TJ of final energy could be saved annually in Factory A and B, corresponding to reduction of 29.4% and 13.6% total energy consumption respectively for the case factories. The CO 2 reduction potential was 32.3% for Factory A compared with that of 16.6% in Factory B. It suggests that the pulp and paper mills should encouraged to use this method estimating energy saving potential, and improve their energy efficiency with suggested measures in order to reduce energy consumption and related carbon emissions further in the coming years. • Energy savings of pulp and paper production were estimated at the factory level. • A techno-economic evaluation tool was applied to access the energy savings and carbon emission reductions. • Two typical pulp and paper factories from China were investigated to estimate their energy savings in the base year. • It is useful to assess energy savings and select feasible EETs in achieving energy saving and emission reduction targets. [ABSTRACT FROM AUTHOR]

In an era of increasing energy demands and environmental concerns, optimizing energy consumption within buildings is crucial. Despite the vast improvements in HVAC and lighting systems, plug loads remain an under-studied area for enhancing building energy efficiency. This paper studies smart plug active operating mode detection, plug-level load forecasting, and plug scheduling methodologies. This research leverages a unique dataset from the University of California, San Diego, consisting of readings from over 150 smart plugs in several office buildings for more than a year, notably during the post-Covid era. This dataset is made publicly available. A comprehensive literature review on plug, i.e. , appliances operating mode detection is presented. Novel unsupervised learning approaches are applied to identify plug operating modes. A pipeline integrating the detected modes with forecasting and scheduling is developed, aiming at building energy consumption reduction. Our findings offer valuable insights and promising results into smart plug management for energy-efficient buildings. • A novel year-long dataset of power readings from 169 office smart plugs is introduced. • The first review of plug load mode detection methods and terminology is presented. • The paper proposes an unsupervised method to identify plugs load operating modes. • The proposed smart plug scheduling pipeline reduces energy consumption by 20%. [ABSTRACT FROM AUTHOR]

Nanomaterials may have a key role since they can be applied in several vehicle components (such as H 2 storage, vehicle structure, batteries), but there is the concern that some nanomaterials may lead to relevant environmental impacts. This paper addresses a revision of the environmental impacts of different types of nanomaterials applied to alternative vehicles in order to reduce energy use (and consequently the global greenhouse gases emissions). A literature review is performed in order to analyze the recent improvements in nanomaterials applied to alternative vehicles. This revision will be based on life cycle assessment and risk analysis. [ABSTRACT FROM AUTHOR]

• A printed Zn-air/Ag hybrid paper battery with switchable working modes is developed. • In Zn-air mode, OCV of 1.5 V and peak power density of 17.8 mW cm−2 are obtained. • In Zn-Ag mode, a high energy efficiency of 95.2% is achieved with 400 stable cycles. • This hybrid battery can switch its working modes smoothly without performance loss. • The battery flexibility is proved to be high in both working modes by bending test. Paper-based battery is a low-cost, lightweight, flexible and environmentally-friendly technology for small-power and flexible electronics, which can be conveniently fabricated by printing. In this work, we propose an innovative paper-based hybrid battery using Zn foil as anode and Ag grid-supported oxygen catalyst as cathode. Benefited from its composite cathode, this hybrid battery can work in both primary Zn-air mode and secondary Zn-Ag mode in different mission profiles. When working as a primary battery, the Zn anode is oxidized and the ambient air is reduced by the oxygen catalyst inside cathode, producing an OCV of 1.5 V and a peak power density of 17.8 mW cm−2. When working as a secondary battery, the Zn anode is reduced and oxidized periodically while the Ag grid inside cathode is oxidized and reduced accordingly. The charge and discharge voltage plateaus are closely around 1.6 V, leading to an excellent energy efficiency of 95.2%. Moreover, this hybrid battery can switch its working modes smoothly without performance loss, and the battery flexibility is proved to be high in both working modes. In summary, this paper-based Zn-air/Ag hybrid battery is especially suitable for powering flexible electronics in both long-term discharge missions and multi-cycle rechargeable tasks. [ABSTRACT FROM AUTHOR]

Power generation by variable renewable energy (VRE) is expected to expand for decarbonization, although it is difficult to ensure stabilization of the energy demand due to fluctuations in the power output from VRE. To accelerate VRE implementation, wind-powered thermal energy systems (WT th -ES), which can provide dispatchable power using wind–thermal energy converter (WEC th) and thermal energy storage (TES), have been proposed. In this study, we are tackling the installation of VRE, i.e., wind energy, by TES with WEC th compared with wind turbine (WT p) in paper mills to demonstrate the applicability of TES in an industrial sector. Conventional and alternative energy systems in paper mills with TES were mathematically modeled and simulated to analyze the transmittable power output and the greenhouse gas (GHG) emissions by life cycle assessment. With the installation of TES and wind energy, transmittable power could be increased with GHG emissions reduction. However, their excess installation or unbalanced combination resulted in an increase in GHG emissions and a decrease in transmittable power. By comparing the cases, the combination of paper mill, TES, and WEC th could convert thermal energy efficiently and mitigate fossil fuel consumption for multiple production of paper and power from the paper mill. • A wind-thermal energy converter (WEC th) and a wind turbine (WT p) were compared. • Energy flows and GHG emissions of paper mills with TES and wind were simulated. • Paper mills reduced GHG of power generation less than fossil fuel-fired power plants. • Excess TES reduces dispatchable power generation and increases GHG emissions. • Paper mills with WEC th s and TES have the potential to be regional energy suppliers. [ABSTRACT FROM AUTHOR]

