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Power‐to‐methane (PtM) offers an efficient opportunity for surplus renewable energy storage, but heat management is a major challenge for conducting the highly exothermic methanation reaction. To address this challenge, this study presents the first successful demonstration of core‐shell catalyst pellets in a pilot‐scale reactor for CO2 methanation. Experiments in a wall‐cooled fixed‐bed reactor are conducted with diluted and undiluted reactant feed under systematic variation of cooling temperature and inlet gas flow rate. The results show that core‐shell catalyst pellets significantly reduce the hot‐spot temperature while maintaining comparable reactant conversions to uncoated catalyst pellets at the same conditions. Additionally, core‐shell catalyst pellets allow for undiluted reactant feed at comparably low hot‐spot temperatures (approx. 600 °C). [ABSTRACT FROM AUTHOR]

This paper highlights the emergence of green hydrogen as an eco-friendly and renewable energy carrier, offering a promising opportunity for an energy transition toward a more responsible future. Green hydrogen is generated using electricity sourced from renewable sources, minimizing CO2 emissions during its production process. Its advantages include reducing carbon emissions, energy storage, and its diversity of applications in different sectors. However, challenges remain, particularly in terms of production cost, infrastructure, logistics, research, and development. Despite this, green hydrogen has enormous potential to help fight climate change and promote more resilient energy systems, but its widespread adoption will require global cooperation to overcome these challenges. This review presents a comprehensive examination of green hydrogen, covering multiple aspects, including production methods, infrastructure, advantages, disadvantages, and challenges. It provides an in-depth examination of the current state of hydrogen infrastructure, emphasizing the transition from restricted-access stations to customer-friendly retail stations. Moreover, it explores the complex interplay between hydrogen production, storage, and transportation, addressing issues like energy density and infrastructure demands. The paper also emphasizes the crucial significance of research and development in improving green hydrogen production and utilization, considering advanced materials, safety, and life cycle assessment. [ABSTRACT FROM AUTHOR]

South Africa's extensive marine energy resources present a unique opportunity for advancing sustainable energy solutions. This study focuses on developing a sustainable hybrid power generation system that combines offshore wind and tidal current energy to provide a stable, renewable energy supply for off-grid coastal communities. By addressing the challenges of intermittency and unpredictability in renewable energy sources, the proposed system integrates wind and tidal energy with energy storage and diesel backup to ensure reliability while reducing greenhouse gas emissions and minimizing the environmental footprint. The system is optimized for sustainability, with a configuration of one wind turbine, five tidal turbines, and a diesel generator demonstrated to be the most effective in increasing the renewable energy fraction and lowering the net present cost. Simulations conducted using HOMER Pro version 3.20 software underscore the potential of this hybrid system to support South Africa's transition to a more sustainable energy future, aligning with national and global sustainability goals. The results emphasize the environmental benefits of combining these renewable energy sources, offering a blueprint for achieving energy security and sustainable development in coastal regions. [ABSTRACT FROM AUTHOR]

Abstract The increasing demand for cost-effective materials for energy storage devices has prompted investigations into diverse waste derived electrode materials for supercapacitors (SCs) application. This review examines advancements in converting waste into carbon-based SCs for renewable energy storage. In this context, different carbon-based waste precursor sources have been explored over the years as electrodes in SCs. These waste sources comprise of industrial, plastics and biowastes, including plant and animal wastes. The energy storage capabilities of the various waste derived SCs electrodes are highlighted to provide an understanding into the unique features that make them applicable to SCs. In addition, some challenges associated with the waste-derived SCs electrodes in terms of energy storage have been emphasized. Here, we also provided insights into the recent progress in SCs electrode synthesis techniques and their effects on electrochemical performance. SCs performance tailoring with material structures through the incorporation of different materials to form composites and optimized synthesis methods is an effective strategy. Hence, the synthesis methods outlined include pyrolysis, hydrothermal, microwave-assisted, template-assisted, and sol–gel techniques. The effect of the various synthesis methods on SCs performance has also been discussed. Overall, this review highlights waste valorization with future research directions and scaling challenges.

The increasing demand for cost-effective materials for energy storage devices has prompted investigations into diverse waste derived electrode materials for supercapacitors (SCs) application. This review examines advancements in converting waste into carbon-based SCs for renewable energy storage. In this context, different carbon-based waste precursor sources have been explored over the years as electrodes in SCs. These waste sources comprise of industrial, plastics and biowastes, including plant and animal wastes. The energy storage capabilities of the various waste derived SCs electrodes are highlighted to provide an understanding into the unique features that make them applicable to SCs. In addition, some challenges associated with the waste-derived SCs electrodes in terms of energy storage have been emphasized. Here, we also provided insights into the recent progress in SCs electrode synthesis techniques and their effects on electrochemical performance. SCs performance tailoring with material structures through the incorporation of different materials to form composites and optimized synthesis methods is an effective strategy. Hence, the synthesis methods outlined include pyrolysis, hydrothermal, microwave-assisted, template-assisted, and sol–gel techniques. The effect of the various synthesis methods on SCs performance has also been discussed. Overall, this review highlights waste valorization with future research directions and scaling challenges. [ABSTRACT FROM AUTHOR]

