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The economic feasibility of retrofitting an amine based post-combustion CO 2 capture process to an existing Kraft pulp mill and an existing integrated pulp and board mill has been assessed. This study builds on the technical assessment of the energy performance of the mills when retrofitting a post-combustion CO 2 capture process by Onarheim et al. (2017). Between 75 to 100% of the CO 2 emissions from the pulp and paper industry originate from the combustion of biomass. If the raw material is sourced sustainably, these emissions are categorized as carbon neutral. Applying sustainably managed biomass in the pulp and paper processes and capturing the resulting CO 2 for permanent storage enables the industry to go carbon negative. In this study, the economic impact of retrofitting CO 2 capture from the flue gases of the recovery boiler, the multi-fuel boiler and the lime kiln were assessed. The levelized cost of pulp and the cost of CO 2 avoided were evaluated based on six different scenarios varying the CO 2 tax, incentives for renewable electricity production, with and without recognizing biogenic CO 2 emissions as neutral (exempting CO 2 emissions from tax or not), and rewarding captured and permanently stored CO 2 with negative emissions credit. Results show that the pulp and paper industry has a potential for realizing feasible implementation of large-scale industrial Bio-CCS. For cases where 60–90% of total site CO 2 emissions are captured, the cost of avoided CO 2 amounts to 52–66 €/t for the Kraft pulp mill and 71–89 €/t for the integrated pulp and board mill. The cost of avoided CO 2 , and thus the realization of Bio-CCS in the pulp and paper industry, is strongly dependent on prevailing policy frameworks such as the EU ETS. In order to reach a levelized cost of pulp similar to the reference mill without CO 2 capture, a negative CO 2 emission credit of 60–70 €/t CO 2 for the Kraft pulp mill and 70–80 €/t CO 2 for the integrated pulp and board mill will be required. As long as biogenic CO 2 emissions that are captured and permanently stored are not recognized as negative and rewarded accordingly there is no economic incentive for the owners of pulp and paper mills to implement CCS. The only way to get the pulp and paper industry to implement and deploy Bio-CCS will need the support of the decision-makers in promoting the right policy framework and regulations to encourage the investment such as strong incentives for negative emissions which are bankable during the long term operation of the mills. [ABSTRACT FROM AUTHOR]

Increasing levels of variable renewable energy require additional flexible resources in the global energy system. In countries with energy-intensive industries, flexibility may be increased through industrial demand side management (IDSM). In most studies, the potential of IDSM is estimated from a technical or theoretical viewpoint. However, IDSM capacity is only utilized if the industry finds it profitable, and thus the economic potential should also be assessed. The focus of this paper is on the intra-day IDSM potential of a paper mill site that is active in the Nordic power market. An optimization model is built to estimate the costs that occur when the paper mill executes regulating power bids, if the original production schedule has been optimized against a spot price forecast. The costs are estimated for different sizes of bids and a marginal cost curve is provided for pricing them. Using this marginal cost curve, the market potential of the case mill site is assessed. It is found that this potential is greatly influenced by the costs of executing regulating power bids. The results indicate that transmission system operators and policy makers should account for economic factors when assessing the potential of market based IDSM. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste office paper was utilized as a substrate for microbial lipid production. • A detailed optimization study has been conducted for biomass and lipid yield. • Optimization results in10.55 g/L biomass, 6.13 g/L lipid with 58% lipid content. • Biodiesel properties of the produced lipids met with the international standards. • A solution to mitigate the hazardous effects caused by waste and fossil fuel. Environmental issues caused by fossil fuel and its rapid depletion demand the need to produce biofuel from renewable energy resources. The disposal of waste paper in landfills causes air pollution and contaminates groundwater. Hence, exploiting paper waste as a renewable resource for microbial lipid production can solve these environmental issues in a greener way. Further, these microbial lipids are a reliable source for biodiesel production. In this study, waste office paper was utilized as a substrate to produce microbial lipids through fermentation by the oleaginous yeast, Rhodosporidium toruloides, using a biorefinery approach. The production conditions were optimized using the Box-Behnken design; a fermentation time of 116.16 h, a C/N ratio of 60, and an inoculum concentration of 9.67% yielded a biomass of 10.55 g/L and a lipid yield of 6.13 g/L with a total lipid content of 58%. The major lipids produced were oleic acid (42%), palmitic acid (36%), stearic acid (9.8%), and myristic acid (8%), which clearly indicates the suitability of the lipids produced by R. toruloides for biodiesel production. The predicted biodiesel properties of the transesterified product met the international standard specifications. Hence, utilizing waste office paper for biodiesel production will be an effective way of mitigating the environmental pollution caused by waste paper and the harvesting of fossil fuels. [ABSTRACT FROM AUTHOR]

Pulp and paper mills generate large amounts of waste organic matter that may be converted to renewable energy in form of methane. The anaerobic treatment of mill wastewater is widely accepted however, usually only applied to few selected streams. Chemical oxygen demand (COD) removal rates in full-scale reactors range between 30 and 90%, and methane yields are 0.30–0.40 m 3 kg −1 COD removed. Highest COD removal rates are achieved with condensate streams from chemical pulping (75–90%) and paper mill effluents (60–80%). Numerous laboratory and pilot-scale studies have shown that, contrary to common perception, most other mill effluents are also to some extent anaerobically treatable. Even for difficult-to-digest streams such as bleaching effluents COD removal rates range between 15 and 90%, depending on the extent of dilution prior to anaerobic treatment, and the applied experimental setting. Co-digestion of different streams containing diverse substrate can level out and diminish toxicity, and may lead to a more robust microbial community. Furthermore, the microbial population has the ability to become acclimated and adapted to adverse conditions. Stress situations such as toxic shock loads or temporary organic overloading may be tolerated by an adapted community, whereas they could lead to process disturbance with an un-adapted community. Therefore, anaerobic treatment of wastewater containing elevated levels of inhibitors or toxicants should be initiated by an acclimation/adaptation period that can last between a few weeks and several months. In order to gain more insight into the underlying processes of microbial acclimation/adaptation and co-digestion, future research should focus on the relationship between wastewater composition, reactor operation and microbial community dynamics. The potential for engineering and managing the microbial resource is still largely untapped. Unlike in wastewater treatment, anaerobic digestion of mill biosludge (waste activated sludge) and primary sludge is still in its infancy. Current research is mainly focused on developing efficient pretreatment methods that enable fast hydrolysis of complex organic matter, shorter sludge residence times and as a consequence, smaller sludge digesters. Previous experimental studies indicate that the anaerobic digestibility of non-pretreated biosludge from pulp and paper mills varies widely, with volatile solids (VS) removal rates of 21–55% and specific methane yields ranging between 40 and 200 mL g −1 VS fed. Pretreatment can increase the digestibility to some extent, however in almost all reported cases, the specific methane yield of pretreated biosludge did not exceed 200 mL g −1 VS fed. Increases in specific methane yield mostly range between 0 and 90% compared to non-pretreated biosludge, whereas larger improvements were usually achieved with more difficult-to-digest biosludge. Thermal treatment and microwave treatment are two of the more effective methods. The heat required for the elevated temperatures applied in both methods may be provided from surplus heat that is often available at pulp and paper mills. Given the large variability in specific methane yield of non-pretreated biosludge, future research should focus on the links between anaerobic digestibility and sludge properties. Research should also involve mill-derived primary sludge. Although biosludge has been the main target in previous studies, primary sludge often constitutes the bulk of mill-generated sludge, and co-digestion of a mixture between both types of sludge may become practical. The few laboratory studies that have included mill primary sludge indicate that, similar to biosludge, the digestibility can range widely. Long-term studies should be conducted to explore the potential of microbial adaptation to lignocellulosic material which can constitute more than half of the organic matter in pulp and paper mill sludge. [ABSTRACT FROM AUTHOR]