Among all public buildings, on account of their educational purpose, school buildings have a major social responsibility. Therefore energy performance in this type of building is of great importance. The overall purpose of this research is to achieve a functional benchmarking, based on the real operation conditions of school buildings, by the exploitation of the results made public, through an intensive literature survey on energy consumptions in schools. The survey was made to gather data that is relative to energy consumption in school buildings, documented in the most diverse fields and units: global energy consumption values, electrical energy consumption; fuel consumption for heating, energy data consumption of schools expressed in annual cost per unit of heated/cooled surface area ($/m 2 ) or per unit of heated/cooled volume ($/m 3 ) or, finally, as the annual cost per student ($/student). The literature was analyzed to determine if a worldwide comparison among the published data could be established. The results suggest that when attempting to determine an energy benchmark some considerations should not be forgotten: standard indoor environmental conditions (IEC) for classrooms (set-point for indoor operative temperature of 20 °C in winter and 26 °C in summer as suggested in EN 15251:2007), electrical and heating consumption values should be kept separately, different education levels usually require different energy consumption values. A good way to normalize heating energy consumption is going through a climatic adjustment based on Heating Degree Days (HDD). For an impartial data comparison, based either on an operating rating or on a simulation carried out for reference conditions, benchmark reference values should be expressed in terms of billed energy data. [ABSTRACT FROM AUTHOR]

A new numerical procedure is presented to enable a hydrogen-fuelled two-stroke resonating free-piston generator target ideal Otto cycles to provide tracking paths for feedback control to maximise efficiency. Piston trajectories and design parameters are obtained for specified power, compression-ratio, and air-fuel-ratio. These parameters include scavenge port locations, heat release position, equivalent bottom-dead-centre position, and an electrical machine constant which is generally power-switched to take two values within a cycle. The main objectives of the paper are to develop the numerical procedure, and to demonstrate its use in finding a generator with maximum efficiency, and a generator with a single electrical machine constant, avoiding in-cycle power switching. To develop the procedure, a multi-physics generator model provides kinematics to an energy equation, culminating in a novel two-stage procedure. Stage-1 involves iteration and minimisation; Stage-2 just involves minimisation. Testing by simulation involves a 14-kW generator case study with compression ratio of 9, lean air-fuel equivalence ratio of 0.4, plus friction and electrical machine losses. An overall maximum generator efficiency of 54.9% is obtained using the procedure, compared to 51.3% without power switching. Computationally, the two-stage procedure proves highly efficient, typically taking around 11 min in total to complete on a desktop computer. The novelty of the procedure is its ability to optimally design and operate a hydrogen-fuelled resonating free-piston generator to meet a target specification, thereby offering a potentially inexpensive way to decarbonize transport, particularly in heavy duty applications. • Resonating free-piston generator is ideal energy converter for use with hydrogen. • New two-stage procedure able to target maximum efficiency. • Key cylinder positions and electrical machine constant easily found. • Planned Otto trajectories provide ideal two-stroke tracking paths. • New procedure tested on 14-kW generator maximises efficiency to 55%. [ABSTRACT FROM AUTHOR]

• A life cycle assessment (LCA) of solid recovered fuel (SRF) was conducted. • SRF production process contributes to about 35.6 kg CO 2 -eq per ton. • A maximum of −1752.03 kg CO 2 -eq was obtained with about 80 % of SRF biogenic carbon. • A footprint of −542.09 to −1729.05 kg CO 2 -eq can be found due to coke substitution. • The study recommended SRF production to mitigate the global carbon footprint. Solid recovered fuel (SRF) from non-recyclable waste obtained from source separation and mechanical treatments can replace carbon coke in cement plants, contributing to the carbon neutrality. A life cycle assessment (LCA) of the SRF production from non-recyclable and selected waste was conducted in an Italian mechanical treatment plant to estimate the potential environmental impacts per ton of SRF produced. The analysis would contribute to evaluate the benefits that can be obtained due to coke substitution in best- and worst-case scenarios. The avoided impacts achieved were assessed, together with an evaluation of the variables that can affect the environmental benefits: SRF biogenic carbon content (in percentage of paper and cardboard); transportation distances travelled from the treatment plant to the cement kiln; the renewable energy used in the mechanical facility. On average, about 35.6 kgCO 2 -eq are generated by the SRF transportation and production phase. These impacts are greatly compensated by coke substitution, obtaining a net value of about −1.1 tCO 2 -eq avoided per ton of SRF. On balance, the global warming potential due to SRF production and consumption ranges from about −542 kgCO 2 -eq to about −1729 kgCO 2 -eq. The research recommended the use of SRF to substitute coke in cement kilns also in low densely-populated areas to mitigate environmental impacts and achieve carbon neutrality at a global level. [ABSTRACT FROM AUTHOR]

This paper presents a novel off-grid hybrid renewable energy system integrated with hydrogen production and retired electric vehicle (EV) batteries for combined power and heat supply to a small rural community. The system consists of photovoltaic (PV) panels, evacuated tube solar collectors, a proton exchange membrane fuel cell (PEMFC), an alkaline electrolyzer, compressed hydrogen storage tanks, and reused lithium-ion batteries from EVs. A new battery model is developed in the Transient System Simulation Program (TRNSYS) to capture the capacity degradation of retired batteries. A two-stage energy management strategy is proposed to regulate power flow and maximize solar energy utilization. The system is optimized for minimum power supply disruption, hot water supply disruption, energy waste, and annualized costs over a 20-year lifetime using a multi-objective NSGA-II algorithm coupling MATLAB and TRNSYS. Optimization results reveal tradeoffs between the competing objectives. Dynamic simulations show the water tank temperature fluctuates between 20 and 100 °C with mean values dropping slightly in later years due to battery degradation. Energy waste from components rises in later years for the same reason. The replacement interval for a retired EV battery module is around 2.5 years. The integrated system proves feasible for off-grid combined power and heat supply using solar energy and retired EV batteries as storage, though battery degradation impacts long-term performance. • Integrates solar, hydrogen, retired EV battery for off-grid power and heat supply with optimized storage and backup. • Utilizes multi-objective optimization to balance system reliability, waste minimization, and costs through Pareto solutions. • Implements long-term performance over twenty years to provide insights into component lifetimes and replacement needs. [ABSTRACT FROM AUTHOR]

