Oxygen vacancies enable modulating surface reconstruction of transition metal oxides containing metal-oxygen polyhedrons into metallic oxyhydroxide for oxygen evolution reaction(OER),while revealing reconstructing mec...Oxygen vacancies enable modulating surface reconstruction of transition metal oxides containing metal-oxygen polyhedrons into metallic oxyhydroxide for oxygen evolution reaction(OER),while revealing reconstructing mechanism is stuck by the requirement to precisely control exact sites of these vacancies.Herein,oxygen vacancies are localized only within MoO_(4)tetrahedrons rather than CoO_(6)octahedrons in CoMoO_(4)catalyst,guaranteeing coherent reconstruction of CoO_(6)octahedrons into pure CoOOH with tunable activities for OER.Meanwhile,distorted tetrahedron accelerates the dissolution of Mo atoms into alkaline electrolyte,triggering spontaneous transition of partial CoMoO_(4)into Co(OH)_(2).CoO_(6)octahedrons in both CoMoO_(4)and Co(OH)_(2)can transform pure CoOOH completely at lower potential,resulting in excess intrinsic activity whose summit is identified by overpotential at 10 mA cm^(-2)with 22.9%reduction and Tafel slope with 65.3%reduction.Well-defined manipulation over the distorted polyhedrons offers one versatile knob to precisely modulate electronic structure of oxide catalysts with outstanding OER performance.展开更多
Water electrolysis at high current density(1000 mA cm-2 level)with excellent durability especially in neutral electrolyte is the pivotal issue for green hydrogen from experiment to industrialization.In addition to the...Water electrolysis at high current density(1000 mA cm-2 level)with excellent durability especially in neutral electrolyte is the pivotal issue for green hydrogen from experiment to industrialization.In addition to the high intrinsic activity determined by the electronic structure,electrocatalysts are also required to be capable of fast mass transfer(electrolyte recharge and bubble overflow)and high mechanical stability.Herein,the 2D CoOOH sheet-encapsulated Ni2P into tubular arrays electrocatalytic system was proposed and realized 1000 mA cm-2-levelcurrent-density hydrogen evolution over 100 h in neutral water.In designed catalysts,2D stack structure as an adaptive material can buffer the shock of electrolyte convection,hydrogen bubble rupture,and evolution through the release of stress,which insure the long cycle stability.Meanwhile,the rich porosity between stacked units contributed the good infiltration of electrolyte and slippage of hydrogen bubbles,guaranteeing electrolyte fast recharge and bubble evolution at the high-current catalysis.Beyond that,the electron structure modulation induced by interfacial charge transfer is also beneficial to enhance the intrinsic activity.Profoundly,the multiscale coordinated regulation will provide a guide to design high-efficiency industrial electrocatalysts.展开更多
Objective Evidence on potential cardiovascular benefits of personal-level intervention among the elderly exposed to high levels of particulate matter(PM)remains limited.We aimed to assess improvements in surrogate mar...Objective Evidence on potential cardiovascular benefits of personal-level intervention among the elderly exposed to high levels of particulate matter(PM)remains limited.We aimed to assess improvements in surrogate markers of cardiovascular injury in vulnerable populations at risks by using indoor air filtration units.Methods We conducted a randomized crossover trial for 2 separate 2-week air filtration interventions in 20 households of patients with stable chronic obstructive pulmonary disease and their partners in the winter of 2013,with concurrent measurements of indoor PM.The changes in biomarkers indicative of cardiac injury,atherosclerosis progression and systemic inflammation following intervention were evaluated using linear mixed-effect models.Results In the analysis,average levels of indoor PM with aerodynamic diameters<2.5µm(PM2.5)decreased significantly by 59.2%(from 59.6 to 24.3µg/m3,P<0.001)during the active air filtration.The reduction was accompanied by improvements in levels of high-sensitivity cardiac troponin I by−84.6%(95%confidence interval[CI]:−90.7 to−78.6),growth differentiation factor-15 by−48.1%(95%CI:−31.2 to−25.6),osteoprotegerin by−65.4%(95%CI:−56.5 to−18.7),interleukin-4 by−46.6%(95%CI:−62.3 to−31.0)and myeloperoxidase by−60.3%(95%CI:−83.7 to−3.0),respectively.Conclusion Indoor air filtration intervention may provide potential cardiovascular benefits in vulnerable populations at risks.展开更多