Deploying renewable energy to unit design energy-efficient technologies may fulfill the additional demand of various energy-intensive industries for their sustainability and resiliency. Multiple Stage Evaporator (MSE) is one of the most energy-intensive units used to extract the water content of the weak liquor in various industries, including the paper industry. This energy intensiveness may be reduced by integrating various Energy Reduction Schemes (ERSs). Hence, this work proposes a ERSs integrated MSE model to analyze its energy efficiency. These ERSs includes Thermo-Vapor Compressor, Steam-, Feed- Split, Feed Preheater, and Flash Tanks. Further, the performance of the proposed model is investigated under two important real-time plant complexities: Boiling Point Elevation and Fouling to achieve more realistic results. The performance analysis is initiated with the formulation of a nonlinear constrained optimization problem to increase the steam economy (SE). Also, the simulation is extended to validate at two different product concentrations (52% and 65%) by employing state-of-art optimization algorithms: CONOPT, and SCA in GAMS and MATLAB respectively. The simulated results shows an increment 1.64% and 1.37% of SE for both 52% and 65% concentration of weak liquor respectively in case of CONOPT than SCA. Also, the waste heat of the condensate, feed, and product may be further utilized for the heat recovery by incorporating the flash tanks which leads to a countable energy saving. Eventually, integrating the solar fields: PTC and LFR ensures a notable reduction in conventional heat utilization by 85.96% and 92.85%, respectively and hence, enhance the energy efficiency. • Expounded energy modeling of ERSs based MSE with BPE and Fouling. • Implementation of NLP and metaheuristic approaches for performance optimization. • Reutilization of waste heat to maximize the energy efficiency. • Integration of solar fields (PTC and LFR) to reduce conventional fuel utilization. • Prospecting the challenges and direction of energy management optimization. [ABSTRACT FROM AUTHOR]

Abstract This work demonstrates an innovative Al-air battery made of paper, which can inhibit Al corrosion, simplify battery system and reduce electrolyte storage. One major advantage of it is its minimum cost of fabrication. The corrosion inhibition effect originates from the high porosity and tortuosity of paper, which restricts the diffusive transport of hydroxyl ions to the Al surface. In this manner, low-grade Al can be directly utilized. Targeted for different application fields, three battery subtypes are proposed. The mechanically-rechargeable battery can be used repeatedly by refreshing its Al anode, providing relatively high power for charging portable electronics. The flexible battery employs embedded Al inside paper as anode and oxygen reduction ink as cathode, which is suitable for various single-use and flexible devices. Lastly, a printable battery is proposed by developing a successful Al ink for anode fabrication. Combined with existing printing techniques, this design may lead to a much smarter and more economic battery application in the future. Highlights • A low-cost and green paper-based Al-air battery technology is developed. • It can achieve simplified system, reduced liquid storage and inhibited Al corrosion. • A mechanically-rechargeable battery is designed for portable electronic recharge. • A flexible battery is designed for powering single-use and flexible devices. • A printable battery is also tentatively explored for smarter battery utilization. [ABSTRACT FROM AUTHOR]

Due to the increased use of variable renewable energy sources, more capacity for reserves is required. Non-generating resources such as large industrial consumers can arbitrage energy prices and provide reserve capacity by exploiting the inherent flexibility in selected industrial processes. A large enough industrial consumer can capitalize on this flexibility through optimized bidding in electricity markets. In this work, the day-ahead cost minimization of a risk-averse pulp and paper mill is formulated as a two-stage stochastic problem, considering thermodynamic and electrical constraints. The bids in the energy and reserve markets are jointly optimized subject to price uncertainty as well as uncertainty of frequency realization. The results of a case study in Sweden display a significant economic benefit in exploiting the flexibility of integrated pulp and paper mills with electric boilers. The expected cost of the pulp and paper mill resulting from different strategies are compared and the risk-aversion of the pulp and paper mill is investigated. Reserve offers are mainly facilitated by fast-acting electric boilers and supported by flexibility in the steam network. We show that reserve offers can significantly improve the profitability of the pulp and paper mill. • Pulp and paper mills with electric boilers can supply primary frequency reserves. • Electric boilers can provide up to 50 MW flexibility of 100 MW rating. • An algorithm is developed to optimize the energy & reserve bids of the mill. • Expected cost savings range between 7.4% in summer and 2.3% in winter. [ABSTRACT FROM AUTHOR]

Waste paper as a kind of biomass contains a great quantity of cellulose which is a renewable energy resource. However, complex cellulose supramolecular structure restricts the conversion of waste paper in near-critical water. This study aimed to investigate the change characteristics of cellulose supramolecular structure (hydrogen bond models and crystallinity) during hydrolysis and its effects on 5-HMF yield. Waste paper has been treated in near-critical water at 375 °C and 22.5 MPa for a reaction time (160–240 s) and correlation between 5-HMF yield and the supramolecular structure of cellulose residues has been built up. The 5-HMF yield was increased with the increase of intermolecular hydrogen bonds content in cellulose residues and was increased first and then decreased with the increase of crystallinity of cellulose residues. The rate of decrystallization was out of sync with that of depolymerization, which also influenced 5-HMF yield. Reaction time can be a macro method to adjust the supramolecular structure of cellulose during the conversion of waste paper to obtain more 5-HMF. It showed that 5-HMF yield reached maximum 9.41% ± 0.47% when the intermolecular hydrogen bonds content of cellulose in residue was 67.77% and the crystallinity of cellulose in residue was 57.14% at 200 s. [ABSTRACT FROM AUTHOR]

The development of renewable energy sources minimizes the burning of fossil fuels for clean and green environment. Electrochemical energy storage/conversion device pays a way towards sustainable development that concludes an emerging field in the trends of the research community. Prominently, the functional materials with suitable structure and property determine the performance and durability of the devices. In recent times, graphene with its tremendous properties play a major role in electrochemical energy device applications. Meanwhile, the graphene-based electrodes were fabricated by various coating techniques on existing electrodes that utilized for energy device fabrication. Apart from these, it is also fabricated in a paper like a form (self-supported or free-standing) with its remarkable high conductivity, flexibility, robustness and electrochemical behavior which have been nominated for fabrication of flexible energy devices. Paper-like electrodes become an emerging field to fabricate a light-weight and flexible electronic devices for future prospects. Thus, we have summarized a synthetic strategy of graphene paper and its properties that potentially focused on flexible device fabrication in both the energy storage and conversion system. Hence, this review boosts up the forthcoming researchers to enhance the device performance with interrelating free-standing graphene and other host material. Number of publications from 2009 to 2018 based on free-standing graphene-paper in energy device applications gathered from Web of Science database search engine. Image 10612 [ABSTRACT FROM AUTHOR]

Pulp and paper industry is one of the most polluting, energy and water intensive industries in the world. Produced pulp and paper mill sludge (PPMS) faces a major problem for handling and its management. An anaerobic digestion has become an alternative source. This review provides a detailed summary of anaerobic digestion of PPMS – An overview of the developments and improvement opportunities. This paper explores the different pretreatment methods to enhance biogas production from the PPMS. First, the paper gives an overview of PPMS production, and then it reviews PPMS as a substrate for anaerobic digestion with or without pretreatment. Finally, it discuss the optimal condition and concentration of organic and inorganic compounds required for the anaerobic metabolic activity. Future research should focus on the combination of different pretreatment technologies, relationship between sludge composition, reactor design and its operation, and microbial community dynamics. [ABSTRACT FROM AUTHOR]

