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

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]

This paper explores opportunities for effective policy intervention for residential energy savings in southern China, by analyzing achievable potential of residential energy savings in the city of Xiamen as a case study. In contrast to static technical and economic potential analyses, the achievable potential analysis is based on dynamic energy consumption projections, which consider two real-world factors: (1) gradual ramping-up adoption process of advanced technical measures; and (2) consumers’ adoption of these measures. A bottom-up type Residential Energy Consumption (REC) projection model specifically tailored for southern China was developed in this paper, based on the general logic and calculation principles utilized in the U.S. EIA’s “National Energy Modeling System (NEMS),” and the adoption theory of advanced technical measures proposed by Kastovich. This REC projection model was then used as a policy analysis tool to quantitatively evaluate the impact of various policies on residential energy savings in the case study city of Xiamen. The analysis of the Xiamen case shows that although there is a significant technical potential for residential energy savings in the city (about 20.9–24.9%), the maximum achievable potential (MAP) in 2020 is only about 8.3–8.4% of that year’s business-as-usual baseline consumption. Moreover, with existing policies only about one-fourth to half of the calculated MAP is likely to be achieved by 2020. These findings indicate that in order to realize a larger share of achievable potential for residential energy savings in China, additional and more effective polices are needed. [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]

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]

Zero energy buildings (ZEBs) are targeted by several developed countries around the world which consequently promotes the progress toward achieving ZEBs. The concept of ZEBs is, however, uncommon in developing economies such as Oman. In 2011, The Research Council of Oman has announced a competition to design, construct and operate buildings that embrace sustainability principles. The first five eco-friendly buildings were designed and constructed by academic institutions in different climatic conditions of Oman. This project has significantly contributed toward raising awareness of energy efficiency and renewable energy systems in buildings. This paper outlines the design of sustainable energy systems of one of these five buildings. The ZEB prototype is located at the Sultan Qaboos University campus in Muscat, which is an extremely hot climate as classified by the ASHRAE Standard 169-2013. The ZEB building was designed with full manipulation of natural energy. This paper also reports the experimental results of its one year of operation. The results showed that energy use intensity (EUI) of 103 kWh/m2 was achieved by this building. The building was less than 3% from achieving its net-zero energy source/site/emissions status. Nonetheless, it was able to achieve a positive energy cost status because of the financial credits received from the exported energy, which is subjected to high cost feed-in tariffs. When grid interaction was considered, 40% of the building load was met by site generation. For 33% of the time, this building was independent of the electrical grid, which is comparable to other net-zero energy buildings located in other climates. While several experimental studies for ZEB performance have been described in literature for heating dominated climates, very few experimental studies have been published for cooling dominated climates. Hence, this study aims to fill the gap in the knowledge of energy performance of ZEBs located in this region. • The design of sustainable energy systems for ZEB in a hot climate is described. • ZEB is feasible in cooling dominated climate. • Experimental result for one year of operation for a prototype ZEB is described. • For 33% of the time, the building was independent of the electrical grid. 40% of the building load was met by the site generation. [ABSTRACT FROM AUTHOR]

Energy efficiency of current Waste-to-Energy plants is mainly limited by high temperature corrosion combined with temperature fluctuation of flue gas. This paper introduces a technology based on Phase Change Materials in the combustion chamber and its contribution to higher overall electrical efficiency. This technology encapsulates aluminium alloy-based Phase Change Materials in ceramic bricks similar to traditional refractory bricks in the combustion chamber. The proposed brick allows steam superheating on waterwall by absorbing temperature fluctuations and delivering a higher heat flux. Two studies are carried out to realize the technology development from refractory bricks to waterwall system. Study One adopts Dynamic Thermal Network method to model the heat transfer on waterwall with and without the novel brick. Real plant information is used as boundary condition to locate the design points of the novel bricks. Study Two conducts experiment to validate the numerical model, and performs a transient analysis of the waterwall to compare the thermal dampening and superheating effect of Phase Change Material-based waterwall. From the result, there is a 10% improvement in energy conversion efficiency on the waterwall by introducing the novel technology. Lastly, this paper introduces an integration scheme of three types of Phase Change Materials-based bricks in the waterwall to achieve continuous superheating of steam. A 34% electrical efficiency can be achieved by producing over 600 °C of superheated steam with this new plant configuration. The result shows that this new technology is highly applicable and promising to upgrade the overall efficiency of Waste-to-Energy plants. • Latent heat-based brick is proposed to buffer temperature fluctuation in waterwall. • Thermal network model is used to study the transient response of the new brick. • Experimental result is employed to validate the numerical model in system level. • Technology integration of new brick-based waterwall to Waste-to-Energy plant proposed. • High steam parameter over 600 °C can be achieved with proposed plant configuration. [ABSTRACT FROM AUTHOR]

