I. Introduction: The Green Hydrogen Imperative and PEM's Role

The global energy landscape is undergoing a profound transformation, with green hydrogen emerging as a cornerstone for decarbonizing critical sectors. Produced through the electrolysis of water using renewable electricity, green hydrogen offers a viable pathway to significantly reduce carbon emissions in industries traditionally reliant on fossil fuels, including refining, chemicals, steel production, heavy-duty transport, and energy storage.¹ The urgency to achieve net-zero emissions by 2050 underscores the need for a rapid and substantial scale-up of low-emissions hydrogen production, with projections indicating a requirement of approximately 50 million tonnes of electrolysis-based hydrogen annually by 2030.¹

Among the various electrolysis technologies, Proton Exchange Membrane Water Electrolyzers (PEMWEs) are positioned at the forefront of this transition. Their inherent advantages, such as the ability to efficiently integrate with intermittent renewable energy sources like solar and wind, make them particularly appealing.³ PEMWEs boast high current density, superior hydrogen purity, rapid response times to fluctuating power inputs, and a compact design, all of which contribute to their suitability for dynamic operation within modern energy systems.³

Despite their significant potential, PEMWEs currently represent a modest fraction of the global hydrogen market, with less than a gigawatt of installed capacity recorded at the end of 2023.⁶ Nevertheless, the sector is experiencing accelerated growth. Installed electrolyzer capacity dedicated to hydrogen production nearly doubled in 2023, reaching 1.4 GW, while manufacturing capacity simultaneously expanded to 25 GW per year.⁷ Looking ahead, ambitious forecasts suggest a global installed capacity ranging from 230 GW to 520 GW by 2030, although a substantial portion of these projects remains in early development stages, with only about 20 GW having secured a Final Investment Decision (FID).¹ To align with the Net Zero Emissions by 2050 (NZE) Scenario, an even more aggressive target of 560 GW by 2030 is required.¹

The substantial disparity between announced project pipelines and those reaching FID highlights a critical phase for the green hydrogen industry. This gap, often referred to as a "valley of death" for large-scale projects, stems from several interconnected challenges. Key barriers include uncertainty surrounding future hydrogen demand, a lack of clear regulatory frameworks and certification standards, and insufficient infrastructure for hydrogen delivery to end-users.¹ For emerging economies, limited access to affordable finance further exacerbates these difficulties.⁷ Overcoming these hurdles is paramount, as technological advancements alone will not suffice to bridge this investment gap and accelerate deployment to meet global climate objectives. The industry faces the daunting task of achieving an unprecedented compound annual growth rate exceeding 90% from 2024 to 2030 to realize the full potential of its project pipeline, a pace significantly faster than even the most rapid expansion phases observed in solar PV deployment.⁸

II. Current Landscape: Performance, Costs, and Core Challenges

The widespread adoption of PEM electrolyzers hinges on continuous improvements in performance, substantial cost reductions, and enhanced durability. Understanding the current benchmarks and the underlying technical and economic challenges is crucial for charting the path forward.

Performance Benchmarks and Degradation

As of 2022, the typical stack performance for PEMWEs was characterized by a current density of 2.0 A·cm⁻² at 1.9 V/cell. Future targets are set to achieve 3.0 A·cm⁻² at 1.8 V/cell by 2026, with an ultimate goal of 3.0 A·cm⁻² at 1.6 V/cell.⁶ In terms of efficiency, current system efficiency stands at 65% Lower Heating Value (LHV), aiming for 69% by 2026 and an ultimate target of 72%. Stack efficiency is currently 70% LHV, with an ultimate target of 75%.⁶ The operational lifetime is currently around 40,000 hours, with an ambitious target of 80,000 hours.⁹ Some reports indicate a current operational lifetime of 60,000 hours.⁶

A critical metric for long-term viability is the degradation rate. The U.S. Department of Energy (DOE) reported an average degradation rate of 4.8 mV/kh (equivalent to 0.25%/1,000 hours) as of 2022, with targets to reduce this to 2.3 mV/kh (0.13%/1,000 hours) by 2026 and ultimately to 2.0 mV/kh (0.13%/1,000 hours).⁹ It is important to clarify a notable discrepancy in some reports that cite a "current degradation rate for PEMWEs of 25% per 1000 hours".⁶ Such a high degradation rate would imply a complete loss of performance in merely 4,000 hours, rendering the technology economically impractical for any significant operation. A detailed analysis from the same source that initially mentioned the 25% figure explicitly states that it does not contain this specific degradation rate.¹⁰ Therefore, the more credible and widely accepted degradation rate for current PEMWEs aligns with the U.S. DOE figures, approximately 0.25% per 1000 hours. Accurate and consistent benchmarking of performance metrics, particularly degradation rates, is fundamental for fostering investor confidence and accelerating technology adoption. Large variations in reported figures can create confusion and impede market development. The industry's focus remains firmly on reducing degradation to meet stringent targets, such as less than 14 μV/h ¹¹ or even less than 5 μV/hr ¹², to ensure long-term economic viability.

