China, People’s Republic
Operational Optimization of Regional Integrated Energy Systems with Heat Pumps and Hydrogen Renewable Energy under Integrated Demand Response
Jan 2024
Publication
A regional integrated energy system (RIES) synergizing multiple energy forms is pivotal for enhancing renewable energy use and mitigating the greenhouse effect. Considering that the equipment of the current regional comprehensive energy system is relatively simple there is a coupling relationship linking power generation refrigeration and heating in the cogeneration system which is complex and cannot directly meet various load demands. This article proposes a RIES optimization model for bottom-source heat pumps and hydrogen storage systems in the context of comprehensive demand response. First P2G electric hydrogen production technology was introduced into RIES to give full play to the high efficiency advantages of hydrogen energy storage system and the adjustable thermoelectric ratio of the HFC was considered. The HFC could adjust its own thermoelectric ratio according to the system load and unit output. Second through the groundsource heat pump’s cleaning efficiency function further separation and cooling could be achieved. The heat and electrical output of RIES improved the operating efficiency of the system. Thirdly a comprehensive demand response model for heating cooling and electricity was established to enable users to reasonably adjust their own energy use strategies to promote the rational distribution of energy in the system. The model integrates power-to-gas (P2G) technology leveraging the tunable thermoelectric ratio of a hydrogen fuel cell (HFC) to optimize the generation of electricity and heat while maximizing the efficiency of the hydrogen storage system. Empirical analysis substantiated the proposed RIES model’s effectiveness and economic benefits when integrating ground-source HP and electric hydrogen production with IDR. Compared with the original model the daily operating cost of the proposed model was reduced by RMB 1884.16.
Optimal Scheduling of Power Systems with High Proportions of Renewable Energy Accounting for Operational Flexibility
Jul 2023
Publication
Yi Lin,
Wei Lin,
Wei Wu and
Zhenshan Zhu
The volatility and uncertainty of high-penetration renewable energy pose significant challenges to the stability of the power system. Current research often fails to consider the insufficient system flexibility during real-time scheduling. To address this issue this paper proposes a flexibility scheduling method for high-penetration renewable energy power systems that considers flexibility index constraints. Firstly a quantification method for flexibility resources and demands is introduced. Then considering the constraint of the flexibility margin index optimization scheduling strategies for different time scales including day-ahead scheduling and intra-day scheduling are developed with the objective of minimizing total operational costs. The intra-day optimization is divided into 15 min and 1 min time scales to meet the flexibility requirements of different time scales in the power system. Finally through simulation studies the proposed strategy is validated to enhance the system’s flexibility and economic performance. The daily operating costs are reduced by 3.1% and the wind curtailment rate is reduced by 4.7%. The proposed strategy not only considers the economic efficiency of day-ahead scheduling but also ensures a sufficient margin to cope with the uncertainty of intra-day renewable energy fluctuations.
Capacity Configuration Optimization for Green Hydrogen Generation by Solar-wind Hybrid Power Based on Comprehensive Performance Criteria
Aug 2023
Publication
Green hydrogen generation driven by solar-wind hybrid power is a key strategy for obtaining the low-carbon energy while by considering the fluctuation natures of solar-wind energy resource the system capacity configuration of power generation hydrogen production and essential storage devices need to be comprehensively optimized. In this work a solar-wind hybrid green hydrogen production system is developed by combining the hydrogen storage equipment with the power grid the coordinated operation strategy of solar-wind hybrid hydrogen production is proposed furthermore the NSGA-III algorithm is used to optimize the system capacity configuration with the comprehensive performance criteria of economy environment and energy efficiency. Through the implemented case study with the hydrogen production capacity of 20000 tons/year the abandoned energy power rate will be reduced to 3.32% with the electrolytic cell average load factor of 64.77% and the system achieves the remarkable carbon emission reduction. In addition with the advantage of connect to the power grid the generated surplus solar/wind power can be readily transmitted with addition income when the sale price of produced hydrogen is suggested to 27.80 CNY/kgH2 the internal rate of return of the system reaches to 8% which present the reasonable economic potential. The research provides technical and methodological suggestions and guidance for the development of solar-wind hybrid hydrogen production schemes with favorable comprehensive performance.