Base station(BS)backup batteries(BSBBs),with their dispatchable capacity,are potential demand-side resources for future power systems.To enhance the power supply reliability and post-contingency frequency security of ...Base station(BS)backup batteries(BSBBs),with their dispatchable capacity,are potential demand-side resources for future power systems.To enhance the power supply reliability and post-contingency frequency security of power systems,we propose a two-stage stochastic unit commitment(UC)model incorporating operational reserve and post-contingency frequency support provisions from massive BSBBs in cellular networks,in which the minimum backup energy demand is considered to ensure BS power supply reliability.The energy,operational reserve,and frequency support ancillary services are co-optimized to handle the power balance and post-contingency frequency security in both forecasted and stochastic variable renewable energy(VRE)scenarios.Furthermore,we propose a dedicated and scalable distributed optimization framework to enable autonomous optimizations for both dispatching center(DC)and BSBBs.The BS model parameters are stored and processed locally,while only the values of BS decision variables are required to upload to DC under the proposed distributed optimization framework,which safeguards BS privacy effectively.Case studies on a modified IEEE 14-bus system demonstrate the effectiveness of the proposed method in promoting VRE accommodation,ensuring post-contingency frequency security,enhancing operational economics,and fully utilizing BSBBs'energy and power capacity.Besides,the proposed distributed optimization framework has been validated to converge to a feasible solution with near-optimal performance within limited iterations.Additionally,numerical results on the Guangdong 500 kV provincial power system in China verify the scalability and practicality of the proposed distributed optimization framework.展开更多
Fossil fuel depletion and environmental pollution problems promote development of renewable energy(RE)glob-ally.With increasing penetration of RE,operation security and economy of power systems(PS)are greatly impacted...Fossil fuel depletion and environmental pollution problems promote development of renewable energy(RE)glob-ally.With increasing penetration of RE,operation security and economy of power systems(PS)are greatly impacted by fluctuation and intermittence of renewable power.In this paper,information gap decision theory(IGDT)is adapted to handle uncertainty of wind power generation.Based on conventional IGDT method,linear regulation strategy(LRS)and robust linear optimization(RLO)method are integrated to reformulate the model for rigorously considering security constraints.Then a robustness assessment method based on hybrid RLO-IGDT approach is proposed for analyzing robustness and economic performance of PS.Moreover,a risk-averse linearization method is adapted to convert the proposed assessment model into a mixed integer linear programming(MILP)problem for convenient optimization without robustness loss.Finally,results of case studies validate superiority of proposed method in guaranteeing operation security rigorously and effectiveness in assessment of RSR for PS without overestimation.Index Terms-Hybrid RLO-IGDT approach,information gap decision theory(IGDT),operation security,robustness assessment,robustness security region(RSR).展开更多
Metal–organic frameworks have garnered attention as highly efficient pre-electrocatalysts for the oxygen evolution reaction(OER).Current structure–activity relationships primarily rely on the assumption that the comp...Metal–organic frameworks have garnered attention as highly efficient pre-electrocatalysts for the oxygen evolution reaction(OER).Current structure–activity relationships primarily rely on the assumption that the complete dissolution of organic ligands occurs during electrocatalysis.Herein,modeling based on NiFe Prussian blue analogs(NiFe-PBAs)show that cyanide ligands leach from the matrix and subsequently oxidize to corresponding inorganic ions(ammonium and carbonate)that re-adsorb onto the surface of NiFe OOH during the OER process.Interestingly,the surface-adsorbed inorganic ions induce the OER reaction of NiFe OOH to switch from the adsorbate evolution to the lattice-oxygen–mediated mechanism,thus contributing to the high activity.In addition,this reconstructed inorganic ion layer acting as a versatile protective layer can prevent the dissolution of metal sites to maintain contact between catalytic sites and reactive ions,thus breaking the activity–stability trade-off.Consequently,our constructed NiFePBAs exhibit excellent durability for 1250 h with an ultralow overpotential of 253 mV at 100 mA cm2.The scale-up NiFe-PBAs operated with a low energy consumption of4.18 kWh m3 H2 in industrial water electrolysis equipment.The economic analysis of the entire life cycle demonstrates that this green hydrogen production is priced at US$2.59 kg^(-1)H_(2),meeting global targets(<US$2.5 kg^(-1)H_(2)).展开更多
