Dynamic Performance Enhancement of Hydrogen PEM Electrolyzer Membranes

Solid Oxide Electrolysis Cells (SOECs) are advancing toward global commercialization, driven by significant improvements in cell performance, extended lifetimes, and effective applications. Leading companies like Bloom Energy and Topsoe are demonstrating the feasibility of industrial-scale SOECs hydrogen production and synthetic fuel generation. Additionally, SOECs are being integrated with renewable energy and industrial heat sources to reduce green hydrogen cost and improving energy efficiency. Despite challenges like degradation and expensive costs, ongoing research are paving the way for SOECs to play a pivotal role in the global energy transition.China has been actively involved in the SOECs development since the early stages of this technology. However, the Chinese SOEC industry has not yet reached the same level of maturity as its international counterparts. Currently, SOEC technology in China remains in the research and small-scale demonstration phase, hindered by challenges such as expensive capital costs, poor lifespan, and unclear applications. Despite these barriers, China boasts the world's largest green hydrogen market, where alkaline electrolyzers (AECs) currently dominate due to their lower costs. However, SOECs known for their superior efficiency, have good potential application prospects in the future if key bottlenecks such as cost, and durability can be effectively addressed. This transition could significantly enhance global green hydrogen production capabilities and contribute to decarbonization goals.The primary objectives for the Chinese SOEC industry are: (1) enhancing durability, and (2) reducing hydrogen production costs. To achieve these goals, specific efforts are being directed at three key areas: (1) Material and cell: develop advancing surface defect theory and novel cell (micro-)structures to achieve higher current densities at lower temperatures; (2) Stack: design advanced stack structures and improve manufacturing procedures to enhance stack consistency, reliability, robustness, and performance; (3) System: develop cost-effective BoPs, enable high-value chemical production via effective integration. These targeted initiatives aim to address critical challenges and position the Chinese SOEC industry as a global leader in green hydrogen area. SOEC development is vital for building a green energy and chemical industry and promoting China's energy structure transformation.

Hydrogen energy has been hailed as a versatile energy of the future that could aid the transition to net-zero emissions. It has large potential as an alternate fuel source for mobility and power, heating and feedstock for the industry. The energy carrier is produced from water electrolysis technology using different types of electrolyzer (i.e., Proton Exchange Membrane (PEM) or Solid Oxide Electrolysis Cells (SOECs)) for hydrogen separation process. In this energy research journey, PETRONAS has jointly worked with SLB to evaluate the feasibility of using SOECs for green hydrogen production. The study's focus is to explore integrating SOECs into existing industrial facilities creating hybrid systems, specifically with available flue gas from combustion process e.g. power generation. This allows for the utilization of waste heat from existing processes to enhance overall energy efficiency in hydrogen production. To understand hydrogen production and its utilization in the existing facility, the full system including existing gas turbines, solid oxide electrolyzer cells (SOECs), a hydrogen compression train, and a temperate cooling water system were modeled in a process simulation software. The model also included a heat recovery steam generator (HRSG) to recover the energy from gas turbine exhaust gases to heat water feed to produce saturated steam which will be the feed to SOEC. Several configurations considering heat integrations were explored, including heat recovery from SOEC product stream. Various sensitivities were run for different configurations of the process to study hydrogen purity, hydrogen blending, overall power required, water required in the overall process, and power produced by the hydrogen generated from SOEC and CO2 emission values in all the configuration. The results were compared and evaluated to help assess how variation in parameters affect the performance or outcome. The results were evaluated for blending the produced hydrogen with the existing export gas before and after export gas compression and how it influences the hydrogen purity. Hydrogen blending with the fuel gas to the gas turbine also helped in overall reduction of CO2 emission. It was observed that additional cooling of the hydrogen stream to achieve better hydrogen purity did not significantly help in reducing CO2 emissions when hydrogen is used as fuel gas; therefore, cooling with temperate water system can be considered. All the cases were compared and evaluated for expanding the application of green hydrogen technologies in the facility considering viability and reduction in emissions. The study was a part of a collaborative research initiative by the industry players to accelerate the development and deployment of SOEC technologies in existing facilities. The results from the study provided an overall understanding of adding SOEC in the facility and valuable insights to the stakeholders to make well-informed choices on the configuration.