The valorisation of the organic fraction of municipal solid waste (OFMSW) in the circular economy context is of outmost importance. This review aimed to examine the state-of-the-art valorisation technologies of OFMSW as resource for bioethanol and biodiesel. Firstly, feedstock mapping was performed, where high fluctuation of parameters was revealed. Considering the mean values, the stoichiometries of mechanically and source-sorted OFMSW are C 22 H 44 O 28 N and C 20 H 36 O 16 N, respectively. The substrate's mean carbohydrates (50%) and lipids (13%) contents reflect its potential in bioethanol and biodiesel production, respectively. As far as bioethanol is concerned, this paper critically reviewed the existing variance of second-generation bioethanol production methodologies from OFMSW revealing that high bioethanol yields (over 80%) could be achieved if the treatment steps of pretreatment, enzymatic hydrolysis and fermentation are synergistically compiled. To this end, bioethanol yield could benefit from suitable enzymatic blends. Furthermore, this paper discussed about different ways of oil extraction from OFMSW and various biodiesel production techniques. Soxhlet extraction combined with alkaline transesterification emerged as the most widely applied biodiesel production line from OFMSW. The novelty of this literature review lies in the integration of both bioethanol and biodiesel production processes, in a biorefinery concept that would allow the production of both biofuels along with that of biogas. This integration scenario rendered an energy efficiency expressed as energy content in products per energy in raw materials equal to 68%, proving that OFMSW is a feedstock that could meet the sustainability criteria for biofuels production. Image 1 • Up to date information on the composition of OFMSW. • Bioethanol production from OFMSW; pretreatment, hydrolysis, fermentation, stillage. • Biodiesel production from OFMSW; oil extraction, transesterification. • Bioethanol, biodiesel, biogas production from OFMSW under the biorefinery concept. • Integrated biorefinery exhibits various technical and energy benefits. [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]

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]

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]

Abstract The present work investigates solid biofuel, derived from household food waste (food residue biofuel, FRB) as a potential bioenergy source in cement manufacturing. Up-to-date investigations of household food waste as a solid fuel focused on composition and heating value, yet no results are available regarding impact on plant efficiency and emissions upon utilization. A multidimensional model based on fundamental principles (mass and enthalpy balances) is used together with actual data from fossil fuel operation to identify and quantitatively asses the impacts on plant performance, product quality and atmospheric emissions. Τhe energy needed to prepare low moisture FRBs is determined and suitable processes are singled out. Key issues of cement plant operation are identified and quantitatively assessed via simulation in an actual dry-process plant, when FRBs substitute 20% of thermal energy (provided by petcoke). The facility utilizes 1.65 × 105 tpa of fossil fuels to produce 1.5 × 106 tpa clinker. It is found that energy efficiency falls and clinker production diminishes by about 0.5 t clinker/t FRB. Refractory thermal rating and main blower capacity constraints remain satisfied. Non-biogenic green-house-gas emissions are reduced by ~60 kg/t clinker. Emitted concentrations slightly increase for several pollutants, mainly nitrogen oxides (NO x) hydrogen chloride (HCl) and metals; they decrease for sulphur dioxide (SO 2) and particulates. Maximum emission limits are observed for all regulated pollutants but NO x. Incombustible chlorine and inclusions of alkalis in cement increase by ~9%. To reap the bioenergy benefits and mitigate impacts, blends of FRB (~80%wt) with paper residues (~20%wt) are investigated. Conforming to plant operational constraints and product specifications, the blends ensure production level, environmental compliance and reduced emission rates. The results direct towards customer-tailored FRB blends with lignocellulosic residues, that best suit the design, specific quarry raw materials, operating conditions and individual parameters of the cement plant towards more sustainable cement manufacturing. Highlights • Food waste can be valorized to biochemicals and biofuels, including solid fuels. • Drying to ≤ 15% moisture gives stable, nonhazardous food residue biofuels (FRBs). • Substitution of petcoke by FRBs in cement kilns decreases clinker level. • Lower CO 2 , SO 2 and mercury but higher chlorines and NO x emissions result. • Superior blends of FRB with paper residues improve clinker production and emissions. [ABSTRACT FROM AUTHOR]

Graphical abstract fx1 Abstract Biomass raw materials are widely regarded as a significant source of renewable energy, which significantly reduces the dependence on traditional fossil fuels, especially in the case of countries that are able to obtain biomass from various sources. Recently, pelletization has been widely used for mass and energy densification of biomass to overcome the problems associated with raw material use. As the global pellet market has developed quickly, the use of wood residues became no longer sufficient to fulfill the market needs. The standards of pellets provide limits for both physical and mechanical characteristics of produced pellets. Characteristics of produced pellets depend mainly on the feedstock characteristics as particle size and moisture content and operating conditions as applied pressure and die temperature. Thus, this paper provides rich information on the factors affecting the physical and mechanical properties of granules included in pellets. The main goal of the paper is to review the latest and comprehensive research on the physical and mechanical properties of most types of single and mixed pellets from biomass. The analysis of the effect of properties, adhesives, humidity, pressure and temperature as well as the physical and mechanical properties of the pellets studied was carried out. In addition, the critical and optimal values of various factors for different materials in which the following is of importance: high quality of pellets and biomass from which they are produced were analyzed. The principle and effect of applying post-production conditions as steam explosion and torrefaction on the characteristics of the pellets were reviewed in details. Moreover, this study proposes some recommendations for further development of the pelletization analysis and characteristics. Highlights • Comprehensive research on the characteristics of biomass pellets was studied. • The effect of operating parameters on the characteristics of pellets was analyzed. • New types of binder materials and their impact on the pellets have been introduced. • Future prospects for of the pelletization analysis have been suggested. [ABSTRACT FROM AUTHOR]

