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This paper addresses the challenge of active fault-tolerant coordination control (AFTCC) for proton exchange membrane fuel cells (PEMFCs), which are complex nonlinear systems with multiple inputs and outputs. Conventional fault-tolerant control methods cannot properly coordinate multiple operating variables and prevent constraint violations in PEMFCs. Our proposed AFTCC method seeks to stabilize the output performance of four operating variables and avoid PEMFC operating constraint violations during failure scenarios. Our method is supported by a curriculum-based multiagent deep meta-deterministic policy gradient (CMA-DMDPG) algorithm, which integrates meta-reinforcement learning, multiagent reinforcement learning and curriculum learning to achieve multitask collaboration of multiple agents, thereby enhancing PEMFC robustness. The algorithm consists of a meta-learner and a base learner. The base learner regards the hydrogen controller, oxygen controller, pump controller and radiator controller as four independent agents and thus achieves a cooperative control policy. The meta-learner detects PEMFC faults and selects an appropriate cooperative control policy. The performance of AFTCC under various stochastic and fault conditions is evaluated using a 75 kW PEMFC model. The results showed that the performance of AFTCC surpassed 11 other fault-tolerant control methods in terms of output voltage, oxygen excess ratio, and stack temperature, and avoided constraint violations. • An AFTCC method is proposed to realize active fault-tolerant control of the PEMFC. • A CMA-DMDPG algorithm is proposed to realize multi-task collaboration of controllers. • The AFTCC improved PEMFC control performance and prevent constraint violation. [ABSTRACT FROM AUTHOR]

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

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

In the context of carbon neutrality, renewable energy, especially wind power, solar PV and hydropower, will become the most important power sources in the future low-carbon power system. Since wind power and solar PV are specifically intermittent and space-heterogeneity, an assessment of renewable energy potential considering the variability of wind power and solar PV with high temporal resolution in different regions will facilitate more accurate identification of the decarbonization pathway of power system. In this paper, the complementary output potential of wind-solar-hydro power every 15 min in 31 Chinese provinces is evaluated by developing a multi-objective optimization model based on Nondominated Sorting Genetic Algorithm II. The results show that the total annual complementary power generation potential in China is 17.57 PWh, of which the three components account for 47.8%, 25.3% and 26.9%, respectively. Inner Mongolia and Tibet are the major renewable energy source provinces with annual complementary power generation potential of 5330 TWh and 3907 TWh, accounting for 30.3% and 13.7% of the total power generation potential, respectively. The temporal potential of wind-solar-hydro power varies greatly, with daily potential is more volatile than monthly. Seasonal and spatial heterogeneity of the complemental renewable potential makes some provinces suffer power shortage during long-hours period especially in winter. Our findings will encourage a higher penetration of renewable energy, the promotion of multi-energy complementarity, and the development of inter-provincial power transmission and energy storage infrastructure in China's future power sector. • A multi-objective wind-solar-hydro complementary optimization model is developed. • Electricity supply and demand have gaps at different temporal and spatial scales. • Wind-solar-hydro complementary potential shows great temporal and spatial variation. • Renewable complementarity can improve China's future power system stability. [ABSTRACT FROM AUTHOR]

This paper models two strategic decisions made by industrial entities: the intention to adopt a renewable energy system (RES) and the timeframe for this adoption. The methodology presented considers multiple layers of "unobserved heterogeneity." The results of random parameters imply that the parameters exhibit unobserved heterogeneity across industrial entities. For example, high non-electric energy costs increase the probability of selecting a shorter timeframe in 81.8% of entities and reduce that probability in 18.2% of entities. The results of this study also show that the majority (60%) of responding entities intend to adopt an RES within a short timeframe, generally one to two years, while 40% intend to adopt an RES three or more years after 2022. According to our findings, green bank loans, electricity tariffs, the type of industry, government bureaucracy, and entities' export capabilities predominantly influence their intention to adopt an RES. The results also show that energy-intensiveness (e.g., industrial entities in the plastic and rubber, food and drinks, and chemicals and paints sectors), high electricity tariffs, and elevated non-electric energy costs often expedite the adoption process (resulting in shorter adoption timeframes). Government impediments tend to cause entities to delay their adoption decisions. Capital costs are by far the largest impediment to adoption, as indicated by 29.3% of the surveyed entities, followed by government legislation at 18.6%. The findings presented offer crucial knowledge for creating opportunities to implement new policies and produce an environment in which industries can expedite their transitions to renewable energy. • Solar PV demand by the industrial sector is addressed through heterogeneity models. • Two key decisions are addressed: the intention to adopt and the adoption timeframe. • Heterogeneity in means and variances of the random parameters are accounted for. • Several explanatory variables turned out to influence the two demand decisions. • Heterogeneity models are statistically superior to fixed parameters models. [ABSTRACT FROM AUTHOR]

Although there is large consensus regarding the significance of flexibility in power systems, there exists significant disparity in the definitions and models employed to describe flexibility. To structure existing flexibility descriptions, this work classifies the mathematical principles underlying the flexibility models and finds quality metrics, machine learning models, and flexibility envelopes to be the main higher-order classes, with envelopes being the most popular one. It finds that there is a significant degree of mathematical incompatibility among different flexibility models, even within the same class. This is primarily due to the utilization of distinct flexibility metrics. To address the ambiguities in flexibility definitions and terminology, this paper introduces FLEXBLOX, a formal flexibility taxonomy. FLEXBLOX encompasses three core building blocks: a power system's flexibility requirements, the flexibility potentials provided by flexibility resources, and flexibility mediators that facilitate between the requirements and the potentials. An analysis of 49 flexibility models shows that three of them cover both flexibility requirements and potentials. However, only one of the three approaches also considers a flexibility mediator between them. Two models are generic enough to describe the flexibility potential of diverse flexibility resources, but certain resource characteristics are often excluded. To date, there is no flexibility model that addresses all three flexibility building blocks of the FLEXBLOX taxonomy coherently. This leaves room for future research directions that are suggested in this work. • Flexibility taxonomy based on the concepts of flexibility requirements and potentials. • Categorization of existing flexibility concepts to structure the research area. • Classification scheme for flexibility models based on mathematical principles. • Analysis of 49 flexibility models with regard to the flexibility taxonomy. • Discussion of future research directions in formal flexibility modeling. [ABSTRACT FROM AUTHOR]

Wireless power transfer (WPT) promises to be an alternative solution for secure and versatile charging of electric vehicles. However, some challenges still exist in this contactless technology, such as electromagnetic safety, low transmission efficiency and power capacity. A vast research literature focuses on improving the design and optimization of WPT systems. This paper provides an in-depth literature review on the current status and potential trends of wireless charging for electric vehicles and brushless excitation technology for drive motors, including the power electronic structure, coupling mechanism, and compensation topology of WPT systems. In addition, several emerging research topics are proposed and highlighted. • Fundamental theory, types, and performance of wireless power transmission is reviewed. • The application of WPT systems in electric vehicle charging and non-contact excitation is summarized. • The performance of inductive and capacitive power transfer is compared. • Challenges on coupling mechanism, electromagnetic compatibility, and optimization persist. [ABSTRACT FROM AUTHOR]