Nickel-iron layered double hydroxides(NiFe LDHs)represent a promising candidate for oxygen evolution reaction(OER),however,are still confronted with insufficient activity,due to the slow kinetics of electrooxidation o...Nickel-iron layered double hydroxides(NiFe LDHs)represent a promising candidate for oxygen evolution reaction(OER),however,are still confronted with insufficient activity,due to the slow kinetics of electrooxidation of Ni^(2+)cations for the high-valent active sites.Herein,nanopore-rich NiFe LDH(PR-NiFe LDH)nanosheets were proposed for enhancing the OER activity together with stability.In the designed catalyst,the confined nanopores create abundant unsaturated Ni sites at edges,and decrease the migration distance of protons down to the scale of their mean free path,thus promoting the formation of high-valent Ni^(3+)/^(4+)active sites.The unique configuration further improves the OER stability by releasing the lattice stress and accelerating the neutralization of the local acidity during the phase transformation.Thus,the optimized PR-NiFe LDH catalysts exhibit an ultralow overpotential of 278 mV at 10 mA∙cm^(−2)and a small Tafel slope of 75 mV∙dec^(−1),which are competitive among the advanced LDHs based catalysts.Moreover,the RP-NiFe LDH catalyst was implemented in anion exchange membrane(AEM)water electrolyzer devices and operated steadily at a high catalytic current of 2 A over 80 h.These results demonstrated that PR-NiFe LDH could be a viable candidate for the practical electrolyzer.This concept also provides valuable insights into the design of other catalysts for OER and beyond.展开更多
Power-to-hydrogen by electrolysis(PtHE)is a promising technology in the carbon-neutral evolution of energy.PtHE not only contributes to renewable energy integration but also accelerates decarbonization in industrial s...Power-to-hydrogen by electrolysis(PtHE)is a promising technology in the carbon-neutral evolution of energy.PtHE not only contributes to renewable energy integration but also accelerates decarbonization in industrial sectors through green hydrogen production.This paper presents a comprehensive review of PtHE technology.First,technical solutions in PtHE technology are introduced to clarify pros and cons of one another.Besides,the multiphysics coupling and the multi-energy flow are investigated to reveal the insight mechanism during operation of compactly assembled industrial PtHE plants.Then,the development trends of core components in PtHE plants,including electrocatalysts,electrode plates and operation strategy,are reviewed,respectively.Research thrusts needed for PtHE in carbon-neutral transition are also summarized.Finally,three configurations of the PtHE plant in energy system integration are introduced,which can achieve renewable energy integration and efficient energy utilization.Index Terms-Carbon neutrality,power-to-hydrogen nby electrolysis(PtHE),multiphysics coupling,multidisciplinary.展开更多
Generator regulation and wind power curtailment are two conflicting ways to deal with the inaccurate prediction and volatility of wind power.This study focuses on planning the day-ahead schedule based on optimal trade...Generator regulation and wind power curtailment are two conflicting ways to deal with the inaccurate prediction and volatility of wind power.This study focuses on planning the day-ahead schedule based on optimal trade-off between regulation of generators and wind curtailment.Compared to traditional economic dispatch methods,the proposed schedule is more robust and adaptive to multiple forecast scenarios instead of a single forecast scenario.The works of this paper are as follows:First,an economic dispatch problem based on multiple scenarios is formulated with the objective of minimizing both generator regulation and wind curtailment.Next,a forecast method for wind power scenarios is given.Finally,the proposed model is verified by comparing with other dispatch models that are based on single forecast scenario.The simulation results demonstrate the effectiveness of the proposed method with less wind curtailment,generator regulation,and operational cost.In addition,the penalty factors are set as parameters and the influences on the generators’regulation and wind curtailment are analyzed,providing the reference for system operators with different regulatory purposes.展开更多