Abstract A continually growing awareness of the finiteness of fossil fuel availability coupled with an ever better understanding of the negative effects of fossil fuel consumption has motivated a search for fuels that can be used in place of fossil fuels, but which can be derived from sustainable sources such as growable organic matter. The effects of using biodiesel in existing gas turbines has received less attention than the effects of its use in more traditional internal combustion engines, due to the challenges of using this fuel in the typical aviation environment. This paper will provide a basic knowledge of biodiesel production and qualities, some of the limitations of its use, and modeling techniques for determining its performance within certain applications. A significant part of this paper is focused on reviewing the current state of experimental validation of our understanding of biodiesel performance in gas turbines. Particularly the experiments conducted to date that have measured the gaseous emissions of gas turbines operated with biodiesel as a fuel are reviewed and discussed. The outcome of this study is that turbines are shown to operate quite similarly when operated with biodiesel as they do with jet fuel, but there are significant challenges concerning material compatibility, energetic content, and low temperature characteristics that must be overcome when using biodiesel for aviation purposes. These challenges are less substantial when turbines are operated at ground level, since ground level operations are not generally hindered by extremely low temperatures and limited volume and weight requirements. Unfortunately, very few experiments have been conducted and published concerning this subject. The paper also proposes further research to better understand and optimize the application of biodiesel to gas turbines. Graphical abstract fx1 Highlights • Previous experimental works on utilizing biodiesel in gas turbines are summarized and discussed. • Flue gas composition and engine performance is very comparable between Jet-A and biodiesel in gas turbines. • Biodiesel fuel consumption is higher than Jet-A due to lower comparative heating value. • Several challenges need to be addressed in order to use biodiesel as a fuel replacement for aviation gas turbines. [ABSTRACT FROM AUTHOR]

Abstract Whilst a plethora of literature has viewed technological progress as one of the critical influencing factors in relation to energy consumption and CO 2 emissions, little effort has been made to identify the sectoral differences in the relationship between technological progress and CO 2 emissions. Thereby, this paper remedies the inadequacies in the extant literature by empirically investigating the impact of technological progress on CO 2 emissions, specifically taking into account its heterogeneous effect in various economic sectors. This paper first decomposes the effect of technological progress as taking place in heavy industry, in light industry, in construction industry, and in service industry. A panel quantile regression approach and a balanced city panel data model are then applied, covering the period 2001–2013 in China. The empirical results show that technological progress in heavy industry and light industry surprisingly facilitates a higher level of CO 2 emissions, despite its prominent contribution to energy efficiency improvement. Meanwhile, as distinct from the effect it shows in the heavy and light industries, technological progress in construction and service industries exerts a negative effect on CO 2 emissions. Additionally, this paper further discovers that the strength of the multiple impacts of technological progress also varies with the level of emitters. By studying the heterogeneous effect brought about by technological progress in different economic sectors and emitters, this paper provides a comprehensive understanding of the relationship between CO 2 emissions and technological progress. Highlights • The study considers the sectoral and scale heterogeneity of technological progress in relation to CO 2 emissions. • We apply a panel quantile regression approach to balanced city-level panel data. • Technological progress within different economic sectors exerts different effects on CO 2 emissions. • The role of technological progress in moderating energy intensity varies across emitters. [ABSTRACT FROM AUTHOR]

Abstract Demand response programs offer efficient solutions for many power system problems, such as high generation cost, high demand's peak to average ratio, high emissions, reliability issues and congestion in generation, transmission and distribution systems. Their main function is to assist power systems during peak demand hours and also during contingencies. They are a subcategory of the family of demand side management (DSM) strategies. DR programs are classified into two broad categories; price-based DR programs and incentive-based DR programs. In order to exploit their full potential, DR programs must be implemented optimally. Such a problem, which here is referred to as "DR optimisation problem", is a hot research topic and has been frequently researched in the literature. This paper aims to review different research works on DR optimisation problems. Based on the conducted review, some directions for future research are proposed. Highlights • Demand response programs offer efficient solutions for many power system problems. • Their main function is to assist power systems during peak hours and contingencies. • To exploit their full potential, DR programs must be implemented optimally. • This paper reviews different research works on DR optimisation problems. • Based on the conducted review, some directions for future research are proposed. [ABSTRACT FROM AUTHOR]

