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Microfluidic fuel cell (MFC) is a burgeoning category of micro fuel cell technology based on laminar flow electrolytes. The merits of MFC, such as the absence of membrane electrolyte, flexible reactants selection, and high electrolyte conductivity, have been attracting researchers to explore this frontier area over the past two decades. However, realizing practical applications of MFCs remains a tremendous challenge. Many research works have been done to expedite research progress and obtain results reflecting inner mechanism via computational modeling and simulation, the general procedure of which is introduced in this paper. These studies primarily investigate the effects of various geometrical and operational parameters on diverse cell performance metrics, such as open-circuit voltage, current and power densities, and fuel utilization efficiency. However, contradictory outcomes and conclusions may arise due to disparities in the structural and parametric characteristics among different MFC models. In this regard, this review comprehensively summarizes prior computational modeling studies on MFC technology, with specific emphasis on different cell components including microchannels, inlets and outlets, electrodes, etc., as well as effects of different operational conditions encompassing electrolyte input, cell vibration, gas bubbling, and gravity. In addition, other related studies involving paper-based MFCs, cell stacking, and twin models are also introduced. Lastly, the future research perspective on MFC computational modeling is proposed, including potential structural innovations and modeling methods. This review paper shows the big puzzle of MFC modeling, the missing part of which is worthy of further study in the future. [Display omitted] • A comprehensive review on microfluidic fuel cell modeling is presented. • Governing equations and modeling method for microfluidic fuel cell are introduced. • Studies on different cell configurations and operational conditions are introduced. • Studies on paper-based fuel cell, fuel cell stack and twin model are also presented. • Future research directions for microfluidic fuel cell modeling are proposed finally. [ABSTRACT FROM AUTHOR]

In recent years, the severe environmental degradation and high levels of fossil fuel consumption linked to conventional ship energy systems have drawn attention to the advancement of alternative ship energy systems. Consequently, ship energy systems based on the use of an electrical microgrid are coming to the fore as an increasingly popular alternative solution. However, managing the energy flows within a shipboard microgrid can be highly challenging due to the multiple energy sources (including renewable energy sources) and types of loads involved. Additionally, the integration of an energy storage system has been identified as an effective solution for improving the reliability of shipboard power systems, pointing out the important role of energy storage systems in maritime microgrids and their potential to enhance the energy management process. As such, effective energy management strategies are necessary to optimize performance and ensure that the vessel's energy demands are met while minimizing fuel consumption and reducing cost and environmental impacts. This paper presents a comprehensive review of such strategies and methods recently presented in the literature associated with energy management in shipboard microgrids integrating energy storage systems and examine the different techniques that can be utilized to achieve optimal system performance. Moreover, the paper also sheds light on the future challenges and perspectives imposed by the modern shipboard microgrids operation on the energy/power management of these systems. The aim of this paper is to provide a helpful guideline for researchers and engineers conducting research in the field of electrically powered ships. [Display omitted] • A comprehensive review of EMS for electrical and hybrid ship is presented. • A comprehensive review of ESS which can be used in such ships is presented. • Technologies of ESS and their suitability to ships are discussed and commented. • Future challenges and perspectives imposed by modern SMG operation are presented. [ABSTRACT FROM AUTHOR]

Energy simulations are extensively employed by researchers and designers to assess strategies aimed at enhancing the thermal performance or energy efficiency of buildings. However, the methodologies for conducting these simulations and analyzing their outcomes vary according to regional standards and among research groups. This work aims to investigate the methods for evaluating the thermal performance of buildings through energy simulations, through a systematic literature review. Initially, the authors surveyed articles published between 2011 and 2022 on Scopus and Web of Science. From an initial pool of 1463 articles that met the research criteria, a refined list of 158 papers were read completely. The authors examined prevalent trends in the methods and identified future research directions. Most publications originated from authors in Northern Hemisphere, with only Brazil showing expressive numbers in the Southern Hemisphere. The results revealed the three most employed methods: Thermal Load (94 %), Degree-Hour (or Degree-Day) (9 %), and Design Days (5 %). EnergyPlus stands out as the widely preferred software (65 % of studies), and 62 % of them incorporate some form of validation or calibration. Articles often lack complete simulations parameters and/or clarity in their presentation. In response to the identified gaps, this study introduces a checklist of best practices for presenting the simulation steps. As such, this work serves as a valuable theoretical framework for future assessments of building thermal performance through computer simulation. • We reviewed 185 papers on methods to evaluate therm. Perform. Via energy simulations. • Thermal Load (94 %), Degree-Hour (9 %) and Design Days (5 %) are the most used methods. • EnergyPlus and ASHRAE are the most used software and standard, respectively. • Literature gaps include comparative studies and conversion strategies among methods. • Standardized protocols for model calibration and validation are still limited. [ABSTRACT FROM AUTHOR]

This paper presents a critical advancement in Building Energy Modeling (BEM) through an empirical validation approach using a high-quality dataset from a multizone commercial office building in Oak Ridge, TN, USA. BEM is widely utilized in diverse construction applications, but its effectiveness relies on the accuracy of its predictions. The study focuses on empirical validation of input parameters in BEM, including building envelope data, infiltration modeling, and rooftop unit system performance curves. The validation of simulation input parameters leads to substantial improvements in the accuracy of simulation results. Notable both NMBE and cv (RMSE) values are reduced by 0.5 % for indoor air temperature and 17 % for indoor air relative humidity compared to the previous model. At the system level, both NMBE and cv (RMSE) values are reduced by 2 % for fan energy consumption and 4 % for cooling energy consumption, compared to the previous model. A literature review highlights a significant gap in empirical validation studies, which predominantly concentrate on either component-level or whole building validation. Furthermore, many studies employ simplified setups that may not faithfully represent the complexities of multizone commercial buildings. This paper distinguishes itself by emphasizing the critical importance of component-level input parameter validation. It underlines the need to validate data related to building envelope components and HVAC system performance curves, resulting in more accurate simulation outcomes. The utilization of actual multizone commercial building data enhances the study's practical relevance. In summary, this research underscores the pivotal role of input parameter validation in enhancing the accuracy and reliability of BEM. • The EnergyPlus simulation model input parameters have been empirically validated. • Building envelope input parameters have been evaluated. • Tracer gas and blower door tests have been performed to update infiltration model. • The rooftop unit performance curve has been developed using field datasets. • The simulation results are well-matched with field data at zonal- and system-level. [ABSTRACT FROM AUTHOR]

Malaysia is one of the leading producers and exporters of oil palm, and the industry contributes significantly to the growth of the national economy. Nonetheless, the consequential oil palm biomass (OPB) with a potential yield of ∼97 million tonnes annually presents both challenges and opportunities, demanding innovative waste management solutions. This paper explores the feasibility of converting OPB into valuable commodities by employing concentrated solar-driven pyrolysis. A detailed overview of the biomass produced from oil palm plantations and mills is provided, along with a discussion of the industry stakeholders and associated biomass management challenges. The pyrolysis of OPB is explored, emphasizing benefits, potential barriers, and techniques. The focus then shifts to Malaysia's solar potential, which ranges from 1470 to 1900 kWh/m2 annually. The potentials of solar pyrolysis are explored, encompassing discussions on solar concentrator types, reactors, and the distribution of solar and OPB resources throughout Malaysia. The paper then recommends Tawau in Sabah, as an ideal location for OPB solar pyrolysis, due to its solar availability (up to 1873 kWh/m2), potential OPB resources from 19 mills and 241 plantations, and supportive infrastructure. The paper proposes solar-driven pyrolysis as a sustainable solution for Malaysia's OPB management, offers insights for policy initiatives and technological innovations in optimizing OPB and solar energy utilization. • Analyzes oil palm biomass potential for solar pyrolysis in Malaysia. • Explores solar resources in Malaysia for solar-driven pyrolysis. • Examines solar concentrators and reactors for pyrolysis. • Identifies potential city, as the optimal location for solar pyrolysis. • Discusses commercialization challenges of solar-driven pyrolysis. [ABSTRACT FROM AUTHOR]

Energy storage technology is recognized as an underpinning technology to have great potential in coping with a high proportion of renewable power integration and decarbonizing power system. However, the costs of energy storage facilities remain high-level and it makes energy storage a luxury in many application fields. To address this issue, a new type of energy storage business model named cloud energy storage was proposed, inspired by the sharing economy in recent years. This paper presents a review and outlook on cloud energy storage technology. The paper starts with the introduction of the basic concept, fundamental structure, and superiorities of cloud energy storage. Facing the energy storage utilization demands of the users on the source side, grid side, and demand side, the typical application scenarios of cloud energy storage are analyzed, and the corresponding state-of-art pilot trials are introduced. After that, the theoretical research framework of the cloud energy storage technology is presented, and the research status of cloud energy storage technology is surveyed. Finally, considering the combination of cloud energy storage and other advanced energy and information technology such as multi-energy coordination and blockchain, the evolution path and development prospects of cloud energy storage are discussed. • Basic attributes including concept, framework and superiorities, as well as corresponding pilot trials of cloud energy storage for different application scenarios are concluded. • The achievements, shortcomings and key research directions of the three most concerning areas of cloud energy storage technology are summarized. • The development prospects of cloud energy storage technology considering the combination with multi-energy technology, virtual energy storage and distributed information technologies are analyzed. [ABSTRACT FROM AUTHOR]