The following table summarizes the current performance metrics and future targets for PEMWEs:

Table 1: Current PEMWE Performance Metrics and Future Targets (U.S. DOE)

Cost Barriers

The high cost of green hydrogen production remains a significant impediment to its widespread adoption. Currently, green hydrogen costs range from $4.0–$9.0/kg H₂, substantially higher than hydrogen produced from greenhouse gas-intensive methods like Steam Methane Reforming (SMR), which costs $1.0–$2.5/kg H₂.⁶ Capital Expenditures (CapEx) for PEMWEs are a major contributor to this cost, currently ranging from $800–$1500/kW. To achieve the ambitious target of $1/kg H₂ by 2031, CapEx needs to be drastically reduced to $150/kW.⁶

Material costs within the Membrane Electrode Assemblies (MEAs) are a primary driver of stack costs, accounting for nearly half due to the reliance on expensive Platinum Group Metal (PGM) catalysts, specifically Iridium (Ir) and Platinum (Pt).³ Iridium, being a scarce and costly element, constitutes a substantial portion of the PGM content in PEM electrolyzers.⁹ Porous Transport Layers (PTLs) and Bipolar Plates (BPPs) also contribute significantly to overall costs, primarily because of their titanium base and expensive PGM coatings.⁶ Beyond capital costs, electricity expenses represent the single largest component of green hydrogen production costs. Even with relatively inexpensive electricity at $0.03/kWh, the electricity cost alone can amount to $3/kg H₂.⁶

Durability and Degradation Mechanisms

Ensuring long-term durability is a critical challenge for PEMWEs, particularly given the dynamic operating conditions often associated with renewable energy integration. Several degradation mechanisms affect key components:

• Anode Catalyst Layer (ACL) Degradation: Iridium dissolution is a prominent issue, with studies showing significant loss of iridium over time. This degradation is accelerated by dynamic operation and open-circuit voltage (OCV) conditions, which are common during startup and shutdown cycles.⁶ Further contributing to performance loss are the agglomeration of Iridium catalyst particles and ionomer, as well as the deposition of titanium and calcium on the cathode side.¹⁰
• Membrane Degradation: The durability of the membrane is a major concern, especially as the industry moves towards thinner membranes to improve efficiency.⁶ Membrane failure can occur through mechanical modes, such as creep, pinhole formation, and dry-out, or through chemical/electrochemical degradation, often induced by radical species or cation contamination. Higher operating temperatures can accelerate these degradation processes.⁶
• Porous Transport Layer (PTL) Degradation: The titanium PTLs are susceptible to surface passivation, which leads to a decrease in electronic conductivity. While coatings are applied to mitigate this, the coatings themselves can undergo dissolution and delamination over time.⁶
• Bipolar Plate (BPP) Degradation: BPPs face challenges from corrosion in the acidic and oxidizing environment of the anode, as well as hydrogen embrittlement on the cathode side due to hydrogen absorption, which weakens their mechanical integrity.⁶ The formation of oxide layers is a primary degradation phenomenon for both PTLs and BPPs, leading to increased high-frequency resistance.¹⁰
• Impact of Dynamic Operation: While PEMWEs are highly flexible and well-suited for coupling with fluctuating renewable energy sources, this dynamic operation can unfortunately accelerate the degradation of critical components, thereby reducing the system's overall lifetime.⁴

Manufacturability and Supply Chain Challenges

Scaling up PEMWE production from laboratory settings to gigawatt capacities presents significant manufacturing and supply chain hurdles. Many high-performing, low-loading catalyst layers developed in research are produced using lab-scale methods, such as ultrasonic spray coating, which are not amenable to large-scale, high-throughput manufacturing.⁶ Furthermore, ensuring consistent quality control during the scale-up of components like PTLs and catalyst layers is challenging, and defects at this stage can lead to costly failures at the stack level.⁶ The existing global supply chain for critical components, including catalysts, membranes, and PTLs, is not yet equipped for the rapid production scaling required to meet future demand, potentially leading to bottlenecks and increased costs.⁶