Mathematical modeling of an integrated photovoltaic-assisted PEM water electrolyzer system for hydrogen production

The transition to carbon neutrality is critically dependent on the development of sustainable power sources and energy storage solutions. One of them is green hydrogen production via water electrolysis from renewable energy. Proton Exchange Membrane (PEM) electrolysis is recognized as one key technology in this domain due to its high efficiency, eligibility for transient operation and compact design. One primary development goal is to reduce the Levelized Cost of Hydrogen production (LCOH) by improving efficiency and durability while assuring safe operation at all conditions. This can only be achieved by a holistic approach on system level, optimizing every aspect of the technology, including cell design, material selection, stack configuration and its integration with all kinds of balance of plant components. In this context, the application of multi-scale and multi-domain system simulation, incorporating precise thermodynamic and electrochemical models, is a promising measure to reduce development time and cost. Simulation models account for the key processes such as cell polarization, reactant cross-diffusion, auxiliary power demands, and hydrogen purification with their related losses.This work employs a system simulation method for the thermodynamic and electrochemical optimization of a state-of-the-art PEM electrolysis system with a target hydrogen pressure of 70 bar and product purity of 99.999%. The baseline system operates at 30 bar stack pressure, with a two-bed Pressure Swing Adsorber (PSA) for hydrogen purification and a subsequent hydrogen compressor. The part-load limit, given the hydrogen in oxygen concentration due to reactant cross-diffusion is at 20%. The study first explores an increase in the stack operation temperature for reducing the activation overpotential and ohmic losses. Subsequently, it examines the potential of advanced membrane materials featuring lower hydrogen cross-diffusion characteristics. These materials allow for higher stack pressure, reduced membrane thickness, or for extended part-load operation, all while maintaining the hydrogen in oxygen safety limits. The results show that, on system level, increasing the stack pressure is more efficient than reducing the membrane thickness. The reduced power consumption for hydrogen compression and the reduced PSA losses more than compensate the effects of cell polarization characteristics. Finally, the system model serves to determine an optimal load profile for minimal LCOH at volatile electricity prices. Figure 1

The intensification technologies to water electrolysis for hydrogen production – A review

Development and application of flexible integrated microsensor as real-time monitoring tool in proton exchange membrane water electrolyzer

The global push towards cleaner energy sources has heightened the demand for high-performing, durable proton exchange membrane water electrolyzer (PEMWE) electrocatalysts. Green hydrogen, generated through water electrolysis powered by renewable energy, stands as a prominent solution in this endeavor to transition away from fossil fuels. Among various electrolyzer technologies, PEMWE systems currently offer the most competitive pathway for green hydrogen production. These systems typically employ a platinum on carbon supported (Pt/C) cathodic electrocatalyst for the hydrogen evolution reaction (HER) and an iridium oxide (IrOx) anodic electrocatalyst for the oxygen evolution reaction (OER). Efforts to enhance PEMWE performance primarily focus on improving the kinetics of the OER process, which accounts for the majority of activation overpotential during operation. To address cost concerns associated with IrOx, researchers are exploring alternative formulations, including doping with materials like niobium (Nb), aiming for comparable performance at reduced Ir loading [1], [2], [3]. It is argued that higher surface area and lower crystalline IrOx catalysts lead to lower activation overpotentials and enhanced durability, respectively. In this study, we investigate the performance of high-surface-area IrOx electrocatalysts (>200 m2/g) and Nb-doped IrOx variants, comparing them with commercially available benchmarks. Through rigorous examination utilizing Rotating Disk Electrode (RDE), Gas Diffusion Electrode (GDE) half-cell, and Membrane Electrode Assemblies (MEAs), we report on the performance and stability of our in-house prepared materials. Preliminary results examining various loadings of IrOx suggest that lower loadings lead to durable and active electrocatalyst layers. Our findings underscore the potential of Nb-doped IrOx as a cost-effective alternative for PEMWE electrocatalysts, offering promising advancements in the pursuit of efficient and sustainable hydrogen production.