Global warming, and the energy crisis, both caused by the unregulated overconsumption of fossil fuels, are some of the main problems humanity has to face along with freshwater shortage. The importance of safe access to freshwater and various forms of energy to the survival of modern societies is undeniable. Water- and energy-related technologies are independent, but thermal energy storage can bind such technologies. Salts, which are well-known phase-change materials that can be used as thermal energy storage media, can be extracted from the brine produced by desalination plants, which is usually rejected into the environment. Evaporation, electrodialysis, membrane distillation-crystallization, and adsorption/desorption are suitable techniques for extracting salts from brine in conjunction with desalination. Obtained salts can be used as phase change materials in thermal energy storage units. Salt-based thermal energy storage units can be integrated into concentrated solar power plants, geothermal power plants, fossil fuel, and biomass fuel power plants, load-following nuclear power plants, and various industrial processes for energy production and optimization. Although there are many papers on molten salt-based thermal energy storage, the direct utilization of salts extractable from the brine produced by desalination plants for thermal energy storage units has not been thoroughly investigated. In order to provide a guide for researchers in investigating such systems, this paper reviews salt extraction technologies in conjunction with desalination, applications of salt-based phase change materials in thermal energy storage, and challenges and perspectives of binding desalination plants with energy production or optimization systems using thermal energy storage. • Desalination plants produce brine which can be used to obtain salts. • Salts are phase change materials that can be used in thermal energy storage. • Salt-based thermal energy storage units can be used in various applications. • Co-generation of water and electricity is possible using thermal energy storage. • Developing thermal energy storage technology demands a multidisciplinary approach. [ABSTRACT FROM AUTHOR]

Retrofitting the building stock is pivotal to achieving climate neutrality by 2050. Most of the existing research on energy efficiency focuses on new residential buildings. The focus must shift to multi-building retrofits, thereby more frequently including non-residential buildings. As multi-building and non-residential projects are given a lighthouse role in achieving current global climate goals, more research should focus on this potential. This study covers single- and multi-building retrofitting projects. It also explores the role of non-residential projects, typical project settings, energy reduction achievements and the added complexity of the multi-building scale. The chosen methodology combines a systematic literature search with a subsequent critical metadata and full-text review of more than 80 peer-reviewed scientific papers. The results show that the number of studies in the research field has increased substantially in the last few years, while the research mostly originates from Europe and focuses on the residential building typology. This research is partly transferable to similar climate zones elsewhere, while a large proportion of climate zones remains unexplored. The current body of definitions and requirements regarding energy retrofitting is an impediment to the comparability of projects, and particularly the multi-building scale is in need of international guidance. Future research should focus on making retrofit measures more applicable internationally, while unifying project boundaries. The stronger inclusion of non-residential retrofitting projects as lighthouse projects including social aspects is needed. Retrofitting that covers energy production and sharing has great potential and should be seen as an opportunity. [Display omitted] • Multi-building retrofitting is emerging but requires clearer international guides. • Europe stands for most publications, motivated by policies and climate goals. • Most of the reported energy retrofits do not satisfy "deep retrofitting" goals. • Multi-building retrofitting results in added social and technical difficulties. • Clearer international guidelines and best practices needed to reach climate goals. [ABSTRACT FROM AUTHOR]

Existing pieces of literature on previous studies advocate the research focus by various researchers to reach the benchmark of energy efficiency of Wastewater Treatment Plants (WWTPs). The driving factors to improve the energy efficiency and mitigate the energy self-sufficiency of WWTP have been identified as the increase in population growth, rising energy costs, and tightening effluent discharge requirements. WWTP economy is directly related to energy consumption and thus affects smart grid economy. There has been limited research on energy self-sufficiency and optimizing the energy demand and cost of WWTP, where the significant contributing factors are in development an optimal pumping system and advanced motor technologies. Moreover, high quality WWTP's effluent depends on the concentration level of biochemical oxygen demand (BOD) and total kjedhal nitrogen (TKN). Even so, WWTPs are always subject to evident nonlinearities and uncertainties, making it difficult to define proper optimization objectives. Besides, controllers and control systems have a strong influence on the performance of the plants. Therefore, existing research gaps to achieve optimal efficiency with minimized energy consumption and costs are the design of the WWTP plant, pumping system, motors, selection of suitable controllers and control systems, and their parameter optimizations to get the optimal output from the plant, switching techniques, challenges and uncertainties associated with plant are highlighted in this paper. Thus, as a novel contribution to the literature, this study aims to review and analyze the history, current issues, and future directions of WWTP control technologies in the context of sustainable development. The rigorous study by the authors in this paper will definitely lead the academic researchers and industry partners toward the development of optimal WWTP technologies with improved efficiency and minimized energy consumption and costs. • Effective control techniques and monitoring of the wastewater treatment plant. • Optimal energy-efficient WWTPs with renewable sources and the utility grid. • Uncertainties of WWTP can be considered for improved operation. • Effective policies should be imposed by combining academics and industry. • Reduced energy consumption and cost can be achieved. [ABSTRACT FROM AUTHOR]

Power-to-Gas technologies are high-capacity systems, which can be used to optimise the use of renewable energy to meet energy demands. Among them, Power-to-Methane (PtM) stands out due to the ease of storage and use of the produced methane. However, its total storing efficiency (Power-to-Methane-to-Power) is likely still low as there are various losses. This paper presents an overview of PtM improvement through the utilisation of low-temperature waste heat produced upon the two steps by converting power to gas, namely electrolysis and methanation. An organic Rankine cycle, Stirling engine, and thermoelectric generator were chosen as promising technologies that could be implemented to recover the waste heat and improve the PtM system. Several experimental studies of each technology were reviewed. Moreover, some technological and economic surveys are described and discussed. At the end of the article, the study discussed the direction of further research and development for waste heat recovery in the system to increase the competitiveness of the PtM system and its efficiency. • Some possible Power-to-Methane configurations are described. • Power-to-Methane offers high energy density and long-term capabilities. • An improvement of Power-to-Methane based on waste heat recovery is discussed. • Selected promising waste heat recoveries below 100.0 °C are described and compared. • Several techno-economic parameters for assessing the improvement are described. [ABSTRACT FROM AUTHOR]

Research on greenhouse gas (GHG) emissions in the building sector has concentrated on the use phase of buildings, and more recently embodied emissions from construction materials. Much less research has focused on reducing GHG emissions from onsite fuel use during construction, in part because predicting and measuring fuel use is complex and lacks guidance to help modelers focus on key factors that drive variability in results. This paper addresses that challenge by examining the state-of-the-art in onsite fuel use accounting with a focus on earthworks, one of the largest drivers of onsite fuel consumption. It provides a comprehensive summary of the existing literature, describes and quantifies the ways in which factors influence fuel use, and fills several gaps identified during the review process by drawing from research in related fields. The result is a new taxonomy for categorizing fifteen factors which influence fuel use, including equipment factors (e.g., engine specifications, attachment selection), operational factors (e.g., operator skill, fleet configuration), and site factors (e.g., soil type, excavation depth). Drawing on earthwork productivity and productivity/fuel use in related fields (e.g., freight hauling, military equipment) to augment the construction emissions literature, most notably to investigate the influence of weather on earthwork GHG emissions. Across case studies, soil type, attachment selection, engine specifications, weather and hauling conditions arise as the most influential factors. Finally, this work presents recommendations for structured fuel use data collection to improve the consistency of future data collection and reporting, along with subsequent fuel use modelling and optimization efforts. [Display omitted] • A comprehensive review of how fifteen factors influence earthwork fuel use. • Presenting a taxonomy for categorizing factors affecting earthwork fuel use. • Preliminary analysis of weather's impact on earthwork fuel use. • Presenting a framework for earthwork fuel use data collection. [ABSTRACT FROM AUTHOR]

Literature has highlighted the existence of a gap in clean fuel usage between the social groups in most emerging nations across the world, which is detrimental to global efforts to achieve Sustainable Development Goal (SDG) 7 (access to clean energy) and SDG 10 (reducing inequalities) and just energy transition with recognition justice. This paper, assesses the clean fuel gap across social groups in India using three rounds of representative data (2004, 2014, and 2018) by applying the logit model, exogenous switching treatment effect regression (ESTER), and the Blinder–Oaxaca Decomposition Model. Such an analysis is instrumental in identifying the clean energy usage gap and its causes, thereby providing insight to policymakers to design policies to achieve just energy transition and carbon neutrality by 2060. The results show a substantive clean fuel gap between social groups in India, which is a cause of concern for just energy transition. Clean energy utilization gaps among social groups are alarming across geographical locations and consumption quartiles, highlighting the importance of recognition justice for just energy transition. The results show that in rural areas, only 19.6 % of the General Caste households and 14.5 % of the disadvantaged social groups (Scheduled Tribes, Scheduled Castes, and Other Backward Class) in quartile one use clean energy, while in urban areas, the shares are 60.4 % and 46.3 %, respectively. To achieve a just distribution of the benefits of energy transition, energy policies should focus on disadvantaged social groups and simultaneously target General Caste households from a lower economic status and those residing in rural areas, indicating the need for targeting the neglected regions. [Display omitted] • Clean energy use has steadily increased among all social groups in India, indicating some improvement in energy justice. • Clean energy access gap among social groups has declined, but this gap still persists. • Scheduled Castes and Scheduled Tribes are the most disadvantaged social groups in terms of clean energy. • All social groups from low-income families have limited access to clean energy. • All social groups from households with low education have limited access to clean energy. [ABSTRACT FROM AUTHOR]

