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The miniaturization, portability, and reduction in power consumption of wearable devices have greatly facilitated significant advancements in the field of wearable human energy harvesting systems. Human metabolism results in waste heat production and dissipation to the surroundings via skin radiation, convection, and evaporation. Wearable flexible thermo-electric and moist-electric devices uses skin waste heat harvesting to convert thermal energy into electricity without user involvement. The principle and structure of the device is simple and pollution free with great application potential in generating power supply. Skin waste heat can be dissipated in the forms of both sensible and latent heat. Wearable thermo-electric generators (WTEGs) collects sensible heat, and wearable moist-electric generators (WMEGs) collects latent heat. This paper reviews the mechanism behind the generator of WTEG and WMEG, as well as state-of-the-art research progress made in material properties and structural design of thermoelectric devices. The performance optimization and design of wearable, flexible thermoelectric devices for skin waste heat harvesting at the material and device levels are studied, followed by a breakdown on the fibers and fabrics used in the foundation for future development of WTEG and WMEG's. The research findings provides valuable insight on the future development of WTEG and WMEG's, providing integration into wearable applications for health and physiological monitoring and disease diagnosis. This paper reviews the mechanism behind the generator of WTEG and WMEG, as well as state-of-the-art research progress made in material properties and structural design of thermoelectric devices. The performance optimization and design of wearable, flexible thermoelectric devices for skin waste heat harvesting at the material and device levels are studied, followed by a breakdown on the fibers and fabrics used in the foundation for future development of WTEG and WMEG's. The research findings provides valuable insight on the future development of WTEG and WMEG's, providing integration into wearable applications for health and physiological monitoring and disease diagnosis. [Display omitted] • Explored the theory of thermoelectric energy conversion from skin waste heat. • Overviewed advancements in material properties and structural design of thermoelectric devices. • Studied on improved designs for wearable thermoelectric devices using fiber and fabric materials. • Future directions for wearable flexible thermoelectric devices. [ABSTRACT FROM AUTHOR]

To facilitate a successful integration of distributed energy resources into the electricity generation mix, new forms of energy markets must be considered. Concepts such as Peer-to-peer energy trading (P2P), transactive energy (TE) and community/collective self-consumption (CSC) are frequently mentioned as solutions to this challenge. Despite increasing interest from industry, policy, and academia, the field lacks a shared understanding of this class of models. This need is addressed by presenting sets of shared and distinct characteristics which define P2P, TE and CSC. Our analysis is based on a series of expert group interviews with regulators, industry, and academics across 13 countries, and a systematic and targeted literature review of 133 papers. Findings show that P2P/TE/CSC models can be described as sub-markets that operate within or alongside traditional energy markets and enable trading or sharing of energy using an automated approach. They focus on promoting and supporting local energy generation and consumption using price negotiation mechanisms that reflect the aims of the market. The paper also presents sets of characteristics which differentiate P2P, TE, and CSC from one another and sets out guiding definitions to be used as a reference point. The main differences between these models stem from the goal they are trying to achieve and the contexts they are deployed in. Findings from this analysis can support development of a shared understanding of this class of models across multiple disciplinary perspectives and applications. • Decentralised energy trading models lack a unified definition. • Expert interviews and literature review identify defining characteristics. • Decentralised models can operate as sub-markets alongside traditional markets. • Distinctions between models stem from their goal and the contexts they are deployed in. [ABSTRACT FROM AUTHOR]

Australia has significant offshore wind resources that can support ever-increasing power demand and hence provide a long-term contribution to the net-zero target by 2050. Although some offshore wind farm projects are proposed in Australia, the industry is not mature enough to justify the benefits and display economic opportunities. More specifically, the techno-economic analysis of offshore wind energy has not been systematically mapped in Australia. Therefore, the investigation of the spatial variation of technical feasibility and economic potential of offshore wind is vital to identify the potential regions and to develop strategies for future offshore wind farm developments in Australia. This paper presents detailed mappings of the techno-economic potential of offshore wind energy in Victoria-Tasmania's exclusive economic zone. Offshore wind energy resources are assessed in the paper in terms of energy availability and variability and the feasibility of various offshore wind technologies is investigated, including turbines, foundation types and transmission topologies. In addition, the high-fidelity life-cycle cost models and two innovative evaluation matrices are developed to assess the economic potential of offshore energy farms in South-eastern Australia. The impact of local power system regulation costs and future carbon prices on the viability of offshore wind is also investigated in this paper. It is concluded that the detailed mapping approach and analysis in the paper can provide a systematic tool for industry partners, investors and policymakers at the pre-planning stage of developing offshore renewable energy systems. • The technical feasibility of offshore wind is mapped under various constraints. • The novel LACE and high-fidelity LCC assessment models are developed. • The techno-economic potential is systemically mapped in South-eastern Australia. • The impacts of electricity market regulation and future carbon prices are studied. [ABSTRACT FROM AUTHOR]

China has been introducing reforms in the electricity market. Since 2016, electricity retailers are allowed to operate in the market once monopolized by traditional power companies. This regulatory environment demands new types of purchase contracts to remunerate the energy agents and deliver better prices for consumers fairly and sustainably. This paper proposes two new electricity purchase contracts with risk sharing mechanism and studies on wind power supplier's optimal capacity investment problem under supply and demand uncertainty. Firstly, a basic model for fixed demand contract is developed, and the optimal capacity is obtained. Secondly, the fixed commitment order contract and the forecast order contract with risk sharing mechanism are proposed to manage the fluctuation of wind power supply randomness. With backward induction, the optimal investment capacity of wind power supplier is solved, and then the fixed order quantity or forecast demand quantity of the electricity retailer can be obtained. Our results show that the fixed order quantity may have a positive influence on the wind power supplier's capacity investment decision. While, the forecast order quantity may have a negative influence on the wind power supplier's capacity investment decision. In addition, wind density has a strong influence on wind power capacity investment, and it has a positive impact on wind power supplier's profit, but it does not always have a positive impact on electricity retailer's profit. At last, based on numerical analysis, we examine how the wind density distribution coefficient change affect members' profit in the electricity supply chain. We also find that even with wind curtailment punishment, the forecast order contract can make a Pareto improvement on the whole electricity supply chain. [Display omitted] • Risk sharing mechanism is introduced to the fixed commitment order contract and the forecast order contract in the electricity supply chain. • Increasing the forecast order quantity may reduce the capacity investment. • The forecast order contract can improve the performance of the whole electricity supply chain. [ABSTRACT FROM AUTHOR]

Brazil is a case of the achievement of a high share of wind energy integration to an interconnected power system in an emerging market. A series of successful energy supply programmes and a strong renewable-oriented finance framework implemented since 2002, have promoted alternative renewables – wind installed capacity increased over 22-fold from 927 MW in 2011 to 21 GW in 2022, reaching 11.77% of total procured power. From this, about 90% are concentrated in Brazil's least developed region, the Northeast, where wind investment should create jobs and propel socioeconomic development. Despite that, there is no studies specific assessing the regional and economy-wide effects of those programmes, gap that this paper aims to fill by applying the regional Computable General Equilibrium (CGE) model TERM-BR10. We assess that by modelling an alternative scenario for the period 2010-19 based on an official electricity matrix built in 2010, that projected 3.4 additional GW of wind power while not considering all the success of renewable policies, against the observed installed capacity expansion, where wind power was 3.7 times higher than what had been planned. Our results show that in the absence of renewable policies, Brazil would have faced economic losses such as GDP (−0.27%) and investment (−4.76%). The Northeast region would have been the most impacted in terms of GDP (−1.3%), real wage (−2.99%) and employment creation (−0.1%). We propose that such socioeconomic co-benefits are incorporated in energy planning, which could promote regional equality through renewable energy expansion. • Wind power capacity increased over 20-fold from 2011 to 2022. • 90% are in the poorest region where policies propel development and job creation. • Policy absence would entail a GDP loss of 0.27% nationally and of 1.3% in the region. • Negative impacts to labour market are mostly over skilled jobs. [ABSTRACT FROM AUTHOR]