The design and optimization of the flow field structure significantly impact the performance of the proton exchange membrane electrolyzer. However, the pumping power should be added to the flow field selection criteria system in the flow field evaluation criteria of the electrolyzer. This paper first establishes and experimentally verifies a three-dimensional, two-phase, steady-state, non-isothermal proton exchange membrane electrolyzer model. Secondly, a new type of combined flow field structure is proposed by combining the cross-finger flow field, serpentine flow field, and cross-flow field and compared with the traditional flow field in many aspects. Finally, an evaluation index (current density-pressure ratio) considering pumping power is proposed. The results show that the current density of the combined flow field is 7.6% higher than that of the serpentine flow field, 13.0% higher than that of the cross-finger flow field, 13.7% higher than that of the double-serpentine flow field, and 29.4% higher than that of the parallel flow field when the voltage is 2.0 V. The combined flow field has the optimal performance, increasing the reaction rate and improving the gas discharge efficiency. In addition, the combined flow field has the best current density-pressure ratio. This means the combined flow field has lower energy consumption than the conventional one under the same performance conditions. The study's results can provide a new research idea and theoretical basis for developing a new type of flow field in a proton exchange membrane electrolyzer and provide simulation and experimental support for developing a high-performance flow field. • Modeling PEMEC and verifying it experimentally. • Proposing a new combined flow field structure. • Removal of air bubbles by forced convection. • Proposing a PEMEC evaluation index considering pumping power. [ABSTRACT FROM AUTHOR]

• To improve data center performance, it must be efficiently cooled. • This paper undertakes a detailed examination of the most recent cooling optimization techniques. • Several methods are discussed like regular air conditioning, free cooling, and liquid cooling. • An assessment of overhead and underfloor air delivery technologies is presented. • The effects of baffles, variable airflow control, and server placement are investigated. In order to increase data centers' efficiency and performance, a proper cooling system should be applied. This article provides a comprehensive assessment which explores current cooling optimization technologies for data centers. Standard traditional technologies like air conditioning, free cooling, and liquid cooling are investigated. Their limitations as well as proposed improvements are thoroughly discussed. The article also delves into underfloor and overhead air supply technologies, presenting their advantages and drawbacks. The review introduces novel approaches at the rack level cooling, including baffles, variable airflow management, and optimal server placement. Key findings stress the efficacy of optimized airflow systems and innovative rack-level cooling, underlining their role in reducing energy consumption and enhancing overall performance. Notably, potential energy savings of up to 67.2 % compared to traditional methods are demonstrated. The adoption of advanced cooling technologies, such as direct and indirect natural cooling, liquid-cooling cold plates, submersion, heat pipe, and thermosiphon-based cooling, exhibits promising energy efficiency gains and reduced Power Usage Effectiveness (PUE) values. Research into content-specific efficiency enhancements, adaptable energy-saving tactics, and all-encompassing server power consumption models is necessary. To work toward future sustainable, energy-efficient data centers, researchers should investigate how CRACs and server fans interact, find ways to integrate thermal and power management, and how artificial intelligence can be used to cool servers in an eco-friendly way. [ABSTRACT FROM AUTHOR]

• Advantage of hot water cooling was proven by entropy and entranspy theory. • Thermodynamic model of a waste heat recovery-free cooling data center was established. • Heat transfer efficiency of waste heat recovery-free cooling data centers was proven by entranspy theory. • Performance indicators of waste heat recovery-free cooling data center was predicted. This study investigated the potential of integrating separate heat pipe and adsorption refrigeration systems as a data center efficient cooling system. Compared to water-cooled data centers, this approach demonstrates improved heat transfer efficiency and reduced energy consumption. The effectiveness of heat transfer in this approach is illustrated by applying exergy and entranspy theories. By conducting numerical simulations across five representative Chinese cities with different climates, both Power Usage Effectiveness (PUE) and key cooling system performance indicators are assessed. The analysis reveals that all cities can achieve a PUE below 1.095, realized a 65.87 % and 13.60 % reduction in cooling system energy consumption and entransy dissipation, respectively. Data centers using mechanical chiller cooling cause a high energy consumption. This paper indicates the benefits of integrating heat pipe and adsorption refrigeration systems in reducing energy consumption and optimizing overall data center performance. [ABSTRACT FROM AUTHOR]

Decentralized offshore wind power to hydrogen production is one of the potential solutions for wind energy utilization in deep sea area, of which the electrolysis is integrated with the wind turbine, so that how to gather and transport the produced hydrogen from the decentralized wind turbines to the processing terminals becomes very crucial. This paper focuses on this topic and proposes a mixed-integer linear programming model to optimize the layout of the "ship+pipe" transmission system, aiming at minimizing the average annual total cost. Through the model, the locations and sizes of hydrogen gathering platforms, their allocations with wind turbines, the shipping routes could all be figured out. Two aspects of contributions are made in this work. First, the concept of "Pipe + Ship" transmission mode is proposed, providing a feasible solution for offshore hydrogen transportation with long distance; Second, the proposed model integrates subsea pipe network and the sea level shipping route as a whole system, revealing their interactions. Case studies present the model's validity and feasibility as well as providing inspirations about the investment management. [Display omitted] • Hydrogen transmission for decentralized offshore wind power-hydrogen is studied. • Layout optimization model for the "Pipe + Ship" transmission mode is proposed. • Interaction between pipe network and shipping routes are revealed. • Results of case studies indicate the characteristic of each cost components. • The study provides inspirations about the investment management. [ABSTRACT FROM AUTHOR]