The depletion of fossil fuels in the current world has been a major concern due to their role as a primary source of energy for many countries. As non-renewable sources continue to deplete, there is a need for more research and initiatives to reduce reliance on these sources and explore better alternatives, such as renewable energy. Hydrogen is one of the most intriguing energy sources for producing power from fuel cells and heat engines without releasing carbon dioxide or other pollutants. The production of hydrogen via the electrolysis of water using renewable energy sources, such as solar energy, is one of the possible uses for solid oxide electrolysis cells (SOECs). SOECs can be classified as either oxygen-ion conducting or proton-conducting, depending on the electrolyte materials used. This article aims to highlight broad and important aspects of the hybrid SOEC-based solar hydrogen-generating technology, which utilizes a mixed-ion conductor capable of transporting both oxygen ions and protons simultaneously. In addition to providing useful information on the technological efficiency of hydrogen production in SOEC, this review aims to make hydrogen production more efficient than any other water electrolysis system.

Water splitting coupled to renewable power systems is an attractive way to generate green hydrogen and achieve zero carbon emissions, and represents a strategic technology to meet the high demand of carbon-neutral development. Catalysts essentially determine the efficiency and cost of water splitting technologies, and are a class of key materials for green hydrogen production. In this review, we summarize the catalyst developments for the mainstream green hydrogen production technologies, including water electrolysis, water photolysis, and photoelectrocatalytic water splitting. We first present basic catalytic mechanisms of these water splitting pathways, as well as emphasize their current research status and challenges for practical application. We subsequently introduce the recent progress in representative catalysts and design strategies toward these photo(electro)catalytic technologies, paying particular attention to water electrolysis, including alkaline water electrolyzer (AWE), proton exchange membrane water electrolyzer (PEMWE), anion-exchange membrane water electrolyzer (AEMWE) and solid oxide electrolysis cell (SOEC). Finally, we propose future prospects to develop more desirable catalysts for green hydrogen production at a large scale.

To achieve carbon neutrality, extensive research is ongoing to produce green hydrogen via water electrolysis combined with renewable energy sources. Understanding and developing catalysts for membrane electrode assembly (MEA) type water electrolysis systems, such as proton exchange membrane water electrolysis (PEMWE) and anion exchange membrane water electrolysis (AEMWE), are critical steps toward this goal. Therefore, this presentation will focus on catalyst development for PEMWE and AEMWE, with emphasis on cost-effective catalysts.For oxygen evolution reaction (OER) catalysis in PEMWE, the primary challenge is to minimize iridium (Ir) usage for sustainable green hydrogen production. Layered monoclinic iridium nickel oxide (IrNiOx) platelets were synthesized using a molten salt method and employed for the OER. These platelets exhibited high OER activity with reduced Ni dissolution in acidic conditions. When applied in MEA, they demonstrated enhanced interconnectivity within the catalyst layer, promoting electron transfer. Even at low Ir loading (0.2 mgIr cm-2), the platelets showed good performance with an initial cell voltage of 1.70 V at 1 A cm-2 and minimal degradation over 100 hours. This highlights the effectiveness of incorporating transition metals into Ir oxide to reduce Ir usage in PEMWE.For oxygen evolution reaction (OER) catalysis in AEMWE, attention is focused on nickel iron (NiFe) hydroxide catalysts for their high activity and stability in alkaline conditions. However, the lack of initial electrical conductivity of as-prepared NiFe LDH limits its potential as an electrocatalyst. To address this issue, a monolayer structuring approach was proposed. This method improved mass transport to allow a high energy conversion efficiency of 72.6% with exceptional stability over 50 hours at 1 A cm-2. Additionally, lack of initial electrical conductivity hinders determination of electrochemically active surface area (ECSA) of NiFe LDH using conventional double layer capacitance method. Use of electrochemical impedance spectroscopy (EIS) at reactive OER potentials to extract the capacitance that is hypothesized to arise due to reactive OER intermediates (O*, OH*, OOH*) adsorbed on the catalyst surface was thus investigated. This allowed the estimation of ECSA and intrinsic activity of NiFe LDH, validating the methodology through rigorous catalyst loading and support studies.For hydrogen evolution reaction (HER) catalysis in AEMWE, replacing platinum (Pt) with Ni-based alloys containing molybdenum (Mo) species has shown promise. Dynamic active sites of Ni catalysts with Mo species require innovative approaches to maintain initial performance, warranting material innovation or careful manipulation of operating protocol. The approaches in which this is made possible is shortly presented, together with the innovations that allows probing of such phenomenon.