There is a lack of empirical analysis of macro-level energy policy through a gender lens, and there exists a research gap in tools for such analysis. This paper proposes a novel empirical approach to explore the gender dimension of the language used in energy policy documents such as the National Energy and Climate Action Plans (NECPs) of European Union (EU) member states. We first review the literature to identify existing approaches that analyse the energy/gender nexus. We then describe how we adapt Natural Language Processing (NLP) techniques to quantify the degree to which the language used in the NECPs is male or female associated. Our work shows the gap in suitable tools. We demonstrate using NLP that all EU NECPs tend to use more male associated language than female. In a ranking of EU member states, the Portuguese NECP demonstrated the most bias, while the Slovenian demonstrated the least. Our work provides novel insights using NLP to understand the genderised use of language, and contributes a methodology to conduct empirical analysis of energy policy documents. [Display omitted] • Review of methods used in energy/gender nexus analysis. • Empirical approach to analyse energy/gender concepts in the Global North. • Measurement of a gender dimension (bias) of the language used in European Union National Energy and Climate Plans. • Identification of Energy Domain NLP training corpora and vocabulary. [ABSTRACT FROM AUTHOR]

This article has been withdrawn: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been withdrawn at the request of the editor and publisher. The publisher regrets that an error occurred which led to the premature publication of this paper. This error bears no reflection on the article or its authors. The publisher apologizes to the authors and the readers for this unfortunate error. [ABSTRACT FROM AUTHOR]

Adsorption carbon capture has shown its superiority in energy consumption and cost investment when compared with common amine scrubbing technologies. However, high regeneration energy demand of adsorbents is still a challenge for large-scale application. This paper proposes a temperature vacuum swing adsorption system integrated with auxiliary heating and cooling technology. Absorption chiller and double-stage absorption heat transformer (DAHT) are introduced from the perspective of adsorption and desorption process of CO 2 capture system. Results indicate that when the duration of each step increases from 25 min to 45 min, the CO 2 recovery rate decreases from almost 100 %–75.7 %, and CO 2 purity increases slightly from 89.6 % to 91.1 %. Considering the temperature grade of waste heat, heat consumption of the absorption chiller assisted system is lower than that of DAHT for original and adjusted cases at a generation temperature of 58 °C. If the desorption temperature decreases from 120 °C to 100 °C, heat consumption of the absorption chiller decreases from 1.90 GJ·ton−1 to 1.76 GJ·ton−1, but the average capture capacity decreases from 306.3 ton·ton−1 ad to 272.1 ton·ton−1 ad. It is demonstrated that both absorption chiller and absorption heat transformer could be promising solutions to reducing the energy consumption of CO 2 capture system. Absorption chiller has a priority over DAHT in regions with low temperature heat sources. Moreover, a tradeoff between adsorbent loss and heat consumption should be found when choosing the appropriate heat pump for practical application. [Display omitted] • Adsorption carbon capture integrated with absorption chiller is initially proposed. • Absorption chiller is beneficial for reduction of heat consumption of capture. • Decrease of desorption temperature has great influence on system performance. • Heat pump assisted adsorption capture is a promising way for energy saving. [ABSTRACT FROM AUTHOR]

The African continent is endowed with massive energy resources such as hydropower, solar, wind, natural gas, wave energy, and many more, yet it is the continent with the least energy supply in the world thereby resulting in a lack of sufficient energy to meet its growing energy demand. Though the continent holds 100 GW of wind capabilities, the current installed capacity as at 2018 was 5.7 GW with countries in northern Africa as well as South Africa capturing over 90% of the wind energy share on the continent. Therefore, this paper reviews the wind energy industry in Africa by identifying the current installed and potential capacity of wind energy on the continent. The challenges faced by the wind energy industry such as policy, competition, technical and economic are also reviewed. Transitions, technological innovation systems, and strategic niche management theoretical sustainability transition framework as well as proposed pathways to overcome these prevailing challenges hindering the full exploration of the wind energy sector in Africa are also highlighted in order to uplift the continent's socio-economic status. Basically, this can be achieved through the adoption of strong 'political-will' by African national governments to drive wind energy development. There is also the need for institutional frameworks to ensure the practical adoption of new wind energy technologies. Furthermore, the major benefits Africa stands to gain from investment in wind energy are enumerated by comparing with the benefits realized by other countries' economies as a result of investing in the wind energy industry. For instance, cheap electricity, job creation, industrial growth, and eco-friendly energy source. • Reviewing wind energy industry in Africa and existing challenges. • The challenges faced by African's wind energy industry can be categorized under policy, competition, technical and economic. • Framework for transiting Africa's wind energy industry from small-scale production to large-scale commercial industry.. [ABSTRACT FROM AUTHOR]

Data centers have attracted increasing attention worldwide over the last decades due to their high energy consumption. Cooling accounts for about 30–40% of the total energy consumption of data centers. High-temperature data centers could save large amounts of cooling energy by changing their cooling mechanism. More effective use of "free cooling" is the basic and effective means for high-temperature data centers to reduce cooling energy consumption. It is possible to build chiller-less or even chiller-free data centers. They require less capital investment for cooling and allow more hours of "free cooling". However, a few essential concerns need to be addressed before the wide application of high-temperature data centers, particularly the technical bottlenecks and the reliability and performance of servers and IT equipment. Though many reviews on data centers exist in the existing research, a systematic review of high-temperature data centers, particularly on the above essential concerns, is still unavailable. This paper is intended to fill in these gaps and provide a comprehensive review of these critical aspects. The main benefits and the major bottlenecks for implementing high-temperature data centers as well as the existing efforts and latest technologies to tackle the bottlenecks are categorized and analyzed systematically. In addition, a through review of the main temperature-sensitive IT components (e.g., hard disk drives and CPU) is done, and their current states and potential solutions are analyzed. Finally, the paper elaborates on future perspectives for the development and applications of the high-temperature data center. [Display omitted] • A comprehensive review of high-temperature data center development is done. • Bottlenecks and benefits for implementing high-temperature data centers are analyzed. • Existing efforts and latest technologies to tackle the bottlenecks are analyzed. • A review of temperature-sensitive IT components & technology development is given. • Future perspectives for high-temperature data center development are elaborated. [ABSTRACT FROM AUTHOR]

Wood chips are the primary sources of raw materials for numerous industries, including pelleting mills, biorefineries, pulp-and-paper industries, and biomass-based power generation facilities. Unfortunately, when wood chips are utilized as a renewable and environmentally friendly resource, industries are constantly challenged by the consistency of the wood chip qualities (e.g., moisture/ash contents, size distributions) - a historically recognized problem on a global scale. Among other wood chip quality attributes, the moisture content is considered the most pressing one as it directly impacts the energy content, storage stability, and handling properties of the raw and finished products. Therefore, accurate wood chip moisture content prediction can help optimize the drying process and reduce energy consumption. In this review, a survey was conducted on various techniques and models employed for predicting wood chip moisture content. The advantages and limitations of these approaches, as well as their potential applications and future directions were also discussed. This review aims to provide a comprehensive overview of the current state-of-the-art in wood chip moisture content prediction and to highlight the challenges and opportunities for further research and development in this field. • Oven drying is the most used method despite being slow and prone to sampling errors. • Indirect methods are fast but have individual shortcomings based on applications. • Due to reliance on direct method for data labeling, wood chip datasets are small. • Box-based data collection methods and regression-based models are prevalent. [ABSTRACT FROM AUTHOR]

Agricultural practices such as successive cropping and irrational fertilization have led to a steady decline in soil fertility in many regions. Humic acids (HAs) are a type of effective additives for enhancing soil fertility, but natural HAs reserves are limited. Artificial HAs can be produced from biomass by biotic composting and abiotic hydrothermal reaction (HTR). The principles, influencing factors, and product characteristics of these methods have been comprehensively summarized in previous reports, but less attention has been paid to issues linked to scaling up production, such as facilities, equipment, process control, and energy consumption. This paper presents a systematic review on the potential engineering issues involved in artificial HAs production to serve as a reference for actual project designs. Biotic method was summarized as mainly based on the type, scale, configuration and control of the reactor. The multifunctional compost reactor showed better HAs production performance, with yields ranging from 35 to 82 g kg−1 and 139–248 g kg−1 at lab- and pilot-scale, respectively. The abiotic method was categorized based on the HTR reaction steps. The two-step and hydrochar methods have high potential for HAs production from recalcitrant biomass, with maximum reported yields of 283 and 435 g kg−1, respectively. A method for evaluating the energy consumption of HTR is presented, estimating the energy input of HTR at 1825–31987 kJ kg−1 HAs, which is mainly influenced by the HAs yield and reaction duration. [Display omitted] • Three types of bioreactors for producing humic acids are summarized. • The structure and function of 16 compost facilities or equipment are analyzed. • Intelligent composting based on classical PID and machine learning is presented. • Hydrothermal reactions classified into three pathways. • Energy input analysis model developed for hydrothermal reactions. [ABSTRACT FROM AUTHOR]

