电流密度和运行温度对PEM水电解制氢能耗的影响

质子交换膜(PEM)水电解制氢技术是采用绿电制取绿氢的重要方法,对我国实现双碳目标具有重要意义。优化运行参数是降低PEM水电解制氢系统能耗的一种重要途径。建立一套工业级PEM水电解制氢实验装置,通过现场实验,考察电流密度和运行温度对PEM水电解制氢系统能耗的影响,探讨优化运行参数降低运行能耗的方法。结果表明,当电流密度为0.2～1.4 A/cm²、运行温度为20～60℃,PEM水电解制氢系统单位能耗分别与电流密度、运行温度负相关。提高运行温度会引起电解电压下降,系统单位直流能耗显著降低。提高电流密度会造成系统单位直流能耗升高,而单位交流能耗降低。     

质子交换膜电解水制氢技术在电厂的应用

质子交换膜(PEM)电解水制氢技术具有工作电流密度高,电解效率高,反应无污染、质量轻、结构紧凑等优点,该技术的小型电解水制氢设备在发电厂氢冷发电机组领域具有广泛的应用前景。首先介绍了PEM电解水制氢技术的工作原理及技术优势,通过与碱性电解水制氢技术方案的定量结果进行对比,分析了PEM电解技术在电厂氢冷发电机组方面应用的技术方案、设备组成及经济可行性,进一步展望了PEM电解水技术在电厂及其他民用领域的发展前景。     

太阳能光伏-PEM水电解制氢直接耦合系统优化

利用水电解制氢进行氢储能是我国可再生能源弃电问题的解决方案之一。本文建立了太阳能光伏阵列与质子交换膜（proton exchange membrane, PEM）水电解直接耦合系统的分析模型,研究耦合系统优化运行工况。结果表明,天气变化易导致直接耦合系统工作点偏离光伏最大功率点,引起耦合失配并降低太阳能利用率。通过匹配太阳能光伏阵列串并联结构和水电解器工作槽数进行“粗调”,改变PEM水电解器工作温度进行“精调”,可使直接耦合系统工作在最大功率点附近,使系统能量损失最小。本研究为太阳能光伏-PEM水电解氢储能直接耦合技术的运行策略和优化奠定了理论基础。     

基于链式分配策略的风氢耦合系统设计与控制

针对风力发电“弃风”电量耦合制氢问题,提出一种基于链式分配策略的风氢耦合系统。首先建立能表征弃风电量与质子交换膜电解槽主要特性的风氢耦合拓扑电路结构,围绕高降压比交错Buck变换器及其控制方法构建风氢耦合系统,并提出多堆质子交换膜电解槽风氢耦合系统链式功率分配策略。最后通过算例仿真验证该系统可提升弃风利用率和系统可靠性,可有效解决弃风电量水电解制氢耦合控制与功率分配问题。     

重力对PEM燃料电池性能的影响

水对质子交换膜(PEM)燃料电池的性能有极其重要的影响,良好的水管理是PEM燃料电池保持高性能的必要条件.通过试验,观察了在重力作用下液态水对PEM燃料电池性能及其内部传质的影响,分析了PEM燃料电池单体电极的不同摆放位置对其性能的影响.试验结果发现:在电流密度较小时,重力对PEM燃料电池性能的影响不明显,电流密度较大时,重力对PEM燃料电池性能的影响比较明显.试验结果对优化PEM燃料电池的结构和水管理有一定的参考价值.     