Regulatory and Policy Uncertainties

Inconsistent regulations, varying site permitting processes, and differing codes across diverse geographical regions complicate the standardization of PEMWE designs for global deployment.⁶ Beyond technical and manufacturing challenges, the uncertainty surrounding future demand for green hydrogen, a lack of clear certification standards, and limited access to low-cost finance continue to impede the realization of many announced projects.¹

III. Driving Innovation: Advancements in PEM Electrolyzer Technology

The challenges facing PEM electrolyzers are being met with a wave of innovation across materials science, component design, and manufacturing processes, all aimed at improving performance, reducing costs, and enhancing durability.

A. Catalysts: Thrifting Precious Metals and Non-PGM Alternatives

The high cost and scarcity of Platinum Group Metals (PGMs), particularly Iridium and Platinum, are major drivers for research into alternative catalyst strategies. Significant efforts are underway to reduce the PGM loading required in PEM electrolyzers.⁹ One key approach involves optimizing porous transport layers (PTLs) to improve the interface with the catalyst layer, thereby enhancing catalyst contacting and utilization, which in turn allows for a reduction in Iridium loading.¹⁸ The U.S. DOE has set aggressive targets to reduce total PGM content from 3.0 mg/cm² (2022 status) to 0.5 mg/cm² by 2026, with an ultimate goal of 0.125 mg/cm².⁹

Beyond reducing PGM use, the development of non-precious metal (NPG) catalysts is gaining substantial momentum due to the cost and supply chain volatility associated with PGMs.²⁰ Recent breakthroughs include the successful integration of cobalt phosphide (CoP), a highly active NPG catalyst, into a commercial-scale PEM electrolyzer. This system demonstrated over 1700 hours of continuous operation with negligible activity loss, marking a crucial step in translating lab-scale advancements to industrial applications.²¹ Furthermore, Argonne National Laboratory has developed a PGM-free Oxygen Evolution Reaction (OER) catalyst derived from electrospun metal-organic frameworks. This catalyst exhibits unprecedented activity and durability, approaching the performance of commercial Iridium, and can operate effectively in both acidic and alkaline media. It achieved a high current density of 2A/cm² at 2.4 V in an operational PEM electrolyzer, with material costs remarkably 2,000 times lower than commercial Iridium catalysts.²²

These demonstrations of NPG catalysts at commercial-scale and relevant current densities represent a pivotal moment for the industry. They signify a potential shift away from the reliance on scarce and volatile PGMs, which have long been a major bottleneck for the large-scale production of green hydrogen.²¹ If these NPG catalysts prove to be durable and scalable, they could drastically reduce the capital cost of PEM electrolyzers, making green hydrogen more competitive with fossil-fuel-based alternatives and accelerating its widespread adoption. This also contributes to strengthening supply chain resilience by diversifying the critical raw materials required for electrolyzer manufacturing.²³

B. Membranes: Enhancing Durability and Performance

Membrane technology is undergoing rapid evolution, with a dual focus on enhancing performance and addressing environmental sustainability. The implementation of thinner membranes is a key strategy to reduce ohmic losses and improve overall efficiency.¹⁸ Some experts project that thinner membranes could enable electrolyzers to produce 150% more hydrogen or operate with 10% lower energy consumption.¹⁹ However, this advancement must be carefully balanced with maintaining sufficient mechanical strength and preventing unwanted gas crossover.⁶

In the realm of advanced materials, novel perfluorosulfonic acid (PFSA) proton exchange membranes are being developed using a "self-enhancement" concept. This involves reinforcing PFSA with its own nanofibers, effectively addressing the compatibility issues often encountered in traditional composite materials. These "self-enhanced" membranes have demonstrated significantly increased proton conductivity (up to 1.1 S cm⁻¹, an order of magnitude higher than bulk PFSA), doubled mechanical strength, and suppressed water uptake and swelling.²⁴

A broader trend in membrane development is the growing shift towards hydrocarbon ion exchange membranes. This movement is largely driven by increasing concerns and potential restrictions on per- and poly-fluoroalkyl substances (PFAS), which are traditionally used in PFSA membranes.¹² Hydrocarbon membranes offer advantages such as lower cost and high performance, with ongoing advancements in their conductivity, durability, and resistance to chemical degradation.²⁶ Companies like Toray Industries are actively supplying proprietary hydrocarbon electrolyte membranes for large multi-megawatt PEM water electrolyzers, signaling their increasing commercial viability.²⁶ Furthermore, Ionomr Innovations has introduced its breakthrough Pemion™ hydrocarbon-based proton exchange membrane, which offers exceptional chemical and mechanical stability, high conductivity, enhanced durability, and efficiency, specifically targeting heavy-duty transport and industrial applications.²⁶