In recent decades, freshwater reserves have been under high threats, generated mainly by anthropogenic causes such as rapid population growth and climate change. Currently, one of the technologies that has been used to meet the freshwater global demand is seawater desalination. However, this solution has two major drawbacks. First, the discharge of reject brines with a high concentration of pollutants and nitrates, causing environmental problems such as eutrophication processes. Second, desalination systems, both membrane and thermal technologies, have a high energy consumption that is supplied with fossil fuels, contributing to the emission of greenhouse gas. Recently, to solve both problems, the zero —or minimal— liquid discharge strategy has emerged. This alternative for brine management is based on recovery of more than 90% of the freshwater fraction and salts, which can be revalued. Currently, there are some zero liquid discharge desalination plants that incorporate renewables to supply the necessary energy, making desalination a totally sustainable and environmentally-friendly process. Zero liquid discharge desalination plants powered by renewables already exist, although in an immature stage. This paper analyzes and discusses the potential of combining different renewables with the most developed and efficient desalination technologies. In addition, the most important plants and solutions currently installed on a real scale, mostly the result of different research projects, are described and compared. [Display omitted] • Water scarcity is a global problem that has promoted policies included in SDG 6. • Over 21,123 desalination plants produce 142 million m3/day of freshwater. • Reject brine and GHG emission reductions are crucial for sustainable desalination. • MLD and ZLD combined with RES are a strategy to solve desalination's negative impact. • The newest ZLD-desalination plants powered by RES are discussed. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive review on the status of renewable energy developments and hydrogen economy in the Middle East and North Africa region. This region is heavily reliant on fossil fuels for its domestic energy supply and is also considered a global energy exporter. In this regard, an overview of the current state of energy sector in the region is provided. Moreover, the region possesses great potential for renewable energy exploitation due to its climatic advantages. Therefore, the current status of renewable energy utilization within the region's various countries is reviewed by presenting several operational renewable energy-based plants and future projects for deployment of renewable power in the region. Green hydrogen is an important sustainable clean fuel, and its utilization is essential for both environmental preservation and energy security. Thus, the status of hydrogen production and utilization in the region is discussed considering the various operational systems and future hydrogen generation projects. The concept of source, system and service is also incorporated which considers the utilization of clean energy sources for sustainable hydrogen production through environmentally benign pathways. The potential deployment opportunities for the renewable hydrogen production are also discussed based on available renewable sources in the region. Moreover, this paper discusses the challenges of increasing renewable energy utilization in the region. Furthermore, this paper provides a road map for achieving renewable hydrogen economy including a reduction in domestic utilization of oil and gas sources, subsidization of renewable production sector, and financial support to hydrogen production and transportation infrastructure. • Providing an overview of the status of energy sector in the region. • Providing an overview of the status of renewable energy utilization in the region. • Discussing the challenges and opportunities of renewable and hydrogen energy development in the region. • Providing a road map for renewable hydrogen development in the region. [ABSTRACT FROM AUTHOR]

In 2007 was settled the first minimum energy performance standards for air conditioners in Brazil. After more than 14 years since the first regulations and looking upon future perspectives, this paper presents a review of regulatory developments in the country and an assessment based on scenario simulation to verify potential impacts of new minimum energy performance standards for air conditioners. The methodology employed is a bottom-up approach designed to estimate the energy consumption of air conditioners. A spreadsheet-based computational tool was developed to perform sensitivity analysis of key parameters such as ownership rate, average temperature and cooling degree days. The results show a significant energy savings potential that could be captured through a minimum energy performance standards revision. For the scenarios simulated these savings potential would reach up to 417 TWh, with respective greenhouse gases emissions reduction that would be 249 million tons, over the period from 2023 to 2040. An economic analysis of minimum energy performance standards impact is also provided and indicate that even in conditions that involve higher costs and discount rates, new more restrictive minimum energy performance standards allow capturing significant benefits for the society as a whole and for consumers individually. Reviewing the minimum energy performance standards is a critical and urgent issue for Brazil and the methodology presented in this paper can be useful in the process of decision-making related to new regulatory developments. • More restrictive MEPS for air conditioners is urgently needed in Brazil. • The synergy between the CGIEE, Procel and PBE/INMETRO should be improved. • The methodology presented in the paper can support the process of MEPS revisions. • Energy, economic and environmental benefits of more stringent MEPS can be very significant. [ABSTRACT FROM AUTHOR]

Smart Grid benefits from information and communications technology (ICT) to integrate data from different sources across the network. The growing market for electric vehicles (EV) and electric devices is increasing energy demand. To manage a large amount of complex intelligent equipment, EV charging and discharging, and data-intensive devices, a reliable modern smart grid with a service-oriented, secure, efficient, and cost-effective system is compelling. Cloud computing is a promising approach to achieve that objective as monitoring power grid data flow and data center management are the key. This paper proposes an optimization model for energy management within the power cloud. Our energy system model enables accessible services to computing resources and real-time data stream processing within an integrated environment. Using digital technology, the proper implementation of our model reduces costs and energy consumption and improves the smart grid reliability for customers and energy providers in a distributed manner. This paper presents the implementation of a three-procedure optimization algorithm within a novel Multi-Agent Cloud-fog Structure (MACS) to meet the requirements raised by smart grid communication and distribution. Our model promotes reliable energy consumption adjustments by end-users who can choose power supplied by solar, wind, geothermal, biomass, or other renewable sources or from non-renewable sources in ways that reveal opportunities for demand-supply balance and energy saving. • Comprehensive review of cloud approaches in the context of specific areas. • Enhancing dynamic energy network communications using a multiagent cloud-fog. • Considering IoT and advanced meter infrastructure integration in smart grid. • Optimization modeling development for energy network management in smart grid. • Detailed analysis of simulation results considering modeling assumptions. [ABSTRACT FROM AUTHOR]

The energy and water sectors are intrinsically linked to meet several consumer needs. A holistic analysis is required to quantify the technoeconomic and environmental benefits and impacts of energy–water interactions. Despite ongoing investigations into assessing the integrated energy and water resource use such as those covered in this review paper, the energy–water nexus linkages seem to remain analytically undefined in a systemic relationship to assess trade-offs among different objectives of energy and water usage, thereby revealing synergies between energy and water. Given an observed lack of quantitative assessments of integrated energy and water resource use in local sites such as urban precincts, the present study comprehensively reviewed literature covering energy and water systems, technologies, management measures, schemes and approaches for integrated planning at various scales. Planning challenges were identified for energy and water system integration at precinct scale. To advance state-of-the-art applications, this paper proposes research directions for integrated precinct-scale energy–water system planning. In addition, planning opportunities for integrated energy and water systems were identified towards precinct-scale deployments. Several findings indicated critical roles of complex inter-building effects from precinct elements with energy–water system interdependencies. In urban precincts, integrated energy and water system plans could enhance resource sustainability at a lower cost. The strategic approach outlined in this paper will help facility custodians to optimise complex energy–water portfolio capital investments for precinct-scale developments, including available retrofit projects supported by appropriate financing options. • Enabling energy–water system integration to move towards sustainable urban precincts. • Managing polygeneration key to enhance renewable energy and nonpotable water usage. • Coupling energy–water resource distribution networks boosts energy–water cost savings. • Deploying decentralised community microgrids augments energy–water system flexibility. • Driving integrated energy–water system plans for robust optimal investment portfolios. [ABSTRACT FROM AUTHOR]

Over the last few decades, the construction sector's energy consumption has increased tremendously. Buildings consume both embodied energy (EE) and operational energy (OE) during their life cycle. EE is consumed by processes associated with construction, whereas OE is spent operating the building. Studies show that improving the operational efficiency of a building may have serious implications for EE. Building life cycle energy assessments (LCEA) is, therefore, essential to understanding the dichotomy between EE and OE. In recent years, increased availability and accessibility of large-scale data have made data-driven approaches a popular choice for building performance assessments. In this context, numerous review articles have highlighted and tracked current trends in building load prediction methods. While this work is significant, there remains a lack of reviews focusing on data-driven approaches from a building life cycle energy perspective. In this paper, we conduct a systematic review of literature to identify key factors hindering the application of machine learning techniques specifically for building LCEA. They include: (i) issues of data collection, quality, and availability; (ii) lack of standardized methodologies; and (iii) temporal representativeness and granularity of prediction. Finally, we discuss potential solutions, future directions, and research opportunities for data-driven LCEA research. • Building life cycle energy (LCE) consists of embodied energy (EE) and operating energy (OE). • Current research shows that data-driven approaches for building performance assessment are focused only on OE. • This paper identifies key issues hindering the application of machine learning techniques for evaluating building LCE. • This paper discusses potential solutions, and future research opportunities for data-driven LCEA research. [ABSTRACT FROM AUTHOR]

Improving energy performance has been recognized as an effective measure to promote the energy saving and emission reduction and to realize the sustainable development. Methods of improving energy performance towards sustainable manufacturing are numerous and scattered, resulting in insufficiency from the perspective of overall strategies and system integration. After the intensive selection of advanced literatures, about 166 research papers directly related to energy performance improvement are analyzed. A comprehensive review and analysis from multi-perspectives of energy monitoring, evaluation, optimization and benchmarking are performed, which is conducive to understand the energy consumption pattern and take effective energy-saving measures. This paper establishes a framework of energy performance integrated method, and four energy management methods and their energy models in energy monitoring, evaluation, optimization and benchmarking phase are analyzed and summarized. Besides, the proposed framework analyzes potential applications and key advantages, and some challenges and potential opportunities for energy performance improvement methods are discussed. This study will provide a significant foundation for energy-efficient production through various methods application. • Performing a review on methods of improving energy performance. • Constructing a framework of methods of improving energy performance. • Summarizing advances in energy monitoring, evaluation, optimization and benchmarking. • Discussing challenges and opportunities of improving energy performance. [ABSTRACT FROM AUTHOR]