Abstract African countries are in a unique position to reap the socio-economic and environmental benefits of renewable resources as a means for meeting increasing energy demand in a sustainable way. A critical obstacle for the deployment of renewable energy technologies in Africa is the difficulty of attracting sufficient and affordable finance. This paper compares the impact of financial conditions on the cost of electricity generation across six renewable and three fossil-based technologies in 46 African countries. The results show large cost variations and highlight the extent to which renewables are disadvantaged by current financial practices. The energy-economy-environment model TIAM-ECN is used to show how lowering financing costs results in a much higher deployment of renewables. For example, solar PV could account for 10–15% of total electricity generation by 2050, even without explicit climate policy, thanks to financial de-risking programmes. The results demonstrate that changes in financing schemes could outweigh the impact of technology learning. This paper also demonstrates that, once ambitious climate policies are in place, reducing financing costs for renewables could be an efficient way to lower greenhouse gas emissions. Financial de-risking is thus a key ingredient for unlocking the renewable energy potential in Africa. Highlights • We show how renewables are disadvantaged by today's financial practices in Africa. • We show how lower financing costs result in a higher deployment of renewables. • PV can account for 10–15% of electricity generation by 2050 without climate policy. • Changes in financing schemes could outweigh the impact of technology learning. • Financial de-risking is key for unlocking the renewable energy potential in Africa. [ABSTRACT FROM AUTHOR]

Abstract Energy efficiency measures and climate policies are closely related to strategic concerns of companies, and reduction of greenhouse gas (GHG) emissions has become an important indicator of energy efficiency measures. This paper discusses the application aspects of organizational carbon footprint (CF) for telecommunications companies. In order to better understand the structure of overall (direct and indirect) GHG emission, the model for calculating the organizational CF was established for the case of a telecom operator in its initial stages of carbon policy. In order to understand the importance of scope 3 categories in the overall CF, calculated results were compared to CF results reported by three other European telecommunications operators. The results for a particular case based on Slovenian operator revealed that the largest contributor to GHG emissions is the consumption of purchased electricity. The employees' commute to and from work, the use of company-owned vehicles, and heating represent the next major sources of GHG emissions. It was shown that the most contributive upstream scope 3 aspects are similar for various European telecommunication operators and that exclusion of some categories along the supply chain may give a distorted image of organizational CF. However, the comparative analysis revealed that using only the company's own-recorded in-house data can be far from sufficient to make conclusions which GHG emissions scope contributes the highest share to the overall organizational CF of telecommunications companies. In this context, this paper reveals new findings on the relevance of CF determination for telecommunications companies as a guideline for reconsidering their energy efficiency and sustainability plans. Highlights • Carbon footprint analysis can be used to reconsider the energy efficiency plans of a telecom operator. • The most contributive scope 3 aspects are similar for various European telecommunication operators. • Giving attention to scope 1 and 2 emissions only may be misleading. • Exclusion of scope 3 categories may give a serious distorted image of organizational carbon footprint. [ABSTRACT FROM AUTHOR]

Abstract In recent years, China's wind power industry has developed rapidly, and become the global wind power leader. At the same time, China's wind power industry is also facing many problems and challenges. In this paper, a comprehensive assessment is presented to reveal the development history of China's wind power industry, power demand and cost, regional distribution of wind power, wind turbine manufacturers, and government incentives to wind power industry. Subsequently, future development and challenges are proposed, focusing on the challenge of wind power integration and consumption, the challenge of management and market competition mechanism, and the challenge of large-scale and rapid development. Finally, the corresponding measures are put forward. The fundamental goal of this paper is to understand the history, current situation and future challenges of China's wind power industry. Highlights • A comprehensive assessment on the development of China's wind power industry is presented. • The development history of China's wind power and energy demand are introduced. • Multi factors related to China's wind power industry are investigated. • Future challenges and corresponding measures of China's wind power industry are proposed. [ABSTRACT FROM AUTHOR]

Abstract As a result of the increased awareness of the dangers posed by global climate changes (mainly caused by growing global energy consumption needs), the quest for clean and sustainable energy future is becoming of paramount importance. This can be largely realized via a large-scale integration of variable renewable energy sources (RESs) such as wind and solar, which have relatively low carbon footprints. In many power systems, the level of integration of such resources is dramatically increasing. However, their intermittent nature poses significant challenges in the predominantly conventional power systems that currently exist. Among others, frequency and voltage regulation issues can, for example, arise because of improperly balanced and largely uncoordinated RES supply and demand. Generally, the higher the integration level of intermittent power sources is, the higher the flexibility needs are in the system under consideration. Flexibility, in a power systems context, refers to the ability of such a system to effectively cope with unforeseen changes in operational situations, which are mainly induced by the inherent uncertainty and variability arising from the supply side, demand side or any other external factors. In the absence of appropriate flexibility mechanisms, it is increasingly difficult to manage the imbalances between generation and demand as a result of their natural variations in real-time. This paper presents an extensive and critical review of the main existing and emerging flexibility options that can be deployed in power systems to support the integration of "carbon-free" and variable power production technologies. Starting from a broader definition of flexibility, we highlight the growing importance of such flexibility in renewable-rich energy systems, and provide insights into the challenges and opportunities associated with various flexibility options provided by different technologies. Highlights • This paper presents an extensive and critical review of the main existing and emerging flexibility options. • Starting from a broader definition of flexibility, we highlight the growing importance of such flexibility. • Insights into the challenges and opportunities associated with various flexibility options are provided. • Certain barriers that may hinder their developments in the short to medium terms are also provided. [ABSTRACT FROM AUTHOR]