An Overview of Application-orientated Multifunctional Large-scale Stationary Battery and Hydrogen Hybrid Energy Storage System
Dec 2023
Publication
The imperative to address traditional energy crises and environmental concerns has accelerated the need for energy structure transformation. However the variable nature of renewable energy poses challenges in meeting complex practical energy requirements. To address this issue the construction of a multifunctional large-scale stationary energy storage system is considered an effective solution. This paper critically examines the battery and hydrogen hybrid energy storage systems. Both technologies face limitations hindering them from fully meeting future energy storage needs such as large storage capacity in limited space frequent storage with rapid response and continuous storage without loss. Batteries with their rapid response (90%) excel in frequent short-duration energy storage. However limitations such as a selfdischarge rate (>1%) and capacity loss (~20%) restrict their use for long-duration energy storage. Hydrogen as a potential energy carrier is suitable for large-scale long-duration energy storage due to its high energy density steady state and low loss. Nevertheless it is less efficient for frequent energy storage due to its low storage efficiency (~50%). Ongoing research suggests that a battery and hydrogen hybrid energy storage system could combine the strengths of both technologies to meet the growing demand for large-scale long-duration energy storage. To assess their applied potentials this paper provides a detailed analysis of the research status of both energy storage technologies using proposed key performance indices. Additionally application-oriented future directions and challenges of the battery and hydrogen hybrid energy storage system are outlined from multiple perspectives offering guidance for the development of advanced energy storage systems.
Review on the Thermal Neutrality of Application-orientated Liquid Organic Hydrogen Carrier for Hydrogen Energy Storage and Delivery
Aug 2023
Publication
The depletion and overuse of fossil fuels present formidable challenge to energy supply system and environment. The human society is in great need of clean renewable and sustainable energy which can guarantee the long-term utilization without leading to escalation of greenhouse effect. Hydrogen as an extraordinary secondary energy is capable of realizing the target of environmental protection and transferring the intermittent primary energy to the application terminal while its nature of low volumetric energy density and volatility need suitable storage method and proper carrier. In this context liquid organic hydrogen carrier (LOHC) among a series of storage methods such as compressed and liquefied hydrogen provokes a considerable amount of research interest since it is proven to be a suitable carrier for hydrogen with safety and stability. However the dehydrogenation of hydrogen-rich LOHC materials is an endothermic process and needs large energy consumption which hampers the scale up of the LOHC system. The heat issue is thus essential to be addressed for fulfilling the potential of LOHC. In this work several strategies of heat intensification and management for LOHC system including the microwave irradiation circulation of exhaust heat and direct LOHC fuel cell are summarized and analyzed to provide suggestions and directions for future research.
Experimental Study on the Self-ignition of Pressurized Hydrogen Released into Three-way Tubes
Sep 2021
Publication
To explore the effect of bifurcation structures on the spontaneous ignition and shock wave result from the sudden release of pressurized hydrogen. Three-way tubes with different bifurcation angles (90° 120° 150°) were used in the experiments. They are two Y-shape tubes and one T-shape tube. The photoelectric and pressure signals in the tube were recorded by the sensor. The results show that the reflected shock wave will be formed at the bifurcation. In addition the intensity and velocity of the leading shock wave will attenuate sharply when it passes through the bifurcation.The smaller bifurcation angle of tubethe smaller overpressure decay rate of shock wave at bifurcation position.The smaller the bifurcation angle of tubes the weaker the reflected shock wave transmitted downstream and the greater attenuation of shock wave intensity. Experimental results have reference value for the safety of hydrogen storage at high-pressure and are helpful to understand the influence of different tube structures on spontaneous ignition when hydrogen is transported at high pressure.