An enormous gap exists between Africa's current electrification rate and the 2030 UN goal to ensure universal access to modern energy. A study by Sanoh et al. published in Renewable Energy in 2014 [1] is a rare example of finding a cost minimal solution for the Africa-wide generation and transmission network. Unfortunately, however, the paper exhibits a number of relatively serious flaws that demand attention given the alarming paucity of such research on Africa. Five issues of the study by Sanoh et al. are identified and discussed in this commentary paper. Specifically, the study does not account for capacity factors when deriving required capacity additions, misses transmission losses when sizing generation capacity, models country-level import constraints incorrectly, introduces a supply option redundancy, and reports optimisation results that can be shown to be mathematically sub-optimal. As a result of some of these issues, the Sanoh et al. significantly underreport the required capacity to meet additional African demand in 2025. In addition to discussing these flaws, this paper provides potential approaches to avoid each of the five issues. [ABSTRACT FROM AUTHOR]

The rapid growth of environment pressures and fast depletion of fossil fuels compel public to pay more attention on developing affordable and efficient catalysts for renewable energy production. Metal (Co, Fe, Ni, etc.) phosphide nanoparticles uniformly encapsulated in porous N,P-codoped nanofibrous carbon coated on carbon paper (MeP@NPC/CP) are prepared through one-pot carbonization-phosphorization strategy, which are potential for effective electrocatalytic water reduction/oxidation reactions. The well-designed self-supported structure and the abundant accessible active centers together contribute to the high electrocatalytic performance for hydrogen and oxygen evolution. Remarkably, an alkaline electrolyzer assembled from CoP@NPC/CP as cathode and anode can afford the current density of 10 mA cm −2 at the voltage of 1.67 V for overall water splitting in alkaline media with excellent stability. The easily prepared route with suitable structural and textural properties endows this self-supported materials with versatile function as abundant metal catalysts for realistic energy conversion and storage systems. [ABSTRACT FROM AUTHOR]

This work reports an innovative simulation method for effectively utilizing paper-mill sludge based on the co-gasification approach for energy-enriched renewable fuel production. An Aspen plus-based co-gasification model was developed to simulate and examine the synergetic effects of biomass and paper-mill sludge co-gasification. Initially, the model was validated using experimental data from the reported literature and found good agreement regarding gasification and co-gasification approaches. Sensitivity analysis of biomass gasification revealed that the maximum H 2 content of 29.6% and CO (36.0%), LHV (7.8 MJ/Nm3), 72.2% (CCE) was obtained at optimal (850 °C: temperature; 1 bar: pressure; 0.2: ER) conditions. Further, the H 2 proportion enhanced, and CO declined to 38.8 and 30.7% at the same operating conditions, respectively, with a co-gasification ratio of 50% compared to 0% (H 2 : 29.6% and CO: 36.0%). However, with increasing the co-gasification ratio beyond 20%, the CO content started to follow upward trends; at the same CGR, the H 2 , LHV, and CCE observed were 36.0%, 7.76 MJ/Nm3, and 65.2%, respectively. Hence, the developed co-gasification model can provide vital information for large-scale gasifier design, operating decisions, and optimization using different biomass blends. • Biomass and PMS utilization to produce renewable fuel. • Co-gasification parametric effects evaluation on product yield. • Increasing the proportion of PMS in feedstock mixture increases H 2 content. • 20% PMS co-gasification provided consistency with reported literature. [ABSTRACT FROM AUTHOR]

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

Highlights • Agave tequilana bagasse was pretreated with 1-ethyl-3-methylimidazolium acetate. • Biomass loading, reaction time and temperature conditions were optimized. • High sugar yield was achieved at milder conditions than those previously reported. • Solid recovery after pretreatment was a key factor for improving sugar yield. • Saccharification was improved by decreasing crystallinity and lignin content. Abstract Sequential 2k factorial and central composite designs were used to optimize Agave tequilana bagasse (ATB) pretreatment by using 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]). Reaction time, temperature and solids loading were the studied factors while sugar yield was the response variable. Results indicated that optimal conditions (119 °C, 142 min) using high solids loading (30%) were achieved at lower temperatures and reaction times than those previously reported in the literature. It was also revealed that solid recovery after pretreatment with [Emim][OAc] is a key factor. The increase in enzymatic digestibility of pretreated ATB was correlated to a decrease in crystallinity and lower lignin content as observed using microscopy techniques and weaken chemical bonds by Fourier transform infrared spectroscopy. Yields of glucose and xylose in the hydrolysate were 41.3, and 13.0 kg per 100 kg of untreated ATB, which are equivalent to glucan and xylan conversions of 75.9% and 82.9%, respectively. [ABSTRACT FROM AUTHOR]

• The study promotes a standardized framework for the analysis of complex systems. • Life Cycle Assessment (LCA) and Emergy Accounting (EMA) are integrated for synergy. • Differences and similarities between LCA and EMA add value for deeper understanding. • The proposed framework is based on ex-ante LCA, EMA and ex-post LCA procedures. The analysis of complex systems requires an integrated application of different assessment methods also taking into account different scales and points of view to gain a systemic understanding of the investigated case study. Life Cycle Assessment (LCA) and Emergy Accounting (EMA) are both environmental assessment methods, showing many similarities in the way they are performed, especially with respect to the inventory construction and to the interpretation of results. They also show great differences, the main residing in the different perspectives they give. LCA applies a consumer side perspective, and its space and time scales are set at a boundary capable to include all the process phases in terms of location and durability and their direct impacts on the investigated areas. On the other hand, throughout its donor side perspective, EMA expands the boundaries of the system over the entire biosphere space and time scales. Differences and similarities between LCA and EMA may gain added value by their implementation within a procedural framework which exploits the characteristics of the two methods. The present work proposes a methodological procedure based on the sequential and integrated application of LCA and EMA methods, called LEAF (LCA & EMA Applied Framework). The traditional Amalfi paper production is used as a test case study. The procedure stems include: (i) an ex-ante LCA analysis, to identify the hotspots of the investigated case study; (ii) the assessment of the environmental performance of the system through the development of different EMA-based improvement scenarios built around the chosen hotspots; and (iii) an ex-post LCA application built on each scenario results in order to detect the different environmental burdens. The application of LEAF to the traditional Amalfi paper production shows that the use of a more sustainable energy source is an effective solution (among the set of proposed options) to increase the sustainability of the investigated system. [ABSTRACT FROM AUTHOR]

Hydrogen has become an essential element in the pursuit of sustainable and clean energy solutions. Especially with the fast-paced advancement in demand, supply, and policy environment, its impact on hybrid renewable energy (HRE) management is becoming increasingly relevant. Efficient energy consumption, cost reduction, and enhanced user comfort are now critical factors in energy optimization. The production of green hydrogen, which is generated through water electrolysis using renewable energy sources (RES), has shown great potential as a sustainable energy solution. It offers several advantages, such as zero greenhouse gas emissions, high energy density, and versatile applications. This paper presents a detailed study on the power management and control of a hybrid renewable system (HRES) equipped with a diesel generator (DG) as a backup power source. The main objectives of the hybrid system are to satisfy the load power demand, ensure the most efficient use of the HRES, and keep the battery bank charged to prevent blackouts and extend the battery's life. To guarantee the system's reliability, the DG should be sized to meet the peak load demand when the RES generates less electricity than the load demand. This study explores the feasibility of modified versions of the load following and cycle charging control strategies to overcome the limitations of managing generation and storage systems' operations in different operating modes and to enhance the performance of an HRES with a DG that supplies electricity to a small and remote location. The proposed method not only maximizes the use of RES production but also enables multi-energy source management under different power generation and load demand scenarios. The study's outcomes demonstrate the feasibility of this proposed power dispatch strategy in a remote location environment. The paper includes a detailed discussion of overall control, mathematical models, energy storage in the battery model, and energy dispatching based on load following. To design and simulate the hybrid model system, MATLAB-SIMULINK is used, and the results are analyzed to identify the appropriate operation requirements, component selection, and energy management of the hybrid renewable energy system. [ABSTRACT FROM AUTHOR]