This paper aims to study the feasibility of municipal sewage sludge utilization as an energy source in a polygeneration system. This system offers distinctive benefits such as contribution to the principled removal of sewage sludge, simultaneous utilization of raw and digested sludge in different parts of the system, and production of renewable hydrogen from bio-waste. 4E (energy, exergy, exergoeconomic, and environmental) analyses, are performed to understand the system performance comprehensively. Then, parametric studies are examined the impact of changing the values of main parameters on the system operation. Afterward, a multi-objective optimization based on a genetic algorithm is carried out to achieve optimal values, considering a trade-off between the exergy efficiency and the total cost rate. Meanwhile, this work harnesses the potential of artificial neural networks to expedite complex and time-consuming optimization processes. According to the results, the gasifier exhibits the highest rate of exergy destruction, and the primary cost of consumption is attributed to its heat supply. The multi-objective optimization findings show that the optimum point has an exergy efficiency of 38.26 % and a total cost rate of 58.17 M$/year. The hydrogen production rate, energy efficiency, and net power generation rate for the optimal case are determined as 1692 kg/h, 35.24 %, and 4269 kW, respectively. Also, the unit cost of hydrogen in the optimal case is obtained 1.49 $/kg which offers a cost-effective solution for hydrogen production. [Display omitted] • 4E analysis and optimization performed on a bio-waste driven polygeneration system. • Plant optimized using artificial neural network and multi-objective genetic algorithm. • The feasibility of integrating a membrane for hydrogen separation investigated. • The optimum exergy efficiency and total cost rate obtained 38.26 % and 58.17 M$/year. • Hydrogen and electricity cost of 1.49 $/kg and 0.0145 $/kWh achieved for optimal case. [ABSTRACT FROM AUTHOR]

Improving the energy efficiency of a vehicle fleet is a complex task that can be identified as having multiple variables and nonlinear feedback loops influenced by different mobility, socio-economical, and environmental factors. Due to the prevailing concerns on the fuel economy and vehicular emissions, formulating a clear policy for electric and other alternative mobility forms requires a clear decision support tool to adequately consider the complexities involved. This paper presents a novel System Dynamics (SD) approach based on the cause-and-effect analysis and feedback loop structures as a suitable tool. The proposed SD model comprises four sub-models: socio-economic, new vehicle registrations, environmental influence, and fuel economy and e-mobility policy measures. The study presents the analysis of historical data and results from the impact analysis of fuel economy policies in Sri Lanka, including the introduction of electric mobility. The authors leveraged the Vensim SD software package for modelling, expert-in-the-loop sensitivity analysis and optimization. Three strategic fuel economy and e-mobility policy intervention scenarios have been developed to estimate the forecasted fuel economy for Four-Wheeled Passenger Vehicles (FWPVs) as per strategic interventions to change the fuel type of new vehicles registered. It is shown that hybrid and electric FWPVs can improve fuel economy by between 13 and 39% by 2030. • A System Dynamics approach is proposed to model the energy efficiency of Four-Wheeled Passenger Vehicles' registrations. • Four sub-models are developed to report the impacts of fuel economy and e-mobility policies. • Three policy scenarios have been formulated to test the application of a target of reaching 50% of the conventional fuel registrations. • The effective change of fuel economy improvement under three scenarios vary between 13 to 39%. [ABSTRACT FROM AUTHOR]

The transition to increasingly renewable electricity grids and the electrification of industrial processes are two recent developments promising to be potential solutions towards net zero in industrial production processes. Generally, grid electricity is perceived as a stable and reliable resource that can be accessed on demand. However, that is not always the case for large industrial users (100 MW+), and a key future challenge that must be overcome is the inherent uncertainty of the electricity supply by renewable sources, as well as in pricing. In methanol production, the concept of using electrolysis and CO2 capture is being explored as a way of replacing reforming to produce syngas for "green" methanol production. With the omission of the reforming process which supplies energy as steam for the process, there is now a need to electrify the affected downstream unit operations. Distillation is a key unit operation in chemical operations that consumes large amounts of energy for reboiler duty and holds the key to making on-specification AA-grade methanol, a precursor chemical. With the volatility of the electricity market, hence supply, these columns must be able to withstand a sudden large reboiler duty drop. This paper developed a novel process operations and control principle to allow for the flexible operation of a high-purity methanol distillation column in volatile energy markets. At its core is the concept of using a distillation column as a "process battery". Results obtained from a validated process simulation show that the novel "process battery" operations principle can withstand a supply-side change as great as 75% within a time span of 5 min without breaking complex quality and performance specifications of the column. This control philosophy is a major departure from the traditional process control and operating regimes that are focused on maintaining steady operations under all conditions. • Novel control philosophy developed for flexible operation of high-purity methanol distillation in volatile energy markets. • A major change from traditional operations and control focused on maintaining steady operations under all conditions. • The concept of using a distillation column as a "process battery" is defined. • Validated process simulation results show the strategy withstands large supply-side changes without breaking specifications. [ABSTRACT FROM AUTHOR]

Energy efficiency can help facing the climate crises. Yet the energy intensity has decreased more slowly than required to achieve climate goals. Based on this premise, we build an agent-based model to study the effects of different energy efficiency policies. Policies analysed range from indirect policies – taxes, incentives, and subsidies – to direct technological policies, where a public research laboratory invests in R&D to establish a new technological energy efficiency paradigm. Results reveal that, although most of the policies effectively reduce energy intensity, the research lab is the most efficient in promoting energy efficiency without negative impacts on macroeconomic and public finance conditions. However, the success of this policy requires a long-term commitment, highlighting the importance of complementing this strategy with more "ready to use" measures. The findings also indicate that most policies do not induce significant macroeconomic rebound effects. Concerns about macroeconomic rebound effects may likely be overstated. • Improvements in energy efficiency help face the ongoing climate and energy crises. • Yet, energy intensity has declined more slowly than needed to meet climate goals. • The paper builds an agent-based model to study different energy efficiency policies. • Indirect policies work but are outperformed by direct technological policies. • The macroeconomic rebound effect induced by most of the policies is rather small. [ABSTRACT FROM AUTHOR]