Knock Mitigation and Power Enhancement of Hydrogen Spark-Ignition Engine through Ammonia Blending
Jun 2023
Publication
Hydrogen and ammonia are primary carbon-free fuels that have massive production potential. In regard to their flame properties these two fuels largely represent the two extremes among all fuels. The extremely fast flame speed of hydrogen can lead to an easy deflagration-to-detonation transition and cause detonation-type engine knock that limits the global equivalence ratio and consequently the engine power. The very low flame speed and reactivity of ammonia can lead to a low heat release rate and cause difficulty in ignition and ammonia slip. Adding ammonia into hydrogen can effectively modulate flame speed and hence the heat release rate which in turn mitigates engine knock and retains the zero-carbon nature of the system. However a key issue that remains unclear is the blending ratio of NH3 that provides the desired heat release rate emission level and engine power. In the present work a 3D computational combustion study is conducted to search for the optimal hydrogen/ammonia mixture that is knock-free and meanwhile allows sufficient power in a typical spark-ignition engine configuration. Parametric studies with varying global equivalence ratios and hydrogen/ammonia blends are conducted. The results show that with added ammonia engine knock can be avoided even under stoichiometric operating conditions. Due to the increased global equivalence ratio and added ammonia the energy content of trapped charge as well as work output per cycle is increased. About 90% of the work output of a pure gasoline engine under the same conditions can be reached by hydrogen/ammonia blends. The work shows great potential of blended fuel or hydrogen/ammonia dual fuel in high-speed SI engines.
Research Progress on Corrosion and Hydrogen Embrittlement in Hydrogen-Natural Gas Pipeline Transportation
Jun 2023
Publication
Hydrogen clean efficient and zero-carbon is seen as a most promising energy source. The use of existing gas pipelines for hydrogenenatural gas transportation is considered to be an effective way to achieve long-distance large-scale efficient and economical hydrogen transportation. However the pipelines for hydrogenenatural gas transportation contain lots of impurities (e.g. CH4 high-pressure H2 H2S and CO2) and free water which will inevitably lead to corrosion and hydrogen embrittlement. This paper presents a systematic review of research and an outlook for corrosion and hydrogen embrittlement in hydrogenenatural gas pipeline transportation. The results show that gasphase hydrogen charging is suitable for hydrogenenatural gas transportation but this technique lacks technical standards. By contrast the liquid-phase hydrogen charging technique is more mature but has large deviation from the engineering reality. In the hydrogenenatural gas transportation pipelines corrosion and hydrogen embrittlement are synergetic and competitive but the failure mechanism and change law when corrosion and hydrogen embrittlement coexist remain unclear which need to be further clarified by experiments. The failure mechanism is believed to be mainly sensitive to three key factors i.e. the H2S/CO2 partial pressure ratio the hydrogen blending ratio and material strength. The increase of the three factors will make the pipeline materials more corrosive and more sensitive to hydrogen embrittlement. The research findings can be used as a reference for research and development of long-distance hydrogenenatural gas transportation technology and will drive the high-quality development of the hydrogenenatural gas blending industry.
Low Carbon Optimal Operation of Integrated Energy Systems Considering Air Pollution Emissions
Apr 2023
Publication
To reduce carbon sulfur dioxide (SO2) and nitrogen oxide (NOX) emissions from the integrated energy system (IES) a low carbon optimization strategy for the IES is proposed taking into account carbon SO2 and NOX emissions. Firstly hydrogen production storage and use equipment such as methane reactor electrolysis tank hydrogen fuel cell and hydrogen energy storage are added to the traditional IES to build a multi-energy complementary system of electricity gas cooling thermal and hydrogen. Then this paper introduces a stepped carbon trading mechanism and the model of the emissions of SO2 and NOX. Finally to further reduce its pollutant emissions the model of combined heat and power units and hydrogen fuel cells with adjustable thermoelectric ratio is built. To compare and account for the impact of air pollutant emissions on the optimal low-carbon operation of IES this paper construsted three scenarios with the lowest cost of carbon trading the lowest penalty cost for SO2 and NOX emissions and total operation cost as objective functions respectively The results show that the strategy is effective in reducing air pollutant emissions from integrated energy systems and the outputs of CHP and HFC with adjustable thermoelectric ratios are more flexible and can effectively achieve carbon reduction and pollutant emission reduction.