Optimizing domestic energy use and increasing the efficiency of residential power supply chains depend much on home energy management (HEM) systems. This paper examines the utilization of advanced meta-heuristics, namely the Siberian Tiger Optimization (STO) and Sand Cat Swarm Optimization (SCSO) algorithms, for developing HEM systems. The paper presents an integrated STSC algorithm, enhanced by artificial intelligence, that monitors and optimizes household energy usage. To optimize electricity distribution, this algorithm seeks a compromise between reducing costs and lowering the peak-to-average proportion of power. After extensive simulations, the STSC algorithm outperforms previous meta-heuristics in Peak Average Ratio. It demonstrates the possibility of substantial cost reductions in residential settings, reaching up to 8.5%. This improves the overall efficiency of households' power supply chains. In addition to reducing costs, the STSC algorithm contributes to sustainability objectives by utilizing AI to minimize carbon emissions, including renewable energy sources, and facilitate adaptable demand solutions. This highlights its role in promoting sustainable supply chain practices in energy efficiency. The combined use of STO and SCSO algorithms in the STSC method is a new and innovative development in HEM systems. This study highlights the capacity of AI-driven technologies to effectively and environmentally optimize household energy consumption. [ABSTRACT FROM AUTHOR]

This paper examines the problem of synthesizing a two-loop control system for a three-phase voltage source inverter designed for an autonomous power supply system. This type of DC/AC converters is an essential part of power supply systems with renewable energy sources as primary sources, and, accordingly, must corresponds to the requirements for the electric power quality. These requirements are met through circuit design solutions, as well as through the construction of high-precision automatic control systems. The system integrates: a hydrogen electrolyzer, a hydrogen storage system, and a hydrogen fuel cell. The paper proposes a method for calculating the parameters of PI controllers with resonant components, based on the time-scale separation method and allowing independent adjustment of the controller components. The introduction of a resonant component ensures high tracking accuracy for a desired main voltage harmonic and selective suppression of external harmonic influences. The proposed approach allows to synthesize an automatic control system that significantly improves the quality of the voltage inverter output parameters. [ABSTRACT FROM AUTHOR]

The global pursuit of sustainable energy solutions has led to an increased interest in green hydrogen as a significant contributor to the transition towards a low-carbon economy. This comprehensive analysis delves into the progress made in green hydrogen production using alkaline water electrolysis, shedding light on the fundamental principles, materials, design, operational conditions, and integration with renewable energy sources. The paper critically evaluates the economic and environmental aspects, providing valuable insights into the challenges, future prospects, and real-world applications. The importance of green hydrogen as a clean energy carrier is emphasized in the context of mitigating climate change and achieving energy independence. The paper outlines various methods for hydrogen production, with a focus on alkaline water electrolysis, highlighting its role in sustainable hydrogen generation. The structure of the review paper is well-detailed, guiding the reader through a systematic exploration of key aspects related to green hydrogen production. The fundamentals of alkaline water electrolysis are explained in detail, covering the basic principles, reactions at electrodes, components, working mechanisms, efficiency calculations, and existing challenges. An in-depth examination of materials and electrodes is presented, showcasing recent innovations that enhance performance. Electrolysers design and system configurations are discussed, incorporating recent developments aimed at improving efficiency and scalability. The paper explores operating conditions and optimization strategies, emphasizing the impact of temperature, pressure, and current density on electrolysis efficiency. The integration of renewable energy sources, such as wind and solar power, with alkaline water electrolysis is analyzed, addressing both the benefits and challenges. The economic feasibility of green hydrogen production and its environmental impacts, including life cycle assessments and carbon footprint, are meticulously examined. The paper concludes with an overview of current challenges and limitations, ongoing research insights, and future prospects for alkaline water electrolysis technology. Real-world case studies are presented to showcase the practical applications of this technology in industries, transportation, and energy storage. In summary, this review highlights the pivotal role of alkaline water electrolysis in advancing green hydrogen production, offering a promising pathway towards a sustainable and decarbonized energy future. [ABSTRACT FROM AUTHOR]

Hydrogen is emerging as a critical player in transitioning to sustainable and renewable energy systems, serving roles in energy storage, grid balancing, and decarbonization. This paper explores various aspects of hydrogen, including its production through renewable-electricity-driven electrolysis, advanced storage techniques, and incorporation into current energy systems. It highlights primary electrolysis methods like PEM and alkaline, noting their improved efficiency and cost-effectiveness. Various hydrogen storage methods, such as physical, chemical, and advanced porous materials, are examined for their benefits and limitations. The review further explores hydrogen's integration into grid storage systems and microgrids to enhance energy reliability. It discusses hydrogen's application in fuel cells for electricity generation, focusing on technological advancements that improve efficiency and reduce costs. Additionally, the paper underscores hydrogen's crucial role in reducing CO 2 emissions in industrial processes like steel production and its use in residential and commercial energy supply through combined heat and power systems. Economic aspects and supportive policies from regions are analyzed, highlighting the global efforts and policies supporting the potential hydrogen in renewable energy systems. This analysis emphasizes hydrogen's comprehensive role in enhancing renewable energy systems and achieving global sustainability objectives, providing a thorough review of recent progress and challenges. • Identifies PEM and alkaline as efficient electrolysis methods. • Analyzes varied H 2 storage options for mobility and stationarity. • Highlights advancements in H 2 fuel cells for vehicles. • Discusses global policies supporting H 2 integration. • Reviews economic impacts of scaling H 2 infrastructure. [ABSTRACT FROM AUTHOR]

The transition to sustainable energy sources is a global imperative in the face of climate change and dwindling fossil fuel reserves. Hydrogen, as a clean and versatile energy carrier, has garnered significant attention as a potential solution. This paper provides a comprehensive overview of various electrolyzer types, their features, advantages, disadvantages, and future expectations in the context of sustainable energy generation. The article begins by outlining the fundamental principles of electrolysis, highlighting its potential to harness surplus renewable energy. Four main types of electrolyzers are discussed: alkaline electrolyzers, proton exchange membrane electrolyzers, anion exchange membrane electrolyzers, and solid oxide electrolyzers. Each type is explored in depth, with a focus on their unique operating principles, efficiency, scalability, and suitability for different applications. The paper further delves into recent advancements in electrolyzer technology, discussing emerging trends, improved catalysts, and innovative system designs aimed at enhancing efficiency and reducing costs. It also explores the role of policy support and research initiatives in accelerating the adoption of electrolysis for sustainable hydrogen production. • Water electrolyzer systems are one of the most promising technologies for green hydrogen production. • This review provides insights into the current state and future potential of water electrolysis technologies. • Challenges, advantages, and future directions of electrolyzer types are discussed. • Green hydrogen plays a crucial role in decarbonization efforts and offers a sustainable solution for future energy needs. [ABSTRACT FROM AUTHOR]

• A simple, large-scale fabrication of cooling paper via pulping and papermaking technology. • The cooling paper is facilely deconstructed and regenerated to architect the secondary cooler. • The cooling paper features a high solar reflectance of 94% and emissivity of 0.95. • The cooling paper shows the sub-ambient temperature drop of 6 ∼ 8.8 °C under directly solar radiation at daytime. Passive radiative cooling materials provide coldness without energy consumption for all-day thermal comfort by reflecting solar irradiation and emitting heat into the 3 K universe. However, the conventional radiative cooling materials involve complex multilayer structures and unsustainable polymers, showing the non-recyclable disadvantage, which induces resource waste and environmental issues. Herein, we reported a low-cost, scalable, and eco-friendly radiative cooling material (namely cooling paper), consisting of the delignified, fibrillated cellulose fibers and nano-sized hydroxyapatite (HA) via the mature pulping and papermaking process. The resulting cooled paper can be recycled, and it can be easily deconstructed to harvest cellulose fibers and HA, individually. The recovered source materials can be reused to prepare secondary products that show comparable performance to the original cooling paper, including a high solar reflectance of ∼94% and an infrared emissivity of ∼0.95 in the atmospheric transparency window. Such cooling paper enables superior cooling performance with the temperature drop of 6 ∼ 8.8 °C under directly solar radiation. Based on the EnergyPlus simulation, our cooling paper shows a average cooling energy saving of ∼29 % in buildings across China. The recyclable cooling paper with high cooling capability and scalability, as well as environmental friendliness, shows promising potential for sustainable energy-efficient buildings. [ABSTRACT FROM AUTHOR]