As part of the initiative to achieve Singapore's Green Plan 2030, we propose to investigate the potential of utilizing micro-pumped hydroelectric energy storage (PHES) systems in multi-level carparks (MLCP: a stacked car park that has multiple levels, may be enclosed, and can be an independent building) as a more environmentally friendly alternative to traditional battery storage for a surplus of solar energy. This study focuses on an MLCP with a surface area of 3311 m2 and a height of 12 m, considering design constraints such as a floor load capacity of 5 kN/m2 and the requirement for a consistent energy discharge over a 12 h period. The research identifies a Turgo turbine as the optimal choice, providing a power output of 2.9 kW at a flow rate of 0.03 m3/s with an efficiency of 85%. This system, capable of storing 1655.5 m3 of water, can supply power to 289 light bulbs (each consuming 10 W) for 15.3 h, thus having the capacity to support up to three MLCPs. These results underscore the environmental advantages of PHES over conventional batteries, highlighting its potential for integration with solar panels to decrease carbon emissions. This approach not only aligns with Singapore's green initiatives but also promotes the development of a more sustainable energy infrastructure. [ABSTRACT FROM AUTHOR]

Seasonal underground hydrogen storage (UHS) in porous media provides an as yet untested method for storing surplus renewable energy and balancing our energy demands. This study investigates the technical suitability for UHS in depleted hydrocarbon fields and one deep aquifer site in Taranaki Basin, Aotearoa New Zealand. Prospective sites are assessed using a decision tree approach, providing a "fast-track" method for identifying potential sites, and a decision matrix approach for ranking optimal sites. Based on expert elicitation, the most important factors to consider are storage capacity, reservoir depth, and parameters that affect hydrogen injectivity/withdrawal and containment. Results from both approaches suggest that Paleogene reservoirs from gas (or gas cap) fields provide the best option for demonstrating UHS in Aotearoa New Zealand, and that the country's projected 2050 hydrogen storage demand could be exceeded by developing one or two high ranking sites. Lower priority is assigned to heterolithic and typically finer grained, labile and, clay-rich Miocene oil reservoirs, and to deep aquifers that have no proven hydrocarbon containment. • UHS could provide temporary storage for a large surplus of renewable energy. • The technical feasibility of potential storage sites in Taranaki Basin is assessed. • Two methods for site evaluation are applied, using multi-criteria decision analysis. • Depleted gas fields are considered the best option for demonstrating UHS technology. • The projected 2050 storage capacity demand for NZ could be met by developing 1–2 sites. [ABSTRACT FROM AUTHOR]

The power industry is currently undergoing a rapid transformation toward the maximum utilization of renewable energy resources. In grid-connected renewable energy systems, enhancing the voltage stability during the fluctuations in renewable energy outputs can be achieved using a transformer with built-in on-load tap changing. It is one of the main traditional voltage regulation techniques utilized to improve the voltage profile in the power grid. Due to the unpredictable nature of renewable energy penetration, the frequent operation of an on-load tap changer (OLTC) may increase significantly. Despite the proposed methods used to optimize the location and size of renewable generation, there is a lack of empirical or detailed studies that have been looking at the issue of tap changers, mainly the impact of renewable energy storage allocation. The main aim of this paper is to find a compromise approach to mitigate unnecessary tap-changing operation time by wisely siting and sizing the renewable energy storage system (RESS). Initially, a generalized method is proposed to formulate an analytical optimization framework coupled with a renewable storage index. This approach is employed to evaluate the behavior of OLTC in a grid-connected renewable energy system. The formulation is then used to model a decision-making approach to confirm the location and size of RESS, using the analytic network process (ANP) with entropy and technique for order of preference by similarity to an ideal solution (TOPSIS). The performance of the proposed approach is evaluated and compared using the IEEE benchmark networks. Aspects in relation to the predictions of future operations about the management of renewable energy storage in coordination with voltage regulators in the smart grid context, that will be the subject matter of additional studies are also discussed. [ABSTRACT FROM AUTHOR]

As part of the initiative to achieve Singapore’s Green Plan 2030, we propose to investigate the potential of utilizing micro-pumped hydroelectric energy storage (PHES) systems in multi-level carparks (MLCP: a stacked car park that has multiple levels, may be enclosed, and can be an independent building) as a more environmentally friendly alternative to traditional battery storage for a surplus of solar energy. This study focuses on an MLCP with a surface area of 3311 m2 and a height of 12 m, considering design constraints such as a floor load capacity of 5 kN/m2 and the requirement for a consistent energy discharge over a 12 h period. The research identifies a Turgo turbine as the optimal choice, providing a power output of 2.9 kW at a flow rate of 0.03 m3/s with an efficiency of 85%. This system, capable of storing 1655.5 m3 of water, can supply power to 289 light bulbs (each consuming 10 W) for 15.3 h, thus having the capacity to support up to three MLCPs. These results underscore the environmental advantages of PHES over conventional batteries, highlighting its potential for integration with solar panels to decrease carbon emissions. This approach not only aligns with Singapore’s green initiatives but also promotes the development of a more sustainable energy infrastructure.