Implementing Nature-Based Solutions (NBS) is a promising way to reduce building energy demand and facilitates the achievement of United Nations Sustainable Development Goal 7, as they provide shading, evapotranspiration cooling and other influences on buildings. Although this field has attracted much attention, uncertainty persists regarding the potential of different NBS types to impact building energy demand in different climate conditions. To clarify this uncertainty, 101 papers were studied based on the Web of Science and Scopus databases. The current status analysis explored the development state of this field. Building energy performance analysis evaluated the potential reduction in cooling and heating energy in different climates by applying different NBS types at building scale. The review revealed that the cooling energy saving potential of NBS varies from 3% to 90%, while the potential reduction in heating energy demand ranges from 0.58% to 60%. The extent of the reduction in both cases is dependent on the NBS type and climate. Notably, some NBS types may lead to an increase in heating energy demand by between 5.9% and 25% in climates with short and mild winters. This review found that maximizing the energy-saving potential of NBS requires a comprehensive consideration of multiple factors rather than maximizing an individual factor. Further, most studies in this field have only concentrated on a few NBS types and climate zones, resulting in significant differences in research depth among different NBS categories. Future work should focus on neglected NBS types and climates to fully understand their energy-saving potential. • Different types of nature-based solutions regarding building energy demand reduction were reviewed. • Climate zone dependency of NBS impact on building energy demand was analyzed and quantified. • Influential factors to optimize the impact of nature-based solutions on building energy performance were identified. • Research gaps regarding nature-based solutions impact on building energy demand were identified. [ABSTRACT FROM AUTHOR]

The building sector accounts for over one-third of global energy consumption and a significant share of carbon emissions. Improving building energy efficiency, particularly in the tropics, where most of the future development is foreseen, is thus crucial. One of the main factors that determine building energy performance is the building envelope. This paper presents a comprehensive review of the impact of several envelope design variables, such as thermal, optical, physical, and geometrical, on the energy performance of buildings in the tropics. A correlational analysis that elaborates on the effectiveness of each of these measures is discussed in detail. The findings indicate that insulation, glazing properties, and Window-to-wall ratio (WWR) are promising solutions for improving energy efficiency in tropical buildings. Among these, insulating the building envelope has the most significant impact on energy savings. The variables of building orientation and the thermal mass of building materials have the least influence on total energy consumption. The latter exhibits complex effects in regions characterized by hot-humid climates. An optimized design in cooling-dominated climates should have a large aspect ratio, a higher WWR in the north and south facades, and an ideal shading system. With all variables combined and appropriate ventilation, a building can save 35% of annual energy and up to 60% in some cases. This study further reveals that available research on the effect of building shape and the context of surrounding built environment on energy consumption remains limited. • Combining all envelope variables can provide annual average savings of 35%. • Average savings can drop by over 20% without insulation. • Insulation, WWR, and glazing type are the most promising solutions in Tropics. • Use insulation based on WWR, shading, thermal mass, and glazing type. • Shading, glazing, SHGC, and WWR have been mainly studied together. [ABSTRACT FROM AUTHOR]

Demand-side management (DSM) can transfer the dynamic fluctuations of load to match the renewable energy sources and realize the interaction of source-load. In most existing combined cooling heating and power (CCHP) system scheduling, user-side and system-side resources are independently optimized to achieve optimum economic performances without efficiently combining resources. In this paper, the devices with adjusted loads on the system-side and the user-side are integrated to construct generalized energy storage (GES) model, including traditional flexible resources, batteries, electric vehicles, cooling and heating load response, and electro-to-thermal conversion devices. Then, the GES model is integrated into the system for optimization including economy, load fluctuation, energy efficiency, and exergy efficiency. A case study demonstrates the application of the proposed method. The scheduling results of four DSM cases under different objectives are comprehensively obtained and compared. The optimized schemes are assessed in multi-dimension decision-making method and the effects of objective weights on decision results are analyzed. The simulation results illustrate that the load variation is decreased by 54% to obtain a smooth electrical load, resulting in the stable operation of equipment and improving the security and stability of the CCHP system. The exergy efficiency, energy efficiency, and economy performances through the DSM optimization are improved by up to 8.7%, 2.5%, and 2.4%, respectively. The system optimized with the objective of load fluctuation achieves the highest score in the TOPSIS decision-making scenarios and has the best comprehensive performance. [Display omitted] • A multi-dimension day-ahead scheduling optimization model is proposed. • The transformation model between rigid and flexible electric load is built. • The multi-dimensional performance indicators are applied to demand response. • The load variance index has the most prominent performance improvement, 54%. • The exergy efficiency, energy efficiency and cost boosted by 8.7%, 2.5% and 2.4%, respectively. [ABSTRACT FROM AUTHOR]

The wastewater sector accounts for up to 7 and 10% of anthropogenic CH 4 and N 2 O emissions, respectively. Nowadays wastewater treatment plants are going through a paradigm shift to approach a net-zero carbon condition. Numerous ongoing measures have taken place to identify the sources of greenhouse gases and minimize the carbon footprint. This paper systematically reviews all known practices leading towards net-zero carbon wastewater treatment. The greenhouse gas emissions from the wastewater sector are identified and carbon footprint quantification tools, such as reliable models and emission factors are compared. The direct process emissions can contribute to over 60% of the carbon footprint in wastewater treatment plants, while around 30% of the carbon footprint is due to energy-related indirect emissions. Therefore, greenhouse gas mitigation via process optimization and energy usage in wastewater treatment plants are comprehensively described. The implantation of novel nitrogen removal processes can reduce both greenhouse gas emissions and energy consumption. Other techniques such as source separation systems can potentially allow mitigation of N 2 O emissions by 60% while avoiding energy-intensive nitrogen fertilizer production. Nutrient recovery methods are another approach which offer negative value for the net carbon footprint. Recovering N 2 O for energy production is a promising method which can lead to both direct and indirect carbon footprint reductions. Ultimately, to achieve full decarbonization any remaining emissions need to be offset, including carbon footprint of chemicals usage and transportation. [Display omitted] • Wastewater sector is going through a paradigm shift towards decarbonization • GHG emission hotspots are identified and emission factors are reviewed • WWTPs may be responsible for approximately 5% of total GHG emissions • Direct emissions can contribute to >60% of the carbon footprint in WWTPs • Process modifications and energy optimization play key roles towards net-zero WWTPs [ABSTRACT FROM AUTHOR]

This paper provides a review of negative carbon capture technologies. Based on these technologies, here it is proposed an innovative negative emissions power plant combining the generation and storage of energy from biomass, photovoltaic, and concentrated solar power, capturing and recovering CO 2 by producing H 2 or CH 4 as green energy carriers. The main features of the system are i) large-scale energy production system with negative CO 2 emissions; ii) 100% renewable system based on biomass and solar energy with the possibility of integrating other renewables; iii) synergistic integration of processes and systems; iv) recovery of O 2 generated by photovoltaic-driven electrolysis within the process of partial biomass oxycombustion and v) solar-driven limestone calcination. A detailed model of the entire plant is developed to evaluate the integration of the process. The model performance is assessed on an hourly basis throughout the whole year. The base case results show an energy consumption from 1 to 2.1 MJ/kg CO 2 to capture 60–77% of CO 2 emitted from the biomass plant and green methane production of more than 7500 tons/year. The negative emissions associated with the process are -612 kg CO 2 /MWh. It justifies the interest in the proposed negative emissions power plant. [Display omitted] • A synergetic integration of CO2 capture, energy storage and methane production is proposed. • A biomass power plant is considered, resulting in -612 kg CO2/MWh negative emissions. • Solar PV and CSP are integrated into the process to reduce the SPECCA to 1–2.1 kg CO2/MWh. • A large amount of solids storage is required to achieve 70–90% CO2 capture capacity. [ABSTRACT FROM AUTHOR]

A comprehensive review of flapping foils for Wave Devouring Propulsion (WDP) is presented. The flapping foil can effectively utilize wave energy and generate thrust. The development of WDP is discussed, followed by an introduction to the geometry, modes of motion, and operating principles. These research studies are classified as theoretical, experimental, and numerical and are provided in detail. They demonstrate that marine equipment with a flapping foil system can achieve high energy conversion efficiency and low resistance. Several prototypes of the combination of WDP with human-crewed and uncrewed vessels have been shown, including the latest initial concept models and company products. There is a huge prospect for self-driven, pollution-free propulsion of marine devices, and this paper suggests several future studies. • A comprehensive overview of research on wave-induced flapping foils was provided. • Detailed descriptions of the foil geometry and associated parameters was summarized. • A comprehensive summary is presented, from theoretical, experimental, and numerical perspectives. • Potential applications of WDP and future research were suggested. [ABSTRACT FROM AUTHOR]