The ongoing research and development in membrane technology reflect a dual imperative: to improve performance and simultaneously enhance environmental sustainability. The shift towards non-fluorinated materials is a direct response to regulatory pressures and the broader need for a more sustainable hydrogen economy. This ensures that new materials are free of hazardous properties and minimize contamination risks.¹² The successful deployment of these next-generation membranes will not only boost PEM electrolyzer performance and reduce costs but also significantly improve the environmental footprint of green hydrogen production, aligning with overarching sustainability goals and potentially opening new markets where PFAS concerns are paramount. This diversification of materials also contributes to strengthening supply chain resilience.

C. Porous Transport Layers (PTLs) & Bipolar Plates (BPPs): Optimizing Flow and Durability

Porous Transport Layers (PTLs) and Bipolar Plates (BPPs) are fundamental components within PEM electrolyzers, playing crucial roles in water and gas transport, thermal and electrical conduction, and providing mechanical support.¹⁸ Innovations in these areas are closely linked to overall system efficiency and durability.

Fraunhofer ISE has made notable advancements in PTL technology by demonstrating ultrafine microporous titanium layers (MPLs) produced using a screen printing process. These MPLs are strategically applied between the PTL and the catalyst-coated membrane.¹⁸ These optimized MPLs significantly reduce surface roughness by 46%, leading to improved catalyst contacting and utilization. This enhancement, in turn, allows for a reduction in expensive Iridium loading and facilitates the use of thinner membranes, contributing to both cost reduction and efficiency gains.¹⁸

Advanced Bipolar Plates (BPPs) are essential for efficient reactant distribution, effective water removal, and maintaining electrical conductivity within the electrolyzer stack.²⁷ Recent innovations include novel flow-field geometries designed to optimize fluid dynamics and electrochemical reactions, thereby improving cell performance and preventing issues like hot spots and accelerated degradation.²⁸ One novel design features round, horizontally oriented flow field plates with radial, interdigitated anode channels and a spiral cathode channel. This configuration aims to achieve uniform water distribution and reduce shear stresses, which can be critical for high-pressure hydrogen generation.¹⁴

To address corrosion and hydrogen embrittlement, BPPs are increasingly being coated with precious metals like platinum or gold using Physical Vapor Deposition (PVD).²⁹ PVD-applied coatings enhance electrical conductivity, provide superior corrosion protection, and prevent hydrogen embrittlement, ultimately extending the operational lifespan of the electrolyzer and saving manufacturers millions of dollars over time by maximizing operational effectiveness.²⁹

The advancements in PTLs (specifically MPLs) and BPPs (through flow-field design and PVD coatings) are not isolated improvements. Instead, they are intricately linked to the performance of other components within the electrolyzer. For example, optimized MPLs directly enable lower catalyst loading and the use of thinner membranes.¹⁸ Similarly, advanced BPP flow fields improve reactant distribution, which has a direct positive impact on catalyst utilization and helps prevent localized degradation.¹⁴ The enhanced durability provided by PVD coatings on BPPs contributes to longer stack lifetimes and reduces overall operational costs.²⁹ This integrated approach to research and development, often termed "interface engineering" ¹⁸, emphasizes optimizing layers together rather than in isolation, recognizing the complex interplay between components.¹⁸ This synergistic innovation across materials science, electrochemistry, and mechanical engineering is crucial for achieving the simultaneous cost, performance, and durability targets necessary for gigawatt-scale deployment.

D. Stack Design & Manufacturing: Scaling for Gigawatt Capacity

The transition from laboratory-scale prototypes to mass manufacturing at gigawatt capacities is a pivotal phase for PEM electrolyzers. This industrialization imperative is driving significant advancements in stack design and manufacturing processes.