This comprehensive review examines the enduring relevance and technological advancements in lead-acid battery (LAB) systems despite competition from lithium-ion batteries. LABs, characterized by their extensive commercial application since the 19th century, boast a high recycling rate. They are commonly used in large-scale energy storage and as backup sources in various applications. This study delves into the primary challenges facing LABs, notably their short cycle life, and the mechanisms underlying capacity decline, such as sulfation, grid corrosion, and positive active material (PAM) degradation. We present an in-depth analysis of various material-based interventions, including active material expanders, grid alloying, and electrolyte additives, designed to mitigate these aging mechanisms. These interventions include using barium sulfate and carbon additives to reduce sulfation, implementing lead-calcium-tin alloys for grid stability, and incorporating boric and phosphoric acids in electrolytes for enhanced performance. In contrast, operation-based strategies focus on optimizing battery management during operation. These include modifying charging algorithms, employing desulfation techniques, and integrating novel approaches such as reflex and electroacoustic charging. The latter, a promising technique, involves using sound waves to enhance the electrochemical processes and potentially prolong the cycle life of LABs. Initial findings suggest that electroacoustic charging could revitalize interest in LAB technology, offering a sustainable and economically viable option for renewable energy storage. The review evaluates the techno-economic implications of improved LAB cycle life, particularly in renewable energy storage. It underscores the potential of extending LAB cycle life through material and operation-based strategies, including the innovative application of electroacoustic charging, to enhance the competitiveness of LABs in the evolving energy storage market. [ABSTRACT FROM AUTHOR]

The flywheel energy storage system (FESS) is a cutting-edge device that stores electrical energy with great efficiency by using a revolving rotor that transforms electrical energy into kinetic energy. Flywheel systems provide some benefits, including cheap maintenance costs, a long lifespan, quick reaction times, and an excellent round-trip efficiency of over 90%. Because of these qualities, FESS has a lot of promise in the energy sector. As a result, the study looked at the system's architecture, characteristics, and contributions to future improvements. To provide the essential knowledge and understanding about the technologies and applications of FESS, this study gave an informative overview of its structure and components by conducting a literature search and screening to clearly define the structure and components. Amber Kinetics, an industry leader in manufacturing FESS, collaborated on the research, which resulted in a descriptive characterization and interpretation of it in terms of control method, stability enhancement, and future possibilities. The M32 Flywheel is composed of 98% steel. It has a mechanical battery that does not decrease in function, unlike lithium-ion batteries, which are chemically based, prone to fire, and difficult to dispose of. FESS significantly contributes to the existing energy market by consistently storing and preserving energy and augmenting and delivering the power required by consumer requests. [ABSTRACT FROM AUTHOR]

Lignin, obtained as a waste product in huge quantities from the large‐scale cellulose processing industries, holds a great potential to be used as sustainable electrode material for large‐scale electroactive energy storage systems. The fixed number of redox‐active phenolic groups present within the lignin structure limits the electrochemical performance and the total energy storage capacity of the lignin‐based electrodes. Herein, the way to enhance the charge storage capacity of lignin by incorporating additional small catechol molecules into the lignin structure is demonstrated. The catechol derivatives are covalently attached to the lignin via aromatic electrophilic substitution reaction. The increased phenolic groups in all functionalized lignin derivatives notably increase the values of capacitance compared to pristine lignin. Further, solvent fractionation of lignin followed by functionalization using catechol boosts three times the charge capacity of lignin electrode. [ABSTRACT FROM AUTHOR]

Extensive study on renewable energy storage has been sparked by the growing worries regarding global warming. In this study, incorporating the latest advancements in microbial electrochemistry and electrochemical CO2 reduction, a super‐fast charging biohybrid battery was introduced by using pure formic acid as an energy carrier. CO2 electrolyser with a slim‐catholyte layer and a solid electrolyte layer was built, which made it possible to use affordable anion exchange membranes and electrocatalysts that are readily accessible. The biohybrid battery only required a 3‐minute charging to accomplish an astounding 25‐hour discharging phase. In the power‐to‐formate‐to‐bioelectricity process, bioconversion played a vital role in restricting both the overall Faradaic efficiency and Energy efficiency. The CO2 electrolyser was able to operate continuously for an impressive total duration of 164 hours under Gas Stand‐By model, by storing N2 gas in the extraction chamber during stand‐by periods. Additionally, the electric signal generated during the discharging phase was utilized for monitoring water biotoxicity. Functional genes related to formate metabolism were identified in the bioanode and electrochemically active bacteria were discovered. On the other hand, Paracoccus was predominantly found in the used air cathode. These results advance our current knowledge of exploiting biohybrid technology. [ABSTRACT FROM AUTHOR]