Abstract Given the significance of the residential sector in terms of energy consumption, a comprehensive understanding of households’ energy consumption patterns and choices is imperative. This paper focuses on analysing and understanding the South African residential sector's energy characteristics considering their energy-use profile, and other characteristics such as their geographical distribution and demographic characteristics. The findings show that despite poorer households who are connected to the national grid receiving 50 kW/h of free electricity per month to help them cover their basis energy needs, South African households – particularly low-income households – still use various sources of energy including wood and paraffin to satisfy their basic energy requirements. Solid fuels are predominantly used in rural areas where around 75% of non-electrified households rely on solid fuels for cooking, heating and lighting. Low-income South African households consume between 5% and 10% of their total energy in lighting; space heating and cooking account for the remainder 85–90% of their total energy consumption. After evaluating the relevant data regarding households’ access to electricity, the type of energy used by households and households’ expenditure on electricity and energy in South Africa from the NIDS dataset; it was concluded, that electricity access is reasonably high across South African households. Additionally, an increasing trend can be observed in their total expenditure on electricity. However, approximately 70% of households still spend on other energy sources. Highlights • This paper evaluates the evolution and characteristics of energy consumption in the South African residential sector. • Emphasis was given to the behaviour of households in using energy for cooking, lighting and heating. • Around 70% of low-income households rely on sources of energy other than electricity to satisfy their basic energy needs. • Around 10% of low-income households are energy poor and cannot afford using electricity to cover their basic energy needs. • Results from the NIDS dataset indicated that electricity access is reasonably high across South Africa. [ABSTRACT FROM AUTHOR]

Abstract Consumers are often blamed for not making necessary investments in energy-efficient durables despite that these investments have positive net present value (NPV). Several papers have argued that when investments have option-like characteristics (e.g., irreversibility, uncertainty, flexible timing, and lumpiness), the aphorism “invest if the net present value of investing exceeds zero” isn’t the best advice. Yet, curiously, the Department of Energy (DOE) in the United States proposes new regulations mandating higher energy efficiency standards for consumer durables on the basis of non-negative NPV over an investment's lifetime. In this paper, we provide a step-by-step deconstruction of DOE's NPV methodology and show that DOE's method purges volatility, volatility persistence, and nonstationarity that are otherwise present in energy prices. As a result, DOE's projections of future energy prices are artificially smooth and statistically biased, casting serious doubt on the reliability of the magnitude of energy savings from energy-efficient durables. Highlights • This paper criticizes the misuse of net present value (NPV) in energy efficiency standards. • We compared historical energy prices to the US Department of Energy's (DOE) monthly projections. • We find that DOE's NPV methodology artificially suppress volatility, nonstationarity that are present in energy data. [ABSTRACT FROM AUTHOR]

Abstract Usage of eco-friendly refrigerants could be an effective solution to the global warming problem. However, a comprehensive assessment is necessary when selecting new refrigerants. Any substance should be evaluated for its overall impact on the global environment, energy efficiency, cost-effectiveness, and safety. This paper reviews the experimental and theoretical studies that have been carried out with environmentally friendly refrigerants such as hydrocarbons, hydrofluorocarbons, R744 (carbon dioxide), hydrofluoro olefin, and nanorefrigerants. The article's main aims are to evaluate the potential of all refrigerants used in the refrigeration and air conditioning industries and to present the primary applications of environmentally friendly refrigerants and nanorefrigerants. The paper also identifies the gaps in the literature and introduces opportunities for future work. Highlights • The review of environmentally friendly refrigerants and nanorefrigerants. • The scrutiny of newly developed refrigerants’ application. • Analysis of the performance of eco-friendly and nanorefrigerants in the refrigeration cycles. [ABSTRACT FROM AUTHOR]

The small island developing states of the Pacific suffer from both the high cost of fossil fuel imports and from numerous climate-related disasters. These vulnerabilities will worsen unless there is a substantial global shift away from fossil fuels towards renewable energy (RE) sources, coupled with significant improvements in energy efficiency. Apart from traditional biomass-fuelled cooking, the most substantial uses of RE in the Pacific in 2016 were hydropower in some of the hillier island countries and the thousands of household photovoltaic (PV) systems in the remoter parts of island countries. This paper considers also the prospects for grid PV, geothermal, and biofuels – all of which have good technical potential in at least some islands. Barriers to wider use of RE in the region are mostly institutional and financial, but also include opportunity costs, environmental factors, and the limited skills base in small island states. The paper examines the mixed progress since the 1990s towards overcoming these barriers. The Fiji Electricity Authority has a reasonably realistic plan to have 81% of its supply from RE by 2020, drawing on hydropower (~ 50% in 2015), biomass (including bagasse), and some solar and wind. Tonga has its Renewable Energy Roadmap with clear milestones. Several other Pacific Island countries have ambitious RE targets but some are rather vague about how they are to be achieved. [ABSTRACT FROM AUTHOR]