Ocean renewables (such as offshore wind and wave) are abundant and essential energy resources for supporting future emission-free targets. However, their energy intermittency and high cost have hindered commercialization and wide-scale implementations of these ocean energy technologies. This paper focuses on both issues and aims to increase the dispatchability of ocean energy farms by investigating the potential of a hybrid wind and wave energy platform with energy storage systems (ESS). This research introduces an innovative method to assess the necessary ESS capacity for offshore renewable energy farms, ensuring energy dispatchability to the local demand. In addition, the key criteria and the economic feasibility of deploying ESS in offshore energy farms are also discussed. A life-cycle cost model is presented that quantitatively compares different farm configurations, specifically a standalone offshore wind farm and a hybrid configuration incorporating both wind and wave generation systems. The results indicate that the combined wind and wave energy farm significantly reduces the ESS requirement and provides competitive lifecycle costs compared to the stand-alone wind energy farm, though the amount of these benefits vary on the local resource characteristics. The quantitative assessment presented in this study also provides realistic and practical justifications for combined energy farms that complement statistical conclusions derived from variability indexes in previous studies. [Display omitted] • The techno-economic benefits of combined wind–wave farms are quantified. • A novel method of sizing and evaluating ESS for offshore farms is proposed. • The combined energy farm reduces ESS requirement compared to wind-only farms. • The benefits of combined energy farms are sensitive to the resource characteristics. [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]

The paper presents an enhanced scheme to control the dynamic response that can be delivered by distributed generation (DG) and renewable energy resource (RER) to be more reliable and stable than other electric systems. Robust Adaptive Emulated- Controller (RAEC) has been included to control and tune the adoption of controller parameters across a broad range of operating conditions. Some existing challenges related to high loading profiles that will be handled by new performance features. The objective of paper is to propose robust adaptive emulated-controller that is incorporated with high-speed fluctuations and dynamic energy systems. That can achieve an integrated system to reflect the enhanced structure and operation of electric systems, in addition to, Enhanced Mud Layers (EML) optimization will be applied to control and optimize the performance parameters. • A novel robust system is proposed to enhance the sustainable energy and renewables operation and dynamic performances. • The proposed technique supports the implications of energy resources for the sustainable communities and networks. • There are scenarios to consider the changes in the loading profiles, beside to the uncertain conditions. • The obtained results by the proposed technique have been appraised and examined. [ABSTRACT FROM AUTHOR]

Wind energy is a mature and cost-effective solution to greenhouse gas emission reduction and climate change mitigation. Wind resource assessment is the most pivotal activity before wind farm development since it determines the bankability of the wind project. Based on the joint use of a Doppler wind sodar (sonic detection and ranging) system and a microwave radiometer, this paper investigates the wind and thermal characteristics and wind energy resources in a coastal region of Hong Kong. First, wind climatology and variability, as well as their correlation with large-scale and local meteorological and geographical conditions, are analyzed and discussed. Then, statistical distributions of wind speed are evaluated, and the goodness-of-fit of the Weibull, Kappa, Wakeby, Normal-Weibull mixture, and Weibull-Weibull mixture distributions is assessed. Subsequently, the probability distribution and variation of atmospheric stability are examined, and their effects on vertical wind shear, wind profile, and wind speed at turbine hub height are revealed. Lastly, the spatiotemporal variation of wind power density is investigated with attention paid to air density. The results presented in this paper are expected to offer insights into coastal wind and thermal characteristics, provide references for vertical extrapolation of wind speed and wind turbine load evaluation, and facilitate wind farm development in coastal regions. • Investigation of coastal wind climatology and variability in Hong Kong. • Evaluation of statistical distributions of wind speed, gradient Richardson number, and air density. • Exploration of vertical variation of wind speed, air density, and wind power density. • Analysis of wind shear coefficient under different atmospheric stability conditions. • First known study of wind resources that jointly uses sodar and microwave radiometer. [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]

Regional integrated energy systems (RIES) have garnered increased attention because they highly utilize renewable energy, comprehensive efficiency, and flexible operation. However, the current research on RIESs is mainly based on burning natural gas and supplemented by renewable energy, which will consumes much primary energy and generates corresponding carbon emissions. Therefore, a RIES contained various renewable energy sources and station energy sharing was constructed in this paper. Both the collaborative optimization model, which considered the operating parameters and system configuration, and the hierarchical optimization model, which optimizes the equipment configuration at the upper layer and the operational parameters at the underlayer, were constructed, respectively. Taking a multi-function low-carbon park as an example, the isolated integrated energy system (IIES) and RIES performances were explored. Finally, the operation cost, carbon emission, and interactive power in the separated production system, IIES and RIES were analyzed and discussed from a long-short time scale perspective. The results showed that the carbon emission, interactive power, and energy supply cost of the RIES's unit area are 7.62 kg/m2, 10.07 kWh/m2, and 40.55 CNY/m2, respectively. Long time scale perspective (Years or months), RIESs could significantly reduce carbon emissions and interactive power. However, on a short time scale viewpoint (Hours), the system's instantaneous energy conservation and carbon reduction effect was general; meanwhile, the maximum grid-connected power in IIES and RIES was 2617.7 and 2712.0 kW, respectively. • A RIES is constructed integrating various renewable energy sources and energy sharing between stations. • Collaborative and hierarchical optimization is used to solve the complex RIES optimization problem. • Carbon emission and interactive power of the unit area for the RIES are 7.62 kg/m2 and 10.07 kWh/m2. • The maximum grid-connected power of IIES and RIES is 2617.7 and 2712.0 kW, respectively. [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]

The electricity market is being increasingly challenged by new trends, such as the high penetration of intermittent renewables and the transformation of the consumers' energy space. To accommodate these new trends and improve the performance of the market, several modifications to current market designs have been proposed in the literature. Given the vast variety of these proposals, and focusing on the short-term timescale within the context of European electricity markets, this paper provides a comprehensive investigation of the modifications proposed in the literature as well as a detailed assessment of their suitability for improving market performance under the continuously evolving electricity landscape. To this end, first, the barriers present in current market designs hindering the fulfilment of an efficient performance are identified. Then, the different market solutions proposed in the literature, which could potentially mitigate these barriers, are extensively explored. Finally, a taxonomy of the proposed solutions is presented, highlighting the barriers addressed by each proposal and the associated implementation challenges. The outcomes of this analysis show that even though each barrier is addressed by at least one proposed solution, no single proposal is able to address all the barriers simultaneously. In this regard, a future-proof market design must combine different elements of proposed solutions to comprehensively mitigate market barriers and overcome the identified implementation challenges. Thus, by thoroughly reviewing this rich body of literature, this paper introduces key contributions enabling the advancement of the state-of-the-art towards increasingly efficient electricity markets. • Proposals to modify the current electricity market design are vastly numerous. • Most design modifications for the short-term focus on new players' constraints. • Significant attention is also given to how electricity prices should be defined. • Potential advantages of design changes to the market performance are substantial. • Implementation challenges of the new market design solutions need to be addressed. [ABSTRACT FROM AUTHOR]

The use of photovoltaic power plants is rapidly expanding, despite the continued growth in the production of traditional mineral resources. This paper analyses photovoltaic panels (PVP) in order to identify the best values of their various nominal (rated) parameters in terms of lifetime and efficiency. The authors have created a database of one-sided PVPs from 100 to 450 W power range, which includes PVPs from 72 manufacturing companies around the world. The paper analyzes 1300 mono- and polycrystalline, heterostructural and thin-film PVPs. The following PVP parameters were analyzed: efficiency, temperature coefficients of power, short circuit current, open circuit voltage, square per power, mass per power, number of cells, operating temperature and lifetime. The results obtained can be widely applied in simulating the operating modes of photovoltaic power plants and will improve the accuracy of feasibility studies of the implementation of autonomous power supply systems. • Parameters of photovoltaic panels (PVPs) is necessary for modeling and analysis of solar power systems. • The best and the median values of the main 16 parameters among 1300 PVPs were identified. • The results obtained help to quickly and visually assess a given PVP (including a new one) in relation to the existing ones. • The median and the best parameters will reduce the time of feasibility studies for the implementation of autonomous photovoltaic power plants. • According to the medians of parameters, the most efficient are heterostructural PVPs, the least efficient are thin-film PVPs. [ABSTRACT FROM AUTHOR]

Southeast Asia is a significant stakeholder in the global action against climate change, given its growing population, rising greenhouse gas emissions, and vulnerability to climate change impacts. Public policy makers in this region are faced with the challenge of transitioning to cleaner energy sources to enable the attainment of Paris Agreement goals, while also expanding access to affordable and reliable energy supplies. Southeast Asia has one of world's fastest growing rates of greenhouse gas emissions due to rising fossil fuel combustion, second only to South Asia. As such, it is imperative to decouple its energy consumption from emissions growth. This paper reviews Southeast Asia's energy sector trends, with a focus on electricity supply and demand vis-à-vis global decarbonization efforts. Based on global and regional best practices, the paper highlights the crucial role that governments and public policy can play in accelerating the region's clean energy transition, namely through the establishment of mandatory long-term climate and renewable energy targets and binding policies; use of iterative and adaptive power system planning; support for effective market development; financing of pioneering investments and trunk infrastructure; and support for a just and equitable transition. • Countries of Southeast Asia need to accelerate the clean energy transition. • Governments and public policy play a key role in the energy transition. • Policy prescriptions provided based on global and regional best practices. [ABSTRACT FROM AUTHOR]