Large-scale wind farm integration has brought several aspects of challenges to the transient stability of power systems.This paper focuses on the research of the transient stability of power systems incorporating with...Large-scale wind farm integration has brought several aspects of challenges to the transient stability of power systems.This paper focuses on the research of the transient stability of power systems incorporating with wind farms by utilizing risk assessment methods.The detailed model of double fed induction generator has been established.Wind penetration variation and multiple stochastic factors of power systems have been considered.The process of transient stability risk assessment based on the Monte Carlo method has been described and a comprehensive risk indicator has been proposed.An investigation has been conducted into an improved 10-generator 39-bus system with a wind farm incorporated to verify the validity and feasibility of the risk assessment method proposed.展开更多
Growing penetration of wind power challenges to power system security,since the conventional generators may not have sufficient capacity to compensate wind power fluctuation plus the reverse peak regulation.In this pa...Growing penetration of wind power challenges to power system security,since the conventional generators may not have sufficient capacity to compensate wind power fluctuation plus the reverse peak regulation.In this paper,the high-capacity pumped-storage and fast-response battery-storage are coordinated to compensate the variation of both wind power and load,aiming at shifting peak load,responding to wind power ramping,reducing the curtailment of wind and stabilizing the output of thermal units.A practical framework is designed for optimizing the operation of the hybrid system consisting of the wind,pumped-storage,and battery storage,which can take full advantages of pumped-storage and battery-storage.The detailed mathematical formulations of the pumpedstorage and battery-storage are built.Three cases are studied to demonstrate the advantages of the proposed coordination method.展开更多
Sulfide compounds provide a type of promising alternative for oxygen evolution reaction(OER)electrocatalysts due to their diversity,intrinsic activities,low-price and earth-abundance.However,the unsmooth mass transpor...Sulfide compounds provide a type of promising alternative for oxygen evolution reaction(OER)electrocatalysts due to their diversity,intrinsic activities,low-price and earth-abundance.However,the unsmooth mass transport channel,the collapse of the structure and insufficient intrinsic activities limit their potential for OER performance.In respond,the dense Fe-doped Co_(9)S_(8) nanoparticles encapsulated by S,N co-incorporated carbon nanosheets(Fe-Co_(9)S_(8)@SNC)were proposed and synthesized via fast thermal treatment from ultrathin metal-organic frameworks(MOFs)nanosheets.In designed catalysts,the nanosheet configuration connected by nanoparticles retained rich access for permeation of electrolyte and precipitation of O_(2) bubbles during OER process.Meanwhile,the outer carbon layer of Co9S8 provided additional catalytic activity while acting as armor to keep the structure stability.At the atomic scale,the doped Fe regulated the local charge density and the d-band center for facilitating desorption of oxygen intermediates.Benefiting from this multi-scale regulation strategy,the Fe-Co_(9)S_(8)@SNC displays an ultralow overpotential of 273 mV at 10 mA·cm^(-2) and small Tafel slope of 55.8 mV·dec^(-1),which is even close to the benchmark RuO_(2) catalyst.This concept could provide valuable insights into the design of other catalysts for OER and beyond.展开更多
The ongoing development of cogeneration technology has promoted public awareness on the integration of different types of energy systems.Integration of power and heating systems is the most common approach for energy ...The ongoing development of cogeneration technology has promoted public awareness on the integration of different types of energy systems.Integration of power and heating systems is the most common approach for energy transmission.The heat and power coupling of combined heat and power(CHP)units constrains the improvement of flexibility to accommodate more wind power,especially in winter.To address this problem,electrical boilers(EBs)are utilized as independent heat sources in one heat station to enhance their flexibility.This paper proposes a subsidy based bi-level optimal model.The objective of the upper problem is to minimize the operating cost,while the lower problem is to maximize the benefits of CHP and EBs based on the subsidy signals sent by the power system operator(PSO).The bi-level model is reformulated as a single-level linear problem by Karush Kuhn Turck(KKT)conditions and recast to a mix integer quadratic program using strong duality theory.Numerical results performed on an IEEE six-bus system with a eight-node district heating system validate the proposed model.The results demonstrate that the subsidy strategies can make the EB and CHP units operate according to the system operators’preferences to accommodate more wind power.展开更多