基于PV/T的质子交换膜电解制氢系统动态性能研究

将太阳能光伏光热综合利用技术（PV/T）与质子交换膜电解水制氢技术（PEMWE）结合，提出基于PV/T的质子交换膜电解制氢系统（PV/T-PEMWE）。系统由PV/T模块与PEM电解槽通过耦合而集成，建立数学模型分析其在白天的动态光电光热性能及制氢性能，并在相同条件下将其性能与光伏电解制氢系统（PV-PEMWE）进行对比。结果表明：PV/T系统全天总发电量为0.5 kWh，电效率维持在13%～15%之间，总发热量为9.4 MJ，热效率维持在30%～40%之间；PV/T-PEMWE系统制氢效率高于PV-PEMWE系统，PV/T-PEMWE系统全天的制氢量为153 L，平均制氢速率约为19 L/h。     

碳中和愿景下绿色制氢技术发展趋势及应用前景分析

围绕目前主流的绿色制氢技术,综述国内外“绿氢”技术的最新研究进展,重点阐述电解水制氢技术（碱性电解水法、质子交换膜电解水法、固体氧化物电解水法）、太阳能分解水制氢技术（光催化法、光热分解法、光电化学法）以及生物质制氢技术（热化学转化法、微生物法）的产氢原理、技术难点和改进方法等,讨论比较各类“绿氢”技术的优缺点,分析未来绿色制氢技术的应用前景和发展方向。     

质子交换膜电解池二维两相流综合模拟研究

建立一个二维、非等温质子交换膜电解池两相流稳态模型，研究不同电压下电解池膜电极组件（MEA）中温度、液态水饱和度、膜态水分布以及温度、液态水饱和度和膜厚对质子交换膜电解池性能的影响，并通过实验验证模型的可靠性。实验结果表明：即使忽略接触电阻，膜润湿性较好，高电压（2.0 V）下欧姆损失占比仍可达到34.7%；随着电压的增大，极化损失的主导部分由活化损失变为欧姆损失，且传质损失占总极化损失的比例最小；当电压较小时，膜水含量是质子交换膜（PEM）电导率的主要影响因素，当电压较大时，温度是PEM电导率的主要影响因素。升高温度、增加液态水饱和度及降低膜厚均能有效提高电解池的性能。     

离子污染对质子交换膜电解制氢的影响研究进展

质子交换膜(proton exchange membrane,PEM)电解制氢运行灵活,具有优异的可再生能源波动适应性,是极具发展前景的绿色制氢技术。然而,在实际PEM电解制氢运行过程中,可能存在离子污染,对PEM电解堆的性能以及运行寿命产生很大影响。为此,首先分析了离子污染的来源,一方面来自水中的残余金属阳离子,如Na⁺、Ca²⁺、Mg²⁺等,另一方面来自电解堆内部关键材料和系统水循环管路因化学或电化学腐蚀产生的痕量金属离子,如Fe³⁺、Cu²⁺、Ni²⁺等;然后综述了不同离子污染对电解性能的影响,包括欧姆过电位、阴极反应过电位与阳极反应过电位;最后,综述了离子污染缓解策略,即如何避免规模化电解制氢过程中杂质离子污染带来的能效和成本问题。     

水电解制氢工艺的节能分析

水电解制氢过程的电能消耗很大,一般占我厂电能消耗的三分之一。因此,想方设法降低水电解制氢的能耗,具有十分重要的意义,本文从降低极间电压,在电解液中加入添加剂以及电解槽的低电流密度经济运行等三个方面对水电解制氢过程进行了节能分析。     

Effects of magnetic field and pulse potential on hydrogen production via water electrolysis

This experiment uses nickel electrodes and adds pulse potential and magnetic force when producing hydrogen via water electrolysis and explores how related parameters are affected by magnetohydrodynamics and pulse potential. Experiments showed that the Lorentz force of the magnetic field changes the direction of convective flow of the electrolyte, which affects the flow of bubbles during electrolysis. Adding a magnetic field increases the rate of current density by roughly 15% under a normal temperature, a distance of 2 mm between electrodes and a potential of 4 V. Pulse potential instantaneously increases current and accelerates both the movement of bubbles from the electrode surface and the mass transfer rate in the electrolyte, which lowers electrochemical polarization in the diffussion layer and further increases hydrogen production efficiency. When the duty cycle is 10% and the pulse on‐time is 10 ms, almost 88% of overall power is converted, and current density increases by 680 mA/cm², which is an increase of roughly 38%. Generally, pulse potential and magnetic field effects enhance each other when added under suitable pulse potential and basic potential. Copyright © 2013 John Wiley & Sons, Ltd.     