The uncertainty of renewable energy undermines the competitiveness of Renewable Energy Generation Companies (REGC) in market bidding. Hydrogen energy storage, as a novel high-energy-density energy storage technology, is considered an ideal solution to address the uncertainty of renewable energy and provide flexible ramping products (FRP) to the grid. Building upon this, this paper combines hydrogen energy storage and renewable energy to build a hydrogen-wind-photovoltaic (HWP) system, and introduces HWP into the flexible ramping market for the first time, while participating in the energy market. To capture the interactions between HWP and market players with different utility functions, this paper establishes a bi-level bidding strategy model for HWP participation in the integrated energy and flexible ramping markets, It enables HWP to optimize its internal unit output to increase revenue based on current market conditions. In addition to this, the uncertainty of renewable energy output is taken into account in the upper-level model. Finally, the effectiveness of the proposed two-stage stochastic bi-level optimization scheduling model was validated on IEEE 6-bus and 36-bus transmission-constrained networks. Tests demonstrated that the proposed model effectively assists HWP in formulating optimal bidding strategies in the joint market under uncertainty. Compared to solely participating in a single energy market, HWP's simultaneous participation in energy and flexible ramping markets increased total revenue by 12.22%. • Utilizing hydrogen energy storage to provide Flexible Ramping Product (FRP). • Hydrogen-Wind-Photovoltaic (HWP) participates in energy and flexible ramping market. • Establishing a bi-level strategic bidding model for HWP. • Considering the influence of renewable energy uncertainty on bidding strategies. • The introduction of the FRP increased HWP's total revenue by 12.22%. [ABSTRACT FROM AUTHOR]

The escalating demand for renewable energy solutions and the imperative for efficient energy storage mechanisms have catalyzed the evolution of Power-to-X (PtX) technologies. Germany has the most PtX projects, accounting for 44% of all projects that have been reported. PtX encompasses a spectrum of processes engineered to convert surplus renewable energy into versatile energy carriers or chemical commodities, such as hydrogen, methane, or synthetic fuels. The Paramount to this domain is to synergistically harness renewable energy sources and hydrogen carriers to curtail waste and bolster sustainability. Central to achieving this synergy is the effective control of PtX processes, ensuring optimal performance, cost efficiency, and seamless integration within existing energy frameworks. This paper delves into the control processes and environmental prerequisites within the PtX landscape, elucidating key challenges, and strategies within this dynamic realm. While providing an initial overview of fundamental PtX process chains, this paper accentuates the critical role of geographical considerations. Subsequently, it conducts a thorough analysis of equipment modeling challenges, addressing performance metrics, operational requisites, and capital investments, particularly focusing on methanol and hydrogen production and storage. Through holistic examination, this paper endeavors to delineate the evolving landscape of PtX control processes and conditions, advancing our understanding of this expanding field. [Display omitted] • Comprehensive overview of PtX control process, challenges, strategies, and advancements. • Overview of PtX process chains and geographical conditions. • Analysis of equipment modeling challenges for methanol and hydrogen. • Addressing crucial storage challenges in PtX system. • Exploration of diverse influences on PtX control processes. [ABSTRACT FROM AUTHOR]

This paper examines the potential of solar and hydrogen (H 2) energy-based hybrid energy systems for residential applications. The growing need for energy and the demand for sustainable energy sources have led to the development of integrated energy systems that combine renewable energy resources to meet energy needs. This paper overviews recent studies on hybrid energy systems for on-grid and off-grid residential utilizations. It discusses the system configuration and components of hybrid energy systems, including solar panels, electrolyzers, fuel cells (FC), and batteries. It also covers the technical optimization of integrated energy systems, including sizing, control strategies, and economic analysis. The key findings of this review paper indicate that hybrid energy systems can offer dependable and sustainable energy for residential applications. Through numerical analyses, the optimal dimensioning of the system elements and control strategies can significantly enhance the system's performance and lower the cost of energy. This study also highlights the challenges and opportunities for integrating hybrid energy systems within residential applications. Overall, it provides in-depth perspectives on the possibilities inherent in solar and hydrogen energy-based hybrid energy systems for residential applications. The findings can guide future research and the advancement of hybrid energy systems for sustainable energy solutions. • Comprehensive review on solar and hydrogen-based residential applications. • Holistic approach to system configuration, optimization, and economics. • Detailed analysis of interconnected components enhancing system efficiency. • Unique focus on real-world residential applications and scenarios. • Broad applicability across diverse geographical regions. [ABSTRACT FROM AUTHOR]

Transitioning to a sustainable energy future necessitates innovative storage solutions for renewable energies, where hydrogen (H₂) emerges as a pivotal energy carrier for its low emission potential. This paper explores unlined rock caverns (URCs) as a promising alternative for underground hydrogen storage (UHS), overcoming the geographical and technical limitations of UHS methods like salt rock caverns and porous media. Drawing from the experiences of natural gas (NG) and compressed air energy storage (CAES) in URCs, we explore the viability of URCs for storing hydrogen at gigawatt-hour scales (>100 GWh). Despite challenges such as potential uplift failures (at a depth of approximately less than 1000 m) and hydrogen reactivity with storage materials at typical conditions (below temperatures of 100°C and pressures of 15 MPa), URCs present a flexible, scalable option closely allied with green hydrogen production from renewable sources. Our comprehensive review identifies critical design considerations, including hydraulic containment and the integrity of fracture sealing materials under UHS conditions. Addressing identified knowledge gaps, particularly around the design of hydraulic containment systems and the interaction of hydrogen with cavern materials, will be crucial for advancing URC technology. The paper underscores the need for further experimental and numerical studies to refine URC suitability for hydrogen storage, highlighting the role of URCs in enhancing the compatibility of renewable energy sources with the grid. • Detailed exploration of unlined rock cavern (URC) technology. • Analysis of URCs' potential for large-scale hydrogen storage. • Insights from historical use of URCs in compressed gas storage. • Examination of the opportunities and challenges in using URCs for hydrogen storage. [ABSTRACT FROM AUTHOR]

Hydrogen is a relatively new source of sustainable energy resources; presently, its usage ranges from direct energy generation in mixed-cycle thermal power plants to its usage in the internal combustion engine. If the generation of hydrogen is coupled with renewable energy resources, the use of hydrocarbons can be substantially reduced in both energy generation and transportation. In this paper, we conducted a national-level assessment to identify the hydrogen generation capacity of Pakistan. The methodology used in this study is a combination of spatial multi-criteria analysis and density-based clustering in a geographical information systems environment. Based on the analysis, the national clusters capable of producing green hydrogen were identified. The results shows that the hydrogen generation capacity for Pakistan is approximately 7 million tons per year using solar photovoltaic energy. The Surab-Gwadar alignment, N-25 national highway, and Quetta-to-D-I-Khan alignment offer potential hydrogen generation sites with water resources. Most of the identified sites for the production of hydrogen in the country were found to be near the national electricity transmission networks. The Best-Worst Method was further employed to provide policymakers with a road map for prioritizing the development of these capacities based on their proximity to the national networks, their terrain suitability, and their generation capacities. • This paper assesses the suitable sites for solar-based green hydrogen production in Pakistan. • The methodology used involves a combination of spatial multicriteria analysis, clustering, and the best-worst method. • Pakistan's theoretical annual hydrogen generation capacity is around 7 million tons annually. • The Surab-Gwadar alignment presents promising hydrogen generation opportunities. [ABSTRACT FROM AUTHOR]