Operating Characteristics Analysis and Capacity Configuration Optimization of Wind-Solar-Hydrogen Hybrid Multi-energy Complementary System
Dec 2023
Publication
Wind and solar energy are the important renewable energy sources while their inherent natures of random and intermittent also exert negative effect on the electrical grid connection. As one of multiple energy complementary route by adopting the electrolysis technology the wind-solar-hydrogen hybrid system contributes to improving green power utilization and reducing its fluctuation. Therefore the moving average method and the hybrid energy storage module are proposed which can smooth the wind-solar power generation and enhance the system energy management. Moreover the optimization of system capacity configuration and the sensitive analysis are implemented by the MATLAB program platform. The results indicate that the 10-min grid-connected volatility is reduced by 38.7% based on the smoothing strategy and the internal investment return rate can reach 13.67% when the electricity price is 0.04 $/kWh. In addition the annual coordinated power and cycle proportion of the hybrid energy storage module are 80.5% and 90% respectively. The developed hybrid energy storage module can well meet the annual coordination requirements and has lower levelized cost of electricity. This method provides reasonable reference for designing and optimizing the wind-solar-hydrogen complementary system.
Operation Optimization of Wind/Battery Storage/Alkaline Electrolyzer System Considering Dynamic Hydrogen Production Efficiency
Aug 2023
Publication
Hydrogen energy is regarded as a key path to combat climate change and promote sustainable economic and social development. The fluctuation of renewable energy leads to frequent start/stop cycles in hydrogen electrolysis equipment. However electrochemical energy storage with its fast response characteristics helps regulate the power of hydrogen electrolysis enabling smooth operation. In this study a multi-objective constrained operation optimization model for a wind/battery storage/alkaline electrolyzer system is constructed. Both profit maximization and power abandonment rate minimization are considered. In addition some constraints such as minimum start/stop times upper and lower power limits and input fluctuation limits are also taken into account. Then the non-dominated sorting genetic algorithm II (NSGA-II) algorithm and the entropy method are used to optimize the operation strategy of the hybrid energy system by considering dynamic hydrogen production efficiency and through optimization to obtain the best hydrogen production power of the system under the two objectives. The change in dynamic hydrogen production efficiency is mainly related to the change in electrolyzer power and the system can be better adjusted according to the actual supply of renewable energy to avoid the waste of renewable energy. Our results show that the distribution of Pareto solutions is uniform which indicates the suitability of the NSGA-II algorithm. In addition the optimal solution indicates that the battery storage and alkaline electrolyzer can complement each other in operation and achieve the absorption of wind power. The dynamic hydrogen production efficiency can make the electrolyzer operate more efficiently which paves the way for system optimization. A sensitivity analysis reveals that the profit is sensitive to the price of hydrogen energy.
Optimized Scheduling of Integrated Energy Systems Accounting for Hydrogen Energy Multi-Utilization Models
Jan 2024
Publication
To cope with the growing penetration rate of renewable energy and to enhance the absorption capacity of wind power this paper investigates the applications of an Integrated Energy System (IES) Hydrogen Compressed Natural Gas (HCNG) and power-to-hydrogen (P2H) devices within the IES. It employs power-to-gas and gas blending with hydrogen to construct an efficient electricity–gas–electricity energy flow loop establishing a Natural Gas–Electricity Coupling System (NGECS) model. On this basis a coordinated scheduling method for gas–electric coupling systems using gas blended with hydrogen is proposed. A carbon trading mechanism is introduced to constrain carbon emissions further reducing the system’s carbon footprint. Multiple scenarios are set up for a comparative analysis in order to validate the effectiveness of the proposed model. This study also analyzes the impact of different hydrogen blending ratios and methods on the low-carbon and economic performance of IES.