Companies are increasingly focusing on modular and containerized PEM electrolyzer solutions to streamline deployment and enhance scalability. Bosch, for instance, premiered its Hybrion PEM electrolysis stacks as a modular container solution with a 2.5 MW output in early 2025. Even before its official sales launch, the company had already secured 100 MW in global pre-orders.⁵ These modular systems are designed for flexible deployment, suitable for plants ranging from 1 MW up to large, gigawatt-scale industrial facilities.³⁰

Manufacturing process improvements are critical to achieving economies of scale. Bosch is leveraging its extensive expertise in volume production, gained from its fuel-cell manufacturing operations, to scale up hydrogen production and drive down costs. A notable innovation is the development of a special clamping tool that significantly simplifies and accelerates the assembly of the more than one hundred electrolysis cells that comprise each stack.³⁰

The global electrolyzer manufacturing capacity is expanding rapidly, reaching 25 GW annually in 2023 and projected to exceed 165 GW per year by 2030.² This expansion is characterized by the development of "gigafactories" by major players in the industry. Nel Hydrogen, Siemens Energy, and Toshiba are among the companies investing heavily in increasing production capabilities. Siemens Energy, in a joint venture with Air Liquide, initiated operations at a new gigawatt-scale plant in Berlin in November 2023, employing robotics and automation to produce high-efficiency PEM electrolyzers.³¹ Similarly, Toshiba established Japan's first 1 GW electrolyzer manufacturing base in Fukushima, with an initial capacity of 500 MW/year, expected to double by 2026.³²

This global race to scale up manufacturing capacity, led by regions such as China and Europe, is fundamental for achieving the necessary cost reductions through economies of scale and meeting the anticipated demand for green hydrogen.² This trajectory mirrors the industrialization of solar PV and battery manufacturing, where China's leadership in mass production has historically driven down global costs.⁸ Successful industrialization will not only make PEM electrolyzers more affordable but also ensure supply chain resilience and enable the rapid deployment essential for meeting ambitious decarbonization targets. This phase necessitates significant upfront investment and strategic collaborations between technology developers and industrial manufacturers.

IV. Integration and Operation: PEM Electrolyzers in the Energy System

The inherent flexibility of PEM electrolyzers makes them uniquely suited for integration into modern energy systems, particularly when coupled with variable renewable energy sources (VRES).

Suitability for Dynamic Operation

PEM electrolyzers are highly compatible with fluctuating renewable energy inputs from sources like wind and solar due due to their fast response times, high current densities, and wide partial load range.³ Their ability to rapidly adjust power consumption to match the variability of renewable energy generation enhances overall renewable energy utilization and contributes to stabilizing power grids.⁴

Providing Grid Services (Ancillary Services)

Beyond simply producing hydrogen, PEM electrolyzers can offer valuable grid services, generating additional revenue and significantly improving grid stability.⁵

• Frequency Regulation: PEM electrolyzers can swiftly adjust their power consumption to help maintain grid frequency within its narrow operational band.¹⁵ They can participate in Frequency Containment Reserve (FCR) markets, requiring a response within 30 seconds, and Automatic Frequency Restoration Reserve (aFRR) markets, which demand a response within 5 minutes.¹⁵
• Voltage Support: When interfaced with advanced power electronics, electrolyzers can provide reactive power support, contributing to the stabilization of voltage levels across the grid.³⁴
• Reserve Capacity: The capacity of electrolyzers to quickly reduce their power consumption can function as a form of "negative spinning reserve" or allow them to participate in non-spinning reserve markets, effectively freeing up generation capacity for the grid when needed.³⁴
• Utilization of Renewable Energy Surpluses: By converting otherwise curtailed renewable electricity into hydrogen, grid-serving electrolyzers can alleviate grid congestion and reduce the need for costly grid expansion, thereby maximizing the overall utilization of VRES.¹⁵ Pilot programs in Denmark have demonstrated that flexible PEM operations can increase revenue by up to 57% through the provision of grid ancillary services.⁵

Challenges and Considerations for Dynamic Operation

While the flexible operation of PEM electrolyzers offers substantial benefits for grid integration, it also presents a critical challenge: dynamic operation can accelerate the degradation of expensive catalytic converters, potentially shortening the service life of the electrolyzers.¹⁵ This creates an inherent trade-off between maximizing revenue from providing grid services and minimizing the costs associated with accelerated component degradation. Currently, economic incentives for flexible operation may be limited due to the high upfront technology costs, which often incentivize continuous, high-load operation to maximize return on investment.¹⁵

The economic viability of flexible operation depends on a delicate balancing act between the revenue generated from grid services and the increased costs incurred from accelerated degradation. Existing regulatory frameworks and economic incentives may not yet fully compensate for the increased wear and tear on components. To fully realize the potential of PEM electrolyzers as grid-balancing assets, continued research and development are necessary to enhance their durability under dynamic loads. Simultaneously, the development of robust regulatory frameworks that provide clear and sufficient economic incentives for grid-serving operation is crucial. This includes appropriately valuing the systemic benefits of avoiding grid curtailment and reducing the need for grid expansion.¹⁵

V. Global Momentum: Key Projects, Market Growth, and Policy Support

The PEM electrolyzer market is experiencing robust growth, driven by a combination of technological advancements, supportive policies, and increasing global commitments to decarbonization.