The paper is devoted to the development of a device for protecting facilities with turn-to-turn insulation, namely transformers and wind generators in order to increase the reliability of operation of electrical power systems, renewable energy installations and energy storage systems. The paper presents the results of experimental studies of the parameters of a prototype frequency-dependent device, as well as an assessment of the effectiveness of suppression of high-frequency surge voltages by the proposed device. The results of four groups of measurements are shown, which were compared with each other and with the results of previously showed computer simulations. The high efficiency of the proposed device when influencing the slope and amplitude of short high-frequency transients is shown. It is indicated that the parameters proposed earlier in the simulation allow the device to be used effectively. A brief analysis of alternative methods and means of protection is provided, and the prospects for using the device as protective equipment for wind power plants are also considered. [ABSTRACT FROM AUTHOR]

Green hydrogen is crucial for society's access to peaceful, secure, and stable energy sources to flourish sustainably and get universal government support. To protect the environment and provide energy security, it is essential to use hydrogen as a sustainable fuel and energy source to cover the energy baseload. This paper investigates the developments of renewable energy (RE) and the potential for green hydrogen in the Middle East and North Africa (MENA) region. There is a considerable chance to use RE because of the MENA region's excellent solar radiation. On the other hand, many countries in the MENA region are classified as one of the poorest in water resources and are known to have water-energy challenges. This paper focuses on the water needed to produce hydrogen in countries with water scarcity. A strengths, weaknesses, opportunities, and threats (SWOT) analysis was performed for green hydrogen generation in the MENA, where recommendations for countries with a water-energy nexus can be made. Additionally, this paper offers suggestions for creating a sustainable hydrogen economy, such as cutting back on the domestic use of fossil fuels, subsidizing the renewable production industry, and supporting hydrogen manufacturing. • Green hydrogen production is highly affected by water scarcity. • SWOT analysis was performed on green hydrogen generation in the MENA. • Recommendations were provided on a country-by-country basis. [ABSTRACT FROM AUTHOR]

This study presents a bibliometric review focusing on the utilization of water electrolysis as a means of generating hydrogen as an energy carrier. The analysis includes research conducted over the past decade, covering from 2014 to 2023 (till August). Several key aspects are highlighted, including publication trends, the leading country in research output, journal rankings, and a citation analysis of papers related to water electrolysis. The findings reveal a notable increase in publication trends, with China emerging as the leading contributor in this research area. Furthermore, the International Journal of Hydrogen Energy is identified as the highest-ranked journal in terms of both publication number and citation impact. Additionally, the top ten most cited research articles and review papers are investigated to determine their influence within the field. To gain a deeper understanding of water electrolysis methods, the three primary approaches: alkaline water electrolysis (AWE), proton exchange membrane (PEM) electrolysis, and solid oxide electrolysis (SOE) is examined. The analysis emphasizes that PEM electrolysis is the most prevalent method for hydrogen generation, particularly when integrated with renewable energy sources such as solar and wind power due to its rapid response to electrical input fluctuation. Finally, the challenges and future directions of water electrolysis in hydrogen production are highlighted, including an exploration of economic and environmental considerations at large scale, offering insights into the path forward for advancing this technology sustainably. • A comprehensive bibliometric analysis of water electrolysis for hydrogen production. • Publication trends, journal rankings, and citation analysis are highlighted. • China is identified as the leading contributor in water electrolysis publications. • International Journal of Hydrogen Energy: the highest-ranked journal in this field. • Specific electrolysis methods, including AWE, PEM, and SOE are examined. [ABSTRACT FROM AUTHOR]

Aerogels, with their exceptional properties such as high insulation performance, lightness, and eco-friendliness, present immense potential for use in the construction industry. This paper reviews the progress in research and application of various types of aerogels in construction, highlighting notable case studies demonstrating energy efficiency gains and sustainability impacts. It delves into the lifecycle of aerogels, discussing environmental implications at each stage. Despite their potential, aerogels face certain limitations including production complexity, brittleness, and high cost which hinder their widespread adoption. The paper further discusses these challenges and highlights the need for continuous research and development efforts to overcome them, with a view to achieving more scalable production, enhanced mechanical properties, and cost reduction. Looking forward, the paper discusses the expansive horizon of aerogel research, emphasizing the potential of smart aerogels, their integration with renewable energy systems, and exploring the possibility of recycling or creating bio-based aerogels to enhance their overall sustainability. While still in early stages, aerogels promise to be a major contributor to the future of construction, leading to more sustainable and efficient built environments. [ABSTRACT FROM AUTHOR]

Clean energy devices have a great ability to change the world because they strengthen the economy and preserve society. The continuous improvement and progress in nanomaterials and nanotechnology have a great role in human life. The increasing prevalence of PEM fuel cells makes them one of the most viable sustainable energy sources. Nanostructured materials synthesis methodologies have introduced a breakthrough and found to overcome the obstacles for PEMFC commercialization. Amongst them, wet chemical approaches are rapidly expanding and beneficial for the fabrication of nanoparticles since they contribute toward the attainment of a range of essential nanoparticle characteristics like sizes, morphologies, structures, and phases. Wet chemical manufacturing enables fine-tuning of reaction parameters to generate the desired nanomaterials. This review article focuses on the latest improvements in wet chemical methods to better regulate the quality of nanomaterials. This paper examines how wet chemical approaches (hydrothermal synthesis, spray pyrolysis, sol-gel processing, and co-precipitate synthesis, among others) can contribute to the scalable manufacturing of nanoparticles to uphold rising industrial requirements. And how wet chemical methods have a significant influence on power generation systems (Fuel cells) along with their pros and cons. This review carefully analyzes and summarizes synthetic methods and optimized factors in order to prepare nanoparticles and carefully analyzes the reported data. In this paper, the electrochemical analysis, morphological evaluation, compositional analysis, and performance testing of materials produced using wet chemical techniques have been investigated. Recent signs of progress and innovative techniques used to overcome the complexities of synthetic nanoparticle processing. This article is a holistic approach including social, economic, and ecological aspects in the wet chemical process and will certainly help in the fabrication, and application of nanoparticles for PEM Fuel cells. [Display omitted] • Introduction to the status of materials synthesis in energy generating devices. • Overview of wet chemistry Approaches for PEMFC. • Impact of synthesis parameters on properties of materials. • Pros and Cons of wet chemistry techniques for material synthesis. [ABSTRACT FROM AUTHOR]

In pursuit of energy transition objectives, Algeria is increasingly focusing on the production and utilization of low-carbon and renewable hydrogen. While hydrogen has predominantly been used in the chemical and refining industries, it holds promise for decarbonizing specific industrial sectors, enabling electricity storage, and powering the transport sector. However, several barriers must be overcome before hydrogen technologies can be widely deployed. Numerous countries, with Japan at the forefront, are heavily investing in this burgeoning market, anticipating the creation of thousands of new jobs. Hydrogen offers Algeria significant potential for greenhouse gas (GHG) reduction and substantial economic benefits. In response, the Algerian government has prioritized energy transition to new and renewable sources as part of its economic recovery plan, aiming for "green" growth through innovative and digital energy technologies. This paper's primary objective is to provide a techno-economic foundation for guiding public policy development, identifying promising opportunities for green hydrogen within Algeria's energy transition context, and outlining sustainable pathways for pilot projects that promote hydrogen adoption within the Algerian society. Additionally, this paper will explore the latest advancements in hydrogen research, technology, and applications relevant to the Algeria's energy transition. The Algerian energy minister, has reaffirmed his desire to "invest in hydrogen", an energy source presented as one of the solutions to the climate crisis. In October 2021, Algeria launched a hydrogen plan worth several billion dinars, including 100 million for research, to enable the country to develop "green" hydrogen, i.e. produced without fossil fuels. • Algeria's energy transition mission focuses on promoting energy transition, innovation, and efficiency. • The Algerian Strategy on Green Hydrogen 2050 intends to establish a supportive framework for hydrogen sector development. • Algeria has set ambitious targets: reducing its GHG emissions by 2030 and lowering its consumption of petroleum products. • Algeria export between 30 and 40 TWh by 2040 of gaseous green hydrogen, liquefied, and derived. [ABSTRACT FROM AUTHOR]