Electrochemical impedance spectroscopy analysis of V–I characteristics and a fast prediction model for PEM-based electrolytic air dehumidification

PEM-based electrolytic air dehumidification is innovative due to its high efficiency, compact size and cleanness. However, high polarization loss and severe performance degradation have been observed, especially at high applied voltages (>2.5 V). Understanding the V–I characteristics is critical to performance optimization. This study experimentally investigated the V–I characteristics and internal response of materials under various operating conditions, with in-situ Electrochemical Impedance Spectroscopy (EIS) methods. Real-time mass transfer, electrochemical polarization and reaction dynamics of PEM components during dehumidification were derived by EIS. Then, a fast prediction model was built to directly predict the dehumidification rate and attenuation without any iteration, suitable for online monitoring and adjustment. Compared to other models, this model can take a quick understanding of the impact of operating conditions on the material characteristics inside the PEM element. The deviations of current density, PEM proton conductivity and moisture removal were 3%, 11.2% and 15.3%, respectively, compared to experiment data. Results showed that when the applied voltage changed from 1.5 to 3.5 V, the high-frequency resistance of the PEM element increased from 1.69 to 2.69 Ω, and the PEM proton conductivity decreased by about 38 times. The sharp drop in PEM proton conductivity resulted in a current attenuation. With this model, requirements for key components of PEM dehumidification were also obtained. Analysis of the overpotential distribution showed that increasing the water retention and reducing the dependence of proton conductivity on water molecules of the PEM can effectively improve the performance. This research provides guidance for the performance optimization and material selection of PEM-based dehumidification.     

Porous electrode improving energy efficiency under electrode-normal magnetic field in water electrolysis

The porous electrodes (Ni, Cu) with 110 pores per inch (PPI) are adopted in water electrolysis for hydrogen production under normal-to-electrode magnetic field. The result shows that the voltage drop between electrodes can be reduced up to 2.5% under 0.9 T field, and the electric energy efficiency is improved correspondingly. Based on the numerical simulation method, the micro-magnetohydrodynamic (micro-MHD) convection induced by Lorentz force within the porous structure is found. The results showed that although the apparent current direction is parallel to magnetic field outside the porous electrode, the electric field may be distorted within the porous structure, and the Lorentz force is involved near the rib of the micro structure where the current is not parallel to the magnetic field any more. Micro-MHD plays the role of strengthening the mass transfer and facilitating bubble to eject from the porous structure, which results in the cell voltage decreasing. The combined application of porous electrode and magnetic field should be potential to further improve energy efficiency of water electrolysis for hydrogen production.     

Predicting efficiency of solar powered hydrogen generation using photovoltaic-electrolysis devices

Hydrogen fuel for fuel cell vehicles can be produced by using solar electric energy from photovoltaic (PV) modules for the electrolysis of water without emitting carbon dioxide or requiring fossil fuels. In the past, this renewable means of hydrogen production has suffered from low efficiency (2–6%), which increased the area of the PV array required and therefore, the cost of generating hydrogen. A comprehensive mathematical model was developed that can predict the efficiency of a PV-electrolyzer combination based on operating parameters including voltage, current, temperature, and gas output pressure. This model has been used to design optimized PV-electrolyzer systems with maximum solar energy to hydrogen efficiency. In this research, the electrical efficiency of the PV-electrolysis system was increased by matching the maximum power output and voltage of the photovoltaics to the operating voltage of a proton exchange membrane (PEM) electrolyzer, and optimizing the effects of electrolyzer operating current, and temperature. The operating temperature of the PV modules was also an important factor studied in this research to increase efficiency. The optimized PV-electrolysis system increased the hydrogen generation efficiency to 12.4% for a solar powered PV-PEM electrolyzer that could supply enough hydrogen to operate a fuel cell vehicle.     