Freshwater scarcity is a problem that is becoming more and more of a concern over the world, and as a result, the search for solutions has become a race against time. One of the most crucial solutions for this issue is seawater desalination. The simplest and easiest type of desalination technology is seawater desalination using a solar still system. This present study reviews the past/current status of vacuum solar still systems to pave the way for researchers to improve this technology. This paper aims to describe the design specifications and highlight the merits and demerits of various vacuum techniques used in solar stills systems upon which research has been done in the recent past. Also, a discussion on future ideas is given with some recommendations in the field of vacuum solar stills improvement to economically produce sustainable potable water. The current study concludes that lowering the operating pressure of solar still systems improves system productivity and efficiency by roughly 100% and 70%, respectively. According to the research, forced vacuums account for 52% of all vacuums, while natural vacuums account for 48%. Forced vacuum is an ideal method since it combines creating vacuum conditions and evacuating the non-condensable gases, which is not possible in a natural vacuum. The system productivity and efficiency of the forced vacuum conditions are higher by 80% and 25% than that of the natural vacuum conditions. The cost of freshwater produced per liter in natural vacuum conditions is less than that of forced vacuum conditions. • Solar still systems are reviewed with an emphasis on vacuum circumstances. • Two methods for applying vacuum conditions; natural and forced vacuum. • Forced vacuums account for 52% of all vacuums, while natural vacuums account for 48%. • Natural vacuum accompanies problems related to maintenance and space requirements. • Forced vacuum is the best technique as it achieves vacuum conditions and expells the NCG. [ABSTRACT FROM AUTHOR]

Due to increasing amounts of energy being supplied by intermittent renewable energy sources, future energy systems need to be able to react flexibly to sudden changes. To address this challenge, a large body of research is devoted to improving the utilization of energy flexibility of various types of energy resources on the supply and demand side. This is commonly done by applying mathematical models. The objective of this paper is to review such models and identify common modeling approaches used to quantify and optimize the use of flexible energy resources. The literature review is conducted systematically, encompassing 215 publications that feature 694 models of different energy resources. The main distinction of this work, in comparison to other reviews on the topic of energy flexibility lies in its focus on the mathematical formulation of models of energy resources and the quantification of the models' level of detail. The aim is to identify common modeling approaches and the corresponding research problems they address. The review shows that the majority of research efforts are directed towards the management and optimization of distributed energy resources. The most commonly employed modeling approach involves abstract black-box models with limited levels of detail. Linear programming and meta-heuristics are frequently used to optimize energy flexibility. A critical reflection of the current common practice is conducted and recommendations for future research are formulated. [Display omitted] • Literature review of 215 reports presenting model approaches for energy flexibility. • Categories of research problems identified and deduction of two main research focuses. • Presenting models of common energy resources classified into different model types. • Mostly low level of detail seen in modeling energy flexibility. • Optimization models are used to represent and quantify flexibility. [ABSTRACT FROM AUTHOR]

Occupant behavior in buildings might result into gap between predicted and actual energy use and cause indoor thermal comfort fluctuations, due to its uncertainty and unpredictability. Previous studies mainly focus on the investigations of occupant behavior impact and modeling methods, whereas few concludes strategic solutions. It is hard to narrow the negative impact of occupant behavior without a clear Impact-Modeling-Solution clue. Thus, the major objective of this research is to review and analyze the impact of occupant behavior and then to summarize modeling methods and strategic solutions by connecting specific techniques and approaches. This paper first investigates the characteristics of occupant behavior and then discusses the impact. It indicates that thermal comfort (environmental condition) triggers occupant actions with corresponding building systems, resulting in energy load changes. The occupant behavior in turn causes thermal comfort fluctuations. The strategic approaches of traditional methods such as surveys, experiments/tests and simulations, and artificial intelligence (AI)-based techniques are analyzed respectively. It is found that the intelligent approach shows high robustness in addressing the uncertain and unpredictable characteristics of occupant behavior in buildings, compared with traditional methods. The AI-based methods and data-driven approaches can enhance the prediction of building energy consumption and the recognition of occupant's thermal comfort. Typical modeling methods and flowchart for occupant behavior are presented with comparisons. The novel physics-based and data-driven model which performs strong adaptability, high decision-making efficiency and fast response of the controller is especially introduced. The corresponding improvements and future directions are also proposed to reach optimal effects. • The research clue of Impact-Modeling-Solution for occupant behavior in buildings is proposed. • Traditional methods and AI-based techniques and data-driven approach are compared. • Typical modeling methods for occupant behavior are presented with comparisons. • Typical strategic solutions are presented upon connections with modeling scopes and methods. • AI-based approaches to address building energy prediction and thermal comfort are summarized. [ABSTRACT FROM AUTHOR]

Over the past few years, numerous countries have rapidly expanded the number and size of their high-tech clean fabrications, to keep pace with electronic devices and Internet needs. Moreover, extremely strict dry-bulb temperature, relative humidity, and particle concentration requirements cause high-tech cleanrooms to consume enormous energy, which is nearly three times the average energy consumed by data centers. Reducing energy use while ensuring the required built environment for normal production has become key challenges in high-tech clean manufacturing, and gradually attracted public and academic attention. However, different from extensive research and review studies conducted on data centers, no study has systematically reviewed state-of-the-art research on the energy aspects of high-tech cleanrooms. Therefore, this paper comprehensively reviews the research work on energy performance and energy conservation methods for high-tech cleanrooms. The main features and energy use status of high-tech cleanrooms are presented and analyzed. The energy models and evaluation metrics of high-tech cleanrooms, as well as the performance assessments and analysis of their environmental control systems (i.e., air-conditioning systems) are summarized and elaborated. Efforts on the performance improvement and energy conservation of high-tech cleanrooms, particularly air-conditioning systems, are also reviewed from multiple aspects, i.e., cold-heat offset reduction, air exchange rate, and airflow resistance optimization, and cooling plant efficiency improvement. A future framework for establishing smart, sustainable, and efficient high-tech cleanrooms is also proposed and discussed. [Display omitted] • A comprehensive review on energy research of high-tech cleanrooms is presented. • Main features and energy use of high-tech cleanrooms are categorized and analyzed. • Energy performance & its assessment methods for high-tech cleanrooms are summarized. • Exiting energy conservation methods and latest technology development are reviewed. • Future perspectives for smart and sustainable high-tech cleanrooms are elaborated. [ABSTRACT FROM AUTHOR]

In view of the current geopolitical situation, the EU and its Member States are accelerating efforts to reduce their dependency on fossil fuel imports, while simultaneously tackling the climate crisis. With heating in buildings accounting for a large share of the energy consumption in the EU, policies to phase-out fossil fuels for heating and to switch to renewables are key elements. In the context of the proposed actions to phase-out fossil fuels at EU level, this article provides a systematic analysis of current and planned phase-out regulations for fossil fuel boilers in the EU Member States. The paper quantifies the share of energy consumption for heating that is addressed by such regulations and finds that the current regulations only address about 10% of the total fossil energy consumption for heating in the EU. The share increases to almost 30% when considering the planned regulations, reflecting the fact that large energy consumers such as Germany and the Netherlands have announced such regulations. The analysis shows that several Member States with high energy consumption for heating have neither implemented nor announced plans to introduce phase-out regulations for fossil fuel heating. The study concludes that immediate policy action is needed both at EU and at Member State levels. At EU level, the proposed introduction of an end-date for stand-alone fossil fuel boilers needs to be substantiated and implemented into the legislative framework. At the national level, phase-out regulations for fossil fuel boilers need to be expanded both in quantity and scope. [Display omitted] • Systematic analysis of phase-out regulations for fossil fuel boilers in the EU. • Only 10% of the EU fossil energy used for heating is covered by phase-out regulations. • Including planned regulations, the share of heating energy covered by phase-out regulations increases to almost 30%. • Comparison of different approaches for implementing regulations for phasing out fossil fuel boilers. [ABSTRACT FROM AUTHOR]

As a non-Arctic country and a major energy consumer, China is increasingly interested in participating in Arctic energy development. This study aims to investigate potential strategies to promote China's participation in Arctic energy development. Accordingly, this study analyzes the strengths, weaknesses, opportunities, and threats (SWOT) of China's participation in Arctic energy development based on a discussion of the current status of Arctic energy development and the Arctic policies of major countries. In addition, this work develops strategies in accordance with the above analysis. The results show that China has strengths in terms of capital, energy demand, policy support, and international cooperation when participating in Arctic energy development, while its weaknesses include the lack of core technology and equipment, high carbon intensity of energy development, and geographical disadvantage. China faces opportunities stemming from conflicts among Arctic states, the advancement of global carbon neutrality, and the development of Arctic waterway while facing threats such as increased competition, international public opinion pressure, high development costs, environmental risks, and pandemic instability. Under an integrated framework, this work offers four strategies: Strength-Opportunity (SO), Strength-Threat (ST), Weakness-Opportunity (WO), and Weakness-Threat (WT). Finally, this study proposes specific measures in four areas, including strengthening policy support, promoting technical research and development, enhancing international cooperation, and improving enterprise competitiveness. [Display omitted] • This study examines China's participation in Arctic energy development. • This paper reviews the status of fossil and non-fossil energy in the Arctic. • This study compares the Arctic energy development strategies of major countries. • This study proposes four strategies, namely SO, ST, WO, and WT. [ABSTRACT FROM AUTHOR]