This paper investigates the position and attitude (pose) tracking control of a rigid body with uncertain mass and inertia. By virtue of the dual quaternion description, a six-degree-of-freedom (6-DOF) relative motion model is established in an integrated and compact way. Then an adaptive pose tracking controller is proposed based on the immersion and invariance (I&I) theory, where the key integrability obstacle is overcome by the dynamic scaling technique. Compared with the existing filter system-based method that constructs a filter system to circumvent the integrability obstacle, the dynamic scaling-based method is directly designed based on the original system, which is capable of retaining all benefits of the I&I design with much lower dimension dynamic extensions. Comparisons with the filter system-based I&I method and the classical certainty equivalent method are first carried out from the theoretical analyses, which elucidate benefits of the proposed method in lower control demands. Then the comparative simulations are conducted to verify the features and effectiveness of the proposed dynamic scaling-based I&I adaptive control scheme. • In the framework of dual quaternions, a six-degree-of-freedom adaptive pose tracking controller is proposed based on the immersion and invariance. • Substantial dimension reduction and structure simplification are achieved by using the dynamic scaling technique. • Ideal closed-loop performances are guaranteed to be recovered by the proposed adaptive controller. • Control demands and energy consumptions are barely affected by the adaptive gain and can always be kept close to those in the ideal case. • Thorough theoretical analyses are presented to elucidate the benefits of the proposed adaptive controller. [ABSTRACT FROM AUTHOR]

Separate sensible and latent cooling (SSLC) is a promising technology for enhancing the energy efficiency of space cooling systems. In this paper, we propose an SSLC configuration consisting of an indirect evaporative cooling (IEC) device and vapor compression cycle (VCC) for handling space sensible load, and a desiccant wheel for handling space latent load. The performance of the proposed configuration is investigated using physics-based or empirical models for each component. A year-round simulation study of the proposed SSLC system is performed for 12 different cities with diverse climatic conditions. This study considers electrical, thermal, or solar energy for desiccant wheel regeneration. Parameters governing the system performance such as the air flowrate ratio in the IEC and the DW, DW regeneration air temperature, and supply temperature are studied. The proposed SSLC configuration is superior to the conventional system in all cities. The enhancement of seasonal coefficient of performance (sCOP) ranges between 50 and 261 %, 67 and 387 %, and 60 and 2072 % with yearly electrical energy savings of 33 and 72 %, 40 and 79 %, and 38 and 95 % for electrical, thermal, and solar energy for regeneration of DW, respectively. [ABSTRACT FROM AUTHOR]

The rapid, safe, and adequate refueling for hydrogen-based fuel cell vehicles relies on deep pre-cooling on the station side, which brings significant energy consumption. Step cooling is an ideal solution for the occasion with a large temperature drop. In this paper, a novel pre-cooling system is proposed by incorporating two-temperature evaporation to realize step cooling in the hydrogen refueling station. The pre-cooling load, system performance, and energy-saving potential are investigated under variable storage configurations and working conditions. The results show that the integral pre-cooling load increases linearly with the ambient temperature. However, the load share and the system performance are affected by the hydrogen intermediate temperature, the optimal value of which exhibits a nearly linear relationship with the ambient temperature. The novel system can save up to 30.2 % electricity relative to the conventional system with a single evaporator. [ABSTRACT FROM AUTHOR]

Improving energy efficiency is regarded as a key path to tackling global warming and achieving the Sustainable Development Goals (SDGs). In 2020, the energy consumption of the world's ten major energy-consuming countries accounted for 66.8% of the global total. This paper applied data envelopment analysis (DEA) to calculate these ten major energy-consuming countries' total-factor energy efficiency (TFEE) at national and sectoral levels from 2001-2020, and explored the influencing factors of total-factor energy efficiency with the Tobit regression model. The results showed significant difference in the ten countries' energy efficiency. The United States and Germany topped the list for total-factor energy efficiency, while China and India were at the bottom. Meanwhile, the energy efficiency of the industrial subsector has increased significantly over the past two decades, while that of the other subsectors has been relatively flat. The industrial structure upgrading, per capita GDP, energy consumption structure, and foreign direct investment had significant impacts on energy efficiency with national heterogeneity. Energy consumption structure and GDP per capita were determinative factors of energy efficiency. [ABSTRACT FROM AUTHOR]

Improving the commercial fuel cell system efficiency is critical to reducing hydrogen consumption and improving the operational economy. This paper studies the power consumption pattern of the air supply subsystem, the most power-consuming auxiliary components, aiming to improve the system's efficiency. A method was proposed to get the extremum of the system net power by optimizing the oxygen excess ratio and cathode pressure. Mathematical models describing the fuel cell stack and air supply subsystem power characteristics were developed based on the mechanism analysis and estimation of unknown parameters. Then, a system net power model for energy efficiency optimization was developed. The operating conditions for optimal efficiency at a specific current density can be obtained by numerical calculation. To verify the method's effectiveness, a series of experiments were conducted, and the results show that the proposed method can maximize system net power output at various current density conditions. Compared with the conventional oxygen excess rate based one-dimensional optimization, the two-dimensional method can improve system efficiency by 2.06%, offering a good application prospect. • A mathematical model describing the fuel cell stack and air supply subsystem power characteristics was developed. • An energy efficiency optimization method based on the oxygen excess ratio and cathode pressure is proposed. • The operating conditions for optimal efficiency can be obtained by numerical calculation. • Maximum efficiency improvement of 2.06% can be achieved compared with One-dimensional optimization. [ABSTRACT FROM AUTHOR]