Two-dimensional multi-physics modeling of porous transport layer in polymer electrolyte membrane electrolyzer for water splitting

Polymer electrolyte membrane (PEM) electrolyzers have received increasing attention for renewable hydrogen production through water splitting. In present work, a two-dimensional (2-D) multi-physics model is established for PEM electrolyzer to describe the two-phase flow, electron/proton transfer, mass transport, and water electrolysis kinetics with focus on the porous transport layer (PTL) and the channel-land structure. After comparing four sets of experimental data, the model is employed to investigate PTL thickness impact on liquid water saturation and local current density. It is found that the PTL under the land may have much lower liquid saturation than that under the channel due to land blockage. The PTL thickness may significantly impact liquid water access to the catalyst layer (CL) under the land. Specifically, the 100 μm thick PTL shows less than 1% liquid saturation at the CL-PTL interface under 4–5 A/cm², leading to water starvation and electrolyzer voltage increase. As the operating current density decreases under 2–3.5 A/cm², the liquid saturation recovers and increases to about 10–20%. In thicker PTLs, the liquid saturation is higher under the land reaching 30–40% at the CL-PTL interface under 5 A/cm² for 200 and 500 μm thick PTLs. For the 100 μm thick PTL, the local current density drops to below 0.5 A/cm² under the land with 5 A/cm² average current density. For the 200 and 500 μm thick PTLs, the local current is almost uniform in the in-plane direction. The numerical model is extremely valuable to investigate PTL properties and dimensions to optimize channel-land design and configuration for high performing electrolyzers.     

Equivalent electrical model for a proton exchange membrane (PEM) electrolyser

In this work, an electrical equivalent model for a proton exchange membrane (PEM) electrolyser has been developed. Through experimental analysis, the input current–voltage (I–V) characteristic for a single PEM electrolyser cell has been modelled under steady-state conditions. It has been developed by using electrical equivalent circuit topology in which the useful power conversion and losses have been taken into account. Electrolytic hydrogen production rates of PEM electrolyser cell have been calculated with respect to the input current and power. The developed model has been tested with experiments results at the nominal operating temperature. The experimental results have been verified with the developed model results and the relative errors between them are around 1–2%. It has been observed that the electrolytic hydrogen production rate increases with the input current in a linear fashion. But the variation of electrolytic hydrogen production rate with the input electrical power is non-linear (i.e. logarithmic). These characteristics are verified by using the developed electrical equivalent model of PEM electrolyser cell. The parameters of the developed model can also be defined by taking into account of temperature and pressure effects. The equivalent electrical model of PEM electrolyser is very useful for analysing the electrical energy system behaviour in which the energy is stored in the form of electrolytic hydrogen.     

Power quality improvement for 20 MW PEM water electrolysis system

Hydrogen is an important alternative as a clean fuel for industry and power-to-gas energy storage. The water electrolysis process is a promising technology in green hydrogen production where proton exchange membrane (PEM) technology has been keenly interested. Industrial large-scale PEM electrolyzers need a high current power supply. When connected to an alternating current (AC) source, high current power rectifiers are used to convert AC to DC. Currently, the most commonly used topology in large-scale PEM electrolysis systems is the thyristor-based topology due to its technology maturity and low cost. However, this topology presents several drawbacks in terms of power quality and consequently leads to higher stack-specific energy consumption (SEC) and additional losses. In the present research, we demonstrate the potential power quality improvement for a 20 MW PEM water electrolysis system by rectifier topology upgrade. Rather than traditional thyristor-based topology, a 3-phase interleaved buck rectifier topology is proposed. The new topology presents advantages on both AC and DC sides via a validated simulation model, which is built using MATLAB/Simulink and then validated with experimental data from an industrial 20 MW PEM water electrolyzer at Air Liquide's Bécancour plant. Results show a great improvement in terms of power factor, Total Harmonic Distortion (THD), and DC-current ripple reducing the total losses and the SEC of the PEM stack, especially under partial load. Towards a higher power efficiency, the proposed rectifier topology may be considered in the construction of future large-scale PEM systems.     