Renewable energy sources, driven by the global concern for climate change and the urgent need to reduce greenhouse gas emissions, are gaining increasing importance. Among them, solar energy stands out as a crucial renewable source and accurate solar irradiance forecasting is vital for its effective utilisation. Deep learning (DL) techniques have emerged as state-of-the-art solar irradiance forecasting methods in past years. However, traditional models that are widely used have inferior accuracy in forecasting. To bridge this gap, this paper presents an improved state-of-the-art model that leverages the convolutional property to forecast the time series data. We got a reduction of 8.32% in MAE compared to the base model. The paper's findings highlight the potential of DL-based approaches to significantly improve the accuracy of solar irradiance forecasts. [ABSTRACT FROM AUTHOR]

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

Hydrogen production from renewable energy sources is one of the important means to solve the world energy crisis. In the past decades, many experts and scholars have made different reviews on electrolyser and hydrogen production power supply. However, few articles have reviewed the actual industrial products of electrolyser and hydrogen production power supply from the perspective of industry. Therefore, this paper reviews the hydrogen production power supply and electrolyser used in practical engineering projects. It is helpful for experts and scholars to understand the development status of hydrogen production power and electrolyser in the industry and to further develop industrial products more suitable for practical applications. • This paper reviews the products of electrolyzers and hydrogen power sources. • This paper expounds the development situation of hydrogen production key products. • This paper summarizes the future development direction of water electrolysis. • This paper helps scholars to propose methods with practical significance. • This paper has guiding value for industrial equipment selection. [ABSTRACT FROM AUTHOR]

The integration of water electrolysis with renewable energy sources (RESs) constitutes a milestone in the transition to neutral and sustainable energy systems. The attractive features of the Proton Exchange Membrane (PEM) electrolyzer such as high purity of hydrogen, operation with high pressure, and high current densities have made it a critical technology to produce green hydrogen from RESs. Accurate models are required for proper design, analysis, and control of the electrolyzer when connected to the grid or renewable energy systems. Amongst the various types of models proposed for modeling the PEM electrolyzer, electrical circuit models are the easiest, most appealing, and straightforward to use for the investigation of electrolyzer operation and control. This paper presents an exhaustive review of the electrical circuit modeling reported in the literature on PEM electrolyzers. The reviewed models are classified analogously to the classifications of physical modeling in terms of voltage components (reversible, ohmic, activation, and concentration voltage drop), model behavior (static/dynamic), and modeling scale (cell/stack). Furthermore, MATLAB simulations of the reviewed models are implemented and the results are compared to pinpoint their similarities and deviations. Moreover, the applications, challenges, benefits, and drawbacks of the electrolyzer's electrical equivalent circuit modeling are discussed and overarching recommendations are set out for further research on the PEM electrolyzer modeling. The paper can be used as a comprehensive reference for choosing the appropriate electrical model of the electrolyzer for beginners as well as for research and industry experts who rely on PEM electrolyzer models in their work. • A comprehensive review of the electrical circuit models of the PEM electrolyzer is presented. • The models are classified in terms of voltage components, model behavior, and scale. • Simulations of the models are implemented to show their similarities and deviations. • Applications, benefits, and drawbacks of electrical circuit modeling are discussed. • Overarching technical recommendations are drawn for further research on electrical circuit modeling. [ABSTRACT FROM AUTHOR]

Renewable energy systems (RESs) have played a vital role in meeting the continuously fast-rising energy demand. While RESs provide limitless and ecologically good possibilities, putting RESs in place has proven to be a challenging task due to their intermittent energy supply. Battery energy storage systems have widely been used in microgrids to manage the issue of intermittent energy supply caused by the RESs. The disadvantages of batteries include, large size, limited lifespan, and high cost. For this reasons, energy planners are looking into hydrogen-based storage systems as a potential solution. This paper aims to provide the recent advancements in the sizing and energy management of hybrid RES (HRES), as well as conventional methods. To achieve this, the authors have employed a review strategy that involves several specific tasks, such as preparing a database of articles related to Hybrid RESs with hydrogen storage, designing inclusion/exclusion criteria to filter out relevant articles, and analyzing each article from critical viewpoints. Thus, this paper elaborates on the general formulation framework for optimization, the classification and review of different optimization methods, and the literature on the application and research of Energy Management Systems (EMS). Additionally, the review presents an analysis and comparison of various system optimization methods and EMS through a study of several cases from the literature. It is hoped that the review will act as a basic framework for researchers looking to investigate HRES incorporated with hydrogen storage. • An efficient energy storage system is essential for managing intermittent energy supply. • A fuel cell generates electricity by combining hydrogen and oxygen to form water. • Soft computing techniques use both single and hybrid algorithms. • Deterministic rule-based controllers operate based on pre-defined rules. • Energy Management System coordinate the flow of power between different components. [ABSTRACT FROM AUTHOR]

Nowadays, grid power loss and power quality deterioration are causing many problems, especially for sensitive uses such as data centers, airports, healthcare, banking, insurance, and telecom. These issues must be resolved through energy continuity coverage and optimization. Dynamic voltage restorers (DVR) are generally used to mitigate network voltage disturbances and maintain a constant voltage value between load terminals for a short and limited duration due to limited energy storage facilities. However, this paper's proposed (DVR) system controlled by the adaptive-network fuzzy inference system (ANFIS) controller can compensate for prolonged power quality disturbances by integrating a hybrid renewable energy system (HRES) managed using classical Proportional Integral (PI) controller power management. This paper proposes a new (DVR) topology coupled with a hybrid renewable energy system (HRES) to exploit free and clean energy, consisting of a solar panel, a PEM fuel cell, and a battery storage device connected through DC-DC converters to a DC transmission, the obtained results from the simulation process of the proposed DVR system in the environment of MATLAB / Simulink showed the ability to eliminate sag that exceeded 0.9 pu in a period of more than 3 min and swells that exceeded 1.2 pu in a period that exceeded one minute. In comparison, the load voltage's total harmonic distortion THDv was reduced from 29% to 5%, and the source current total harmonic distortion THDi from 30.25% to 2.79%. [ABSTRACT FROM AUTHOR]

The continuous growth in global energy demand has led to extensive burning and overconsumption of fossil fuels, resulting in a rapid increase in greenhouse gas emissions, primarily carbon dioxide. On one hand, the frequency and intensity of extreme weather events have increased dramatically due to global climate change. On the other hand, renewable energy sources are rapidly developing. Therefore, CO 2 electrochemical reduction technology has attracted considerable attention as a sustainable solution for converting CO 2 into valuable chemicals. Copper-based catalysts can efficiently reduce CO 2 directly to high-value chemicals, making them one of the focal points in CO 2 electrochemical reduction (eCO 2 RR) research. Many factors influence the activity and selectivity of eCO 2 RR, and this paper systematically reviews the recent advances in CO 2 electrochemical reduction using Cu-based catalysts. Firstly, the fundamental principles and reaction mechanisms of CO 2 electrochemical reduction are outlined. Subsequently, the discussion delves into Cu catalyst structures and composition synergistic control strategies, covering monometallic copper catalysts, multimetallic copper-based catalysts, copper oxides and their derived catalysts, and copper-organic composite catalysts. Finally, we also analyzed the challenges faced by Cu-based catalyst research and provided an outlook on the prospects of CO 2 electroreduction technology in conjunction with emerging AI technology. • Summarized the mechanisms of C 1 and C 2+ products in eCO 2 RR. • Summarized the application of five types of copper-based catalysts in eCO 2 RR. • Discussed the development prospects and strategies of eCO 2 RR in combination with AI. [ABSTRACT FROM AUTHOR]