基金supported by the National Natural Science Foundation of China(52171156,51771078)
文摘Oxygen vacancies enable modulating surface reconstruction of transition metal oxides containing metal-oxygen polyhedrons into metallic oxyhydroxide for oxygen evolution reaction(OER),while revealing reconstructing mechanism is stuck by the requirement to precisely control exact sites of these vacancies.Herein,oxygen vacancies are localized only within MoO_(4)tetrahedrons rather than CoO_(6)octahedrons in CoMoO_(4)catalyst,guaranteeing coherent reconstruction of CoO_(6)octahedrons into pure CoOOH with tunable activities for OER.Meanwhile,distorted tetrahedron accelerates the dissolution of Mo atoms into alkaline electrolyte,triggering spontaneous transition of partial CoMoO_(4)into Co(OH)_(2).CoO_(6)octahedrons in both CoMoO_(4)and Co(OH)_(2)can transform pure CoOOH completely at lower potential,resulting in excess intrinsic activity whose summit is identified by overpotential at 10 mA cm^(-2)with 22.9%reduction and Tafel slope with 65.3%reduction.Well-defined manipulation over the distorted polyhedrons offers one versatile knob to precisely modulate electronic structure of oxide catalysts with outstanding OER performance.
基金financially supported by the National Natural Science Foundation of China(21761004,21805102,21701035 and 21825103)the Hubei Provincial Natural Science Foundation of China(2019CFA002)+2 种基金the specific research project of Guangxi for research bases and talents(AD18126005)the Fundamental Research Funds for the Central University(Grant No.2019kfyXMBZ018)the training program for thousands of backbone young teachers in Guangxi universities。
文摘Water electrolysis at high current density(1000 mA cm-2 level)with excellent durability especially in neutral electrolyte is the pivotal issue for green hydrogen from experiment to industrialization.In addition to the high intrinsic activity determined by the electronic structure,electrocatalysts are also required to be capable of fast mass transfer(electrolyte recharge and bubble overflow)and high mechanical stability.Herein,the 2D CoOOH sheet-encapsulated Ni2P into tubular arrays electrocatalytic system was proposed and realized 1000 mA cm-2-levelcurrent-density hydrogen evolution over 100 h in neutral water.In designed catalysts,2D stack structure as an adaptive material can buffer the shock of electrolyte convection,hydrogen bubble rupture,and evolution through the release of stress,which insure the long cycle stability.Meanwhile,the rich porosity between stacked units contributed the good infiltration of electrolyte and slippage of hydrogen bubbles,guaranteeing electrolyte fast recharge and bubble evolution at the high-current catalysis.Beyond that,the electron structure modulation induced by interfacial charge transfer is also beneficial to enhance the intrinsic activity.Profoundly,the multiscale coordinated regulation will provide a guide to design high-efficiency industrial electrocatalysts.
基金This work was supported by Beijing Natural Science Foundation(7222246)Royal Dutch Philips Electronics Ltd.(Grant NL18-2100478471).
文摘Objective Evidence on potential cardiovascular benefits of personal-level intervention among the elderly exposed to high levels of particulate matter(PM)remains limited.We aimed to assess improvements in surrogate markers of cardiovascular injury in vulnerable populations at risks by using indoor air filtration units.Methods We conducted a randomized crossover trial for 2 separate 2-week air filtration interventions in 20 households of patients with stable chronic obstructive pulmonary disease and their partners in the winter of 2013,with concurrent measurements of indoor PM.The changes in biomarkers indicative of cardiac injury,atherosclerosis progression and systemic inflammation following intervention were evaluated using linear mixed-effect models.Results In the analysis,average levels of indoor PM with aerodynamic diameters<2.5µm(PM2.5)decreased significantly by 59.2%(from 59.6 to 24.3µg/m3,P<0.001)during the active air filtration.The reduction was accompanied by improvements in levels of high-sensitivity cardiac troponin I by−84.6%(95%confidence interval[CI]:−90.7 to−78.6),growth differentiation factor-15 by−48.1%(95%CI:−31.2 to−25.6),osteoprotegerin by−65.4%(95%CI:−56.5 to−18.7),interleukin-4 by−46.6%(95%CI:−62.3 to−31.0)and myeloperoxidase by−60.3%(95%CI:−83.7 to−3.0),respectively.Conclusion Indoor air filtration intervention may provide potential cardiovascular benefits in vulnerable populations at risks.