Lignin, obtained as a waste product in huge quantities from the large‐scale cellulose processing industries, holds a great potential to be used as sustainable electrode material for large‐scale electroactive energy storage systems. The fixed number of redox‐active phenolic groups present within the lignin structure limits the electrochemical performance and the total energy storage capacity of the lignin‐based electrodes. Herein, the way to enhance the charge storage capacity of lignin by incorporating additional small catechol molecules into the lignin structure is demonstrated. The catechol derivatives are covalently attached to the lignin via aromatic electrophilic substitution reaction. The increased phenolic groups in all functionalized lignin derivatives notably increase the values of capacitance compared to pristine lignin. Further, solvent fractionation of lignin followed by functionalization using catechol boosts three times the charge capacity of lignin electrode.

The share of renewable energy in heat and power generation is expected to increase significantly and reach record levels in the coming decades. As a result, emerging energy storage technologies will be key elements in balancing the energy system. To compensate the variability and non-controllability of seasonally generated renewable energy (RES) (daily fluctuations in solar radiation intensity, wind speed, etc.) development of sufficient energy storage infrastructure in the regions will play a major role in transforming RES supply potential into reality. However, local public authorities that are responsible for creating an enabling policy environment for RES infrastructure development in regions encounter numerous challenges and uncertainties in deploying sufficient energy accumulation that often remain unanswered due to a lack of knowledge and on-site capacity, which in turn significantly hinders the regional path to climate neutrality. In this study, the PESLTE analytical framework and composite index methodology is applied to examine the multidimensional factors that influence the deployment of renewable energy storage technologies in municipalities: political, economic, social, legal, technological, and environmental. Developed model is approbated in a case study in a Latvian municipality where four different alternative energy storage technologies are compared: batteries for electricity storage, thermal energy storage, energy storage in a form of hydrogen, and energy storage in a form of biomethane.

The ever-increasing demand for renewable energy storage has led to the development of many energy storage systems, such as redox flow batteries (RFBs), including vanadium, iron–chromium, and the copper redox flow battery (CuRFB). A multitude of materials and electrolytes have been investigated to improve the performance of the CuRFB using an in-house manufactured cell. Using carbon ink coatings for the negative electrode and modern ion exchange membranes (IEMs), this version of the CuRFB was improved to current efficiencies above 95% with high voltage efficiencies of up to 81%, thereby improving energy efficiency by nearly 9% over the previous state of the art at 20 mA cm−2. Additionally, the operating time of the CuRFB was significantly extended over 210 h of operation (50 cycles), 32% of the capacity remaining, without maintenance. Finally, stability of the new system with modern IEMs was proven by operation for over 1200 h operation, with over 300 charge and discharge cycles performed.

Producing green hydrogen from wind energy is one potential method to mitigate curtailment. This study develops a general approach to examine the economic benefit of adding hydrogen production capacity through water electrolysis along with the fuel cell and storage facilities in a wind farm in north Texas. The study also investigates different day ahead market bidding strategies in the existence of these technologies. The results show that adding hydrogen capacity to the wind farm is profitable when hydrogen price is greater than $3.58/kg, and that the optimal day ahead market bidding strategy changes as hydrogen price changes. The results also suggest that both the addition of a fuel cell to reconvert stored hydrogen to electricity and the addition of a battery to smooth the electricity input to the electrolyzer are suboptimal for the system in the case of this study. The profit of a particular bidding scenario is most sensitive to the selling price of hydrogen, and then the input parameters of the electrolyzer. This study also provides policy implications by investigating the impact of different policy schemes on the optimal hydrogen production level. [ABSTRACT FROM AUTHOR]

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Copyright of EMERG: Energy. Environment. Efficiency. Resources. Globalization is the property of Romanian National Committee of World Energy Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The decarbonization of the building stock, in this paper focusing on the single-family house typology in Germany, is essential to achieve the climate goals. In fact, as the largest part of the building stock, it represents more than 65 % of the entire German residential building stock. Current strategies and regulations have demonstrated low impact on carbon emission reduction due to poor renovation rates, particularly in the single-family house typology. The present study analyzes the potential of carbon emission reduction prioritizing local renewable energy generation and storage in combination with improved building energy systems. Through a simulation-based approach, it considers reference buildings of different age classes and formulates variants for improving strategies with different levels of retrofit, under the premise of a fully renewable, locally generated energy supply. Based on the potential for solar energy supply, the variants consider the seasonal shift that needs to be stored and particularly the role of hydrogen as an energy storage medium. The study goal is quantifying the impacts of the local renewable energy production, and its required storage capacity depending on the retrofit depth, for estimating the potential of transforming the single-family house stock to net zero carbon emissions. [ABSTRACT FROM AUTHOR]