Microgrids are highlighted as the technology which can help in providing sustainable and efficient electrical energy solutions. They employ distributed energy resources to efficiently supply local load and increase the reliability of the local network. Design and planning are of a pivotal importance in yielding all of the advantages this concept can provide. Reliability-oriented design is of a special interest for microgrids utilizing a large share of the renewable energy-based, power electronics-interfaced distributed energy resources. A state-of-the-art overview included in this paper has shown that the main reliability-oriented microgrid design improvements are done in the field of distributed energy resources sizing and scheduling combined with the relevant forecasting and optimization methods. It is, further on, concluded that the standard power system reliability assessment within the design often excludes the wear-out failure of power electronics. However, previous field experience has shown that the power electronics is prone to wear-out failure and can have adverse impact on the reliability of the power electronics-dominated system. Therefore, it is necessary to adjust the current reliability methods to enable accurate investigation of power electronics reliability and its impact on system design. To do so, the main characteristics of the wear-out modelling concepts together with the recent publications bridging the power electronics and power system reliability are discussed in detail. Finally, the main findings included in this overview paper can serve as basis for development of the new procedures for reliability-oriented design and planning of future, power electronics-dominated microgrids. • Microgrid design and planning is important in assuring high reliability. • Overview of practices helps indicating reliability critical parts of design. • Microgrids will be dominated by power electronics interfaced distributed resources. • Excluding power electronics reliability can impact finding optimum design solution. • New design methods incorporating power electronic reliability need to be developed. [ABSTRACT FROM AUTHOR]

DC microgrids are becoming integral part of a modern power system due to the growing penetration of DC distributed energy resources and loads, with additional advantages in terms of power quality improvement. They can be used for remote area electrification including villages, mountains, and islands. In this paper, an islanded DC microgrid is considered as a case study for islands with tidal energy potential, which consists of renewable energy resources including solar, wind and tidal, along with Li-ion battery storage. To ensure the efficient operation, an optimal energy management system is proposed for resource scheduling and utilization. In this regard, this paper proposes a two-stage supervisory energy management system for optimal operation of PV/Wind/Tidal microgrid with one-time communication to avoid excessive use of communication bandwidth in real-time. The primary stage schedules the optimal energy share from each energy source thereby enhancing the efficiency of the operation. The secondary stage updates the decision strategies by analyzing aggregated scheduled generation and demand profiles to ensure an effective utilization. The proposed energy management model has been experimentally validated to prove its effectiveness in achieving optimized operation for an islanded DC microgrid. Word Count: 4380 • Off-grid DC microgrid with only green renewable energy sources and battery. • A two-stage (optimization and adjustment stages) energy management system. • The hardware-in-the-loop experimental validation of energy management system. [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]

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]

Internal combustion engines power the great majority of automobiles on the road today. However, the challenges of complying with other propulsion systems and near-zero-emission standards are inevitable. Current stringent emission standards are becoming universal and globally harmonized test cycles are being recommended. As per the BS-VI norms, PM and NOx emissions are to be reduced by 80% and 70%, respectively for diesel engines. Indian OEMs are integrating the Euro-VI emission control technologies into their vehicle and also limiting the production of diesel engines, especially in the passenger sector. In this respect, it is necessary to enhance the current understanding of the improvements in combustion chambers, after-treatment devices, and potential low-carbon fuels for sustainable transport mobility. This paper comprehensively outlines the prospects of future fuels, modified combustion systems, and after-treatment devices. The fuel composition of both fossil and biofuels plays a vital role in altering the exhaust soot and NOx characteristics. Thus an overview of hydrogen formulated fuels, the optimal combinations of the fuel–engine–after-treatment systems are also highlighted. In the end, a brief discussion concerning the total life cycle analysis is also presented in this paper. The review concludes by suggesting potential fuels and technologies for lowering the emission levels and provides directions for future work to address the challenges facing alternate energy resources for automotive applications, particularly in India. • Comprehensively outlines the prospects of future fuels, combustion systems and after-treatment devices. • Fuel composition affects the emissions of NOx and soot formation. • Biodiesel operation enhances the filter regeneration rate and the conversion efficiency of the diesel oxidation catalyst. • Displacing 50% diesel with hydrogen is found to lower the total GHG by 47%. • Implications for technology development roadmap in India are discussed. [ABSTRACT FROM AUTHOR]

The European Union has set the ambitious target of becoming climate-neutral by 2050 and reducing greenhouse gas emissions by at least 55% before 2030, compared to 1990. Greater energy generation can be achieved by increased reliance on renewable energy, but the transmission of this energy to match supply with demand is a likely bottleneck in maximising renewable energy use. In this paper, we examine medium-voltage DC superconductors as a potential solution for low-loss, high-power transmission of offshore renewables. We look at what has been achieved to date in onshore superconducting cable deployment and what needs to be done for such superconductors to be deployed subsea, with the goals of exporting electricity from offshore wind farms and acting as grid interconnectors. The offshore oil and gas industry represents state of the art in terms of subsea pipe design. This paper explores how the experience of the offshore oil and gas industry can be applied to subsea superconductor cable design and identifies aspects of superconductor design likely to present a challenge to subsea deployment. The key areas identified as requiring research are the development of flexible pipes suitable for cryogenic usage that can withstand the dynamic loading encountered in the marine environment; robust and low-maintenance insulation systems suitable for subsea deployment; and cooling systems to enable pipelines greater than 100 km in length. Although the primary focus of this research is on superconductor cables, the information is also applicable to other subsea conduits requiring cryogenic cooling such as 'green' hydrogen. [Display omitted] • Superconductors can facilitate low-loss long-distance offshore energy transmission. • Offshore oil and gas experience provides insight into the challenges of deployment. • Dynamic loading and accessibility issues complicate use for offshore wind farms. • Low-maintenance subsea insulation and cooling systems must be developed. • Materials must be suitable for cryogenic usage and withstand high-frequency loading. [ABSTRACT FROM AUTHOR]

Herein, we highlight the simplistic fabrication of a light-weight, flexible self-charging power pack by the prudent integration of two paper-based high-performance triboelectric nanogenerators (HPTENGs), one commercial semi-flexible photovoltaic/solar cell and a paper-based all-solid-state asymmetric-type supercapacitor (ASSASC) with optimized performance. Each HPTENG unit comprises of a ~20 wt% barium titanate nanoparticles loaded surface micropatterned post-polled PDMS composite (PDMS–20BTO) film-strip impregnated with graphite coated Whatman® 41 filter paper (GFP) as negative and a polypyrrole electrodeposited GFP as positive triboelectric friction layers, respectively. Contrariwise, the ASSASC consists of a nickel-cobalt-molybdenum oxide–graphitic C 3 N 4 hybrid composite coated GFP (NCMO–gCN2/GFP) as positive and a graphitic C 3 N 4 modified reduced graphene oxide coated GFP (gCN–m–RGO/GFP) as negative electrodes, separated by a thin PVA–KOH gel-type electrolyte membrane. Finally, under deformations/stress and illumination of solar light individually on top of our photovoltaic and HPTENGs driven self-charging ASSASC (PTSCASC) power pack, it efficaciously generates electrical energy and consequently stores this generated energy as electrochemical energy for sustainable power supply. Our self-powered PTSCASC# power pack prototype (with two ASSASCs) has been effectually integrated with a medical smart patch for electric pulsatile mediated controlled drug release. Hence, our as-designed self-charging power pack possesses immense potentials for self-powered multifunctional electronics and smart e-healthcare monitoring systems. A light-weight, paper-based self-charging power pack was developed by the judicious integration of a commercial semi-flexible photovoltaic cell, two paper-based triboelectric nanogenerators, and one/two paper-based all-solid-state asymmetric supercapacitors with optimized output performances. The eco-friendly, flexible self-charging power pack exhibits admirable output performances which are indeed auspicious for the incessant operation of self-powered medical devices and multifunctional electronics. [Display omitted] • A light-weight, paper-based flexible self-charging power pack was developed. • The pack comprised of solar cell, triboelectric nanogenerators and supercapacitors. • The pack can be charged: electrically, through deformations or light illuminations. • The paper-based flexible power pack exhibits admirable self-charging performances. • The self-powered pack can trigger medical smart patch for controlled drug release. [ABSTRACT FROM AUTHOR]