PEM Water Electrolysis for Hydrogen Production: Fundamentals, Advances, and Prospects
Jun 2022
Publication
Hydrogen as a clean energy carrier is of great potential to be an alternative fuel in the future. Proton exchange membrane (PEM) water electrolysis is hailed as the most desired technology for high purity hydrogen production and self-consistent with volatility of renewable energies has ignited much attention in the past decades based on the high current density greater energy efficiency small mass-volume characteristic easy handling and maintenance. To date substantial efforts have been devoted to the development of advanced electrocatalysts to improve electrolytic efficiency and reduce the cost of PEM electrolyser. In this review we firstly compare the alkaline water electrolysis (AWE) solid oxide electrolysis (SOE) and PEM water electrolysis and highlight the advantages of PEM water electrolysis. Furthermore we summarize the recent progress in PEM water electrolysis including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts in the acidic electrolyte. We also introduce other PEM cell components (including membrane electrode assembly current collector and bipolar plate). Finally the current challenges and an outlook for the future development of PEM water electrolysis technology for application in future hydrogen production are provided.
Numerical Simulation of Hydrogen–Coal Blending Combustion in a 660 MW Tangential Boiler
Feb 2024
Publication
With the adjustment of energy structure the utilization of hydrogen energy has been widely attended. China’s carbon neutrality targets make it urgent to change traditional coal-fired power generation. The paper investigates the combustion of pulverized coal blended with hydrogen to reduce carbon emissions. In terms of calorific value the pulverized coal combustion with hydrogen at 1% 5% and 10% blending ratios is investigated. The results show that there is a significant reduction in CO2 concentration after hydrogen blending. The CO2 concentration (mole fraction) decreased from 15.6% to 13.6% for the 10% hydrogen blending condition compared to the non-hydrogen blending condition. The rapid combustion of hydrogen produces large amounts of heat in a short period which helps the ignition of pulverized coal. However as the proportion of hydrogen blending increases the production of large amounts of H2O gives an overall lower temperature. On the other hand the temperature distribution is more uniform. The concentrations of O2 and CO in the upper part of the furnace increased. The current air distribution pattern cannot satisfy the adequate combustion of the fuel after hydrogen blending.
Towards a Future Hydrogen Supply Chain: A Review of Technologies and Challenges
Feb 2024
Publication
The overuse of fossil fuels has caused a serious energy crisis and environmental pollution. Due to these challenges the search for alternative energy sources that can replace fossil fuels is necessary. Hydrogen is a widely acknowledged future energy carrier because of its nonpolluting properties and high energy density. To realize a hydrogen economy in the future it is essential to construct a comprehensive hydrogen supply chain that can make hydrogen a key energy carrier. This paper reviews the various technologies involved in the hydrogen supply chain encompassing hydrogen production storage transportation and utilization technologies. Then the challenges of constructing a hydrogen supply chain are discussed from techno-economic social and policy perspectives and prospects for the future development of a hydrogen supply chain are presented in light of these challenges.
China and Italy’s Energy Development Trajectories: Current Landscapes and Future Cooperation Potential
Feb 2024
Publication
In order to achieve the ambitious goal of “carbon neutrality” countries around the world are striving to develop clean energy. Against this background this paper takes China and Italy as representatives of developing and developed countries to summarize the energy structure composition and development overview of the two countries. The paper analyzes the serious challenges facing the future energy development of both countries and investigates the possibilities of energy cooperation between the two countries taking into account their respective advantages in energy development. By comparing the policies issued by the two governments to encourage clean energy development this paper analyzes the severe challenges faced by the two countries’ energy development in the future and combines their respective energy development advantages to look forward to the possibility of energy cooperation between the two countries in the future. This lays the foundation for China and Italy to build an “Energy Road” after the “Silk Road”.
A Bibliometric Study on the Research Trends and Hotspots of Proton Exchange Membrane Electrolyzer
Jan 2024
Publication
The application of hydrogen energy produced by proton exchange membrane electrolyzer (PEMEC) is conducive to the solution of the greenhouse effect and the energy crisis. In order to understand the development trends and research hotspot of PEMEC in recent years a total of 1874 research articles related to this field from 2003 to 2023 were obtained from the Web of Science Core Collection (WoS CC) database. The visualization software VOSviewer is used for bibliometric analysis and the research progress hotspots and trends in the PEMEC field are summarized. It was found that in the past two decades literature in the PEMEC field has shown a trend of stable increase at first and then rapidly increasing. And it is in a stage of rapid growth after 2021.Renewable Energy previously published research articles related to PEMEC with the highest frequency of citations. There are a total of 6128 researchers in this field but core authors only account for 4.5% of the total. Although China entered this field later than the United States and Canada it has the largest number of research articles. The research results provide a comprehensive overview of various aspects in the PEMEC field which is beneficial for researchers to grasp the development hotspots of PEMEC.