The impact of environmental policy stringency on energy efficiency innovation has been studied well without considering renewable energy storage and electrification to meet demand for energy structural transition in China. Based on these past studies, this paper introduces the CGE model to analyze carbon tax stringency via carbon productivity by accounting for the electrification and learning-by-doing effect of renewable energy. Through comparing the performance of the uniform and differentiated carbon tax, it is found that the differentiated carbon tax always has a worse environmental performance in reducing carbon emissions due to less energy efficiency improvement than uniform one. While uniform carbon tax at stricter level gains more economic and environmental benefits on sectoral and overall aspects in long term because of greater improvement on sectoral carbon productivity in energy-intensive industries. Furthermore, these findings at a large level reveal the intricate interaction among carbon tax, sectoral carbon productivity, renewables-related subsidy, electrification, and the learning-by-doing of renewables for accelerating the energy structural transition and simultaneously achieving the coordination between economic growth and environmental protection. • Stringency of carbon tax is analyzed under development of renewable energy storage and electrification. • Sectoral energy efficiency improved by stricter carbon tax directly and indirectly. • Uniform carbon tax gains more economic and environmental benefits in long term. • Differentiated carbon tax achieves more energy structural transition with more energy consumption and carbon emission. • Policy implication is given to evaluate feasibility of differentiated carbon tax in China. [ABSTRACT FROM AUTHOR]

Electrodeposited manganese oxide films are promising catalysts for promoting the oxygen evolution reaction (OER), especially in acidic solutions. The activity of these catalysts is known to be enhanced by the introduction of Mn3+ We present in situ electrochemical and X-ray absorption spectroscopic studies, which reveal that Mn3+ may be introduced into MnO2 by an electrochemically induced comproportionation reaction with Mn2+ and that Mn3+ persists in OER active films. Extended X-ray absorption fine structure (EXAFS) spectra of the Mn3+-activated films indicate a decrease in the Mn-O coordination number, and Raman microspectroscopy reveals the presence of distorted Mn-O environments. Computational studies show that Mn3+ is kinetically trapped in tetrahedral sites and in a fully oxidized structure, consistent with the reduction of coordination number observed in EXAFS. Although in a reduced state, computation shows that Mn3+ states are stabilized relative to those of oxygen and that the highest occupied molecular orbital (HOMO) is thus dominated by oxygen states. Furthermore, the Mn3+(Td) induces local strain on the oxide sublattice as observed in Raman spectra and results in a reduced gap between the HOMO and the lowest unoccupied molecular orbital (LUMO). The confluence of a reduced HOMO-LUMO gap and oxygen-based HOMO results in the facilitation of OER on the application of anodic potentials to the δ-MnO2 polymorph incorporating Mn3+ ions.

Dense ceramic membranes with H+ or O2− conductivity have been widely used for fuel production through electro-hydrogenation/dehydrogenation or electro-oxygenation/deoxygenation. Electrochemical conversion processes demonstrate advantages over conventional redox reaction processes in terms of capital cost, energy savings, process intensification and product selectivity. Intermittent renewable power (e.g., solar and wind power) can be used to drive electrochemical processes so that renewable energy is stored in fuels as energy carriers, including hydrogen, ammonia, syngas, methane and ethylene. This review summarizes the pathways to store renewable energy via ion-conducting membrane reactors and discusses the commercialization progress and prospects of these energy technologies. [ABSTRACT FROM AUTHOR]

• Recent developments in process intensification for the Haber-Bosch process are discussed. • Maintaining its lead in ammonia synthesis, the Haber-Bosch process requires evolution into a less energy-demanding format for decentralized production. • Multifunctional and membrane reactors innovate towards smaller, more efficient systems. • Shifts towards low-temperature, low-pressure synthesis fed with water electrolysis could eliminate the main compressor. • Supported metal halides as a viable alternative for energy-efficient ammonia separation. Ammonia is crucial as it serves as a key nitrogen source in fertilizer production to enhance crop growth and as an emerging energy carrier due to its high hydrogen content and ease of liquefaction. Despite various technological changes proposed and implemented since its inception, the Haber-Bosch process remains the predominant method for ammonia production. We first give a bird's eye view of current ammonia synthesis technologies available based on the latest trends, to justify why we think the conventional Haber-Bosch process is still a relevant technology worth investigation for further improvement. We review the engineering design modifications within the ammonia synthesis loop, examining improvements in the efficiency of ammonia synthesis. This review gives an overview of recent research and advancements focused on process intensification within the loop and its individual key components, i.e., the reactor and the catalyst, separation, and purge gas recovery technologies. It highlights significant progress and explores potential future directions in these areas. [Display omitted] [ABSTRACT FROM AUTHOR]