As a developing nation with its increasing energy demands, Fiji is in the process of introducing renewables to generate green power to minimize its reliance on fossil fuels and to minimize greenhouse emissions. The paper focuses on green power generation with the available renewables. The overview deals with their prospective users and therefore the challenges to those sources within the view of the local context. Photovoltaic standalone systems connect peoples of remote areas with the rest of the country to upgrade their living standard. Power generating authority along with the Ministry of Energy of Fiji are actively involved in evaluating and incorporating these potentials for power generation. Hydropower, bioenergy, solar energy and wind power are the prominent renewables on which Fiji's future power generation would be based. The share of renewable energies in the urban power generation in the calendar year 2019 was about 53% (561.96 million units). 55.9% of the Fijian population lives in rural areas and settlements. The photovoltaic standalone system through the solar home system (SHS) project and mini-hydroelectric-grids have been introduced to electrify these areas. Photovoltaic grid-connected systems are being introduced in the urban population to increase green energy proportion in the country's electricity power generation. Photovoltaic road lights are being planned to replace conventional road lights. The emission of carbon dioxide by the power sector has been gradually reducing since 1993. In 2015, 1925 million metric tonnes of carbon dioxide was emitted which was 21% less than that of 2005. The Government of Fiji is committed to utilize natural renewable energy resources available and generate 99% green electrical power by 2030. This paper sets a benchmark for other pacific island nations in realizing the success that renewables are achieving in the isolated populations of Fiji. • Fiji is blessed with abundant solar energy resources that provide us with the opportunity to explore and utilize renewable energy potentials. The country has a mountainous terrain and powerful rivers that flow from the highlands to the sea making it suitable for the development of Hydro-Electric potential. Electricity Fiji Limited has been working wisely by considering the geographic advantages to produce a liable mix of renewable energy projects across the country, using tailor-suited solutions where they best fit. The analysis of data for different sources of energy demonstrates that the potential renewable resources available to Fiji are hydropower, solar energy (photovoltaic and thermal), bioenergy, wind energy, ocean energy, tidal energy and geothermal energy. The presence of rivers, mountains and data on rainfall make the hydropower the most important source of renewable energy for Fiji • The solar thermal and solar photovoltaic has the potential to be used for water heating, drying crops and fruits (low and medium temperature applications), road and street lighting, off-grid connected PV systems for the scattered and rural population that is far away from the national grid line and photovoltaic power generators of higher rating/capacity to be added with the National grid to reduce the release of CO 2 in the environment using conventional fuels. Fiji Government is seeking to accomplish 99% renewable energy generation by 2030 from a 2013 baseline of 60% and aiming to achieve a 30% reduction in CO 2 emission from the energy sector over the same period. • The Government of Fiji under the Department of Energy's (DOE) Renewable Energy Development Programme (REDP) introduced the use of renewable energy resources for electrification in rural areas. This will reduce Fiji's reliance on imported fossil fuels whilst at the same time improves the livelihood of rural dwellers. • Fiji is located in the active tropical cyclone zone and the cyclone season starts from October and ends in March. The rapid growth in the power generation sector is sometimes adversely affected by these cyclones. Cyclones are accompanied by heavy rain resulting in landslides and can damage the PV standalone generators installed in that vicinity. Such unforeseen disasters not only slow down the preplanned mini-project installation (solar home systems and mini-grids) but also introduce additional liability to replace the damaged PV systems. • The unprecedented weather events, changes in rainfall patterns and temperatures due to climate change enhance the risk for the energy sector in different forms. These risks badly affect economically and as a result delay in the service delivery. This is the main factors delaying to achieve the targeted goals within the specified time. [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]

Meeting decarbonization goals requires taking significant action on electricity systems, which are a major source of CO 2 emissions. Decarbonizing island electricity systems raises additional challenges due to their heavy historical dependence on fossil fuels and strict power-reserve and reliability requirements. To address this challenge, this paper presents a comprehensive optimization model for long-term capacity planning of island electricity systems. Our model determines an optimal mix of generation and transmission capacity to satisfy energy demand at least cost while respecting the strict technical constraints that are inherent in island systems. In addition, our model considers the use of thermal and renewable generation, electric vehicles providing electricity-system services, batteries, pumped-hydroelectric storage, and ac and high-voltage dc transmission lines. We demonstrate our model with a case study of the Canary Islands archipelago. Our results show that combining the aforementioned technologies reduces generation costs by up to 25% and capacity requirements up to 50% (relative to a case without the technologies). In addition, without any mechanism to internalize the social cost of carbon, fossil-fueled thermal generation is the lowest-cost source of energy. Environmental considerations demonstrate the benefits of renewable generation and result in these carbon-free energy sources supplying about 40% of the energy mix. [Display omitted] • Carbon pricing can increase renewable-energy supply up to 40%. • Energy storage reduce costs up to 23% and favors more renewable-energy capacity. • Transmission interconnectors reduce costs but do not increase renewable-energy use. • Combining technologies reduces costs by 25% and capacity requirements by 50%. • Strict reserve requirements may keep renewable-energy shares below 3%. [ABSTRACT FROM AUTHOR]

The prosperity of microgrids and distributed energy resources (DER) promotes the standardization of multiple technologies. A sound and applicable standard system will facilitate the development of renewable energy and provide great guiding significance for technology globalization. As large-scale and high penetration DER integrate, the DER are performing a more active role to support the power distribution system operation, such as active\reactive power regulation and voltage\frequency control. Thus, various market stakeholders have paid enough attention to the technical dynamic change and regional difference at the level of microgrid standard and DER grid-integration standard, including AEPS (area electric power system) operators, AEPS owners, AEPS planners, AEPS designers, AEPS dispatchers, DER developers, DER owners, equipment manufacturers and regulators. However, existing literatures and researches are concentrated on technology innovation rather than the standards application. In our paper, we comprehensively review the standards development and current situation of microgrids and DER grid-integration issued by international organizations or individual countries. Then, based on technological knowledge iteration and engineering experience, the distinction of various standards is comprehensively compared from technical, geographical, and temporal aspectes. At last, the recommendation is provided for both standard maker and audience in the field of renewable technology to better formulate and apply standard. • The distinction of various standards is compared from technical, geographical, and temporal perspectives. • The dynamic change of standards is summarized at the level of DER grid-integration and microgrid level. • The recommendation is proposed for standard stakeholders, such as standard maker and standard audience. [ABSTRACT FROM AUTHOR]

The United States has pledged to develop a 100% carbon-free electric power system by 2035 and a net-zero-emissions economy by 2050. While important advancements have been made in the scale, performance, and economics of clean energy technologies, meeting the nation's ambitious goals will not only require their deployment at scale, but also additional innovation and effective integration of different solutions. Technological developments across the broad suite of low-carbon energy solutions are advancing rapidly, with ongoing innovations in renewable electricity generation, industrial processes, and energy-saving technologies and services, including LED lighting, induction heating, electric vehicles, energy storage solutions, and mobility as a service, plus smart devices, controls, and more efficient and smart buildings. Combining renewable electricity with biotic and abiotic pathways to produce chemicals, fuels, and materials promises to deliver new solutions. Grid-interactive buildings and communities, integrating transportation infrastructure and vehicles, are likely to be significant components of any zero-carbon energy strategy. Low-carbon industrial manufacturing will also make strong contributions to a net-zero economy. While the technical prospects appear promising, variations in the state of infrastructure, jurisdictional and social equity, pollution, economic and socio-cultural constraints, energy resource availability, and supply chain dynamics found in different locations present a range of challenges and demand customized solutions. This paper provides a critical review and offers new insights into the technical, infrastructure, analytic, political, and economic challenges faced in translating the nation's ambitious net-zero-emissions goals into feasible and reliable implementation action plans. • This manuscript brings together multiple experts view on the State of technologies, System level solutions, economics and scaling, for the United States to achieve bold decarbonization goals by 2050. • Key insights are offered on power system decarbonization, the role of hydrogen, storage, transportation, integrated energy systems, and material utilization and circularity. • Technologies, particularly wind and solar, are increasingly cost-effective, yet challenges remain regarding integration, social and political economy issues, and energy and environmental justice. • While the technical and economic factors are increasingly favorable, the US faces a number of non-technical challenges to rapidly scale clean energy technologies in order to achieve its ambitious goals. [ABSTRACT FROM AUTHOR]