Identification of Hydrogen-Energy-Related Emerging Technologies Based on Text Mining
Dec 2023
Publication
As a versatile energy carrier hydrogen possesses tremendous potential to reduce greenhouse emissions and promote energy transition. Global interest in producing hydrogen from renewable energy sources and transporting storing and utilizing hydrogen is rising rapidly. However the high costs of producing clean hydrogen and the uncertain application scenarios for hydrogen energy result in its relatively limited utilization worldwide. It is necessary to find new promising technological paths to drive the development of hydrogen energy. As part of technological innovation emerging technologies have vital features such as prominent impact novelty relatively fast growth etc. Identifying emerging hydrogen-energy-related technologies is important for discovering innovation opportunities during the energy transition. Existing research lacks analysis of the characteristics of emerging technologies. Thus this paper proposes a method combining the latent Dirichlet allocation topic model and hydrogen-energy expert group decision-making. This is used to identify emerging hydrogen-related technology regarding two features of emerging technologies novelty and prominent impact. After data processing topic modeling and analysis the patent dataset was divided into twenty topics. Six emerging topics possess novelty and prominent impact among twenty topics. The results show that the current hotspots aim to promote the application of hydrogen energy by improving the performance of production catalysts overcoming the wide power fluctuations and large-scale instability of renewable energy power generation and developing advanced hydrogen safety technologies. This method efficiently identifies emerging technologies from patents and studies their development trends. It fills a gap in the research on emerging technologies in hydrogen-related energy. Research achievements could support the selection of technology pathways during the low-carbon energy transition.
Optimal Scheduling of an Electric-Hydrogen-Integrated Energy System Considering Virtual Energy Storage
Jan 2024
Publication
In this paper a two-layer optimization approach is proposed to facilitate the multi-energy complementarity and coupling and optimize the system configuration in an electric-hydrogen-integrated energy system (EH-IES). Firstly an EH-IES with virtual energy storage is proposed to reduce the cost of physical energy storage equipment. Secondly a two-layer optimal allocation method is proposed under a multi-timescale strategy to examine the comprehensive evaluation index of environmental protection and economy. The upper layer utilizes the NSGA-II multi-objective optimization method for system capacity allocation while the lower layer performs economic dispatch at the lowest cost. Ultimately the output includes the results of the equipment capacity allocation of the EH-IES that satisfies the reliability constraint interval and the daily scheduling results of the equipment. The results demonstrate that the electric-hydrogen-integrated energy system with the coupling of multiple energy equipment not only enhances the utilization of renewable energy sources but also reduces the usage of fossil energy and improves the system’s reliability.
Current Status and Economic Analysis of Green Hydrogen Energy Industry Chain
Feb 2024
Publication
Under the background of the power system profoundly reforming hydrogen energy from renewable energy as an important carrier for constructing a clean low-carbon safe and efficient energy system is a necessary way to realize the objectives of carbon peaking and carbon neutrality. As a strategic energy source hydrogen plays a significant role in accelerating the clean energy transition and promoting renewable energy. However the cost and technology are the two main constraints to green hydrogen energy development. Herein the technological development status and economy of the whole industrial chain for green hydrogen energy “production-storage-transportation-use” are discussed and reviewed. After analysis the electricity price and equipment cost are key factors to limiting the development of alkaline and proton exchange membrane hydrogen production technology; the quantity scale and distance of transportation are key to controlling the costs of hydrogen storage and transportation. The application of hydrogen energy is mainly concentrated in the traditional industries. With the gradual upgrading and progress of the top-level design and technology the application of hydrogen energy mainly including traffic transportation industrial engineering energy storage power to gas and microgrid will show a diversified development trend. And the bottleneck problems and development trends of the hydrogen energy industry chain are also summarized and viewed.
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