基金supported in part by the National Nature Science Foundation of China(No.52177088).
文摘Base station(BS)backup batteries(BSBBs),with their dispatchable capacity,are potential demand-side resources for future power systems.To enhance the power supply reliability and post-contingency frequency security of power systems,we propose a two-stage stochastic unit commitment(UC)model incorporating operational reserve and post-contingency frequency support provisions from massive BSBBs in cellular networks,in which the minimum backup energy demand is considered to ensure BS power supply reliability.The energy,operational reserve,and frequency support ancillary services are co-optimized to handle the power balance and post-contingency frequency security in both forecasted and stochastic variable renewable energy(VRE)scenarios.Furthermore,we propose a dedicated and scalable distributed optimization framework to enable autonomous optimizations for both dispatching center(DC)and BSBBs.The BS model parameters are stored and processed locally,while only the values of BS decision variables are required to upload to DC under the proposed distributed optimization framework,which safeguards BS privacy effectively.Case studies on a modified IEEE 14-bus system demonstrate the effectiveness of the proposed method in promoting VRE accommodation,ensuring post-contingency frequency security,enhancing operational economics,and fully utilizing BSBBs'energy and power capacity.Besides,the proposed distributed optimization framework has been validated to converge to a feasible solution with near-optimal performance within limited iterations.Additionally,numerical results on the Guangdong 500 kV provincial power system in China verify the scalability and practicality of the proposed distributed optimization framework.
基金supported by the National Key R&D Program of China(No.2022YFB2404000).
文摘Fossil fuel depletion and environmental pollution problems promote development of renewable energy(RE)glob-ally.With increasing penetration of RE,operation security and economy of power systems(PS)are greatly impacted by fluctuation and intermittence of renewable power.In this paper,information gap decision theory(IGDT)is adapted to handle uncertainty of wind power generation.Based on conventional IGDT method,linear regulation strategy(LRS)and robust linear optimization(RLO)method are integrated to reformulate the model for rigorously considering security constraints.Then a robustness assessment method based on hybrid RLO-IGDT approach is proposed for analyzing robustness and economic performance of PS.Moreover,a risk-averse linearization method is adapted to convert the proposed assessment model into a mixed integer linear programming(MILP)problem for convenient optimization without robustness loss.Finally,results of case studies validate superiority of proposed method in guaranteeing operation security rigorously and effectiveness in assessment of RSR for PS without overestimation.Index Terms-Hybrid RLO-IGDT approach,information gap decision theory(IGDT),operation security,robustness assessment,robustness security region(RSR).
基金supported by the Foundation of Basic and Applied Basic Research of Guangdong Province(2023B1515120043)the National Natural Science Foundation of China(22071069 and 22275060)+3 种基金the Yangfan Project of Maoming City(MMGCIRI2022YFJH-Y-014)Guangdong Basic and Applied Basic Research Foundation(2019A1515011512,2021A1515010172,and 2023A1515030274)the Foundation of the Smart Medical Innovation Technology Center in Guangdong University of Technology(ZYZX24-031)support from Analysis and Testing Center of Guangdong University of Technology。
文摘Metal–organic frameworks have garnered attention as highly efficient pre-electrocatalysts for the oxygen evolution reaction(OER).Current structure–activity relationships primarily rely on the assumption that the complete dissolution of organic ligands occurs during electrocatalysis.Herein,modeling based on NiFe Prussian blue analogs(NiFe-PBAs)show that cyanide ligands leach from the matrix and subsequently oxidize to corresponding inorganic ions(ammonium and carbonate)that re-adsorb onto the surface of NiFe OOH during the OER process.Interestingly,the surface-adsorbed inorganic ions induce the OER reaction of NiFe OOH to switch from the adsorbate evolution to the lattice-oxygen–mediated mechanism,thus contributing to the high activity.In addition,this reconstructed inorganic ion layer acting as a versatile protective layer can prevent the dissolution of metal sites to maintain contact between catalytic sites and reactive ions,thus breaking the activity–stability trade-off.Consequently,our constructed NiFePBAs exhibit excellent durability for 1250 h with an ultralow overpotential of 253 mV at 100 mA cm2.The scale-up NiFe-PBAs operated with a low energy consumption of4.18 kWh m3 H2 in industrial water electrolysis equipment.The economic analysis of the entire life cycle demonstrates that this green hydrogen production is priced at US$2.59 kg^(-1)H_(2),meeting global targets(<US$2.5 kg^(-1)H_(2)).