This paper is concerned with the fixed-time fractional-order sliding mode control (FTFOSMC) approach using fixed-time disturbance observer (FTDO) for the load following problem of a pressurized water reactor (PWR), in the presence of load-dependent parameters and perturbations. First, by integrating the merits of the fixed-time stability theory and the disturbance observer technique, an FTDO which can ensure fixed-time convergence is constructed to estimate perturbations induced by model uncertainties, external disturbances, and unmeasured states. Then, an FTFOSMC strategy with the help of the disturbance observer is proposed to achieve strong robustness against perturbations and high-precision load following performance. The fixed-time stability of the closed-loop system is theoretically demonstrated by Lyapunov's theorem. Finally, comparative simulation results are presented to illustrate the superiority of the overall proposed control strategy. • A more accurate PWR model with load-dependent parameters and perturbations is built. • A nonlinear FTDO is developed to estimate perturbations. • A FTFOSMC scheme coupled with FTDO is proposed. • Fixed-time stability of closed-loop system is theoretically demonstrated. • Simulation and comparison results reveal superiority of proposed scheme. [ABSTRACT FROM AUTHOR]

Net-zero emission and self-sustaining carbon-neutral have been widely encouraged and intensively explored in wastewater treatment, as the wastewater industry accounts for approximately 1.6% of global greenhouse gas (GHG) emissions. However, how to achieve net-zero GHG emission in wastewater treatment from a biological standpoint is still lacking. In this paper, the status of GHG (i.e. nitrous oxide (N 2 O), methane (CH 4) and carbon dioxide (CO 2)) production and emission in wastewater treatment was comprehensively reviewed. Generally, N 2 O emission contributes the majority of the total GHG emissions from wastewater treatment, and the dissolved N 2 O and CH 4 in the effluent should be paid more attention for the further GHG mitigation. Based on the newly identified microbial communities capable of nitrogen removal with less GHG emissions, several alternative integration systems for GHG mitigation were discussed. Coupling denitrifying anaerobic methane oxidation with anammox process shows high nitrogen removal performance and low GHG emissions, which is regarded as a more promising integration system for GHG mitigation. Moreover, the novel strategies to manage N 2 O and CH 4 as energy sources were also demonstrated, aiming to offset certain carbon footprint in wastewater treatment and thus attain net-zero GHG emission. In addition, future challenges and perspectives of above integration systems and strategies were discussed to facilitate the development of environmentally sustainable wastewater treatment. Finally, a prospective hybrid system integrating emission reduction and energy recovery was proposed as an example for achieving net-zero GHG emission from wastewater treatment. [Display omitted] • Status on GHG production and emission in each treatment unit is quantified. • Autotrophic microorganisms play important roles in mitigating GHG emission. • CH 4 is more feasible than N 2 O for energy recovery from mainstream wastewater. • Net-zero GHG emission integrates both emission reduction and energy recovery. [ABSTRACT FROM AUTHOR]

The determination of maintenance strategies is subject to complexity and uncertainty arising from variable offshore wind farm states and inaccuracies in model parameters. The most common method in the existing studies is to adopt an open-loop approach to optimize a maintenance strategy. However, this approach lacks the ability to capture periodic operational state of the wind farm and the awareness of eliminating uncertainty. Consequently, the determined strategy is inadequate to instruct maintenance activities, inducing excessive revenue losses. In this paper, a closed-loop maintenance strategy optimization method is proposed for decision-makers to identify a more profitable manner of wind farm maintenance management. The life-cycle maintenance optimization problem is decomposed into a sequence of sub-optimization problems covering multiple time periods by using a rolling-horizon approach. Each sub-optimization problem is intentionally designed based on the monitored state of the wind farm and the available reliability, availability, and maintainability (RAM) database. Meanwhile, the decision maker consciously mitigates the parameter uncertainty in the maintenance model gradually by updating the current database. Compared to conventional strategies covering the entire lifetime of wind farms, the proposed maintenance strategy is periodically adjusted to provide a series of sub-strategies. The proposed approach was applied in a simulation experiment, a generic small-scale offshore wind farm, to assess its performance. Computational results show that adapting maintenance strategies based on the current state of the wind farm can reduce revenue losses in comparison to conventional open-loop strategies. In addition, the benefits of updating the RAM database in decreasing revenue losses is revealed. • Proposing a maintenance strategy with a closed-loop decision-making process. • Dividing the entire maintenance optimization problem into sub-problems covering multiple time periods. • Gradually mitigating model parameter uncertainty over time with new operational data. • Adjusting the entire maintenance strategy into a series of sub-strategies based on wind farm states and updated parameters. [ABSTRACT FROM AUTHOR]

With the intensification of global climate problems, the worldwide call for reducing CO 2 emissions is getting louder and louder. Low-carbon development has become the consensus of all countries. The electric heating film systems (EHFS) have recently attracted much attention as a clean and low-carbon building heating way due to the global target of carbon neutrality. This paper aims to provide a comprehensive review of the materials, performances and applications of the electric heating film (EHF). The conductive materials for the EHF mainly include graphene and carbon nanotubes (CNTs). Moreover, the main preparation methods are redox method, chemical vapor deposition (CVD), vacuum filtration method and screen printing. It was found that the EHF doped with the graphene or the carbon nanotubes (CNTs) has better performance on flexibility and thermal stability. The EHF prepared by chemical vapor deposition (CVD) has the best performance on uniformity and structure. However, this method is costly and difficult to implement for large-scale industrial production. Therefore, the screen printing technology remains the most widely used method. The composite EHF with two or more conductive materials (graphene and multi-walled carbon nanotubes (MWCNT)) has excellent mechanical properties, superb damage resistance and flexibility. In addition, the numerical simulation based on computational fluid dynamics (CFD) will be an important research method to investigate the indoor thermal environment of building heating by EHFS, which needs to be conducted in the future. The high performance EHF will be widely used in international applications such as artificial intelligence, wearable devices, aerospace, solar energy and medical protection. • The influence factors of electric heating film (EHF) conductive materials and composites are reviewed. • The methods of EHF and conductive materials are studied and synthesized. • The performance of the EHF is analyzed by means of experimental and numerical simulation. • The application of EHF is reviewed and prospected. [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]

The gamut of geothermal energy research encompasses the studies aimed at harnessing the abundant and inexhaustible thermal energy within the Earth, and it ranges from heat transfer to the activity of thermophilic microorganisms, 3D printing, and additive manufacturing and impacts the NET ZERO endeavour of humanity. In this paper, computational social network analysis has been employed to discover the subfield clusters of geothermal energy research and further trace the key evolutionary routes from the research corpus. The development, limitations, and opportunities of each cluster are examined, and it becomes evident that the focus of research ranges from geothermal evaluation, long-term effects of borehole heat exchangers, shallow systems that employ urbanisation's ground heating, enhanced geothermal systems (EGS) for district heating, combined and hybridised geothermal power generating models, including multi-generation and poly-generation, geothermal fluids, reinjection and their dual nature, environmental effects in geothermal water and mineral scaling, enhanced geothermal systems aiming to increase permeability without causing seismicity, and finally to social acceptability. We address significant questions, such as whether the waste heat is compatible with the idea of green geothermal heat and the elimination of pollutants and find that further R&D and technological advancements are required for this ubiquitous clean energy to get wider acceptance and employment. The future of this energy depends on the rational and scientifically sound exploration and use of the resources, just as in the case of fossil fuels, and thus precludes geothermal energy as a win-all solution to the energy needs of the whole world. • Computational analysis of geothermal energy research themes and linkages. • Algorithmic theme identification rather than expert-based analysis. • Tracing the key-routes of domain evolution. • Subdomain-specific status, limits, emerging fronts and future research agenda. • Impact analysis of contemporary technologies such as AI and 3D printing. [ABSTRACT FROM AUTHOR]