The economic analysis for hydrogen production cost towards electrolyzer technologies: Current and future competitiveness

Hydrogen production by electrolysis technology spurs as extensive investigation toward new clear energy acquisition. The mainstream hydrogen production electrolyzers, including alkaline electrolyzer (ALK), anion exchange membrane electrolyzer (AEM), and proton exchange membrane electrolyzer (PEM), are traced to compare their current and future hydrogen production cost regarding technology development. Technologies' characteristics are originally described as the polarization curve parameters such as current density, overpotential, and polarization curve slope. The feature of crucial materials such as catalysts and membranes are also taken into consideration. Then, a bottom-up hydrogen production cost prediction model stemming from technical factors is established with a combination of manufacturing and operating considerations. According to model predictions, the cost of hydrogen production of ALK will be 23.85% and 51.59% lower than AEM and PEM technologies in the short term. However, under technological advancement or breakthrough, the hydrogen production cost of AEM and PEM is expected to be 24% and 56.5% lower in the medium-term and long-term, respectively. The lifetime of the electrolyzers is significantly vital to affect the cost of hydrogen production. The cost reduction space brought about by various technical factors is also explored for the blueprint planning of the hydrogen economy.     

Performance and cost modelling taking into account the uncertainties and sensitivities of current and next-generation PEM water electrolysis technology

This paper presents a bottom-up approach to the assessment of model performance and costs of a proton-exchange-membrane electrolysis considering cell, stack and process levels. The cell voltage is modelled dependent on current density and detailed models for stack, investment and hydrogen costs are developed. Taking into account current research on PEM electrolysis, such as the use of thinner membranes or low precious metal loading on the electrodes, allows the prediction of next generation's efficiency and costs. By comparison of a current and next-generation PEM electrolysis, the effectiveness of individual development steps was assessed and remaining space for efficiency and cost improvement was identified. This can help to prioritize and to focus on development steps which are most effective.In the next generation, efficiency will be increased even at higher current density operation. Thus, specific stack costs will drop to less than half of present day costs which is decisive to achieve lower hydrogen production costs in the next generation. Specific installed costs and hydrogen production costs of the current and next generation are calculated for plant sizes up to 100 MW_DC and reveal significant cost decrease for plant capacities up to 25 MW_DC while only changing slightly for capacities larger than this.Costs are always subject to uncertainties due to model assumptions and boundary conditions that need to be defined. Uncertainties and the sensitivities of the model are estimated and assessed to provide an indication of the actual cost range. Main cost model uncertainties are identified to arise from membrane electrode and stack assembly costs, civil engineering and construction surcharge as well as the electrical system. Hydrogen costs are dominated by operating costs and therefore are highly sensitive to the annual operating hours and the electricity price, which have a greater impact on the hydrogen costs than the model assumptions for capital costs.     

Experimental investigation of solar hydrogen production PV/PEM electrolyser performance in the Algerian Sahara regions

This paper presents experimental results on the solar photovoltaic/PEM water electrolytes system performance in the Algerian Sahara regions. The first step is to present a photovoltaic module characterization under different conditions then validate the results by comparing the measured and calculated values. The main objective of this study is to develop a parametric study on the system performance (open-circuit voltage Voc, short circuit current Is, fill factor FF, maximum power Pm and the efficiency η) under hot climate conditions (Ouargla, Algeria). The ambient temperature effects and solar radiation on the solar PV performance characteristics were investigated using modeling and simulation analysis as well as experimental studies. The results show that the root mean squared error (RMSE) error of the currents and voltages and the mean bias error (MBE) are respectively 0.71%, 0.37% and 0.12%, 0.15%. The relative errors in the current and the voltage are respectively 0.83%–1.76%, and −0.58% to 0.83%. The second part provide some general characteristics concerning the indirect coupling of a lab scale proton exchange membrane (PEM) water electrolyser (HG60) powered by a set of our photovoltaic panels. Experimental results provide practical information for the modules and the electrolysis cells by the indirect coupling. The weather conditions effect on hydrogen production from the electrolyser was also investigated. The results showed a high hydrogen production of 284 L in one day for 08 h of running and the electrolyser power efficiency with solar PV system was between 18 and 40%.