The hydrogen isotopes are vital due to their significant applications in scientific research, biomedicine and potential application in fusion energy. D-T fusion, in particular, holds the promise solving human fossil energy reliance and the resulting environmental pollution. Methods including cryogenic distillation and Girdler Sulfide process etc. have been developed to satisfy the demand towards pure D 2 and T 2 but generally suffer high energy consumption and low separation efficiency. Furthermore, emerging methods such as laser catalysis and quantum sieving have been demonstrated but suffers harsh separation conditions, low separation volumes and material life etc. Thermal cycling absorption process (TCAP) delivers seductive aspects regarding hydrogen isotope separation for efficiency and throughput, small footprint and high automation level. Herein, firstly, the advantages and disadvantages of various separation methods are briefly elucidated and provides the necessities for developing new separation methods. Then the preferred TCAP strategy is outlined in detail, containing working mechanisms and optimization process. Finally, the history and outlook of TCAP are listed. We hope this paper would spark some inspirations for further TCAP development towards hydrogen isotope separation. [Display omitted] • The necessity of hydrogen isotope separation was explained. • The pros and cons of the current separation methods were summarized. • The principles, working modes, and optimization of TCAP were summarized. • The future prospects of TCAP were proposed. [ABSTRACT FROM AUTHOR]

In this paper, a novel ammonia-hydrogen-electricity cogeneration system is developed. To mitigate the cost associated with hydrogen storage and transportation in later stages, the proposal is to utilize high-temperature ammonia production instead of conventional hydrogen production. A comparative analysis between ammonia and transportation for hydrogen is conducted to assess cost efficiencies. To improve the system efficiency, a supercritical CO 2 Brayton cycle is applied as the power generation cycle. This choice exhibits superior parameter compatibility with the system compared to the Rankine cycle. The study scrutinizes the impacts of different energy utilization sequences and varying process parameters of the power generation cycle on the system's performance to ascertain the most optimal configuration. The results indicate that the Brayton cycle is more suitable for integration with the nuclear-IS thermochemical hydrogen production system, significantly enhancing the power generation capacity of the ammonia-hydrogen-electricity cogeneration system. These improvements result in 18.8 % increase in power generation efficiency and a 9.3 % boost in overall energy efficiency of the system. Subsequent to this enhancement, the system attains an impressive energy efficiency of 47.0 % along with a system exergy efficiency of 63.4 %. This study introduces an innovative approach for optimizing and enhancing the energy efficiency of a cogeneration system by employing nuclear energy as a high-temperature heat source for hydrogen (ammonia) production. • A novel ammonia-hydrogen-electric cogeneration system is developed. • The system bolsters efficiency by 9.3 % through a synergistic Brayton cycle coupling. • Conducted an assessment and comparison of the transportation and storage expenses associated with hydrogen and ammonia. [ABSTRACT FROM AUTHOR]

The energy consumption of conventional 70-MPa hydrogen refueling stations (HRS) with liquid hydrogen (LH 2) pumps remains at a high level due to the low efficiency of LH 2 pumps working at extremely high pressures, up to nearly 90 MPa. This paper presents a novel HRS with significantly lower energy consumption, based on a step-by-step compression strategy enabled by a highly-efficient 50-MPa LH 2 pump for low-pressure compression and a subsequent thermal compression module for high-pressure compression driven by thermal energy. The performance of the cryogenic pressure vessels in the HRS process is analyzed via a numerical model, and then several improvements to the HRS process are proposed for large-scale refueling requirements. Finally, the techno-economic performance of the HRS is compared with the conventional HRSs and the HRS with pure thermal compression. Compared to the conventional HRSs with 90-MPa LH 2 pumps, the capital cost of the proposed 400-kg/day HRS is reduced to $1.52M from $1.80M, while its energy consumption is reduced to 0.3 kWh/kg H2 from 1.3 kWh/kg H2. This work provides a new solution for low-energy-consumption hydrogen refueling which would be beneficial for reducing the overall cost of the hydrogen supply chain. [Display omitted] • A novel hydrogen refueling station with pump and thermal compression is proposed. • The reliability of this HRS is higher in the high-temperature environment. • A pump can supply more refueling units to increase the capacity of the HRS. • Capital cost of the HRS is $1.52 M, which is much lower than conventional HRS. • Power consumption of the HRS with 50-MPa pump is only 0.3 kWh/kg of hydrogen. [ABSTRACT FROM AUTHOR]

Neural Networks (NNs) can be used for energy management of hybrid vehicles, but they are hard to tune in inference to adapt to different driving conditions. To make the NN-based energy management strategy more flexible, this paper proposes a controllable NN for optimal energy management of fuel cell hybrid electric vehicles. Inspired by the equivalent factor in the Equivalent Consumption Minimization Strategy (ECMS), we introduce an adjustable target variable for the final state as an input to the NN-based strategy. During training, classification and regression networks with single-step and multi-step inputs are considered. An efficient shooting method and an adaptive method are then introduced to realize the precise control of the final state and online parameter adaptation. Simulations of the proposed method and the benchmarking method are carried out in different battery discharge modes. Results demonstrate that the proposed shooting neural classifier can achieve 99.7% fuel optimality of dynamic programming in a similar computational time to the shooting ECMS, and the proposed adaptive neural classifier can adapt to different driving conditions and has better fuel economy than the adaptive ECMS. • A controllable neural model for energy management of fuel cell vehicles is proposed. • Neural regressors and classifiers are trained under single-step and multi-step inputs. • A shooting method and an adaptive method for neural models are proposed. • The proposed method is comprehensively analyzed and compared with benchmarks. [ABSTRACT FROM AUTHOR]