Driven by the recent trends towards a smart power system configuration, there has been a greater focus within the literature on the integration between supply and demand-side resources. The contribution of this research is multifold since it provides a timely and required study, offering valuable insights into how the integration between Demand-Side Management (DSM) resources with clean energy supply options might affect the long-term power planning strategies in high-renewable electricity systems. The innovative aspects of this study are strongly related to a framework proposal for assessing the co-benefits between energy efficiency and demand-response on renewable-based energy systems from a long-term perspective using a co-optimization modelling approach. Overall, the results indicate that a clear benefit of implementing DSM strategies is the percentage reduction of the new installed capacity (−1.0% to −20.6%), CO 2 emissions (−2.4% to −11.8%), and total system costs (−0.5% to −15.8%) for all scenarios compared to Business-As-Usual scenario. The evidence from this study suggests that investments in Energy Efficiency (EE) seem more economically valuable than investing only in Demand-Response (DR) strategies. However, integrating EE and DR would empower the overall power system benefits. Strong evidence for a higher potential to delay investments was found for all scenarios for the first ten years of the planning period. Our findings might provide valuable insights to both governments and policy-makers by delivering supportive information in scaling up EE investments. The methodology proposed offers essential contributions to the scientific community and would benefit energy systems research beyond the cases addressed in this paper. • Integrated assessment of demand-side management for renewable-based energy systems is performed. • The methodology accounts for long-term reinvestments in energy efficiency. • A co-optimization modelling approach is used for the scenario analysis. • Combining energy efficiency and demand-response investments empower the economic benefits. • Demand-side strategies seem to decrease the natural gas capacity for all scenarios. [ABSTRACT FROM AUTHOR]

The multi-energy complementary property enables an integrated energy system with great potential to consume more renewable energy efficiently. However, due to the system complexity, its coordinated scheduling remains a challenge. Inertia of key inertial components must be carefully described to avoid overestimating or underestimating system flexibility, and coordinated system scheduling should be executed on multiple timescales. This paper aims to achieve coordinated scheduling of an integrated energy system, and improve its flexibility description accuracy by considering the inertia of the heat network, the combined heat and power (CHP) unit, and other key inertial components in the proposed multi-timescale scheduling method. Specifically, heat network inertia is considered to explore its heat storage ability and enlarge the operation range of an integrated energy system. To avoid overestimating CHP unit flexibility, the CHP unit ramp process is described to identify gaps between power supply and demand caused by CHP unit inertia. Besides, different temporal resolutions for inertia description are selected to match component features, whilst multiple scheduling periods are chosen to fit component regulation rates. Optimization results show that, by utilizing heat network inertia for heat storage, the daily cost and renewable energy curtailment can be reduced by 3 and 20%. Neglecting CHP unit inertia would underestimate the power output of flexible units, and the daily cost would be underestimated by 0.9%. Additionally, the proposed method can coordinate the system to handle the fluctuation and randomness of renewable energy, reducing the daily cost by 4%. • A multi-timescale hierarchical scheduling method for an integrated energy system is proposed. • Both heat network inertia and CHP unit inertia are considered in system scheduling. • The heat network inertia reduces the daily cost and renewable energy curtailment. • Neglecting CHP unit inertia leads to an underestimate of the power output of flexible units. [ABSTRACT FROM AUTHOR]

Many nations have encouraged the need to fully exploit renewable energy resources and energy-efficient technologies to address the issue of high electricity demand and reduce greenhouse gas emissions. The development of energy pathways and sustainable energy policies of diverse countries for long-term planning has always been a challenging task. This paper investigates the impact of alternative electricity development pathways on system costs and greenhouse gas emissions in Kenya. The Low Emissions Analysis Platform (LEAP) with Next Energy Modeling system for Optimization (NEMO) is used to evaluate the optimized least-cost power system and energy storage. Three scenarios are analyzed: high penetration of renewable energy resources with an energy storage system, internalizing of environmental externalities, and energy productivity. Results from the study indicate that with Kenya's Least Cost Power Development Plan 2017–2037 as the reference, the overall cost savings are up to 26.1 billion US dollars which is equivalent to 55% while the carbon emission saved with high penetration of renewable energy with storage is up to 6.3 Mt. On the other hand, energy productivity shows a downward trend with the existing policies and exhibits an upward trend when two policy instruments are considered. Consequently, those alternative energy planning pathways have the potential to significantly reduce overall system costs and GHG emissions. • LEAP NEMO is used to determine the optimal energy mix. • Simulation of energy storage provides for up to 3% of energy demand. • 6.3 Mt of CO 2 emissions are avoided. • Internalizing environmental externalities increases the costs of LCPDP. • Sustainable policy instruments increase energy productivity. [ABSTRACT FROM AUTHOR]

High penetration of renewable and sustainable Distributed Energy Resources (DER) into the traditional distribution system requires a well-coordinated control strategy for the improvement of system-wide reliability and resiliency. Implementation of such a holistic control architecture requires a flexible, near real-time, and bi-directional communication framework for facilitating the participation of various agents in a multi-vendor heterogeneous smart grid. While the sustainability of energy generation is ensured, this exposes the smart grid to extrinsic cyber threats, and appropriate defense mechanism(s) must be deployed to guarantee continued reliability and resiliency of the power grid. The comprehensive literature review presented in this paper discusses the latest trends in the DER control schemes with fast communication requirements and their accompanying cyber–physical vulnerabilities. These control schemes are compared and contrasted for various traits. A three-level DER system architecture has been depicted, facilitating the deployment of these control schemes. The current developments of standard communication protocols, key security mechanisms, and best practices along major standards and guidelines are explored. The impacts of different attack types with miscellaneous DER functions based on various control schemes and associated mitigation solutions are also provided. Finally, challenges and future research directions for limiting cyber-power susceptibility to enhance resiliency are summarized. The work presented here will help us enabling a cyber-resilient and sustainable smart electric grid. [Display omitted] [ABSTRACT FROM AUTHOR]

Offshore wind and wave power are abundant energy sources and could provide long term contributions to our future energy supply. The combined exploration of wind and wave power has been proposed as an effective way to mitigate the non-negligible power intermittency and variability of offshore renewables. However, the assessments of wind and wave resources have been developed separately in Australia, and the potential of diversified wind and wave power has not been studied systematically. This study investigates offshore wind and wave energy sources in multiple locations around the Australian coastline and their potentials for integration in terms of energy availability, power variability, coherence and correlation, and annual and seasonal variability over the last seven years. In addition, wind and wave mixed energy farms are studied using commercial wind turbine models and various wave energy converter prototype models. The energy availability, power smoothing effect, capacity factor and downtime of these mixed energy farms are also discussed. Moreover, this paper proposes an effective matrix for assessing the potential of hybrid energy farms in multiple sites in terms of power availability, power variability and combination performance and the sensitivity of selecting various wave energy converter (WEC) models is also investigated to provide a general guideline for future work. The regional comparative results indicate that the swell wave dominated sites in Western and Southern Australia present merits for combining wind and wave power, while wind–wave dominated regions, such as Eastern Australia, are not preferable for this diversified system. It can be found that power variability and downtime can be significantly reduced for the specific wind–wave capacity mix if a lower correlation or longer lag time exists between the two renewables. The results also illustrate that the combinations with different WEC systems present varying benefits in the different locations in Australia. • Wind and wave energy resources are assessed in Australian region. • A wave identification system is designed for hybrid exploration. • A matrix to assess the potential of combined energy farm is proposed. • Sensitivity of WEC selection to the combined energy farm is investigated. [ABSTRACT FROM AUTHOR]

The most important aspect of sustainability in manufacturing is the preservation of energy and natural resources. For modern production, optimized processes that minimize negative impacts on the environment are becoming increasingly important. This can be achieved by increasing energy efficiency through low, clean, and renewable energy consumption. There are many ways to produce less pollution, emissions, and waste in machining: by using more environmentally friendly cooling methods; by applying methods that reduce or eliminate the need for utilization of cooling lubrication; improving the energy efficiency of machining operations; determining the optimal cutting conditions that save resources by increasing machining productivity or reducing the metal removal rate (MRR); minimizing power consumption; and reducing carbon dioxide emissions. This article gives an idea of modern manufacturing with a focus on analyzing the current state of machining operations in terms of saving production resources and ensuring more environmentally friendly production using greener cooling methods of machining such as Dry, Conventional cooling systems, Minimum quantity of lubricant (MQL), Minimum quantity of cooling lubrication (MQCL), Nanofluids, Biodegradable Vegetable Oils, Cryogenic Lubrication, and High-Pressure Cooling (HPC). Finally, the important modern trends of providing resource-saving and environmentally efficient technologies in modern sustainable manufacturing are discussed in this paper. • Present review article deals with the sustainability and resource saving aspects during machining operations. • Different cooling conditions were presented. • Waste minimizing, recycling, pollution etc. were discussed during machining oeprations. [ABSTRACT FROM AUTHOR]