The combination of solid oxide electrolysis cells (SOECs) with renewable electricity has enormous potential, but this requires the cells to be able to adapt to strong fluctuation conditions. This work directly combines fluctuating actual wind power with flat-tube Ni-YSZ/YSZ/LSCF-GDC SOECs to study the operational stability and energy consumption under wide fluctuation and constant current electrolysis. The results indicate that under an average electrolysis current density of 0.26 A cm−2, there is little difference in stability between fluctuation and constant current electrolysis. At a high current density of 0.58 A cm−2, the cells operating for 375 h under fluctuation conditions exhibit a larger degradation rate. The current density is dynamically switched between 0 and 0.93 A cm−2 to simulate actual wind turbine power fluctuations from 0 to 100 %. After rapid large-scale current switches for 2000 times in 375 h, little change is observed in the cell structure. Under fluctuating electrolysis, the minimum energy consumption for power-to-gas conversion in SOEC is 2.84 kWh/Nm3, while under constant current electrolysis, the lowest energy consumption is 2.67 kWh/Nm3. In summary, SOECs can efficiently and stably consume and store highly fluctuating renewable power and can also dynamically respond to wide power ranges from 0 to 100 %. • 100 % long-term actual wind power storage was simulated using SOEC. • 2000 rapid large-scale switches did not significantly damage the cell. • Energy consumption of 2.84 kWh/Nm3 was obtained in fluctuation steam electrolysis. • Degradation under fluctuation was significantly higher than constant in high current. [ABSTRACT FROM AUTHOR]

[Display omitted] • Propose and evaluate a MeOH-based renewable energy supply chain. • Exporters synthesize MeOH using green H 2 and circulated CO 2 for long-distance transport. • Importers generate power and capture 100% CO 2 in a MeOH-fueled Allam cycle. • Imported renewable electricity can reach 101 $/MWh e in a sustainable future scenario. • CO 2 emission ranges from 97-249 kg/MWh e for onshore wind and solar PV supply chains. This study addresses the challenge of uneven renewable energy distribution by proposing a renewable energy supply chain using MeOH-fueled Allam Cycle for power generation. With the escalating demand for renewable energy, regions with a surplus can produce MeOH using green H 2 and recycled CO 2 , which can then be transported to energy-deficient regions. In these importing regions, MeOH is used for electricity generation via the Allam Cycle, with captured CO 2 recycled for MeOH synthesis, creating a closed-loop carbon system. This study evaluates the energy, economic and environmental aspects of this supply chain. It projects that electricity costs in importing regions could decrease from USD 233.02/MWh impt to USD 101.33/MWh impt , and MeOH costs could drop from USD 585.39/t to USD 173.40/t, assuming a reduction in renewable electricity costs in exporting regions from USD 45/MWh expt to USD 15/MWh expt. Comparative analysis shows acceptable energy conversion and transportation costs, with an electricity conversion rate of 30.65 %-37.07 %. This design offers a promising, cost-effective solution for a sustainable future, with the onshore wind supply chain exhibiting lower emissions of 111.3–97.2 kg/MWh impt. [ABSTRACT FROM AUTHOR]

Cogeneration is preferred mostly in process industries where both thermal and electrical energies are required. Cogeneration plants are more efficient than utilizing the thermal and electrical energies independently. Present government policies in India made renewable energy generation mandatory in order to minimize fossil fuels consumption and to protect the environment. Hence, many cogeneration plants have been integrated with renewable energy generation. However, post-integration effects increase and introduce inefficiencies in the operation of cogeneration systems. In this paper, a case study of an identified typical cogeneration plant where renewable energy is integrated is considered. Post operational effects on the plant due to integration of renewable energy (solar) are studied and by practical experimentation through cost-benefit analysis the break-even point beyond which renewable energy generation introduces inefficiencies is estimated. Next, a systematic methodology is developed based on the heuristic forward-chaining approach technique to establish the breakeven point. An algorithm/flow chart is developed using an iterative method and executed through MATLAB using practical data from the industry. Suggestions for suitable energy storage devices to store renewable energy beyond the breakeven point, based on a techno-economic analysis of energy storage technologies, are made. Further, the battery energy storage system is designed and the capacity is estimated based on the practical solar irradiance data. A rule-based algorithm is developed to control the charge and discharge cycles of battery storage based on predefined conditions. The payback period is estimated based on the expected monetary benefits of proposed energy storage and the economy of the proposed system is ensured. The post-operational issues are resolved by introducing energy storage. The methodology presented in this paper can be a guiding tool for optimization of various renewable-energy-integrated cogeneration systems. [ABSTRACT FROM AUTHOR]