Computing systems have been focused on performance improvements, driven by the demand of user applications in past few decades, particularly from 1990 to 2010. However, due to their ever-increasing energy demand which causes large energy bills and CO 2 emissions, over the past six years the focus has shifted towards energy-performance aware. The average energy consumption of servers is increasing continuously; and several researchers suggest, if this trend continues further, the cost of energy consumed by a server during its lifetime will exceed the hardware costs. The energy consumption problem is even greater for large-scale infrastructures, such as clusters, grids and clouds, which consist of several thousand heterogeneous servers. Efforts are continuously made to minimize the energy consumption of these systems, but the interest of people in computational services and popularity of smart devices make it a difficult task. In this paper, we discuss the energy consumption of ICT equipment, and present a taxonomy of energy and performance efficient techniques for large computing systems covering clusters, grids and clouds (datacenters). We discuss both energy and performance efficiency, which makes this survey different from those already published in the literature. Key research papers are surveyed and mapped onto taxonomies to characterise and identify outstanding and key issues for further research. We discuss several state-of-the-art resource management techniques, reported in the literature, that claim significant improvement in the energy efficiency and performance of ICT equipment and large-scale computing systems such as datacenters, and identify a few open challenges. [ABSTRACT FROM AUTHOR]

Currently, sustainability is one of the most important subjects in architecture and urban design. Sustainable design strategies reduce energy consumption of buildings and environmental pollution. Moreover, these strategies improve the microclimatic conditions of urban spaces. In this regard, courtyard design is an efficient sustainable strategy to improve thermal and microclimatic conditions of urban spaces. For 5000 years, courtyards have been developed to adapt to severe climatic conditions, particularly in hot and arid climates. Inaccurate courtyard thermal estimations may occur due to the complexity of optimal thermal design and insufficient tools for simulating the thermal conditions of indoor and outdoor spaces simultaneously. In the last four decades, researchers have recommended several methods to study the thermal function of courtyards. Although the variety of the modelling particularities makes it difficult to obtain appropriate results that encompass all influential factors of courtyard climatic performance, this paper provides a comprehensive review of the papers of this type of building form. The main goal is to clarify if and how the construction of courtyards can decrease energy consumption and improve the microclimate of buildings. The present study focuses on the impact of courtyard design factors (such as proportion, orientation, geometry, opening characteristics, and material) and its components (such as shading devices, vegetation, and water pool) on energy consumption, indoor and outdoor temperatures, solar radiation, and natural ventilation in different climates. Regarding the researchers’ frameworks in the reviewed papers, three main categories are identified: 1- those examining the microclimatic function of courtyards, 2- those based on the thermal function of courtyards, and 3- those that incorporate an integrative approach (considering the thermal and microclimatic functions of courtyards simultaneously). Afterward, the paper reviews the role of three main climatic factors — solar gain, humidity, and natural ventilation — in each category. [ABSTRACT FROM AUTHOR]

Improving energy efficiency in industry is recognized as one of the most vital activities for the mitigation of climate change. Consequently, policy initiatives from governments addressing both energy-intensive and small and medium-sized industry have been enacted. In this paper, the energy end-use and the energy efficiency potential among industrial small and medium-sized companies participating in the Swedish Energy Audit Program are reviewed. The three manufacturing industries of wood and cork, food products and metal products (excluding machinery and equipment) are studied. A unique categorization of their production processes’ energy end-use is presented, the results of which show that the amount of energy used in various categories of production processes differ between these industries. This applies to support processes as well, highlighting the problem of generalizing results without available bottom-up energy end-use data. In addition, a calculation of conservation supply curves for measures related to production processes is presented, showing that there still remains energy saving potential among companies participating in the Swedish Energy Audit Program. However, relevant data in the database used from the Swedish Energy Audit Program is lacking which limits the conclusions that can be drawn from the conservation supply curves. This study highlights the need to develop energy policy programs delivering high-quality data. This paper contributes to a further understanding of the intricate matters of industrial energy end-use and energy efficiency measures. [ABSTRACT FROM AUTHOR]

This paper presents the development of methods and mathematical models to determine the DC/AC average efficiency of inverters that allow to optimize estimates of electricity generation of photovoltaic systems. The adaptive hybrid mathematical model of DC/AC average efficiency of inverters of photovoltaic systems proposed in this paper may be composed of three function settings–Linear, Lognormal, and Polynomial–considering the influence of the relative power, which varies with the sizing factor inverter and the DC input voltage. Determining of the average efficiency with a high degree of accuracy guarantees greater reliability in estimating electricity generation of photovoltaic systems. Depending on the specific behavior of each model and topology of inverter, the adaptive hybrid mathematical model determines the fit functions with highest coefficient R 2 , and estimates with accuracy the DC/AC average efficiency that represents the operation and dynamic behavior of the inverters. [ABSTRACT FROM AUTHOR]