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

The Sun is the star in our solar system that beams solar energy towards the Earth, shining it during the day. The researcher discovered different ways to enhance the use of solar radiation to meet daily need because they are aware of how abundant it is. The thermal performance of double pass solar collector (DPSC) is higher compared to flat plate solar collector (FPSC) when comparing their thermal efficiencies. There have been several studies done on the experimental and theoretical analysis of DPSC, where different kind of tests have been carried out on different aspects. This paper aims to reviews recent development (5 years) on double pass solar collector (DPSC) where it highlights the improvement methods, functioning parameters, materials used, and design configurations. By reviewing experimental and theoretical analysis on the double-pass collector with various thermal transfer enhancement, it can help the researchers to keep updated on new development of the double-pass collector. Several methods to improve the convective heat transfer for the system were adding fins, phase change material (PCM), improved absorbers and porous media to the DPSC. Other important things that require improvement are increasing the outlet temperature, efficiency enhancement for DPSC and pressure drop reduction. The effect of using various mass flow rates, solar radiation, temperatures and working fluid on DPSC are also discussed. We wrap this review by identifying numerous applications that are possible for the solar air heating such as space heating and conditioning, water desalination process and drying agricultural food product. • Adding phase change material (PCM), can enhance thermal efficiency for double pass solar collector. • Fins can increase convective heat transfer. • Porous media can accelerate the performance of double pass solar collector. • Adding tubular on absorber can helps to increase the heat efficiency. • New novelty double pass solar collector has been found for the last 5 years. [ABSTRACT FROM AUTHOR]

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

Interspecies electron transfer (IET) between fatty acid-oxidizing bacteria and hydrogenotrophic methanogens is key to stable and efficient methanogenesis in the anaerobic digestion (AD) process. Recently discovered direct IET (DIET) enables energetically and kinetically advantageous methanogenesis and facilitating cell-to-cell electrical connections using conductive additives (mostly metal- or carbon-based) has been recognized a promising approach to enhancing methanogenesis. Over the last decade, extensive efforts have been made to understand the mechanism and role of DIET in AD and to use it to improve AD performance and stability. However, challenges and limitations remain and must be addressed for the practical application of DIET-AD technology, for example, (i) how to prevent the washout loss of particulate conductive materials in continuous operation, (ii) how to further promote DIET so as to achieve better and more stable methanogenic performance, and (iii) how to evaluate the effects of DIET promotion separately from enhanced biomass retention by adding conductive materials with high specific surface areas. This paper discusses these challenges in both research and practical application of engineering DIET in AD using conductive additives, as well as the efforts to address them. Reviewing current technologies and recent advances to tackle the challenges and improve the practicability of the DIET-AD process, it has been suggested that significant further research is needed, especially on the retention of conductive additives and their biocompatibility and interactions with microorganisms. DIET-AD technology is still in its early stages, and ongoing efforts are required to improve its scalability and economic feasibility at the industrial scale. [Display omitted] • Challenges in engineering DIET with conductive additives are critically reviewed. • Strategies to prevent washout of particulate conductive DIET promoters are needed. • External voltage application with conductive additives can further promote DIET. • Tools to separate the effects of DIET promotion and biomass retention are needed. • More studies are needed to evaluate and improve the scalability of DIET-AD systems. [ABSTRACT FROM AUTHOR]

Increased renewable electricity reduced electricity prices but the costs of consumer-funded support schemes were added to utility bills. Previous studies compared these two components to understand the impacts on consumers. This paper constructs a framework for the electricity sector and provides a new angle to examine the impacts of renewable support schemes on consumers and the sector, respectively. Any negative gain to consumers was offset by the positive gain received by renewable generators (and suppliers), leaving the sector unaffected. In contrast, the increase in renewable electricity brought positive gain to the sector as a whole through reduced fossil fuels imports and greenhouse gas (GHG) emissions. We examine the structural change in the generation mix from 2006 to 2020 in the UK and suggest that wind generation replaced coal-fired generation rather than gas-fired generation on the longer horizon. Therefore, using coal-related coefficients and a contribution share of 38.6% for renewable subsidies, we suggest that wind generation supported by the RO scheme brought positive net gain to the sector, exceeding £800 million per annum in 2018–19 and 2019–20. Therefore, the discrepancy in payoffs from the perspective of consumers and the sector imposed a difficult challenge for policymakers, as criticism would be raised if the analysis was done on consumers only. • Renewable support schemes brought net gain to the electricity sector. • The first type of net gain was avoided costs from fewer imports of fossil fuels. • The second type of net gain was avoided costs from reduced GHG emissions. • Wind replaced coal rather than gas in the generation mix in the long term. • The net gain to the electricity sector exceeded £800 million per annum between 2018 and 2020. [ABSTRACT FROM AUTHOR]

The market of batteries for electric mobility is expected to greatly expand in Europe during the next decades. The most sustainable batteries to be produced in the future depend on the primary and secondary resources available and on the capacity to produce and recycle battery cells. This paper proposes an optimization model based on Material Flow Analysis and prospective Life Cycle Assessment which allows us to suggest the types of batteries which should be produced and recycled, the primary and secondary resources to be used, and in which quantities. Several scenarios are proposed to address the uncertainty of the future batteries market. In the Reference Scenario, designed to reflect the European policies, the results show that Europe would achieve high self-sufficiency from external producers (72%), but this percentage could decrease drastically in the case of alternative scenarios (up to 35%). Furthermore, in the Reference Scenario, lithium-iron-phosphates (40%) and lithium-air (23%) batteries result to be the best options. To cut the consumption of lithium and cobalt, sodium-ion cells (3%) could also be considered for manufacturing or even nickel-cobalt-manganese (6%) type to exploit secondary cobalt. In alternative scenarios instead, the proposed algorithm would suggest different choices as a function of the boundary conditions. For instance, in case the demand and the re-use rate of the cells are higher than in the Reference Scenario, the environmental impact of batteries for mobility turns out to increase because of the lower self-sufficiency of the European industry. • Material flow analysis and prospective LCA are integrated into an optimization model. • Several scenarios are set to address the uncertainty of the future batteries industry. • The European batteries' production and recycling to cut GHG emissions are assessed. • The optimal management of primary and secondary resources is evaluated in time. • The model evaluates the batteries industry's relevant GHG mitigation (up to −45%). [ABSTRACT FROM AUTHOR]

The development of off-grid hybrid renewable energy systems (HRESs) is essential to rural electrification and global decarbonization. Based on 299 journal papers in the recent five years, this work conducts a state-of-the-art qualitative review and quantitative bibliometric analysis on the sizing optimization of off-grid HRESs. An overview of system configurations, energy management strategies, performance evaluation indicators, and sizing methodologies are presented, and bibliometric analysis is conducted to reveal the overall scope and mainstream of this research field. Finally, promising future works are summarized on the basis of current research gaps. The results of bibliometric analysis indicate that: (1) solar photovoltaic and batteries are the most common energy source and energy storage respectively, and wind-photovoltaic-battery-diesel is the most popular system configuration; (2) most researchers apply rule-based energy management strategies rather than optimized strategies, owing to their advantages of simple implementation and fast computation; (3) 97.99% of articles considers economic indicators in the sizing optimization model, and techno-economic feasibility is the essential research foundation at the planning stage; (4) meta-heuristic algorithms and the HOMER software tool are the two most popular sizing methodologies for off-grid HRESs. In future works, hybrid energy storage systems, deep reinforcement learning-based energy management strategy, sustainability and resilience indicators, as well as distributionally robust optimization-based sizing methodologies are promising research directions. Overall, the presented overviews and outlooks can provide holistic theoretical knowledge about sizing optimization research for practitioners, thus promoting the academic progress and practical implementation of off-grid HRESs. • Qualitative review and quantitative bibliometric analysis on energy system planning. • Overview of conventional and emerging renewable energy and storage technologies. • Classification of energy management strategies integrated with sizing optimization. • Multi-perspective projection of future works based on current knowledge gaps. [ABSTRACT FROM AUTHOR]