Core of most Power-to-X (PtX) concepts is the utilization of renewable electricity to produce hy-drogen via water electrolysis. This hydrogen can be used directly as final energy carrier or can be converted further into e.g. methane, synthesis gas, liquid fuels, electricity or chemicals. To inte-grate PtX into energy systems, technical demonstration and systems integration are of major im-portance. In total 220 PtX research and demonstration projects to analyze these issues have been realized, are already finished or in the planning in Europe by June 2020. Key issue of this review is the identification and assessment of relevant projects regarding year of commissioning, location, electricity and carbon dioxide sources, applied technologies for electrolysis, capacity, type of hy-drogen post-processing, as well as the aimed field of application. Latter changed over the years. At the beginning, it was fuel production, e.g. for hydrogen busses, and combined heat and power gen-eration, later injection into the natural gas grid. Today industrial applications and once again fuel production are important applications. Focus for the fuel production is synthetic gaseous fuels, while production of liquid fuels is severely under-represented. The SOEC (solid oxide electrolyzer cell) has a very small share in projects compared to PEM (polymer electrolyte membrane) and alka-line electrolyzers. This is also reflected by the different installed capacities. While alkaline electro-lyzers are installed with capacities between 50 and 5000 kW (2019/20) and PEM electrolyzers be-tween 100 and 6000 kW, SOEC have a size of 150 kW. France and Germany show the biggest ef-forts into the development of PtX technologies compared to other European countries. Overall, ac-tivities have progressed considerably faster than predicted just a couple of years ago.

Green hydrogen production is currently on the rise, and it is reshaping the future of the energy sector. Numerous hydrogen roadmaps and projects are scaling up this technology in various target sectors, which necessitates cost reduction for green hydrogen implementation. Proton exchange membrane water electrolysis coupled with the renewable energy source (PEMWE-ReS) is a promising technology that offers notable advantages to decrease the electricity cost by using wind generation and solar photovoltaic system. However, to meet the growth of green hydrogen technology, accurate lifetime assessment and subsequent development of durable materials should be considered. In this regard, this presentation will discuss a comparative analysis of stability test results based on various load-ranges. In particular, to consider the PEMWE-ReS coupling, a realistic solar profile was simulated and applied for PEMWE cell measurement. The results were then compared to previous steady-state and dynamic loads to gain insight into the differences in degradation patterns at field and laboratory scale. For this purpose, the degradation features were systematically analyzed with electrochemical, microscopic, and spectrochemical analyses to see the dynamic of overpotential changes, membrane chemical degradation, catalyst dissolution/migration/diffusion, and Ti porous transport layer passivation. Notably, a realistic solar profile that simulates PEMWE-ReS conditions is featured by the increased fluoride release rate due to cycling to low load, and Pt dissolution/diffusion to the anode. Given the degradation features of the realistic solar operation, it was determined that a combined pattern of specific steady-state and dynamic cycling loads can induce the degradation features of solar operation the most. The findings can provide useful insights for establishing accelerated stress test to diagnose system durability and for setting design guidance for durable materials.