The well-known Fresnel equations solve for the reflection and transmission of light for precise incident angles. The transmission of diffuse radiation incident on a planar or domed surface is often needed for real-world applications. Due to the complexity of the Fresnel equations, the analytical solution of the integration has hitherto been unobtainable over the last centuries. Therefore, this problem was numerically solved by integrating the angular transmittances in space often leading to substantial computing burden and bias in the results. To efficiently estimate the solar energy resource for a glass-covered photovoltaic (PV) module, we derive an analytical solution of diffuse transmission based on the rigorous integration of an alternate form of the Fresnel equations. The approach leads to a simple yet accurate relative transmittance model that reconciles the solar energy sensed by pyranometers and PV panels. With limited and clearly stated approximations, the complex mathematical derivation resulted in an elegant solution. An experiment using 1-year of data at the National Renewable Energy Laboratory's (NREL's) Solar Radiation Research Laboratory (SRRL) shows that the new model dramatically decreases the disparity between the solar radiation measurements by a Kipp and Zonen CM Pyranometer 22 (CMP22) and an IMT reference cell on a 1-axis tracking system. The solution in this paper can be widely used in scientific and engineering research, development, and applications wherever the Fresnel equations are used. • The Fresnel equations solve for transmission in precise incident angles. • This solution can efficiently reconcile the solar energy observation and the realistic energy resource for PV. [ABSTRACT FROM AUTHOR]

This paper proposes a B-splines integrated method combining in-situ data with grey-box modeling to estimate buildings' dynamic solar gain more efficiently than the conventional white-box model and much more precisely than the classic grey-box model. Solar gain, referring to the overall indoor energy gain supplied by solar radiation, plays a vital role in the indoor energy balance. Estimating dynamic solar gain precisely is essential to building energy optimization, e.g., in model predictive control. However, in almost all existing grey-box modeling works, a constant solar gain factor (solar aperture; gA) is assumed to estimate dynamic solar gain, which almost certainly will result in solar gain prediction errors, especially in buildings with unevenly distributed windows. To fill this gap, this study presents an advanced B-splines integrated grey-box model, using customized B-splines to advance the constant gA assumption toward its nature of time-dependence and precisely characterize the dynamic solar gain conclusively. On-site measured datasets of a portable site office (PSO) representing a 'simplified' building, under two scenarios with windows fully or partially uncovered, serve as test cases. To verify the physical interpretation of outcomes estimated by the proposed method, based on the said test cases, the proposed B-splines integrated grey-box model is compared with a classic white-box simulation. It is concluded that the proposed method can reveal the main trends and key dynamic features of solar gain very well, but still has some limitations of quantifying 'local' details with acceptable variations. Nevertheless, given that the proposed method merely asks for a very limited amount of low-frequency data, the proposed method is considered as a much more effective alternative to the classic white-box simulation approach, which requires massive and often hard-to-collect input data. • Assuming solar aperture constantly in data-driven models is demonstrated as less suitable for predicting solar gains. • An advanced B-splines integrated grey-box modelling technique is proposed to offer reliable dynamic solar gain estimations. • Only a short and low frequency dataset with limited number of parameters is required for this enhanced technique. • Limitations of four techniques for estimating dynamic solar gain are discussed. [ABSTRACT FROM AUTHOR]

An understanding of how storage technologies coordinate with other power resources to deliver value for electricity market participants in compliance with climate policy will be vital as policy makers seek to decarbonize electricity generation in a cost-effective way. This paper adopts a game-theoretic electricity market model to evaluate the interaction between pumped hydro storage, electric vehicles, and climate policy under a range of assumptions regarding market power and ownership of generation and storage assets. Using data from the Chinese electricity market, it shows that climate policy may not incentivize storage utilization especially when firms that hold a dominant position in storage operation own a limited portfolio of generation assets. In addition, electric vehicles may not improve consumers' welfare in the presence of pumped hydro storage when perfect competition exists in the market. These results have significant implications for public policy. • A game-theoretic electricity market model is evaluated for China. • The interaction between storage, electric vehicles, and climate policy is studied. • Climate policy may not incentivize storage use depending on the ownership of assets. • The benefits of electric vehicles decline in the presence of pumped hydro storage. • Perfect competition may not always create the best choices for consumers. [ABSTRACT FROM AUTHOR]

This paper presents the results of a multi-model comparison to determine outcome deviations resulting from differences in power system models. We apply eight temporally and spatially resolved models to 16 stylized test cases. These test cases differ in their renewable energy supply share, technology scope, and optimization scope. We focus on technologies for balancing the variability of power generation, such as controllable power plants, energy storage, power transmission, and flexibility related to sector coupling. We use harmonized input data in all models to separate model-related from data-related outcome deviations. We find that our approach allows for isolating and quantifying model-related outcome deviations and robust effects concerning system operation and investment decisions. Furthermore, we can attribute these deviations to the identified model differences. Our results show that trends in the use of individual flexibility options are robust across most models. Moreover, our analysis reveals that differences in the general modeling approach and the modeling of specific technologies lead to comparatively small deviations. In contrast, a heterogeneous model scope can cause substantially larger deviations. Due to a large number of models and scenarios, our analysis can provide important information on which investment and operation decisions are robust to the model choice, and which modeling approaches have an exceptionally high impact on results. Our findings may guide both modelers and decision-makers in properly evaluating the results of similarly designed power system models. [Display omitted] • Harmonized application of eight power sector models with sector coupling. • 16 test cases differing in harmonization scope, optimization scope, and power supply. • Deviations in fully harmonized models are mostly below 20% and can be traced back. • Technology use can vary by more than an order of magnitude for different model scopes. • Use of sector coupling for renewable energy integration is robust across all models. [ABSTRACT FROM AUTHOR]

With the ever-increasing use of Wireless Sensor Networks (WSNs) in scientific and industrial applications, the users' desire to ensure their uninterrupted operation over long periods of time could not be fulfilled by relying solely on batteries with finite energy supply, storage, and lifetime. In pipeline monitoring networks, the finiteness of these resources engenders unavoidable downtimes caused by the replacement of spent batteries, inspection and repairs of resulting failures, including pipe leaks and ruptures. All of this would result in costly operational interruptions, leading to concomitant disruptions in fluid transport logistics, and crippling production losses in the monitored systems. This spurred an ongoing and vigorous research effort into devising a suitable logistics-aware energy management scheme to ensure an uninterrupted and cost-efficient operation. At the core of this scheme, lies energy harvesting which provides monitored networks with vital operation-sustaining energy gathered from natural sources emanating from the sensors' surroundings. This paper therefore aims at giving a comprehensive review of these alternative energy sources, the mechanisms behind harvesting their energies and various ways of integrating each of them into WSNs. This review is vital in providing engineers with an up-to-date comparative study and a valuable roadmap of, and selection guidelines for, the state-of-the-art energy harvesting technologies used. This study reviews the pros and cons of different harvesting technologies and concludes with some pointers towards some research gaps that need to be addressed to facilitate the development of reliable and cost-effective leak detection schemes, with longer operational lifetimes, better reliability, cost efficiency and logistical support. • Gives a comprehensive and timely review of key energy harvesting techniques (EHTs). • Provides a clear and practical taxonomy of both invasive and non-invasive EHTs. • Enriches literature coverage of the EHTs' importance in Renewable Energy research. • Gives key knowledge for informed techno-economic & environmental impact analyses. • Provides practical design roadmap for efficient energy systems design & management. [ABSTRACT FROM AUTHOR]

The rapidly increasing penetration of distributed energy resources (DERs) calls for a hierarchical framework where aggregating entities handle the energy management decisions of small DERs and represent these DERs upstream. These energy management decisions are typically envisaged to be made via market-based frameworks, aspiring the so-called Local Electricity Markets (LEMs). A rich literature of studies models such LEMs adopting various modeling assumptions and proposes various Market Mechanisms towards making dispatch and pricing decisions. In this paper, we make a systematic presentation of a LEM formulation, elaborating on the cornerstone attributes of the market model, i.e. the Market Scope, the Modeling Assumptions, the Market Objective, and the Market Mechanism. We discuss the different market model choices and their implications and then focus on the prevailing approaches of Market Mechanisms. Finally, we classify the relevant literature based on the market model that it adopts and the proposed Market Mechanism, visualize the results and also discuss patterns and trends. • Describe a systematic framework for LEM market models. • Categorize the Market Mechanisms most typically used in LEMs. • Present the main known results regarding the properties of each mechanism family. • Classify the literature within the presented framework. • Visualize the classification, revealing patterns, areas less researched and research gaps. [ABSTRACT FROM AUTHOR]