Dust accumulation on the surface of solar harvesting devices can significantly reduce energy yield. Electrodynamic Shield (EDS) technology can remove dust via an electric field generated on the top layer of the solar harvesting devices. This technology does not require the use of water and can operate with a fraction of the power generated by the solar harvesting devices. The electric field is generated by applying a voltage across electrodes deposited on the surface of the solar harvesting devices. Extensive research is being carried out to: (1) Identify and characterize important parameters and their effect on the cleaning efficiency of the EDS, (2) improve the optical transmission and conductive properties of the electrodes, and (3) develop scalable electrode coatings. This review paper discusses the current state of research on EDS technology, mechanisms of dust removal, parameters that determine cleaning efficiency, and recent advances in the application of EDS for both space and terrestrial applications. The literature on the impact of electrode geometry is less than adequately needed to understand its effects on cleaning efficiency. The independent role of frequency and waveshape applied to an EDS remains an open research question. The main challenges that need to be addressed before this technology can be successfully implemented on a large scale include: (1) increasing the efficiency of fine dust particle removal while optimizing for power consumption, (2) further experimental validation of theoretical models built to calculate cleaning efficiency for simulated EDS, and (3) exploring new materials to manufacture electrodes at scale. • Comprehensive review of Electrodynamic Shield (EDS) for terrestrial applications. • Extremely promising technology to address solar panel soiling issues. • The fundamentals of operations and dust removal mechanisms are discussed in detail. • The most important parameters affecting cleaning efficiency are identified. • Scaling up and field testing remain important open issues. [ABSTRACT FROM AUTHOR]

The growing need to alleviate the environmental impact of fossil fuels demands further technical growth in fuel cell hybrid electric vehicles (FCHEVs). Due to the dynamic nature of electrochemical power resources such as fuel cells (FCs) with auxiliary energy storage systems (ESSs), a variety of power management strategies (PMSs) have been widely developed and analysed for optimal power allocation. In this paper, a comprehensive review of various PMSs is systematically investigated for data acquisition and management regarding the search strategy. Within the data collected, the classification and the performance of PMSs are analysed to determine their characteristics and objectives for optimisation process. Additionally, a thorough examination of various PMSs employed in marine industry provides insights into the research trends and challenges associated with FC and battery hybrid systems and particularly ship propulsion systems. Furthermore, a system-level approach to PMS is explored, highlighting the importance of considering the correlation between component sizing and control as well as a health-conscious management that can enhance cost-effectiveness and life cycle of a FC and battery electric ferry applications. • A comprehensive review of power management system (PMS) in fuel cell electric vehicles. • Detailed analysis of PMS classifications and features. • A review and analysis of PMS in fuel cell ferry. • Discussion of current issues and potential research of PMS in ship propulsion system. [ABSTRACT FROM AUTHOR]

Errors in forecasting load and renewable-based generation in restructured power systems mean that independent system operators (ISOs) must procure sufficient operating reserves to keep the real-time operation of the system reliable and secure. But when procured reserves turn out to be insufficient in real-time due to the lack of resource capacity or ramp capability, operators often set higher prices for reserves and energy to encourage more supply, and to motivate consumers to decrease usage or shift it to other times. This procedure, which is called scarcity or shortage pricing, is a core feature of U.S. electricity markets. It is receiving increased attention from market designers and stakeholders because scarcity will become more important for spot price formation in the future with the increased penetration of zero-marginal cost renewables, and the shrinking role of fuel costs in setting prices. Scarcity pricing is implemented in various ways by different ISOs. These differences have practical implications for the level of prices and incentives for investment, operations, and demand modification. In this paper, general approaches and specific calculation procedures for reserve and energy scarcity pricing practices and calculations across the seven ISO-based U.S. power markets are reviewed and compared. A consistent terminology is used to facilitate the comparison. Current scarcity pricing practices are grouped into three approaches: (1) imposing an adder after the spot market is run; (2) including stepwise demand curves within market clearing procedures for non-contingency reserve products (e.g., the novel flexiramp product), which tends to yield longer right tails for energy scarcity premium curves; and (3) having stepwise demand curves for traditional contingency reserve products only, which results in shorter right tails in energy scarcity curves. A generic numerical example is presented to highlight the large practical differences among the reserve scarcity pricing approaches and specific implementations. To further investigate factors that contribute the most to demand curves differences among ISOs, a sensitivity analysis is performed. This analysis shows that the largest source of differences among the curves is the scarcity prices assumed in the case of severe scarcity, while the number of steps used and whether flexiramp is considered also yields important differences in scarcity prices. As renewable penetration increases, it will become increasingly crucial to employ administrative demand curves so that spot prices more effectively motivate supply and demand adjustments exactly when and where they are needed. This study shows that the different assumptions yield very different scarcity premiums for reserves and energy, and are likely to provide divergent incentives for resources to respond to shortages. It is concluded that to promote market efficiency, a reserve shortage demand curve should have at least three features: inclusion of the marginal value of reserve products at each shortage level, consideration of the magnitude and probability of supply contingencies, and avoidance of abrupt price discontinuities that can cause excessively volatile market outcomes. • Explains principles and specific calculation procedures for reserve scarcity pricing practices across U.S. power markets. • Proposes a novel classification of sources of penalty values applied in the markets, highlighting their relative advantages. • Presents a generic numerical example to illustrate practical differences among the reserve scarcity pricing approaches. • Performs a sensitivity analysis to further investigate the most significant factors in differences among ISO demand curves. • Makes recommendations for defining demand curves for reserve scarcity pricing that accurately reflect the value of reserves. [ABSTRACT FROM AUTHOR]

Researchers have begun to realize first-hand that the causes and effects of telework are much more complex than immediately apparent. While reduced commuting to work is widely beneficial (environment, economy, health, etc.), the impacts of telework are widespread (e.g., long-term urban planning considerations, home and office utilization, demand on communication networks, etc.). This paper aims to review and structure a large body of literature and emerging research from COVID-19-induced teleworking to address the complex relationships and energy impacts of telework on the four domains of homes, transportation, offices, and information and communication technologies (ICT). A systematic search was conducted on databases and the results were categorized. At the centre, we identified many relationships between homes and transportation, as teleworking gives teleworkers to have more flexibility in terms of location. Furthermore, the relationships between offices and homes are important since the operating costs of offices are on the teleworkers' side. Accordingly, cause and effect relationships were mapped out between and within domains. The outcome demonstrates that researchers and policymakers need to consider widespread implications of telework. As a result, it is essential to study items in each domain, intrarelationships in each domain, and most importantly the relationships between domains to capture and quantify the impacts of teleworking comprehensively. • Telework primarily impacts energy use in four domains of homes, offices, transportation, and ICT. • Comprehensive studies on telework should study four domains simultaneously. • Interrelationships between domains are important determinants of teleworking impacts. • There is a major literature gap on interrelationships between domains. • Teleworkers' behavior and decisions are a significant source of uncertainty for energy use. [ABSTRACT FROM AUTHOR]