Cost-effective storage remains one of the greatest challenges facing the adoption of renewable energy generation. Herein we present a cost-effective aqueous rechargeable battery based on MoS2. Increased discharge capacities are achieved by liquid-phase exfoliation, resulting in a 105% increase in capacity and prolonged lithiation plateau. Contributing evidence is provided by High Resolution TEM investigation of the expanded van der Waals gap between adjacent MoS2 layers and particle active surface area. Exfoliated MoS2 and a MoS2/graphite composite cathode is also investigated, resulting in an increase of reversible lithiation levels over 3x that of the base exfoliated material. The preservation of discharge capacities and voltages indicates the composite is highly effective in improving reversible lithiation. Further examination of the cost-effectiveness of the composite reveals vastly superior storage-to-cost ratios relative to other ARB cathodes.

Summary: A novel efficient and entirely green hybrid energy conversion system comprising compressed air energy storage and Kalina KCS11 is proposed for peak shaving application and grid stability. The use of high‐temperature thermal energy storage as a replacement for the traditional combustion chamber and a Kalina KCS11 with clean working fluid aims to minimize greenhouse gas emissions while adequately addressing intermittency and electricity curtailment of power grids with high penetration of renewable sources. The proposed system is comprehensively analyzed from the energy, exergy, and economic viewpoints. The thermodynamic simulation results indicate that the air turbine and pressure regulating valve have, respectively, 595.5 and 477.5 kW exergy destruction, accounting for around 40% of total exergy destruction. In addition, employing a KCS11 cycle recovers 57.95% of the heat dissipated in the CAES outlet. Accordingly, the proposed hybrid CAES‐KCS11 system has round trip energetic and exergetic efficiencies of 52.97% and 46.28%, respectively. The economic analysis reveals that along with environmental benefits, it has a reasonable payback time of around 3.69 years. Moreover, a total benefit of 740 000 $ is gained during the service year of the system. The hybrid system is found to be more efficient compared to a stand‐alone high‐temperature hybrid CAES system. [ABSTRACT FROM AUTHOR]

Solid oxide electrolysis cells (SOECs) have received widespread attention due to their high efficiency, greenness and flexibility. SOECs produce value-added chemicals by electrocatalytically reducing CO 2 , which is of great significance for achieving CO 2 reduction and renewable energy storage. This review first comprehensively explains the mechanism of SOEC electrolysis of CO 2 , followed by a detailed introduction to the classification and synthesis strategies of electrolyte, cathode and anode materials, including the microstructure design of electrodes. The reasons for SOEC performance degradation and countermeasures are discussed next. The related economic benefits of SOEC are also introduced. Finally, the challenges and prospects that SOEC needs to face for further technological utilization and commercialization are summarized. [Display omitted] • The mechanism of CO 2 electrolysis of SOEC is explained. • Critical materials and synthesis strategies are described in detail. • Degradation mechanisms and corresponding preventive measures are described. • The challenges and development prospects of SOEC are presented. [ABSTRACT FROM AUTHOR]

A noteworthy component in upgrading renewable energy conversion and storage device is the development of oxygen reduction reaction (ORR) electrocatalysts. Although micropore active sites sustain high ORR activity, meso-micropores play a crucial role in enhancing single-cell performance. Our breakthrough is that we prepared 0.2 mg cm−2 of AgCo–MoS 2 /rGO (abbreviated as ACMSr) electrocatalyst as the cathode catalyst loading and 0.2 mg cm−2 of Pt/C as the anode catalyst loading in the fuel cell test, and as a result, achieved peak power density and maximum current density of 221 mW cm−2 and 525.41 mA cm−2, respectively. Various parameters, such as relative humidity, operating temperature, amount of injected oxygen, and back pressure, affect the performance of the fuel cell. A decrease in the humidity of the cathode negatively impacts the performance of the fuel cell. At temperatures of 65–75 °C, the fuel cell's performance increased at various temperatures. The performance of the fuel cell is directly affected by the rate of injected oxygen through the amount of gas flow and indirectly by the flooding effect in the cathode and membrane humidity. These achieved data provide a suitable approach for the design and modeling of fuel cells. [Display omitted] • The nanocomposite is made through ethylene glycol reduction method. • ACMSr exhibits the half-wave potential of −0.115 V vs. Ag/AgCl. • The diffusion current density (5.91 mA cm−2) is observed for ACMSr. • ACMSr has only a negative shift of 2 mV in stability test after 3000 cycles. • The maximum power density and current density is 221 mW cm−2, and 525.41 mA cm−2 [ABSTRACT FROM AUTHOR]