The sustained rapid growth and learning rates displayed by solar PV and wind electricity generation capacity over recent decades appear to be unprecedented. With these technologies now available at costs competitive with - or below - those of fossil fuel incumbents in many parts of the world, high rates of growth appear likely to continue. In this paper we use 'top-down' extrapolation of global trends and simple and transparent models to attempt to falsify the proposition that PV and wind have the potential to achieve dominance in global primary energy supply by 2050. We project future deployment of PV and wind using a logistic substitution model, and examine a series of potentially fundamental constraints that could inhibit continued growth. Adopting conservative assumptions, we find no insuperable constraints across physical and raw materials requirements, manufacturing capacity, energy balance (EROEI), system integration and macro-economic conditions, to this outcome. We also demonstrate synergy with direct air carbon capture and storage (DACCS) that would allow the achievement of global net-zero CO 2 emissions by mid-century. Achieving such an outcome would require large scale reconfiguration of the architecture of global and regional energy systems, particularly from 2040 onwards. Low cost primary electricity is likely to be a significant factor in driving such a reorganisation. But given the speed and depth of the transition, hurdles will remain that will require foresight and strategic, coordinated action to overcome. • Extrapolating PV and wind deployment using logistic substitution suggests they may dominate global energy supply by 2050. • There are synergies between PV and wind, and DACCS. DACCS adds flexibility to a renewably powered energy system. • This supply-side transformation would both drive and require a wholesale reconfiguration of the rest of the energy system. • With DACCS, this process could reduce net global CO 2 emissions from energy to zero by 2050, and below zero thereafter. • There appear to be no insuperable physical or economic barriers to such an outcome. [ABSTRACT FROM AUTHOR]

An extensive canal irrigation network in South Asia has developed over the past 170 years that consists of thousands of kilometers of constructed channels and distributaries. These canals cut across many energy-poor regions along their paths. In India, this canal network provides a unique opportunity for renewable energy generation that is yet to be realized. Existing technologies for energy generation on canals include small hydropower on canal falls and, recently, canal-top solar panels. In addition, opportunities for hydrokinetic generation in irrigation canals have received limited attention. This paper develops a novel canal-network level framework for energy planning that integrates generation with local energy needs in a canal-corridor. This framework for integrated spatial assessment analyzes the supply of renewable energy generation potential and the demand of unmet energy needs in a canal-corridor, using the Upper Ganga Canal in Uttar Pradesh, India as a case study. We consider the theoretical and technological potential of hydropower and solar power generation and develop three indices to assess the agricultural, domestic, and composite unmet power demand of the canal-corridor. Our results show an overall theoretical potential of 149.1 MW and 13,213 MW for small hydropower and solar power, respectively, which could more than help meet the current 18 hours per day electricity service standard in Uttar Pradesh. The framework uses standardized irrigation and census datasets and therefore is generalizable for canal networks across India and South Asia more broadly. • Irrigation canal energy technologies include small hydro and canal-top solar power. • Novel canal-network level framework for energy planning. • Integration of generation potential with local energy needs in a canal corridor. • Theoretical and technological potential of energy generation on canals. • Three indices for agricultural, domestic, and composite unmet power demand. [ABSTRACT FROM AUTHOR]

As more distributed energy resources are deployed on electric grid systems across the world, it is important to identify, characterize, and quantify the value elements of different types of distributed energy resources so that policymakers, developers, and utilities can make informed energy deployment decisions. This paper focuses on the value of wind energy as a distributed energy resource (i.e., "distributed wind"). Because of a lack of distributed wind-specific valuation studies, in this review we document the current state of distributed energy resource valuation, analyze a wide array of distributed energy resource valuation metastudies, and identify several value elements for which we recommend developing more robust and standardized calculation methodologies for their potential inclusion in distributed wind valuation. These value elements are ancillary services and locational, resilience, reliability, and resource diversity benefits. This work lays the foundation for a future comprehensive framework for distributed wind valuation studies. • Detailed review of current state of DER valuation. • First specific examination of valuation of wind as a distributed energy resource. • Identification of important value elements for distributed wind valuation. [ABSTRACT FROM AUTHOR]

There has been a dramatic increase in wind power supply due to the growing demand for renewable energy sources across the globe. In this process, technological advancements have led to the emergence of more sophisticated wind turbines with higher hubs and larger swept areas to reduce the unit costs for power generation. However, there is also a growing concern about the visibility impacts of wind turbines. Spatial modelling of the potential visibility of wind turbines holds strategic information for wind power siting decisions. The visibility information is critical to breaking trade-offs between energy production and protecting the visual amenity of landscapes. Currently, public attention to the visual impacts of wind turbines tends to rise in countries with high wind power capacities. Decreases in property values due to wind turbine visibility and negative impacts on scenery are among the factors that draw public attention. These implications make it necessary to use spatial analysis and develop mitigation strategies based on the geospatial outputs. This paper aims to produce Potential Visibility Models (PVM) to analyse wind turbine visibility from candidate observation locations where the scenery is an important asset. These are residential buildings (RB), protected areas (PA), natural and archaeological sites (NAS), tourism development centres (TDC), roads (RD), and the coastal areas (CS). The results showed that potential turbine visibility varied across the study area considering the five qualitative visibility classes. The areas with "very low" and "low" potential visibility were proposed as candidate areas of low visual impact for wind power generation. [Display omitted] • Potential visibility models (PVM) for wind turbines were produced. • The observer locations were selected in the areas where scenery is the key asset. • Target offsets that represent turbine heights ranged from 20 to 140 m. • Potential wind turbine visibility was conceptualized in a "combined visibility" map. • The areas of lower potential visibility scores were proposed for wind power siting. [ABSTRACT FROM AUTHOR]

Extreme weather events are the common causes for power supply interruptions and power outages in electrical distribution systems. Improving the distribution system and enhancing its resilience is becoming crucial due to the increased frequency of extreme weather events. Preparation and allocation of multiple flexible resources, such as mobile resources, fuel resources, and labor resources before extreme weather events can mitigate the effects of extreme weather events and enhance the resilience of power distribution systems. In this paper, a two-stage stochastic mixed-integer linear programming (SMILP) is proposed to optimize the preparation and resource allocation process for upcoming extreme weather events, which leads to faster and more efficient post-event restoration. The objective of the proposed two-stage SMILP is to maximize the served load and minimize the operating cost of flexible resources. The first stage in the optimization problem selects the amounts and locations of different resources. The second stage considers the operational constraints of the distribution system and repair crew scheduling constraints. The proposed stochastic pre-event preparation model is solved by a scenario decomposition method, Progressive Hedging (PH), to ease the computational complexity introduced by a large number of scenarios. Furthermore, to show the impact of solar photovoltaic (PV) generation on system resilience, three types of PV systems are considered during a power outage and the resilience improvements with different PV penetration levels are compared. Numerical results from simulations on a large-scale (more than 10,000 nodes) distribution feeder have been used to validate the effectiveness and scalability of the proposed method. [Display omitted] • The power distribution systems are vulnerable to extreme weather events. • Pre-event preparation can enhance the resilience of the power distribution system. • A two-stage SMILP is proposed for pre-event preparation and resource allocation. • The impacts of PV generations on system resilience are fully considered. • To verify the scalability, a large-scale distribution feeder is tested. [ABSTRACT FROM AUTHOR]

The increasing demand for renewable energy worldwide has contributed to a substantial increase of offshore wind farms in recent years. For this type of generation, submarine power cables are of great importance as they transmit power between the turbines and the offshore substation to the land connection. Last 20 years of experience shows that the power cables are the largest contributor to the failures of power supply from the offshore plants. Additionally, the repairs of such a critical infrastructure are extremely challenging and costly. Therefore, several aspects of the design, transportation, installation and operation of power cables at offshore wind farms require special attention. Based on international experience gathered from various projects over the last few years as well as international references, this paper discusses offshore power cables from the perspective of reducing the risks of failure and increasing supply reliability. • Cable failures are responsible for up to 80 % of the total financial losses in offshore wind farms. • Sound submarine cable design and testing criteria should be established. • Submarine power cables are subjected to high mechanical, electrical and environmental stresses. • Sensitive and non-destructive diagnostic methods have to be applied to detect potential weak spots. • Reducing the risk of failure of the offshore infrastructure is crucial for the reliability of offshore wind farms. [ABSTRACT FROM AUTHOR]