This is the first study utilizing carbon tax revenue to the renewable energy generation with Learning-by-doing (LBD) in the CGE model. This investigation demonstrates how induced technologically change (ITC) in the power sector offsets negative impacts on economic growth caused by the carbon tax in China. Business-as-usual scenario (without carbon tax) shows a significant impact of LBD on GDP growth and CO 2 emission reduction. Under a policy scenario with carbon tax, the results show that the negative impact on economic growth can be alleviated to less than 0.12%. If total carbon tax revenue was used for the subsidy to wind and solar power, even a positive impact on GDP growth will occur in the long-term. Therefore, the results verified and demonstrated the synergic effect of carbon pricing and the LBD process that economic loss caused by carbon tax could be offset by ITC in the renewable energy power sector. GDP decomposition shows that unexpensive electricity affected by ITC is beneficial to drive development of low-carbon energy, which can mitigate shock of carbon tax on heavy dependence on fossil fuel. This paper also provides policy implications that the LBD process will positively play a key role in energy structural shift under climate policy, making a great effort to climate mitigation. [Display omitted] • Combining bottom-up CGE model with top-down module Learning-by-Doing. • Utilizing carbon tax revenue to subsidy to renewable energy generation. • Providing optimistic impacts of carbon tax and subsidy on economic growth and reduction of carbon emission. • Learning-by-doing describes pathway of improved renewable energy. • Giving implication that Learning-by-doing can be boosted by environmental policies. [ABSTRACT FROM AUTHOR]

Recently, with the development of industrial informatization and intellectualization, the development of smart bearings has attracted a lot of significant attention in an attempt to reduce maintenance costs and increase reliability by providing online health condition monitoring. As a result of advances in miniaturization and low power consumption of wireless sensor nodes (WSNs), self-powered technologies have been considered as a promising method to achieve autonomous WSNs in smart bearings. Although the self-powered technology has received considerable achievements, there are less reviews covering the development of self-powered structures towards smart bearing and providing potential guidelines for the future development. To bridge the gap, this paper presents a comprehensive state-of-the-art review and guidelines on self-powered methods to create smart bearings, including outlining the underlying theory, modeling methods, methodologies and technologies. The topology of a self-powered smart bearing is clarified, and the mechanisms and benefits of piezoelectricity, electromagnetism, triboelectricity, thermoelectricity and wireless power transfer for powering WSNs in smart bearing are discussed. To improve the applicability of self-powered smart bearing in a range of working conditions, the design methodologies and technologies of a variety of transducers are reviewed to provide guidelines for performance enhancement. Finally, the future challenges and perspectives are proposed for outlining potential research directions and opportunities in future self-powered smart bearing systems, including the impact on bearing performance, engineering implementation, reliability, power management and storage. • A detailed review of self-powered methods for smart bearing is presented. • Topology and working principle of a self-powered smart bearing are clarified. • Mechanisms, modeling, and methodologies are reviewed for performance enhancement. • Perspectives and challenges of developing self-powered smart bearing are proposed. [ABSTRACT FROM AUTHOR]

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

Renewable energy sources such as wind farms and solar power plants are replacing conventional coal-based synchronous generators (SGs) to achieve net-zero carbon emissions worldwide. SGs play an important role in enhancing system strength in a power system to make it more stable during voltage/frequency disruptions. However, traditional coal-fired SGs are being decommissioned in many parts of the world, owing to stringent environmental regulations and low levelized cost of energy of renewables. Consequently, maintaining system strength in a renewable energy-dominated power system has become a major challenge, and without adequate mitigation techniques, low system strength can potentially cause widespread power outages. This paper provides an overview of system strength and its measurement techniques in a power system with a large number of renewable energy sources (RESs), for example solar and wind farms. The review includes the system strength measurement techniques, mitigation approaches, and future challenges. • A comprehensive review on system strength for Australia. • Integration of power systems with large number of renewable energy sources. • Measurement and mitigation techniques for system strength shortfalls. • Analysis of future challenges and research directions on system strength. [ABSTRACT FROM AUTHOR]

The topic of energy islands is currently a focal point in the push for the energy transition. An ambitious project in the North Sea aims to build an offshore wind-powered electrolyser for green hydrogen production. Power-to-X (PtX) is a process of converting renewable electricity into hydrogen-based energy carriers, such as natural gas, liquid fuels and chemicals. PtH2 represents a subset of PtX, wherein hydrogen is the resultant green energy from the conversion process. Many uncertainties surround PtH2 plants, affecting the economic success of the investment and making the price of hydrogen and the levelized cost of hydrogen (LCOH) of this technology uncompetitive. Several studies have analysed PtH 2 layouts to identify the hydrogen price without considering how component capacities and external inputs affect the breakeven price. Unlike previous works, this paper investigates component capacity dependencies under variables such as wind and hydrogen demand shape for dedicated/non-dedicated system layouts. To this end, the techno-economic analysis finds the breakeven price, optimising the components to reach the lowest selling price. Results show that the hydrogen price can reach 2.2 €/kg for a non-dedicated system for certain combinations of maximum demand and electrolyser capacity. Furthermore, the LCOH analysis revealed that the offshore wind electrolyser system is currently uncompetitive with hydrogen production from carbon-based technologies but is competitive with renewable technologies. The sensitivity analysis reveals the green electricity price in the non-dedicated case for which a dedicated system has a lower optimum hydrogen price. The price limit for the dedicated case is 116 €/MWh. [Display omitted] • Dependencies among hydrogen tank, offshore, electrolyser and demand were identified. • The price of hydrogen for energy islands can reach 2.2 €/kg. • LCOH from offshore is competitive with renewable technologies. • Offshore electricity price will play a role in the energy island system layout. [ABSTRACT FROM AUTHOR]

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

Natural gas hydrate (NGH) is widely accepted as one of the promising sustainable energy resources, whereas the potential geo-engineering risks have become one of the major uncertainties during long-term NGH exploitation. Creep is one of the primary inducements of geo-engineering risks during the long-term exploitation of marine gas hydrates. To understand the current research progresses on the creep behaviors of hydrate-bearing sediments (HBS), this paper summarized laboratory mechanical testing techniques, sensitive analysis, and constitutive models for the creep of HBS. The results showed that triaxial testing plays a leading role in the creep testing of HBS. From the micron perspective, the atomic force microscopy has great potential in determining the creep behaviors of HBS. The current publications reveal that the creep process of HBS under a lower loading may not always experience the initial creep stage, stable creep stage, and reach to accelerated creep stage. The previous studies provide a macroscopic understanding of the mechanical testing method and constitutive model, which is beneficial to the numerical simulation of the ground deformation of HBS during hydrate exploitation. However, the existing constitutive models are far from satisfying the demand for numerical simulations and field applications on the creep behavior of HBS. Developing a creep model by referring to the constitutive creep model of frozen soil is anticipated to be more feasible. • Test methods for HBS creep behavior under different reservoir conditions and scales were reviewed. • Main creep research progress and limitation of HBS on sensitive analysis, constitutive models were discussed. • Cross-scale analyses of creep responses of HBS by combining macro-micro testing methods with numerical simulation were proposed. [ABSTRACT FROM AUTHOR]