The energy sector is undergoing substantial changes in order to promote better efficiency, increase the use of renewable energy, reduce emissions and effectively deploy technologies to trade off costs and benefits One emerging solution is the application of the Power-to-Gas technology, which can be used for different purposes. In recent years, Power-to-Gas has been studied to understand the role it could play in the electrical system. This paper has the aims of analysing the existing literature about the Power-to-Gas technology in detail, by considering some solutions that have a direct impact on the electrical system (in particular electrolyser and CO 2 production) and applications in the different sectors of the electricity value chain (i.e., generation, transmission, distribution and utilisation). This paper sets out the conceptual aspects that are necessary to include Power-to-Gas facilities in a more comprehensive analysis framework of the operation of the electrical system in various sectors. Some perspectives concerning new Power-to-Gas applications are also presented for each sector, and some promising aspects that are expected to play a relevant role in the future technical and economic evolution of electrical systems are discussed. [ABSTRACT FROM AUTHOR]

Faults in any components (modules, connection lines, converters, inverters, etc.) of photovoltaic (PV) systems (stand-alone, grid-connected or hybrid PV systems) can seriously affect the efficiency, energy yield as well as the security and reliability of the entire PV plant, if not detected and corrected quickly. In addition, if some faults persist (e.g. arc fault, ground fault and line-to-line fault) they can lead to risk of fire. Fault detection and diagnosis (FDD) methods are indispensable for the system reliability, operation at high efficiency, and safety of the PV plant. In this paper, the types and causes of PV systems (PVS) failures are presented, then different methods proposed in literature for FDD of PVS are reviewed and discussed; particularly faults occurring in PV arrays (PVA). Special attention is paid to methods that can accurately detect, localise and classify possible faults occurring in a PVA. The advantages and limits of FDD methods in terms of feasibility, complexity, cost-effectiveness and generalisation capability for large-scale integration are highlighted. Based on the reviewed papers, challenges and recommendations for future research direction are also provided. [ABSTRACT FROM AUTHOR]

With the exponential growth in global photovoltaic (PV) power capacity, protection of PV systems has gained prodigious importance in last few decades. Even with the use of standard protection devices in a PV system, faults occurring in a PV array may remain undetected. Inspired by the ever increasing demand for a reliable fault detection technique, several advanced techniques have been proposed in literature; especially in the last few years. Hence, this paper carries out an in depth analysis of various fault occurrences, protection challenges and ramifications due to undetected faults in PV systems. Furthermore, with a widespread literature, the paper critically reviews numerous fault detection algorithms/techniques available for PV systems which are proven to be effective and feasible to implement. The proposed study is not only limited to surveying the existing techniques but also analyzes the performance of each technique with an emphasis on its: 1) Approach, 2) Sensor requirements, 3) Ability to diagnose and localize faults, 4) Integration complexity, 5) Accuracy, 6) Applicability and 7) Implementation cost. Overall, this paper is envisioned to avail the researchers working in the field of PV systems with a valuable resource, which will assist them to enrich their research works. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review on solar tracking systems and their potentials in solar energy applications. The paper overviews the design parameters, construction, types and drive system techniques covering different usage application. There are two main solar tracking systems types that depending on their movement degrees of freedoms are single axis solar tracking system and dual axis solar tracking system, which are addressed in the recent studies. The solar tracker drive systems encompassed five categories based on the tracking technologies, namely, active tracking, passive tracking, semi-passive tracking, manual tracking, and chronological tracking. The paper described the various designs and components of the tracking systems. There are 42.57% of the studies discussed and presented single axis tracking systems while 41.58% of these studies to the dual axes tracking systems. In the recent research studies, the most common solar tracker drive type was active tracker by 76.42% usage in applications while in the second most impact type is the chronological solar tracker by 7.55%. Furthermore, in the solar tracking techniques, Azimuth and altitude tracking achieved 16.67% in usage, Horizontal tracking by 16.67%, Azimuth tracking by 10%, and polar tracking by 4.44%. [ABSTRACT FROM AUTHOR]

Solar thermal technology to supply process heat in different industrial sectors has become very promising in recent years. Industries can reduce their consumption of fossil fuels by replacing them with solar process heat with non-conventional system integration and using clean energy. In this paper, a systematic review of 10 countries is presented which demonstrated extensive use of solar industrial process heating systems in their manufacturing sectors. This country-wise analysis is then used to compare with current Australian scenario and identify future prospects of integrating solar process heating in Australian industrial sectors. The choice of countries is based on a database where promising industrial sectors and solar process heating applications are currently using incident solar energy. These are analyzed for their potential of integration to developing solar heat in industrial processes (SHIP) and a number of potential industrial sectors that have the highest potential like Motor vehicles, Textiles, Printing, Wood, Paper, Fabricated metal, Rubber and plastics, chemicals, Food, beverages, electrical equipment, machinery, and equipment are being identified. An overview of available studies is discussed in this paper focused on specific countries and the industrial heat demand of existing operational plants. Future trends due to solar energy potential are also outlined. [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]

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]