This paper studies the impact of oil prices on financial market volatilities and clean energy investments by including the energy democracy approach to its analysis. Our main intention is to question whether a carbon free sustainable financial market environment. Since crude oil is still the primary energy source and the markets heavily depend on oil prices, any surge in the prices creates uncertainty and increases the fear in the markets. In this study, we contribute to the existing literature in two ways. First, rather than seeking a direct relationship with oil-clean energy returns, we include market fear represented by CBOE volatility index (VIX) to our models. Secondly, we utilize VAR-VECH-TARCH models with three different model systems and two different VAR system specifications for two different time periods. According to our asymmetric volatility model results, long-term volatility spillovers exist between clean energy, brent oil and volatility index. Moreover, considering the cross relationship between clean energy, brent oil and VIX, bad news contributes more to the systemic risk of energy company stock returns than good news. These findings state that the relationship between energy democracy and clean energy investments should be considered in more details while policy implications should support renewable energy investment policies and reduce the pressure of oil suppliers on both financial markets and clean energy investments. • According to energy democracy approach, replacing fossil-fuel resources with clean energy is social restructuring act as well as a technological improvement via deployment of renewable. • Our main research topic is whether clean energy investments can provide sustainability in the markets. • In this study, we include market fear represented by CBOE volatility index (VIX) to our models. While employing VAR-VECH-TARCH models with three different model systems. • Our findings state that the relationship between energy democracy and clean energy investments is a crucial topic to enable clean energy evolution. [ABSTRACT FROM AUTHOR]

Pacific island countries are particularly susceptible to sea level rise as a result of climate change and also face high costs and energy security issues from imported fossil fuels. As a result many Pacific island countries are perusing 100% renewable energy targets. Due to challenges with variable renewable energy sources, detailed studies that balance renewable energy supply and demand at a fine temporal scale have been carried out for many countries to inform policy directions. Despite having adopted renewable energy targets, most Pacific island countries have not been subject to the same level of detailed analysis in the academic literature. In addition, the results from other countries are not directly applicable given the particular local resources, climatic conditions and economic situation of Pacific island countries. In this paper, focusing on the case of Samoa, we use an approach based on historical electricity demand and generation time-series data to investigate future scenarios that achieve very high percentages of renewable electricity. The results show that scenarios of high proportions (above 90%) of renewable energy generation coupled with storage (28%–37% of direct solar, 17%–30% of stored solar and 25%–40% of hydro) are economically viable (Net Present Value > 0) but, there is a significant trade-off between percentage of renewable supply and affordability. These results have important implications for energy policy directions for Samoa and are directly applicable to many other countries in the Pacific. • Future scenarios of very high percentages of renewable electricity for Samoa are explored based on detailed balancing of renewable supply and demand. • A number of scenarios with high proportions of renewable energy generation coupled with storage are economically viable. • There is a significant trade-off between percentage of renewable supply and affordability. • A straightforward and transparent methodology that can be adapted to other Pacific island countries is presented. [ABSTRACT FROM AUTHOR]

In this paper, an optimal off-grid solar photovoltaic (PV)/hydrogen fuel cell (FC) (HFC) based energy system is proposed for renewable energy generation to supply electricity to the end-user load demand in north-east (NE) Indian states. The energy system is modeled and simulated in the HOMER software. The monthly average global horizontal solar radiation (GHSR) and ambient temperature of the NE states are found to be 3.95–4.79 kWh/m2 and 12.9–25.3 °C, respectively. The synthesized typical AC electrical load profile of 10 kWp is assumed to have a scaled daily annual mean value equal to 138 kWh/d and an average base demand value equal to 5.75 kW. With the considered connected load, the available GHSR and ambient temperature, the optimal sizes of renewable energy components for the considered eight geographical locations (latitude: 23° 30′-27° 3′ North, longitude: 88° 37' – 94° 7′ East) are determined based on the minimum levelized cost of energy (COE) and lowest net present cost (NPC). The optimal system architecture range obtained is 110–120 kW PV array, 10–15 kW FC, 30–60 kW electrolyzer, 40–60 kg hydrogen tank capacity and 15 kW converter. Based on optimization results, the levelized COE and NPC range obtained are 0.509–0.689 $/kWh and $ 3,27,557–4,43,004, respectively, which confirm the cost-effectiveness of the proposed optimal energy system. Besides, with a renewable fraction of 100%, the electricity generated by the PV/HFC system satisfied the load demand and produced excess electricity with capacity factor found to be 16.4–31.2% in all the NE Indian states. Moreover, the optimized electrical profile, PV profile, inverter profile, and hydrogen production from an FC are compared and analyzed in terms of monthly average and annualized values for all the NE states. Also, the range of net hydrogen produced by the electrolyzer over the year obtained is 1538–1856 kg/yr. [Display omitted] • Recommended an optimal off-grid PV/HFC energy systems for eight India north east (NE) states. • System profiles are compared, analyzed and discussed for all the NE states. • The levelized COE is 0.509 – 0.689 $/kWh and NPC is $ 3, 27,557-4, 43,004. • Excess electricity produced in NE states ranges from 21.4-41.4%. • Net hydrogen produced by the electrolyzer over the year is obtained as1538-1856 kg/yr. [ABSTRACT FROM AUTHOR]

Amalgamation of distributed energy resources (DER) with power system is developing as an emerging power framework. It is ecumenically based on the paramount issues such as extensive use of technologies based on distributed energy resources, shortage of fossil fuel in future, liberalism of electrical service industries and custom vigilance on environmental impact of the conventional method of generating electrical power. These issues are transmuting the concept of conventional power generation globally and introduce incipient challenges in the generation and distribution system. The interconnection of distributed generators has initiated the concept of microgrid which is the assemblage of interconnected distributed generators, intermediate storage units and loads. The pragmatic application of microgrid faces numerous technical challenges. Scheming with a congruous protection scheme is one of the solemn challenges in a microgrid framework. The level of fault current in both the modes of operation, active distributed generation, two-way flow of power, increased value of impedance and quality of communication network are the profuse challenges in scheming an efficacious protection technique. The protection scheme must be reliable, selective, fast and susceptible in both the working modes. This paper presents the meticulous study of the architecture of AC microgrid, DC microgrid and hybrid microgrid along with the associated protection issues and solutions. It also provides the censorious assessment of available challenges in the protection of microgrid in both grid-tied & islanded mode and available protection strategies for both AC microgrid and DC microgrid. An all-inclusive review has been done in each section considering the latest developments along with the future progression in the field of microgrid protection. • Discuss the various frameworks of microgrid. • Detailed emphasis on the protection issues of AC microgrid and DC microgrid. • Identify the various protection challenges in grid-tied mode and islanded mode. • Critical analysis and comparison of available protection techniques. • An all-inclusive review of the latest developments in the field of protection. [ABSTRACT FROM AUTHOR]

Islanded microgrids (IMGs) provide a promising solution for reliable and environmentally friendly energy supply to remote areas and off-grid systems. However, the operation management of IMGs is a complex task including the coordination of a variety of distributed energy resources and loads with an intermittent nature in an efficient, stable, reliable, robust, resilient, and self-sufficient manner. In this regard, the energy management system (EMS) of IMGs has been attracting considerable attention during the last years, especially from the economic and emissions point of view. This paper provides an in-depth overview of the EMS optimization problem of IMGs by systematically analyzing the most representative studies. According to the state-of-the-art, the optimization of energy management of IMGs has six main aspects, including framework, time-frame, uncertainty handling approach, optimizer, objective function, and constraints. Each of these aspects is discussed in detail and an up-to-date overview of the existing EMSs for IMGs and future trends is provided. The future trends include the need for improved models, advanced data analytic and forecasting techniques, performance assessment of real-time EMSs in the whole MG's control hierarchy, fully effective decentralized EMSs, improved communication and cyber security systems, and validations under real conditions. Besides, a comprehensive overview of the widely-used heuristic optimization methods and their application in EMSs of IMGs as well as their advantages and disadvantages are given. It is hoped that this study presents a solid starting point for future researches to improve the EMS of IMGs. • The six aspects of the energy management system optimization of islanded microgrids. • Overview of heuristic algorithms for EMS optimization problem. • EMS optimization frameworks and uncertainty schemes: Deterministic, stochastic, robust. • Reviewing constraints, cost functions, and time-frames for EMS optimization problem. • Introducing the future trends in energy management system of islanded microgrids. [ABSTRACT FROM AUTHOR]