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

Given the complexity and interconnection of different aspects involved in building evaluation, one of the most relevant, and challenging, research topics is the integration of different domain models (such as thermal comfort, indoor environmental quality and occupant comfort) to effectively describe and inform improvement strategies for the behaviour and performance of a building and building stock. Currently, this problem is unsolved with only one study attempting to integrate building energy simulation and life cycle assessments (separately, both practices are utilised to facilitate the design and management of buildings, traditionally consultancies offer building energy simulation services – most commonly for regulatory purposes – and more recently life cycle impact assessments), whilst no work has attempted this integration in a dynamic manner. This study addresses this gap by developing a dynamic, open building information modelling based co-simulation architecture. This architecture is the first to tightly couple and integrate EnergyPlus and Brightway2, in a way that does not rely upon heuristics or simplified tools. Furthermore, it is the first building energy simulation and life cycle assessment co-simulation to enable time-differentiated (dynamic) results and the first to be enabled only by open technologies. The architecture has been validated against two case-study non-domestic buildings located in the United Kingdom and Luxembourg, demonstrating its applicability to the construction and operational life cycle phases of buildings. The work presented in this paper has shown how a time-differentiated co-simulation approach across energy and lifecycle domains enables a more holistic analysis of whole buildings with greater accuracy and granularity. • There is a lack of studies co-simulating building energy simulation and life cycle assessment. • This study develops an open, building information modelling based co-simulation architecture. • The developed co-simulation architecture tightly couples whole building energy simulation and life cycle assessment models. • Co-simulation architecture has been validated against two non-domestic buildings, in the United Kingdom and Luxembourg. • The developed architecture enables time-differentiated (dynamic) life cycle assessment results. • Time-differentiated life cycle assessment results provide results at a finer level of granularity and accuracy. [ABSTRACT FROM AUTHOR]

Buildings account for about 39% of the total energy consumption in the United States. Developing highly energy-efficient and environmentally friendly systems that are either actively or passively integrated into buildings plays a crucial role in decarbonizing the building sector. Among various technologies, desiccant-based energy systems have received particular attention in recent years due to their unique advantages, such as being thermally driven using low-grade waste or solar energies and being reliable over a wide range of operating ranges. Extensive research efforts have been exerted on desiccant-enabled technologies at both material and system levels aiming to increase their performance and achieve high technological readiness levels. The present review paper comprehensively discusses research works made at the system level. It overviews desiccant-based air conditioning systems, desiccant-based humidity pumps, desiccant-based thermal energy storage systems, and desiccant-based appliances. The study identifies challenges and opportunities to accelerate the commercialization of desiccant-enabled technologies. It is found that desiccant materials offer great promise to improve energy efficiency and functionality of future buildings through decoupling the latent and sensible cooling loads in air conditioning systems, humidity pumps integrated into building facades, and next-generation appliances. However, commercial viability and widespread acceptance of desiccant-based systems have been hampered by several major obstacles, including liquid and air flow mal-distribution and inferior thermo-physical properties of desiccant materials resulting in low ab/adsorption and regeneration rates and bulky/costly systems. • Review the desiccant-enabled technologies at the system level. • Traditional desiccants suffer from limited performance in low-humid climates. • Humidity pumps integrate desiccants into the building facade. • Desiccant materials are promising for clothes dryers and dishwashers. • Identify challenges facing the commercialization of desiccant-enabled technologies. [ABSTRACT FROM AUTHOR]

Using floating platforms to support offshore wind turbines will be necessary for many countries to reach their Net-Zero targets, since much of the wind resource is located at water depths at which fixed offshore wind turbines are uneconomic or technologically unfeasible. However, floating platforms for wind turbines are still at an early stage of development, and there are a wide range of platform designs. This paper reviews the current state-of-the-art of floating offshore wind turbine platform designs which currently have or have previously had a prototype, demonstration, or farm scale project at sea. The most common design goals for the platforms and the corresponding design features of platforms used to achieve those goals are reviewed. Past, current and projected future levelized cost of energy values for floating offshore wind are reviewed and discussed. The development of each platform design is described, including evolving design goals and resulting changes in platform features. Finally, overall trends in platform designs are discussed and divided into three phases, defined by changing goals: (i) influences from the offshore oil and gas industry, (ii) specialization to floating offshore wind, and (iii) further specialization to local environment. [Display omitted] • Floating offshore wind turbine platform designs with a device at sea are reviewed. • Common design goals and associated design features of platforms are summarized. • Levelized cost of energy for floating offshore wind turbines is discussed. • Evolution and trends in design drivers and platform designs are summarized. [ABSTRACT FROM AUTHOR]

Among different solutions to increase flexibility of electricity system, grid interactive water heaters (GIWHs) can make a large contribution, against a relatively low cost. They can advantageously be used within a single building, a local energy community or within an entire distribution grid, thanks to the very fast response time, low cost, highly distributed resource and widely demonstrated technology. In the near future, the flexibility potential of GIWHs will certainly increase, thanks to the advantageous flexibility programs that have been implementing in some area of the world, with the aim of coordinating several million of GIWHs with the electricity network. In this study, we assess the potential value that the flexibility of GIWHs can bring to the electrical power system, compared to the other sources of flexibility, focusing on the US market, specifically California, Oregon and Washington. The GIWH technology and the main GIWH control strategies are described, highlighting the flexibility behaviour of GIWHs. An overview of the GIWH pilot programs currently developed in the US market is provided, and current available technologies are shown, both for new and for retrofit GIWH installations. Most of the papers discussed in the literature focus on different aspects of demand response (DR), but very few of them focus specifically on GIWHs, and none of them offers a review of GIWHs in the US context. The present work thus constitutes a research gap, and could help stakeholders to assess the US GIWH market evolution, identifying the potential value of GIWH flexibility. • Evaluating the potential value of GIWH flexibility in the electrical power system. • Describing control strategies and flexibility behaviour of GIWH. • Discussing the US regulatory context. • Discussing GIWH technologies for new and retrofit installations. • Analyzing GIWH pilot programs developed in the US. [ABSTRACT FROM AUTHOR]

Decreasing HVAC energy consumption through insulation effectiveness enables low energy use, low carbon emissions, and high thermal comfort in sustainable buildings. PCMs for energy storage are an innovative option, but in buildings, their high thermal conductivity is a concern.The PCM latent heat of fusion and thereby it's transition temperature has been a key parameter in PCM selection but little is known of the effect of PCM on building energy contributions arising from increasing thermal conductivity (k), density (ρ) , and specific heat capacity (C p). To resolve this, in this paper, two PCMs with transition temperature above and below the outdoor temperature incorporated in highly porous flexible polyurethane foam were evaluated using a one-dimensional (1D) foam core panel built in COMSOL Multiphysics®. The simulations were run using the summer season in a humid subtropical climate zone with an outdoor temperature of 35 °C. It was found that apart from the latent heat of fusion, the combined effects of high ρ and C p could mitigate the increased k of PU-PCM composites to improve the insulation performance. Building energy modeling using EnergyPlus with the foam core incorporated into a structural insulated panel (SIP), revealed that the use of PCMs regardless of the transition temperature could reduce annual electricity consumption by 15–20%, with a significant amount of energy savings arising from the cooling load in summer. • PCM can be applied in highly porous sprayable foam insulation to decrease energy costs in buildings. • High thermal conductivity in PCM is neutralized by specific heat and density leading to effective insulation metrics. • Inverse thermal diffusivity is more effective for insulation comparison over the R-factor (length/thermal conductivity) approach. • PCMs with phase change temperatures above and below the boundary temperature are effective in thermal management and energy savings. • Latent heat of fusion was not a significant contributor to energy savings for high volume PCM incorporation. [ABSTRACT FROM AUTHOR]