The use of off-shore renewable energy sources can be an adequate strategy to produce hydrogen using water electrolysis, particularly in the marine sector. However, the marine atmospheric conditions are very hostile and corrosive, which can affect the materials of an electrolyzer. Among the different electrolysis technologies, alkaline water electrolysis is optimal for large scale hydrogen production because it is an economic and mature technology. In an alkaline electrolysis cell, the electrodes and the separator are the most critical elements to be analyzed under marine atmospheric conditions due to their great influence on the overpotentials and the efficiency. The present research aims to advance in the study of these effects in order to analyze the influence of marine conditions on the performance of an electrolyzer. For this purpose, the components of an alkaline electrolysis cell have been exposed to a salt spray test. According to the results obtained the materials do not show any morphological or compositional change after the salt spray test. This also happens with the polarization curve and the hydrogen production efficiency. So, alkaline water electrolysis technology can be adequate to work under the environmental conditions that take place in off-shore applications.

In this work, we have performed density functional theory-based calculations to study the adsorption of H 2 molecules on germanene decorated with alkali atoms (AM) and transition metal atoms (TM). The cohesive energy indicates that interaction between AM (TM) atoms and germanene is strong. The values of the adsorption energies of H 2 molecules on the AM or TM atoms are in the range physisorption. The K-decorated germanene has the largest storage capacity, being able to bind up to six H 2 molecules, whereas the Au and Na atoms adsorbed five and four H 2 molecules, respectively. Li and Ag atoms can bind a maximum of three H 2 molecules, while Cu-decorated germanene only adsorbed one H 2 molecule. Formation energies show that all the studied cases of H 2 molecules adsorbed on AM and TM atom-decorated germanene are energetically favorable. These results indicate that decorated germanene can serve as a hydrogen storage system. [Display omitted] • The Li, Na and K atoms are binding strongest to germanene and avoid clustering. • Na functionalized germanene have the largest storage capacity, 6H 2 -molecules. • Cu functionalized germanene is not a good candidate for hydrogen storage. • Hydrogen molecules are physisorbed on metal atoms functionalized germanene. • H 2 -AM(TM)-germanene complexes are energetically more stable than H 2 -germanene. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the environmental impact of storage systems integrated with energy plants powered by renewable sources. Stationary storage systems proved to be a valid solution for regulating networks, supporting frequency, and managing peaks in electricity supply and demand. Recently, their coupling with renewable energy sources has been considered a strategic means of exploiting their high potential since it permits them to overcome their intrinsic uncertainty. Therefore, the storage systems integration with distributed generation can improve the performance of the networks and decrease the costs associated with energy production. However, a question remains regarding the overall environmental sustainability of the final energy production. Focusing on electrochemical accumulators, the problems mainly concern the use of heavy metals and/or impacting chemical components of storage at the center of environmental hazard debates. In this paper, an environmental assessment from a life-cycle perspective of the hybrid energy systems powered by fossil and renewable sources located on two non-interconnected minor islands is presented. Existing configurations are compared with new ones obtained with the addition of batteries for the exploitation of renewable energy. The results show that, for batteries, the assembly phase, including raw material extraction, transport, and assembly, accounts for about 40% of the total, while the remaining part is related to end-of-life processes. The reuse and recycling of the materials have a positive effect on overall impacts. The results also show that the overall impact is strongly related to the actual energy mix of the place where batteries are installed, even if it is usually lower than that of the solution without the batteries. The importance of a proper definition of the functional unit in the analysis is also emphasized in this work. [ABSTRACT FROM AUTHOR]

The Geothermal Battery Energy Storage concept (GB) has been proposed as a large-scale renewable energy storage method. This is particularly important as solar and wind power are being introduced into electric grids, and economical utility-scale storage has not yet become available to handle the variable nature of solar and wind. The Geothermal Battery Energy Storage concept uses solar radiance to heat water on the surface which is then injected into the earth. This hot water creates a high temperature geothermal reservoir acceptable for conventional geothermal electricity production, or for direct heat applications. Storing hot water underground is not new, the unique feature of the GB is its application to sedimentary basins with formations that are water saturated and exhibit high porosity and high permeability. For certain reservoirs like these, calculations suggest that nearly 100% of the stored heat can practically be recovered, and long-term, even seasonal storage is possible. Several publications presented by the authors on the GB, parametrically identified desirable reservoir characteristics [14,17,18]. This is a review of those calculations and the inferred conclusions for a viable GB system. Potential GB system well configurations, injection and production scenarios and ultimate heat recovery for economic value are also noted. Image 1 • A concept to store large amounts of renewable energy daily to seasonally. • Reservoir characteristics for a geothermal battery system. • The conversion of solar or wind to geothermal electricity. • Subsurface sedimentary basin formations for large-scale hot water storage. • Solar heat collection to create a high-temperature geothermal reservoir. [ABSTRACT FROM AUTHOR]