The global demand for utilization of renewable fuels in gas turbines has been on the increase to secure a sustainable, and pollution free environment. In this paper, the reviewed studies were on different liquid biofuels production methods such as the catalytic conversion of biomass, gasification, pyrolysis and transesterification. The review also included different studies on directly fired gas turbine (DFGT) and externally fired gas turbine (EFGT) utilizing biomass and liquid biofuels. Furthermore, this study elucidated the use of biofuels in clean combustion methods scalable to gas turbines such as colourless distributed combustion (CDC), high temperature air combustion (HiTAC), moderate or intensive low oxygen dilution (MILD) combustion and catalytic combustion. The discussion included the effect of different input parameters associated with the clean combustion systems that have influence on the attainment of ultra-low emissions of NOx and CO under premixed and non-premixed modes. As for the fuel types, biodiesel is one of the most studied biofuel in gas turbine especially in small-scale micro gas turbine (MGT) engines. The materials for the path of hot gas, types of fuels, heat recovery and cogeneration techniques are the variables, found to be affecting the performance of the DFGT. As for the EFGT, the high temperature heat exchanger with its lower turbine inlet temperature of 700–900 °C is generally the main limiting factor for this technology. The paper concluded by highlighting relevant and recent findings, thereby proposes a further research to improve the versatility in the utilization of liquid biofuels in gas turbines. [ABSTRACT FROM AUTHOR]

Global depletion of fossil fuels, growing awareness on the effects of carbon emissions and greenhouse gases and, the need for renewable energy, has increased the attention towards biocoke research and active engagement with various research groups and industrial players. Biocoke production and utilisation is crucial as it contributes to the efficient management of agricultural residue and municipal solid waste. The technologies involved in the biocoke production and the viability of Malaysia's agricultural waste as a feedstock was described in this paper. In addition, the paper provided background information about the biocoke characteristics and the feedstocks that dictate quality. Comparisons of commercial coal coke and biocoke production technologies that may be applicable to Malaysia were also addressed. Moreover, the paper demonstrated the challenges towards Malaysia's biocoke commercialisation despite its viability from biomass feedstocks characteristics, availability, and evidence of calorific value estimations. [ABSTRACT FROM AUTHOR]

Photovoltaics (PV) and electric vehicles (EVs) are promising technologies for increasing energy efficiency and the share of renewable energy sources in power and transport systems. As regards the deployment, use and system integration of these technologies, spatio-temporal modeling of PV power production and EV charging is of importance for several purposes such as urban planning and power grid design and operation. There is an abundance of studies and reviews on modeling of PV power production and EV charging available in the literature. However, there is a lack of studies that review the opportunities for combined modeling of the power consumption and production associated with these technologies. This paper aims to fill this research gap by presenting a review of previous research regarding modeling of spatio-temporal PV power production and charging load of EVs. The paper provides a summary of previous work in both fields and the combination of the fields. Finally, research gaps that need to be further explored are identified. This survey revealed some research gaps that need to be further addressed. Improving the accuracy of PV power production ramp-rate modeling in addition to quantifying the aggregate clear-sky index on city-scale are two priorities for the PV potential studies. For the EV charging load models, differences in model assumptions, such as charging locations, charging powers and charging profiles, need to be studied more extensively. Moreover, there is an imminent need for metering the load of charging stations. This is essential in developing accurate models and time series forecasting techniques. For studies exploring both the PV and EV impacts, local weak points in a spatial network need to be discovered, especially for the city-scale studies. Cooperation between eminent researchers in the PV and EV fields might propagate state-of-the-art models from the separate fields to the combined studies. [ABSTRACT FROM AUTHOR]

Integration of renewable energy including solar energy is growing faster than ever before. Solar energy supplies more than 1.3% of global power, and it is predicted to become the largest electricity source by 2050 with about 11% of global power consumption. However, the improper installation, non-frequently scheduled maintenance, and aging effect can accelerate the deterioration of PV system components, which directly increase the possibility of arc fault occurrence. The undetected arc faults pose a severe fire hazard to residential, commercial, and utility-scaled PV systems. To deliver electricity in a safe and reliable manner, such a dangerous event must be detected at early stage. This paper presents a comprehensive review of the-state-of-art techniques for DC arc faults detection in photovoltaic systems (PV). Different methods and the features used for detection are discussed and compared in detail. This paper also emphasizes the importance of DC arc fault simulation for characteristics study and fault diagnosis purpose. Several DC arc fault models have been reviewed and compared. [ABSTRACT FROM AUTHOR]

The built environment is one of the major contributors of greenhouse gas (GHG) emissions. To tackle climate change, global targets have been set for this sector. Although life-cycle assessment (LCA) methods are typically used to evaluate a building project's embodied energy in its final stages of development, this evaluation would be especially valuable at early design stages, when the opportunity to modify the design is greatest. In this paper, an extensive review of methods to improve the usability of LCA at the early design stage is presented. Three major issues regarding the application of LCA arose from this analysis at this stage: its time consumption, the lack of design details, and the non-reproducibility of results. Moreover, LCA makes it possible to assess environmental performance, but does not provide design alternatives, which are crucial to introduce environmental targets into an iterative design process. To that end, existing techniques that can address the major LCA issues were identified, together with their respective limits. These include some promising tools that provide and explore design alternatives and their respective environmental performances. Among these tools are exploration methods, which have not been applied to LCA insofar as it is not possible to do so in a reasonable computational time. To bridge this gap, the paper outlines the structure of an LCA-based data-driven design method, which uses a combination of LCA, parametric analysis, data visualization, sensitivity analysis, and target cascading techniques. [ABSTRACT FROM AUTHOR]