The paper presents a comprehensive review of the current status of integrated high temperature proton exchange membrane fuel cell (HT-PEMFC) and methanol steam reformer (MSR) systems. It highlights the advantages and limitations of the technology and outlines key areas for future improvement. A thorough discussion of novel reformer designs and optimizations aimed at improving the performance of the reformer, as well as different integrated MSR-HT-PEMFC system configurations are provided. The control strategies of the system operation and system diagnosis are also addressed, offering a complete picture of the integrated system design. The review revealed that several processes and components of the system should be improved to facilitate large-scale implementation of the MSR-HT-PEMFC systems. The lengthy system startup is one area that requires improvements. A structural design that is more compact without sacrificing performance is also required, which could possibly be achieved by recovering water from the fuel cell to fulfill MSR's water needs and consequently shrink the fuel tank. Reformer design should account for both heat transfer optimizations and reduced pressure drop to enhance the system's performance. Finally, research must concentrate on membrane materials for HT-PEMFC that can operate in the 200–300 °C temperature range and catalyst materials for more efficient MSR process at lower temperature should be investigated to improve the heat integration and overall system efficiency. • The potential for HT-PEMFC and MSR in the future energy system was emphasized. • Recent advances in reformer design and optimization were presented. • Different integration methods for the MSR-HT-PEMFC system were analyzed. • Dynamics, control and diagnosis of integrated systems were discussed. • System lifetime, efficiency and challenges in future applications were elaborated. [ABSTRACT FROM AUTHOR]

Government and commercial forecasts indicate global ambitions for 2000 GW of installed offshore wind (OW) by 2050 to meet the targets of the Paris Agreement. Set against a current global installed capacity of 56 GW offshore wind, which has taken over 30 years to achieve, the challenge of installing 35 times that capacity in the coming 30 years is considerable. Aside from the issue of the necessary pace of OW installation, another challenge is scale: Where in the ocean could and should this new infrastructure be placed? This paper presents a spatial analysis approach for assessing the location of future offshore wind that collates and integrates, metocean, geoscience, ecological and anthropogenic features and intersects with engineering requirements. A new contribution to the field is made through calibration in relation to current ocean 'crowdedness', which leads to a suitability ranking of new sea regions. A case study is presented to illustrate the workflow and methodology of this approach based on the United Kingdom (UK)-Economic Exclusive Zone (EEZ). The UK has been selected as an exemplar due to its well-developed offshore wind sector, having the greatest installed capacity globally until the close of 2021, and as a region with ambitious and legislated offshore wind targets to meet net zero. The modelling and analysis quantify the need to eliminate the water depth barrier through floating OW technology, open up new sea regions and the associated port and grid infrastructure, as well as to assess the potential impact of increased utilisation of ocean space for OW. • 34-layer GIS model of UK geoscience, metocean, ecological & anthropogenic features. • Interactive map created to show suitable space for future offshore wind (OW). • Scenarios of OW in each sea region illustrated for various net zero future cases. • Need for co-location, floating OW and development of new sea regions quantified. [ABSTRACT FROM AUTHOR]

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

Supercooling is a natural phenomenon that keeps a phase change material (PCM) in its liquid state at a temperature lower than its solidification temperature. In the field of thermal energy storage systems, entering in supercooled state is generally considered as a drawback, since it prevents the release of the latent heat. Conversely, when dealing with plants, animals or preservation processes, supercooling protects organs, tissues or blood from solidification that leads to damage or to death. This paper first reviews the most important applications and cases in which supercooling can take place and dramatically change the performance. Second, the paper discusses the factors affecting the occurrence and the degree of supercooling, such as cooling rate, PCM container characteristics, PCM thermal history, use of additives, etc. The paper includes a supercooling modeling section, which presents the main mathematical and numerical methods used to solve the challenges encountered by researchers. This review shows that to experimentally foster or reduce supercooling, most researchers tend to use similar methods such as controlling the cooling rate, changing container's characteristics or adding additives. The main challenge in supercooling modeling being its unstable and probabilistic nature, most authors tend to perform experimental measurements to obtain some key parameters, notably the supercooling degree, prior to the modeling. This strategy restricts the validity of the models to applications having the same conditions as the experiments. Nevertheless, this review offers the guidelines to select the appropriate experimental parameters and modeling strategies, depending on the specific and practical objectives of each application. • The advantages and disadvantages of supercooling in nature and different daily applications are reviewed. • The latest experimental studies are presented and factors affecting supercooling are discussed. • The challenges in modeling supercooling of PCM are presented. • The most used techniques to model supercooling are discussed. [ABSTRACT FROM AUTHOR]

Rapid urbanization trends claim long-term urban planning and management strategies towards a more sustainable urban growth. In this context, neighborhoods show as fundamental units in large-scale sustainable approaches of socio-economic indicators to be replicated in urban development models. However, the number of evaluated districts is still too low compared to the number of buildings evaluated so far. To lay the potential weaknesses and strengths behind the use of sustainable certification tools at district level, the present study aims to examine all realized neighborhoods aligned with sustainability goals. To this end, a systematic review (SR) on neighborhood case studies that directly or indirectly employed neighborhood sustainable assessment (NSA) tools – in particular, amongst LEED-ND, BREEAM-C, CASBEE-UD, and Green Star- Community, DGNB-NSQ, – or that denied the applicability of NSA tools to develop tailored ones is provided. Case studies found in academic papers and NSA-tool official websites are examined through five research questions (RQs): i) number and level of certifications; ii) geographical and temporal distribution; iii) availability of data related to physical characteristics (i.e., size, density, number of dwellings, etcetera); iv) variety of key performance indicators (KPIs) addressed; v) authors outcomes. Evaluation of these realized case studies testified the practicality of NSA for achieving carbon neutrality target. However, the lack of data consistency and the significance given to the contextual features hindered the replication of the previous experiences and nudged the development of custom-fitted NSA tools. A more flexible framework adaptable to different contextual priorities and integrative of neighborhood projects worldwide is recommended. [Display omitted] • Realized districts analyzed by five candidate NSA tools are examined. • Case studies are selected from academic papers and official website of NSA tools. • Certification levels, characteristics, and key performance indicators are discussed. • The drivers behind the shortages of NSA tools applications are assessed. • Outcomes recommend more integrative and flexible district-scale frameworks. [ABSTRACT FROM AUTHOR]