Under the rising pressure for low carbon energy transitions in Northeast Asia (NEA), interconnecting local power grids for interstate power trade allows to share reserve capacity and to redistribute intermittent renewable energy across time zones, contributing to regional sustainability. Using a linear programming model that minimizes total energy system costs to meet hourly power demand, we build a hypothetical electricity transmission model for three urban demand centers interconnecting China, South Korea, and Japan to test economic and environmental competitiveness of the trilateral power trade with carbon pricing. In the economic perspective our results indicate that interstate electricity trade enables cost savings at all levels of CO2 prices tested (0–180USD/ton of CO2 emitted) through more efficient fuel consumptions on an hourly basis at the NEA regional level. However, ambitious carbon pricing (above 90 USD/ton CO2 emitted) is still essential for trade to ensure equitable trade impacts for all participating nodes. While trade utilizes gaps in resource availabilities and technology costs across nodes in cost minimization, results show inadequate carbon pricing leads to extra thermal combustions at the local level although regional total emissions reduce. • This paper proposes a phased approach to Asia Supergrid by interconnecting the three demand centers of Northeast Asia, China North, South Korea, and Japan West, without remote renewable sources as a regional energy cooperation model to accelerate carbon phaseout. • The trilateral power trade is effective in reducing the total cost of energy system at all levels of CO2 prices tested (0–180USD/ton of CO2 emitted) compared to autarkic generation, but ambitious carbon pricing (above 90) is essential for ensuring low carbon transitions at all participating nodes. • Trade enables cost savings by increasing renewable power output in export nodesfor transmission and avoiding fuel/emission cost at import nodes. New investment cost for line construction and renewable expansion is offset. [ABSTRACT FROM AUTHOR]

Countries with high energy demand but limited renewable energy potential are planning to meet part of their future energy needs by importing green hydrogen. For potential exporting countries, in addition to sufficient renewable resources, industrial preconditions are also relevant for the successful implementation of green hydrogen production value chains. A list of 36 "Green H2 Products" needed for stand-alone hydrogen production plants was defined and their economic complexity was analyzed using international trade data from 1995 to 2019. These products were found to be comparatively complex to produce and represent an opportunity for countries to enter new areas of the product space through green diversification. Large differences were revealed between countries in terms of industrial preconditions and their evolution over time. A detailed analysis of nine MENA countries showed that Turkey and Tunisia already possess industrial know-how in various green hydrogen technology components and perform only slightly worse than potential European competitors, while Algeria, Libya, and Saudi Arabia score the lowest in terms of calculated hydrogen-related green complexity. These findings are supported by statistical tests showing that countries with a higher share of natural resources rents in their gross domestic product score significantly lower on economic and green complexity. The results thus provide new perspectives for assessing the capabilities of potential hydrogen-producing countries, which may prove useful for policymakers and investors. Simultaneously, this paper contributes to the theory of economic complexity by applying its methods to a new subset of products, and using a dataset with long-term coverage. • HS code list of 36 technology components for off-grid green H2 production. • Identified components and related goods are comparatively complex to produce. • China achieved a globally unique increase in relevant exports from 1995 to 2019. • In the MENA region, Tunisia and Turkey score the highest on H2-related green complexity. • Fossil fuel exporters have below-average industrial economic and green complexity. [ABSTRACT FROM AUTHOR]

Energy subsidies can incentivise the overconsumption of energy resources and contribute to other economic or social distortions. In this paper, an ex-post analysis is presented that explores the extent to which electricity subsidy reform could have reduced Iran's energy demand during the period 1984–2017. It also quantifies the techno-economic and environmental benefits that could have been achieved through such reforms. A time-varying econometric model is linked to an energy systems optimisation model. The former estimates electricity demand under different subsidy removal scenarios, and the latter identifies the cost-optimal generation mix to meet the demand. The results of cost-optimal transition pathways under subsidy removal scenarios are compared with the real-world energy system development during the study horizon. The comparison reveals that the subsidy reform could have reduced the total cumulative electricity consumption by 22%. Renewable share in power generation could have increased from 5% to 15%. Moreover, the reform combined with a cost-optimal generation pathway would have saved $69 billion and avoided 944 million tons of CO 2 emissions. The analysis also shows that every five-year delay in subsidy removal causes about 100 million tons of additional CO 2 emissions. Finally, the paper presents lessons learnt for future energy modelling. • An ex-post analysis quantifies the benefits of energy subsidy reform in the power sector. • The total cumulative electricity consumption could have been reduced by 22%. • Renewable share in power generation could have tripled. • Subsidy reforms combined with cost-optimal generation could have saved $69 billion. • The paper presents lessons learnt for future energy modelling. [ABSTRACT FROM AUTHOR]

The parametric uncertainties inherent in the models of renewable and sustainable energy systems (RSESs) make the associated decision-making processes of integrated resource operation, planning, and designing profoundly complex. Accordingly, intelligent energy management strategies are recognised as an effective intervention to efficiently accommodate the variability inherent in various input data and integrate distributed demand-side flexibility resources. To identify the key methodological and content gaps in the area of stochastic dispatch and planning optimisation of RSESs in the presence of responsive loads, this paper systematically reviews and synthetically analyses 252 relevant peer-reviewed academic articles. The review reveals that academic studies have utilised a wide variety of methods for the joint quantification of uncertainties and procurement of demand response services, while optimally designing and scheduling RSESs. However, to minimise simulation-to-reality gaps, research is needed into more integrated energy optimisation models that simultaneously characterise a broader spectrum of problem-inherent uncertainties and make behaviourally-founded use of flexible demand-side resources. More specifically, the review finds that while the research in this area is rich in thematic scope, it is commonly associated with strong simplifying assumptions that disconnect the corresponding approaches from reality, and thereby obscure the real challenges of transferring simulations into the real world. Accordingly, based on the descriptive analyses conducted and knowledge gaps identified, the paper provides useful insights into myriad possibilities for new research to more effectively utilise the potential of responsive loads, whilst simultaneously characterising the most salient problem-inherent parametric sources of uncertainty, during the investment planning and operational phases of RSESs. [Display omitted] • A systematic review of stochastic energy optimisation with demand response is conducted. • 252 relevant publications are identified in the literature and synthetically analysed. • Relevant research is rich in thematic scope, but involves strong simplifying assumptions. • Challenges ahead and opportunities for future research in the area are discussed. • Computational burden remains the most significant barrier to minimising reality gaps. [ABSTRACT FROM AUTHOR]

Given the ongoing transition towards a more decentralised and adaptive energy system, the potential of blockchain-enabled smart contracts for the energy sector is being increasingly recognised. Due to their self-executing, customisable and tamper-proof nature, they are seen as a key technology for enabling the transition to a more efficient, transparent and transactive energy market. The applications of smart contracts include coordination of smart electric vehicle charging, automated demand-side response, peer-to-peer energy trading and allocation of the control duties amongst the network operators. Nevertheless, their use in the energy sector is still in its early stages as there are many open challenges related to security, privacy, scalability and billing. In this paper, we systematically review 178 peer-reviewed publications and 13 innovation projects, providing a thorough analysis of the strengths and weaknesses of smart contracts used in the energy sector. This work offers a broad perspective on the opportunities and challenges that stakeholders using this technology face, in both current and emergent markets, such as peer-to-peer energy trading platforms. To provide a roadmap for researchers and practitioners interested in the technology, we propose a systematic model of the smart contracting process, by developing a novel 6-layer architecture, as well as presenting a sample energy contract in pseudocode form and as open-source code. Our analysis focuses on the two mainstream application areas we identify for smart contract use in this area: energy and flexibility trading, and distributed control. The paper concludes with a comprehensive, critical discussion of the advantages and challenges that must be addressed in the area of smart contracts and blockchains in energy, and a set of recommendations that researchers and developers should consider when applying smart contracts to energy system settings. [Display omitted] • Review of Smart Contracts for energy applications based on 178 peer-reviewed articles • Categorisation of literature into sub-areas for smart contract use in energy • Insights into 13 industrial and demonstration projects in this area • Presentation of a sample "Energy Smart Contract" with open-source sample code • Comprehensive discussion of challenges in smart contracts adoption in this field • Recommendations of issues to consider when implementing smart contracts in energy [ABSTRACT FROM AUTHOR]

Energy subsidies can incentivise the overconsumption of energy resources and contribute to other economic or social distortions. In this paper, an ex-post analysis is presented that explores the extent to which electricity subsidy reform could have reduced Iran's energy demand during the period 1984–2017. It also quantifies the techno-economic and environmental benefits that could have been achieved through such reforms. A time-varying econometric model is linked to an energy systems optimisation model. The former estimates electricity demand under different subsidy removal scenarios, and the latter identifies the cost-optimal generation mix to meet the demand. The results of cost-optimal transition pathways under subsidy removal scenarios are compared with the real-world energy system development during the study horizon. The comparison reveals that the subsidy reform could have reduced the total cumulative electricity consumption by 22%. Renewable share in power generation could have increased from 5% to 15%. Moreover, the reform combined with a cost-optimal generation pathway would have saved $69 billion and avoided 944 million tons of CO 2 emissions. The analysis also shows that every five-year delay in subsidy removal causes about 100 million tons of additional CO 2 emissions. Finally, the paper presents lessons learnt for future energy modelling. • An ex-post analysis quantifies the benefits of energy subsidy reform in the power sector. • The total cumulative electricity consumption could have been reduced by 22%. • Renewable share in power generation could have tripled. • Subsidy reforms combined with cost-optimal generation could have saved $69 billion. • The paper presents lessons learnt for future energy modelling. [ABSTRACT FROM AUTHOR]