基金supported by the National Natural Science Foundation of China(No.22071069).
文摘Nickel-iron layered double hydroxides(NiFe LDHs)represent a promising candidate for oxygen evolution reaction(OER),however,are still confronted with insufficient activity,due to the slow kinetics of electrooxidation of Ni^(2+)cations for the high-valent active sites.Herein,nanopore-rich NiFe LDH(PR-NiFe LDH)nanosheets were proposed for enhancing the OER activity together with stability.In the designed catalyst,the confined nanopores create abundant unsaturated Ni sites at edges,and decrease the migration distance of protons down to the scale of their mean free path,thus promoting the formation of high-valent Ni^(3+)/^(4+)active sites.The unique configuration further improves the OER stability by releasing the lattice stress and accelerating the neutralization of the local acidity during the phase transformation.Thus,the optimized PR-NiFe LDH catalysts exhibit an ultralow overpotential of 278 mV at 10 mA∙cm^(−2)and a small Tafel slope of 75 mV∙dec^(−1),which are competitive among the advanced LDHs based catalysts.Moreover,the RP-NiFe LDH catalyst was implemented in anion exchange membrane(AEM)water electrolyzer devices and operated steadily at a high catalytic current of 2 A over 80 h.These results demonstrated that PR-NiFe LDH could be a viable candidate for the practical electrolyzer.This concept also provides valuable insights into the design of other catalysts for OER and beyond.
基金supported in part by National Natural Science Foundation of China(No.52177089)ABB Power Grids Research(No.ABB20171127REU-CTR)。
文摘Power-to-hydrogen by electrolysis(PtHE)is a promising technology in the carbon-neutral evolution of energy.PtHE not only contributes to renewable energy integration but also accelerates decarbonization in industrial sectors through green hydrogen production.This paper presents a comprehensive review of PtHE technology.First,technical solutions in PtHE technology are introduced to clarify pros and cons of one another.Besides,the multiphysics coupling and the multi-energy flow are investigated to reveal the insight mechanism during operation of compactly assembled industrial PtHE plants.Then,the development trends of core components in PtHE plants,including electrocatalysts,electrode plates and operation strategy,are reviewed,respectively.Research thrusts needed for PtHE in carbon-neutral transition are also summarized.Finally,three configurations of the PtHE plant in energy system integration are introduced,which can achieve renewable energy integration and efficient energy utilization.Index Terms-Carbon neutrality,power-to-hydrogen nby electrolysis(PtHE),multiphysics coupling,multidisciplinary.
基金This work was supported by the Science and Technology Projects of State Grid(DZ71-14-001)the National Natural Science Foundation of China(5137727).
文摘Generator regulation and wind power curtailment are two conflicting ways to deal with the inaccurate prediction and volatility of wind power.This study focuses on planning the day-ahead schedule based on optimal trade-off between regulation of generators and wind curtailment.Compared to traditional economic dispatch methods,the proposed schedule is more robust and adaptive to multiple forecast scenarios instead of a single forecast scenario.The works of this paper are as follows:First,an economic dispatch problem based on multiple scenarios is formulated with the objective of minimizing both generator regulation and wind curtailment.Next,a forecast method for wind power scenarios is given.Finally,the proposed model is verified by comparing with other dispatch models that are based on single forecast scenario.The simulation results demonstrate the effectiveness of the proposed method with less wind curtailment,generator regulation,and operational cost.In addition,the penalty factors are set as parameters and the influences on the generators’regulation and wind curtailment are analyzed,providing the reference for system operators with different regulatory purposes.