To stop the spread of COVID-19, governments have implemented confinement measures unprecedented in modern society. One of the main consequences has been the paralysis of commercial and industrial sectors worldwide, primary electricity consumers. This paper examines the impact of these measures on the electricity sector through a literature review accompanied by fieldwork on the impact of COVID-19 in Ibero-America and its energy regulatory response. First, we will review the causes of the reduction in electricity demand due to the confinement measures and their technical and financial consequences in the electricity sector. Second, we will examine the impact of COVID-19 on the wind and solar PV energy sectors, mainly affected by the paralysis of production and export of materials and components. Third, we will revise the regulatory measures implemented by the countries to avoid the interruption of electricity supply to households. This paper will end by reviewing economic recovery plans and their relationship to the energy transition. Although there are no fundamental differences between developed and developing countries in their regulatory reaction to this crisis in the energy sector, there are significant differences in economic recovery planning. While developed countries aim for a green economic recovery and the creation of green jobs, developing countries are allocating least resources to social protection and general economic stimulus programs, postponing climate objectives. In Latin America, this adds to the high levels of debt faced by utilities and the possible resurgence of social crises that were stopped by the COVID-19 outbreak, making a green recovery even more difficult. [Display omitted] • The reduction in electricity demand has caused technical challenges in the grid. • Electric utilities are facing growing and long-term financial problems. • Renewable energy projects have been delayed and financially harmed. • The measure to ban disconnection for non-payment has been implemented worldwide. • Latin American social crisis tempered by COVID-19 could hinder economic recovery. [ABSTRACT FROM AUTHOR]

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

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

Ocean Thermal Energy Conversion (OTEC) is a promising renewable energy technology that is the most economical at large scale. But contemporary literature does not address how OTEC could reach such scale with current technology, and what the techno-economic impact of location-dependent factors and technological learning are. This paper tackles these issues by simulating OTEC's upscaling with a model that implements OTEC to meet local electricity demand and extrapolates to the global relevance of OTEC. The model uses a learning rate for investment costs and cost of finance. This study shows that up to 45 GW of OTEC capacity can be installed in Indonesia with national demand coverage of 22% in 2050. Even with small cost reduction rates, OTEC could be profitable and cost-competitive against other power generation technologies with an aggregated Net Present Value (NPV) of up to US$ 23 billion. OTEC's upscaling could be funded via state budget reallocation or international financial institutions, e.g. via the feed-in tariff suggested in the paper. However, large-scale OTEC is only feasible in regions with high electricity demand and until that size is reached, upscaling must be coordinated globally, e.g. with the proposed upscaling strategy. To contribute to the global energy transition, OTEC needs to grow by 28% per year, a rate similar to wind power and solar PV. This paper provides good reasons to fight for the attention of global decision makers and future research could focus on refining the concepts of this study. • This novel study assesses OTEC's upscaling from small to large scale. • 16.5 GW e could be cost-optimally deployed at total operating profits of US$ 23 billion. • To make an impact soon, OTEC needs to grow at a rate between wind and solar PV. • To achieve this rate, strong and sustained public and private support will be needed. • This work's feed-in tariff and upscaling strategy could provide such support. [ABSTRACT FROM AUTHOR]

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

Supercooling is a natural phenomenon that keeps a phase change material (PCM) in its liquid state at a temperature lower than its solidification temperature. In the field of thermal energy storage systems, entering in supercooled state is generally considered as a drawback, since it prevents the release of the latent heat. Conversely, when dealing with plants, animals or preservation processes, supercooling protects organs, tissues or blood from solidification that leads to damage or to death. This paper first reviews the most important applications and cases in which supercooling can take place and dramatically change the performance. Second, the paper discusses the factors affecting the occurrence and the degree of supercooling, such as cooling rate, PCM container characteristics, PCM thermal history, use of additives, etc. The paper includes a supercooling modeling section, which presents the main mathematical and numerical methods used to solve the challenges encountered by researchers. This review shows that to experimentally foster or reduce supercooling, most researchers tend to use similar methods such as controlling the cooling rate, changing container's characteristics or adding additives. The main challenge in supercooling modeling being its unstable and probabilistic nature, most authors tend to perform experimental measurements to obtain some key parameters, notably the supercooling degree, prior to the modeling. This strategy restricts the validity of the models to applications having the same conditions as the experiments. Nevertheless, this review offers the guidelines to select the appropriate experimental parameters and modeling strategies, depending on the specific and practical objectives of each application. • The advantages and disadvantages of supercooling in nature and different daily applications are reviewed. • The latest experimental studies are presented and factors affecting supercooling are discussed. • The challenges in modeling supercooling of PCM are presented. • The most used techniques to model supercooling are discussed. [ABSTRACT FROM AUTHOR]

Rapid urbanization trends claim long-term urban planning and management strategies towards a more sustainable urban growth. In this context, neighborhoods show as fundamental units in large-scale sustainable approaches of socio-economic indicators to be replicated in urban development models. However, the number of evaluated districts is still too low compared to the number of buildings evaluated so far. To lay the potential weaknesses and strengths behind the use of sustainable certification tools at district level, the present study aims to examine all realized neighborhoods aligned with sustainability goals. To this end, a systematic review (SR) on neighborhood case studies that directly or indirectly employed neighborhood sustainable assessment (NSA) tools – in particular, amongst LEED-ND, BREEAM-C, CASBEE-UD, and Green Star- Community, DGNB-NSQ, – or that denied the applicability of NSA tools to develop tailored ones is provided. Case studies found in academic papers and NSA-tool official websites are examined through five research questions (RQs): i) number and level of certifications; ii) geographical and temporal distribution; iii) availability of data related to physical characteristics (i.e., size, density, number of dwellings, etcetera); iv) variety of key performance indicators (KPIs) addressed; v) authors outcomes. Evaluation of these realized case studies testified the practicality of NSA for achieving carbon neutrality target. However, the lack of data consistency and the significance given to the contextual features hindered the replication of the previous experiences and nudged the development of custom-fitted NSA tools. A more flexible framework adaptable to different contextual priorities and integrative of neighborhood projects worldwide is recommended. [Display omitted] • Realized districts analyzed by five candidate NSA tools are examined. • Case studies are selected from academic papers and official website of NSA tools. • Certification levels, characteristics, and key performance indicators are discussed. • The drivers behind the shortages of NSA tools applications are assessed. • Outcomes recommend more integrative and flexible district-scale frameworks. [ABSTRACT FROM AUTHOR]

To stop the spread of COVID-19, governments have implemented confinement measures unprecedented in modern society. One of the main consequences has been the paralysis of commercial and industrial sectors worldwide, primary electricity consumers. This paper examines the impact of these measures on the electricity sector through a literature review accompanied by fieldwork on the impact of COVID-19 in Ibero-America and its energy regulatory response. First, we will review the causes of the reduction in electricity demand due to the confinement measures and their technical and financial consequences in the electricity sector. Second, we will examine the impact of COVID-19 on the wind and solar PV energy sectors, mainly affected by the paralysis of production and export of materials and components. Third, we will revise the regulatory measures implemented by the countries to avoid the interruption of electricity supply to households. This paper will end by reviewing economic recovery plans and their relationship to the energy transition. Although there are no fundamental differences between developed and developing countries in their regulatory reaction to this crisis in the energy sector, there are significant differences in economic recovery planning. While developed countries aim for a green economic recovery and the creation of green jobs, developing countries are allocating least resources to social protection and general economic stimulus programs, postponing climate objectives. In Latin America, this adds to the high levels of debt faced by utilities and the possible resurgence of social crises that were stopped by the COVID-19 outbreak, making a green recovery even more difficult. [Display omitted] • The reduction in electricity demand has caused technical challenges in the grid. • Electric utilities are facing growing and long-term financial problems. • Renewable energy projects have been delayed and financially harmed. • The measure to ban disconnection for non-payment has been implemented worldwide. • Latin American social crisis tempered by COVID-19 could hinder economic recovery. [ABSTRACT FROM AUTHOR]