The parametric uncertainties inherent in the models of renewable and sustainable energy systems (RSESs) make the associated decision-making processes of integrated resource operation, planning, and designing profoundly complex. Accordingly, intelligent energy management strategies are recognised as an effective intervention to efficiently accommodate the variability inherent in various input data and integrate distributed demand-side flexibility resources. To identify the key methodological and content gaps in the area of stochastic dispatch and planning optimisation of RSESs in the presence of responsive loads, this paper systematically reviews and synthetically analyses 252 relevant peer-reviewed academic articles. The review reveals that academic studies have utilised a wide variety of methods for the joint quantification of uncertainties and procurement of demand response services, while optimally designing and scheduling RSESs. However, to minimise simulation-to-reality gaps, research is needed into more integrated energy optimisation models that simultaneously characterise a broader spectrum of problem-inherent uncertainties and make behaviourally-founded use of flexible demand-side resources. More specifically, the review finds that while the research in this area is rich in thematic scope, it is commonly associated with strong simplifying assumptions that disconnect the corresponding approaches from reality, and thereby obscure the real challenges of transferring simulations into the real world. Accordingly, based on the descriptive analyses conducted and knowledge gaps identified, the paper provides useful insights into myriad possibilities for new research to more effectively utilise the potential of responsive loads, whilst simultaneously characterising the most salient problem-inherent parametric sources of uncertainty, during the investment planning and operational phases of RSESs. [Display omitted] • A systematic review of stochastic energy optimisation with demand response is conducted. • 252 relevant publications are identified in the literature and synthetically analysed. • Relevant research is rich in thematic scope, but involves strong simplifying assumptions. • Challenges ahead and opportunities for future research in the area are discussed. • Computational burden remains the most significant barrier to minimising reality gaps. [ABSTRACT FROM AUTHOR]

Given the ongoing transition towards a more decentralised and adaptive energy system, the potential of blockchain-enabled smart contracts for the energy sector is being increasingly recognised. Due to their self-executing, customisable and tamper-proof nature, they are seen as a key technology for enabling the transition to a more efficient, transparent and transactive energy market. The applications of smart contracts include coordination of smart electric vehicle charging, automated demand-side response, peer-to-peer energy trading and allocation of the control duties amongst the network operators. Nevertheless, their use in the energy sector is still in its early stages as there are many open challenges related to security, privacy, scalability and billing. In this paper, we systematically review 178 peer-reviewed publications and 13 innovation projects, providing a thorough analysis of the strengths and weaknesses of smart contracts used in the energy sector. This work offers a broad perspective on the opportunities and challenges that stakeholders using this technology face, in both current and emergent markets, such as peer-to-peer energy trading platforms. To provide a roadmap for researchers and practitioners interested in the technology, we propose a systematic model of the smart contracting process, by developing a novel 6-layer architecture, as well as presenting a sample energy contract in pseudocode form and as open-source code. Our analysis focuses on the two mainstream application areas we identify for smart contract use in this area: energy and flexibility trading, and distributed control. The paper concludes with a comprehensive, critical discussion of the advantages and challenges that must be addressed in the area of smart contracts and blockchains in energy, and a set of recommendations that researchers and developers should consider when applying smart contracts to energy system settings. [Display omitted] • Review of Smart Contracts for energy applications based on 178 peer-reviewed articles • Categorisation of literature into sub-areas for smart contract use in energy • Insights into 13 industrial and demonstration projects in this area • Presentation of a sample "Energy Smart Contract" with open-source sample code • Comprehensive discussion of challenges in smart contracts adoption in this field • Recommendations of issues to consider when implementing smart contracts in energy [ABSTRACT FROM AUTHOR]

The demand of urban environments for charcoal and fuelwood is responsible for the unprecedented forest degradation in Mozambique. Not surprisingly, solid fuels comprise the bulk of the energy demand in the country, and a marginal number of urban households use clean energy sources for cooking. Evidence shows that biomass consumption has a disproportional effect on women. Their needs are often overlooked when policies are designed, and they are yet to benefit fully from the outcomes of these policies. Through a systematic integrative literature review of 154 sources, this paper shows that the existing energy transitional frameworks are arguably circumscribed by the Global North where access to modern energy sources is no longer the subject of debate. Instead, the energy transition debates are driven mainly by the climate change paradox. This paper develops arguments for a theoretical framework for gendered energy transition , focusing on developing economies. By exploring the Mozambican context, a localised energy system assessment was performed followed by an analysis of the gender role and the factors that drive fuel choice decisions within urban households. The main finding is that the existing frameworks lack a gender perspective and a theoretical framework to address solid fuels dependence in urban environments. Building on the current literature, we illustrate a potential framework for gendered energy transition using an example of the use of liquified petroleum gas and electricity. The critical recommendation is that debates on the gender-energy nexus require assertion of the efficacy of the existing transition frameworks through gender audit research. • Urban environments demand for solid fuels appears to cause forestry degradation in Mozambique. • Biomass consumption has a disproportional effect on women. • The authors suggest a novel theoretical framework to address gendered energy transitions. • A location-specific approach is adopted to assess gender roles and the factors that drive fuel choice decisions. • The paper illustrates a theoretical framework for gendered energy transition using an example of LPG and electricity. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of reducing the energy consumption of servo-actuated systems by means of the optimal selection of the electric motor and of the gearbox from catalogs of commercially available components. This idea overcomes a lack of literature: on the one hand, the energy efficiency of these systems is usually tackled through the improvement of the efficiency of each individual component rather than on focusing on a global efficiency goal; on the other one, the methods to select these components neglect the specific issue of energy consumption, being usually focused on cost reduction or minimum motor sizing. The aim of this paper is to propose a model-based design approach for the energy-optimal concurrent selection of motor, coupling and gearbox in servo-actuated systems. The method is based on the use of scaling rules, which are developed to condensate all the relevant characteristics of the system into just two parameters: the gearbox transmission ratio and the motor continuous torque at stall. Scaling rules summarize and reveal the complex relations between the system parameters and energy consumption, and hence are incorporated into the analytic formulation of the overall energy consumption. The use of these metamodels, that can be easily obtained from data provided in datasheets, allows casting the design problem as a constrained optimization problem with just two design variables. The outlined procedure is completely automatic and does not require any design iteration. The results, evaluated for two application examples, demonstrate the relevant energy savings provided by the proposed method. • Energy-optimal design procedure for servo-actuated mechatronic systems. • Use of scaling rules to represent the relevant components from catalog data. • Scaling rules do not affect the accuracy of the energy estimation model. • A significant energy reduction is achieved. • The method is appealing for scientists and industry practitioners. [ABSTRACT FROM AUTHOR]

Investing in energy efficiency is considered to be an effective way to reduce the carbon emissions. However, the resulting CO 2 savings may be partially or totally offset by the rebound effect (RE). This paper goes beyond the traditional energy RE to investigate the rebound effect as related to CO 2 emissions, aims to explore the direct CO 2 rebound effect (CRE) in urban households at the provincial level. To achieve the objective, this study uses IPCC carbon emissions accounting method, then proposes an elasticity approach and constructs an individual fixed-effect variable coefficient panel data model. The results show that the total CO 2 emissions from household energy consumption were rising in most provinces during 2002–2017. The purchased electricity and heat CO 2 emissions are growing faster than combustion CO 2 emissions. Regarding the magnitude of the CRE, there are three types of direct CRE among urban households in China: the backfire effect, partial rebound effect and super conservation effect. Overall, the average direct CRE in urban households is 59.90%; specifically, the western region has the highest direct CRE (90.92%), compared with the eastern region (52.84%) and central region (24.88%). The government should take into account the CRE of households, in order to avoid overestimating the carbon reduction. Attention should also be paid to the differences between provinces when formulating energy policies. The analysis above helps local governments to formulate effective energy policies to promote households' carbon emission reduction. • This paper proposes an elasticity method for estimating CO 2 rebound effect. • The carbon emissions from household energy consumption are calculated. • There are three types of direct CO 2 rebound effect among urban households in China. • The average direct CO 2 rebound effect in urban households is 59.9%. [ABSTRACT FROM AUTHOR]

Energy systems models are used to analyze long-term policies and pathways for reducing greenhouse gas (GHG) emissions. A subset of these models is bottom-up, engineering-economic models that minimize the costs of achieving exogenously specified annual reductions in GHG emissions to limit increases in global average temperature. Referred to as deep decarbonization models (DDM), their outputs include the levels and timing of energy investments that satisfy future energy demand projections across all energy sectors over multiple decades. This paper conducts an epistemological review of 42 articles on DDMs published in the last ten years. In its two-part review of the DDM literature, this paper first identifies the mathematical formulations, underlying assumptions, and constraints of the modeling framework that impact their outcomes. Next, it tabulates and discusses the possible limitations in assessing such models in terms of their epistemic values, i.e., creating new knowledge beyond common sense in capturing the possible realities; and non-epistemic values, i.e., policy relevance and usefulness of the modeling framework. This paper suggests the need for more studies and continued discussion on the potential strengths, usefulness, and limitations of the DDM framework. DDMs might be useful in identifying multiple pathways towards deep decarbonization of future energy systems, but there will always be a need to proceed with caution, strive for better models, and be more circumspect with respect to the associated policy conclusions. • Conducted review of 42 articles on DDMs published in the last ten years. • Identifies the mathematical formulations of the DDMs impacting their timing, costs, and other economic outcomes. • Discusses the limitations in assessing such models in terms of their epistemic and non-epistemic values. • No uniformity regarding the terms used for their ability to capture reality or to give policy insights. • Many DDM formulations omit other societal objectives and their associated opportunity costs. • Need for continued discussion on potential strengths, usefulness, and limitations as compared to other policy frameworks. [ABSTRACT FROM AUTHOR]