This paper examines the complex relationship between the role of H 2 , carbon emissions and their impact on global warming and the economy. Despite improvements in energy efficiency, fossil fuel consumption continues to increase. CO 2 from industrial activities at high temperatures, such as cement, iron, steel and glass production, have increased rapidly, resulting in an increase in the concentration of greenhouse gases in the atmosphere. These emissions accelerate climate change, leading to dangerous consequences such as increasing average atmospheric temperature and decreasing agricultural productivity. To combat this, it is advocated to reduce CO 2 emissions by using renewable energy sources such as hydroelectricity, biomass, wind solar energy. Current study also discusses carbon reduction methods, including oxy-fuel combustion capture, pre-combustion capture, and post-combustion capture. Despite their unique advantages and disadvantages, these methods play an important role in reducing CO 2 emissions from power plants. Additionally, the article highlights the importance of H 2 as a cornerstone in the development of synthetic fuels and future energy systems. H 2 from renewable sources holds the potential to use carbon-neutral synthetic liquid fuels and revolutionize transportation. Although traditional H 2 production methods are associated with emissions, sustainable H 2 production techniques can facilitate low-carbon fuel production. The article concludes by highlighting the importance of sustainable energy practices and the role of H 2 in reducing carbon emissions, highlighting research efforts to improve production methods, integrate renewable energy, and develop carbon capture technologies for a sustainable future. • Methods used in synthetic fuel production and sources of hydrogen production. • Carbon capture methods and their comparative discussion. • The importance of hydrogen production in synthetic fuel production and future plan. [ABSTRACT FROM AUTHOR]

The present paper briefly elaborates upon the combination of waste palm and waste sunflower oil methyl ester as post-mixed biodiesel blends being injected into a four-stroke compression ignition engine, which is also fueled with inducted bamboo leaf generated producer gas (BLP.gas) that includes gaseous components of CO (carbon monoxide), H 2 (hydrogen), CH 4 (methane), and C x H y (hydrocarbons). The objective of the present research is to evaluate the overall performance, emission, and combustion behavior of a Kirloskar TAF1 modified dual-fuel diesel engine fueled with induced bamboo leaf-derived gaseous fuel at a fixed mass flow rate of 21.69 kg/h and injected mixed biodiesel-diesel blends. Initially, diesel fuel and post-mixed methyl ester were examined in dual-fuel mode with a fixed gas flow rate for different loads. It can be seen from the analysis that brake thermal efficiency got reduced by 4.66% and brake-specific fuel consumption increased by 5.26% for PMOME20 (20% post-mixed oil methyl ester + 80% diesel fuel) + BLP. gas with respect to diesel fuel at extreme loading conditions. Moreover, smoke opacity, carbon monoxide, and unburnt hydrocarbons were reduced by 11.22%, 20.44%, and 10.36%, respectively. On the other hand, oxides of nitrogen were reduced by 19.17% at maximum load for PMOME20 + BLP. gas in dual-fuel operation in contrast to that of petroleum diesel. In light of this, the current research concluded that the use of biodiesel and BLP. gas for dual-operative engines may be regarded as an appropriate option for reducing pollutant environment and petroleum fuel scarcity. • Influence of mixed biodiesel blends with induced bamboo leaf gaseous fuel were investigated. • NOx and smoke opacity showed trade-off curve of 19.11% and 11.22% lower emission for PMOME20+BLP.gas than diesel. • CO 2 emission for PMOME20+BLP.gas was 38.77% higher than diesel at peak load. • PMOME20+BLP.gas at peak load increased In-CP by 6.15% in contrast to diesel. • HRR and ID for PMOME20+BLP.gas decreased by 72.29% and 9.06% in contrast to diesel. [ABSTRACT FROM AUTHOR]

• MSW gasification by hot recycling BFG is proposed to prepare syngas. • The energy efficiency of the proposed process is as high as 81.29 %. • The investigated influencing factors have coupled effect on syngas formation. • 25.95 vol% H 2 and 37.20 vol% CO are achieved for the proposed process. Waste-to-energy is one of the most effective methods to save energy and reduce carbon emissions. This paper proposes a novel process of municipal solid waste (MSW) gasification by hot recycling blast furnace gas (BFG) coupled with in-situ decarburization to prepare blast furnace injection of hydrogen-rich gas. MSW gasification by the hot BFG is conducted by using Aspen Plus software coupled with equilibrium model or kinetic model. Compared to the equilibrium model, kinetic simulation results exhibit good agreement with the experimental results. Moreover, the technological analysis is also performed to investigate the coupled effects of gasification temperature, MSW/BFG ratio, and steam/MSW ratio on the H 2 -rich syngas generated from MSW gasification. The results reveal that all the investigated influencing factors have been found with a significant effect on the H 2 -rich syngas formation. The 25.95 vol% of H 2 and 37.20 vol% of CO during MSW gasification by the hot BFG are achieved at a gasification temperature of 900 °C, steam/MSW ratio of 0.46 kg/kg, and MSW/BFG ratio of 0.34 kg/Nm3. [ABSTRACT FROM AUTHOR]

In this paper, an experimental study of a magnetic refrigerator was carried out to identify static and dynamic models, which can be used for proposing and tuning control strategies. For the experimental evaluation, a 40 liter thermally insulated compartment was coupled to a magnetic refrigeration system equipped with an active magnetic regenerator. The influence of fluid flow rate, blow fraction, and magnetic cycle frequency on the temperature behavior inside the refrigerated compartment and on the power consumption of the system was evaluated. The results of the characterizations show that it is possible to reach equivalent cabinet temperatures by changing the flow rate of the thermal fluid or the cycle frequency. However, the former has a greater influence on the temperature of the cabinet, and the latter has a greater impact on the energy consumption and is associated with slower transients. Additionally, the temperature of the cabinet at steady state showed a parabolic behavior with respect to the fluid flow rate, demonstrating that there is an optimal flow rate for a given operating condition. • A magnetic refrigerator is experimentally evaluated at different operating conditions. • A thermally insulated compartment and real heat exchangers are employed. • Control-oriented dynamic and static models based on experimental data are provided. • Fluid flow rate, blow fraction, and magnetic cycle frequency are manipulated. • Temperature of the cabinet and energy consumption are measured. [ABSTRACT FROM AUTHOR]