While Iran has notable renewable energy potentials, the renewable energy sector of this country has remained underdeveloped, mostly because of easy access to cheap fossil fuels. This paper discusses and analyzed the possibility for hydrogen generation from wind resource in urban city which is suffered from air pollution and is located in northwestern Iran. Wind energy and power density estimations were performed using the 2-parameter Weibull probability distribution function. These estimates were used to predict the power output, hydrogen output, economic viability, and environmental benefit of building a wind power-hydrogen production unit in one of several candidate sites in the studied area. Ultimately, the most suitable site for such a project was determined using the SWARA/WASPAS method. After investigating 16 different conventional wind turbines, the best one in terms of achievable power and hydrogen output and economic feasibility was determined. The results showed that Gamesa G80 with a capacity of 2 GW was the best wind turbine for the urban area. Gardaneh-Almas with a wind power density of 1252W/m2 was identified as the best site for power generation in the region. Potential wind-powered hydrogen output at this site was estimated to 97 ton/yr. LCOE and LCOH for this site were estimated to 0.047 $/kWh and 4.6 $/kg-H 2 , respectively. • Hydrogen production integrated urban area toward sustainable cities are discussed. • 3E analysis of wind energy for hydrogen production (WHP) is investigated. • A multi-aspect analysis of WHP is analyzed by WASPAS. • A sensitive analysis on wind energy integrated hydrogen system is performed. • The results showed the wind-hydrogen system is best solution in Iranian cities. [ABSTRACT FROM AUTHOR]

Incorporating hydrogen into the natural gas pipeline network (NGPN) plays a key role in absorbing large-scale renewable energy and mitigating the supply-demand contradictions between electricity and natural gas. The gas-electricity integrated energy system (GEIES) using hydrogen as an intermediate carrier is an effective approach for efficient utilization and low-carbon development in the energy sector. To analyze the influence of hydrogen blending on the operation optimization of GEIES, and to study the impact of fluctuating hydrogen supply and different user acceptance on the economic operation of hydrogen-blended GEIES, this paper proposes a gas-electric integrated energy double-way coupling model (GIEDCM), composed of gas turbines, coal-fired units, wind turbines, photovoltaic units, electrolytic cells, and hydrogen storage tanks (HST). The objective function is to minimize system operational costs, establishing a mixed integer nonlinear programming problem considering hydrogen blending. The nonlinear equations are handled using a piecewise linearization method, and the algorithm is solved by the branch-and-bound method and using the GUROBI solver to verify the effectiveness of the algorithm. This ultimately addresses the issue of low utilization of renewable energy sources (RES). Taking the Belgian 20-node NGPN and the IEEE-39-node electric grid system as examples, different scenarios of GEIES operational optimization are analyzed. The optimization results show that natural gas hydrogen blending significantly enhances the utilization level of wind and solar resources, substantially reduces the wastage of RES, and promotes the coupling and complementarity between various energy sources, reducing system operational costs. However, fluctuations in hydrogen supply and changes in user acceptance directly affect the hydrogen content in the NGPN, thereby influencing the hydrogen blending process. Therefore, hydrogen fluctuations should be minimized in the hydrogen mixing process, and if fluctuations are unavoidable, hydrogen should be supplied in intermittent wherever possible. Appropriate improvement of user acceptance can better improve the economic benefits of system operation. • Establish a new GIEDCM considering hydrogen blending. • Piecewise linearization was used to address nonlinearity. • Hydrogen-blended GEIES, hydrogen fluctuation supply, user acceptance. • Hydrogen supply should reduce fluctuations, and appropriately improve user acceptance. • The feasibility and advantages of the present method are verified by comparing with the GUROBI solver. [ABSTRACT FROM AUTHOR]

Renewable energy sources have been widely installed and operated in power systems, particularly in microgrids in the form of distributed generation units. This issue requires efficient energy management tools which take into account the inherent uncertainties of such energy resources. Thus, this paper presents a stochastic framework aimed at scheduling the renewable energy-based and thermal units in a coordinated way. The generation units comprise fuel cell units with proton exchange membrane known as PEMFC-CHP producing heat and power, concurrently. Moreover, the uncertainties arising from wind and solar power as well as market prices are characterized by deploying scenario-based optimization. The mentioned framework considers storing hydrogen and the model is presented within a stochastic mixed-integer nonlinear programming (MINLP) framework. The resulting problem is simulated on a modified 33-bus distribution network and tackled using the modified marine predators algorithm (MMPA)algorithm. The obtained results indicate that the revenue increases by more than 5% compared to other optimization algorithms. Furthermore, taking into account CHP will increase the total profit of the system by more than 15%. • Proposing optimal management of smart parking considering upscale electricity price with Hydrogen Storage Systems (HSS). • Proposing fuel cell units with proton exchange membrane which generate heat and power simultaneously (PEMFC-CHP). • Optimal coordinated scheduling of renewable energy resources in micro-grids improve objective function. • Suggesting the strategy of storing hydrogen is also considered for PEMFC-CHP units. [ABSTRACT FROM AUTHOR]

The gas-liquid separator serves as a crucial component within AEL integrated with renewable energy sources. It is used to separate gas and lye within the circulating solution, thereby enhancing hydrogen production efficiency and mitigating gas crossover phenomena. However, the separation performance of separators is influenced by fluctuations in processing capacity, attributable to the stochastic nature and volatility of renewable energy. The separation efficiency of gravity gas-liquid separators is investigated in this paper. The separation efficiency is 88.28% (experiment) and 90.0% (simulation). Nevertheless, the ability of gravity gas-liquid separators to sustain great separation performance amidst fluctuations in processing capacity is compromised. Moreover, separation efficiency is diminished with increasing gas content and velocity. A spiral diversion gas-liquid separator is proposed with the separation efficiency is up to 96.4%. The spiral diversion gas-liquid separator proves to be a more suitable choice for AEL integrated with renewable energy sources. • Capacity fluctuation is a characteristic of the AEL. • The separation performance is inevitably affected by capacity fluctuation. • The gravity gas-liquid separator exhibits low separation efficiency. • The spiral diversion gas-liquid separator is adaptable to capacity fluctuation. • The separation performance of spiral diversion gas-liquid separator is 96.4%. [ABSTRACT FROM AUTHOR]

For fast-tracking climate change response, green hydrogen is key for achieving greenhouse gas neutral energy systems. Especially Sub-Saharan Africa can benefit from it enabling an increased access to clean energy through utilizing its beneficial conditions for renewable energies. However, developing green hydrogen strategies for Sub-Saharan Africa requires highly detailed and consistent information ranging from technical, environmental, economic, and social dimensions, which is currently lacking in literature. Therefore, this paper provides a comprehensive novel approach embedding the required range of disciplines to analyze green hydrogen cost-potentials in Sub-Saharan Africa. This approach stretches from a dedicated land eligibility based on local preferences, a location specific renewable energy simulation, locally derived sustainable groundwater limitations under climate change, an optimization of local hydrogen energy systems, and a socio-economic indicator-based impact analysis. The capability of the approach is shown for case study regions in Sub-Saharan Africa highlighting the need for a unified, interdisciplinary approach. • Unique multidisciplinary approach for green hydrogen cost-potentials. • Local perspective on land and hydrogen use of Sub-Saharan Africa embedded. • Spatially and temporally highly detailed green hydrogen cost-potentials. • Sustainable water supply under climate change endogenously secured. • Indicator-based impact analysis shed light on socio-economic conditions. [ABSTRACT FROM AUTHOR]