Hydrogen is one of the most efficient energy carriers and can be produced by different methods. Among all the production methods, the proton exchange membrane water electrolyzer (PEMWE) is considered as the most promising technique to produce highly pure hydrogen from renewable energy sources with pure oxygen as by-products with no carbon emissions. The PEMWE technology has reached the early stages of commercial deployment while the mass production is tied to cost reduction. A PEMWE single cell comprises a membrane electrode assembly which considered as a core component where the electrochemical reactions take places in three phase boundaries. It also includes a titanium based porous transport layer (PTL) in anode side and carbon-based gas diffusion layer (GDL) in cathode side for the transportation of water and gas into and out of the cell. Additionally, bipolar plates (BPPs) with grooves provide mechanical support for the cell and distribute the water inside the cell and remove generated gases to the outlet trough flow field distribution channels. PTLs and BPPs, which are metallic components, are designed to endure the corrosive conditions present in the electrolyzer and they both needs protective coatings to stand at high voltage (<2 V), acidic media, temperature (60–80 °C) and oxygen saturated environment (anode).In this research, a modified electroplating process is used to deposit gold thin film as a protective film on both stainless steel (SS) and titanium based BPPs and PTLs, respectively. The electroplating of gold is a mature technology and easy to implement for large scale coating. This process will be impacted by many factors, such as the ingredient of plating solution, arrangement of electrodes, current distribution, and operating parameters. In addition, pre-treating the surface plays an important role to develop the durable thin films with proper adhesion. The gold striking underlayer on the SS substrate passivated the surface oxides and facilitated a dense electroplated chromium layer. Furthermore, a uniform gold protective layer was electroplated on the chromium coated substrate to achieve a promising anti-corrosive property. To evaluate the impact of pre-treatment and the anti-corrosion properties of the developed coating, different physical and electrochemical characterization techniques are conducted. As a result, The Au/Cr/Au coating on the SS substrate showed corrosion current density of 0.84 µA/cm2 and lower degradation as compared to without gold striking underlayer.The surface morphology and the crystallinity and phase analysis are investigated by scanning electron microscopy and X-ray diffraction (XRD), respectively. X-ray photoelectron spectroscopy (XPS) is used to study the surface properties and the bonds between the elements. The contact resistance also is studied under different pressures. In addition, traditional lab-scale durability analysis, using stagnant liquid electrolyte and three-electrode cell setups, might not provide such a precise information for PEM water electrolyzer. The three-electrode setup does not include crucial parameters relating to real cell-operating conditions or contributions to the PTL by other key cell components such as the membrane, catalyst layer, ionomer, and bipolar plates. Flow electrochemical setup is developed in our lab and is used to run the accelerate stress test to check the durability of the coated samples. Potentiodynamic, chronoamperometry and impedance also used to evaluate the samples. Figure 1. (a) Schematic of gold electroplating on the SS substrate, (b) SEM image and EDX analysis of Au/Cr/Au coating.We would like to acknowledge the support of the Natural Sciences and Engineering Research Council of Canada, Canada Research Chair and Mitacs Accelerate program and Intlvac Thin Film for their constant support. Figure 1

Hydrogen energy, as a clean, efficient, and renewable secondary energy source, serves as a pivotal medium for global energy transition and the attainment of “dual carbon” objectives. Among the various production methods, water electrolysis has emerged as the paramount route for generating green hydrogen, owing to its operational zero carbon emissions and the highly purified hydrogen it produces. However, conventional electrolysis techniques rely heavily on noble metal catalysts, such as platinum and iridium oxide, whose prohibitive cost and limited availability significantly impede their widespread industrial application. Consequently, developing high-performance, stable, and cost-effective catalysts for water electrolysis remains a central challenge in advancing the hydrogen energy sector. Polyoxometalates (POMs), a class of nanoscale metal-oxygen clusters composed of transition metals like molybdenum and tungsten, present a promising alternative due to their diverse redox states, molecular-level tunability, pronounced negative charge, and robust structural stability. This review elucidates the advantages of polyoxometalate-based materials for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in water electrolysis. By integrating recent findings, it outlines multiple strategies to overcome current limitations associated with polyoxometalate electrocatalysts. Finally, the discussion addresses the benefits and challenges of employing POM compounds to enhance water electrolysis performance for hydrogen production and, by synthesizing cutting-edge research directions, forecasts future trends in this burgeoning field.

Due to the random fluctuations in power experienced by high-temperature green electric hydrogen production systems, further deterioration of spatial distribution characteristics such as temperature, voltage/current, and material concentration inside the solid oxide electrolysis cell (SOEC) stack may occur. This has a negative impact on the system’s flexibility and the corresponding control capabilities. In this paper, based on the SOEC electrolytic cell model, a comprehensive optimization method using an adaptive incremental Kriging surrogate model is proposed. The reliability of this method is verified by accurately analyzing the dynamic performance of the SOEC and the spatial characteristics of various physical quantities. Additionally, a thermal dynamic analysis is performed on the SOEC, and an adaptive time-varying LPV-MPC optimization control method is established to ensure the temperature stability of the electrolysis cell stack, aiming to maintain a stable, efficient, and sustainable SOEC operation. The simulation analysis of SOEC hydrogen production adopting a variable load operation has demonstrated the advantages of this method over conventional PID control in stabilizing the temperature of the stack. It allows for a rapid adjustment in the electrolysis voltage and current and improves electrolysis efficiency. The results highlighted that the increase in the electrolysis load increases the current density, while the water vapor, electrolysis voltage, and H2 flow rate significantly decrease. Finally, the SOEC electrolytic hydrogen production module is introduced for optimization scheduling of energy consumption in Xinjiang, China. The findings not only confirmed that the SOEC can transition to the current load operating point at each scheduling period but also demonstrated higher effectiveness in stabilizing the stack temperature and improving electrolysis efficiency.