• A direct evaporative cooler (DEC) integrates with split air conditioner (SAC). • DECSAC significantly improves C O P by 10.54 %−70.14 %. • Total cost rate (T C R) of DECSAC reduces by 5.07 %−25.36 %. • Water consumption for 1 kWh energy saving varies between 5.5 – 9.8 L. • Simple payback period lies between 1.21 to 2.99 years with maximum I R R being 59 %. As concerns regarding energy consumption and environmental impact continue to grow, the need for efficient and sustainable cooling technologies becomes increasingly significant. Among various alternatives, direct evaporative cooling (DEC) has emerged as a promising solution due to its energy-efficient operation and low environmental footprint. This paper aims to provide a comprehensive thermo-economic assessment of a 5.25 kW capacity split air conditioner (SAC) integrated with direct evaporative cooling, focusing on evaluating its performance, energy consumption, coefficient of performance (C O P) , and economic viability. A numerical model is developed to determine the reduction in the condenser inlet air temperature due to direct evaporative cooling. The ambient temperature (30–45 ⁰C), relative humidity (20–80 %), and evaporator temperature (3–12 ⁰C) are taken as the design variables. Box–Behnken design (BBD) technique of response surface methodology is applied for multi-objective optimization. The C O P , total cost rate (T C R) , and total exergy destruction ( E ˙ D , t ) are set as the objective functions. Cooling capacity, life period, operation time, interest rate, maintenance factor, and electricity cost are taken as constants. The thermoeconomic optimization evolved maximized C O P enhancement of 68.94 %, and reduction in TCR and E D , t by 26.12 % and 57.23 %, respectively. The water consumption to energy saving ratio varies from 5.5 to 9.8 L/kWh for different months of the cooling season. The thermoeconomic performance and sustainability of DECSAC is observed to significantly improve compared to conventional SAC specifically in hot-dry climates. The simple payback of the proposed system ranges between 1.21 to 2.99 years depending upon the operating conditions. [ABSTRACT FROM AUTHOR]

Nowadays, the increasing consumption of conventional fuels has led to rising pollutant emissions, among which soot has received much attention due to its harmful effects. In this paper, previous typical soot models are reviewed. Based on empirical, semi-empirical and detailed models, phenomenological models, the most popular models of recent years, are also summarized. This work also summarizes the application of existing soot models in combination with other models and methods in turbulent flame and diesel engine development based on existing models. Besides, as the development of clean alternative fuels continues, new fuels have received significant attention as a method to reduce soot formation. For different fuels, the reasons for reducing soot formation have also attracted the interest of researchers, and thus this paper reviews the current research about relevant carbon soot modeling for biodiesel, natural gas, and other new fuels. A detailed understanding of soot generation and soot modelling can help further research into methods to reduce soot emissions. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper investigates the impacts of economic (in)stability on carbon emissions and the role of renewable energy in these effects at the crossroads of accelerated climate change and rising global economic instability. The paper hypothesizes that these implications should be examined not by direct impacts across variables, but rather via indirect effects serially mediated by renewable energy consumption and economic growth. This paper analyzes the United States from January 1980 and April 2022 using manifest structural equation modeling. The paper reaches two major conclusions. First, there are clear distinctions between (i) the direct and indirect effects of economic stability, surrogated by inflation and policy interest rate, on carbon emissions, (ii) the symmetric and asymmetric indirect effects, and (iii) the roles of aggregate renewable energy and its components, such as biomass and hydropower energy use, in mediating these symmetric and asymmetric indirect effects. Second, renewable energy significantly reduces the carbon-increasing effects of inflation and interest rates. The paper contains proper policy suggestions based on the findings. [ABSTRACT FROM AUTHOR]

• Energy consumption based Battery Energy Storage and rooftop Solar PV sizing. • Typical high-end units consumes 22% more than the medium-cost units and 56% more than low-cost units. • Community BESS and rooftop Solar PV has to be sized at maximum or 125% of maximum to supply for VPP. • More n R is needed if sizing is based on max E C while lesser n R if size is based on 125% of the max E C. Virtual Power Plants (VPP) have been seen as one of the techniques to integrate more decentralized and distributed variable renewable energy systems into the grid. They will thus facilitate the greater democratization of the energy systems. VPP is an aggregation of renewable energy technologies, such as solar PV. It is usually operated with battery energy storage system (BESS) facilities to solve the variability issue of solar PV. However, BESS used as part of VPP has to be appropriately sized to work in the electrical network. While VPP operated with BESS may provide significant technical and financial advantage, most of the BESS sized to be used as VPP in the literature are large scale, operated with large scale VRE's in the grid. Some of the literatures also provide the use of BESS sizing with Solar PV but for shared residential community use only. The context of BESS sizing for VPP from a residential community is not prevalent in the literature. In this paper, the context of a sizing BESS for VPP from a residential neighbourhood is studied. It is aimed that by optimally sizing BESS for a residential community with rooftop solar PV can supply power to the community and any excess energy may be used for VPP application for the grid. This paper provides a practical process for evaluating the proper size of a centralized BESS in a community with rooftop Solar PV by considering the energy consumption and peak demand profiles of the residential units in three types of communities with rooftop Solar PV, namely low-cost, medium-cost, and high-end community, by considering the mean and maximum energy consumption and peak demand profiles of each residential unit. Such values are used to allocate for the Solar PV system per residential unit and the centralized BESS at mean, 75% of maximum, maximum, and 125% of maximum energy consumption, to be used for the community and for any excess energy to support the electrical networks reliability improvement. The result shows that using the maximum and 125% of maximum energy consumption can provide more than enough energy capacity for VPP application, particularly electrical networks reliability improvement by supplying for the Energy not Supplied (EnS), E N. The result provides that for a High-end community, the stored energy in the BESS can reach up to 24.578 MW h using 125% of maximum sizing at either mean or maximum energy consumption. While for Medium-cost and Low-cost communities, the stored energy can reach up to 17.549 MW h and 14.527 MW h using 125% of maximum sizing at either mean or maximum energy consumption, respectively. Moreover, the result also shows that to alleviate Energy not Supplied (EnS) and contribute to reliability improvement, more residential units are needed if sizing is based on maximum energy consumption, while a lesser number of residential units if the size is based on 125% of the maximum energy consumption. [ABSTRACT FROM AUTHOR]