基金This work is supported by State Grid Corporation of China,Major Projects on Planning and Operation Control of Large Scale Grid(SGCC-MPLG026-2012)National HI-Tech R&D Program of China(2011AA05A112).
文摘Large-scale wind farm integration has brought several aspects of challenges to the transient stability of power systems.This paper focuses on the research of the transient stability of power systems incorporating with wind farms by utilizing risk assessment methods.The detailed model of double fed induction generator has been established.Wind penetration variation and multiple stochastic factors of power systems have been considered.The process of transient stability risk assessment based on the Monte Carlo method has been described and a comprehensive risk indicator has been proposed.An investigation has been conducted into an improved 10-generator 39-bus system with a wind farm incorporated to verify the validity and feasibility of the risk assessment method proposed.
基金This work was supported in part by the National Key Research and Development Program of China(2016YFB0900101)in part by the National Natural Science Foundation of China(51377027).
文摘Growing penetration of wind power challenges to power system security,since the conventional generators may not have sufficient capacity to compensate wind power fluctuation plus the reverse peak regulation.In this paper,the high-capacity pumped-storage and fast-response battery-storage are coordinated to compensate the variation of both wind power and load,aiming at shifting peak load,responding to wind power ramping,reducing the curtailment of wind and stabilizing the output of thermal units.A practical framework is designed for optimizing the operation of the hybrid system consisting of the wind,pumped-storage,and battery storage,which can take full advantages of pumped-storage and battery-storage.The detailed mathematical formulations of the pumpedstorage and battery-storage are built.Three cases are studied to demonstrate the advantages of the proposed coordination method.
基金supported by the National Natural Science Foundation of China(Nos.21805102 and 22071069)the Foundation of Basic and Applied Basic Research of Guangdong Province(No.2019B1515120087)。
文摘Sulfide compounds provide a type of promising alternative for oxygen evolution reaction(OER)electrocatalysts due to their diversity,intrinsic activities,low-price and earth-abundance.However,the unsmooth mass transport channel,the collapse of the structure and insufficient intrinsic activities limit their potential for OER performance.In respond,the dense Fe-doped Co_(9)S_(8) nanoparticles encapsulated by S,N co-incorporated carbon nanosheets(Fe-Co_(9)S_(8)@SNC)were proposed and synthesized via fast thermal treatment from ultrathin metal-organic frameworks(MOFs)nanosheets.In designed catalysts,the nanosheet configuration connected by nanoparticles retained rich access for permeation of electrolyte and precipitation of O_(2) bubbles during OER process.Meanwhile,the outer carbon layer of Co9S8 provided additional catalytic activity while acting as armor to keep the structure stability.At the atomic scale,the doped Fe regulated the local charge density and the d-band center for facilitating desorption of oxygen intermediates.Benefiting from this multi-scale regulation strategy,the Fe-Co_(9)S_(8)@SNC displays an ultralow overpotential of 273 mV at 10 mA·cm^(-2) and small Tafel slope of 55.8 mV·dec^(-1),which is even close to the benchmark RuO_(2) catalyst.This concept could provide valuable insights into the design of other catalysts for OER and beyond.
基金This work was supported by the National Key Research and Development Program of China(No.2017YFB0902100).
文摘The ongoing development of cogeneration technology has promoted public awareness on the integration of different types of energy systems.Integration of power and heating systems is the most common approach for energy transmission.The heat and power coupling of combined heat and power(CHP)units constrains the improvement of flexibility to accommodate more wind power,especially in winter.To address this problem,electrical boilers(EBs)are utilized as independent heat sources in one heat station to enhance their flexibility.This paper proposes a subsidy based bi-level optimal model.The objective of the upper problem is to minimize the operating cost,while the lower problem is to maximize the benefits of CHP and EBs based on the subsidy signals sent by the power system operator(PSO).The bi-level model is reformulated as a single-level linear problem by Karush Kuhn Turck(KKT)conditions and recast to a mix integer quadratic program using strong duality theory.Numerical results performed on an IEEE six-bus system with a eight-node district heating system validate the proposed model.The results demonstrate that the subsidy strategies can make the EB and CHP units operate according to the system operators’preferences to accommodate more wind power.