Market Growth and Capacity Expansion

The PEM electrolyzer market size was valued at USD 5.24 billion in 2024 and is projected to grow at a compound annual growth rate (CAGR) of 15.7% from 2025 to 2034, with an anticipated market size of USD 9.12 billion by 2034.³¹ Global installed electrolyzer capacity for dedicated hydrogen production reached 1.4 GW at the end of 2023, almost doubling from the previous year.⁷ Manufacturing capacity is also rapidly expanding, reaching 25 GW per year by the end of 2023 and projected to exceed 165 GW per year by 2030.²

Regional Leadership

• China: China is a dominant force, leading in electrolyzer capacity additions with a cumulative capacity of 780 MW in 2023 and over 9 GW at advanced stages of development. It accounts for more than 40% of global Final Investment Decisions (FIDs) in capacity terms and is home to 60% of the world's electrolyzer manufacturing capacity.¹
• Europe: FIDs for electrolysis projects in Europe quadrupled over the past year, exceeding 2 GW. Europe and China are projected to collectively hold approximately half of the global manufacturing capacity by 2030.² The European Commission has set ambitious targets for a tenfold increase in electrolyzer manufacturing capacities by 2025.³¹
• India: India has emerged as a key player, with a 1.3 GW FID and the launch of its National Green Hydrogen Mission, allocating approximately $2.4 billion, which includes a 1.5 GW PEM tender under the Strategic Interventions for Green Hydrogen Transition (SIGHT) program.⁵
• North America: The U.S. PEM electrolyzer market size surpassed USD 234.3 million in 2024.³¹ The U.S. Inflation Reduction Act (IRA) is a significant policy driver promoting local hydrogen production.⁵
• Other Regions: Japan has committed $100 billion for hydrogen development by 2038.⁵ Australia approved a 200 MW Whyalla PEM plant in 2024.⁵ The Middle East and Africa are also emerging as key markets, with mega-scale green hydrogen export projects underway.³³

Key Projects and Commercial Deployments

Several major projects and commercial deployments underscore the global momentum:

• Siemens Energy: Launched advanced 1.25 MW PEM electrolyzer modules in 2024, optimized for decentralized installations.³³ The company is collaborating with EWE on a 280 MW PEM plant in Emden, Germany, designed to reduce CO₂ emissions in the power sector.⁵ In a joint venture with Air Liquide, Siemens Energy also commenced operations at a gigawatt-scale manufacturing plant in Berlin.³¹
• Bosch: Introduced its "Hybrion" modular, containerized PEM electrolyzers (two 1.25 MW units) in early 2025, securing 100 MW in global pre-orders before their official sales launch.⁵
• Plug Power: Deployed a 1 MW PEM electrolyzer at an Amazon facility in Colorado to power fuel-cell forklifts.⁵ The company also signed a technology licensing agreement with Siemens for modular electrolyzer systems.³²
• ITM Power: Secured a 100 MW PEM electrolyzer deployment order from the UK National Grid for a "Green Hydrogen Hub" project.³²
• LONGi Hydrogen: Signed a supply agreement for at least one 2,000 Nm³ alkaline electrolyzer for Saudi Arabia's NEOM project, which is poised to become the world's largest single green hydrogen project.³² While this specific project uses alkaline technology, it illustrates the immense scale of hydrogen initiatives globally.
• Industrial Applications: Over 63% of current electrolyzer installations are in heavy industry.³³ PEM electrolyzers are increasingly being adopted to replace fossil fuels in sectors such as steel production, chemicals, refining, and ammonia manufacturing.⁵
• Mobility: PEM electrolyzers are critical for hydrogen mobility applications, including buses, trains, and trucks. Projects like Plug Power's forklift fueling initiative and India's SIGHT tender include transport-focused PEM systems.⁵

The following table provides a snapshot of selected global PEM electrolyzer projects and manufacturing capacity expansion initiatives:

Table 2: Selected Global PEM Electrolyzer Projects and Manufacturing Capacity Expansion

China's role in the global electrolyzer market presents a complex dynamic. While it is a dominant force in electrolyzer manufacturing capacity, accounting for 60% of the global share, and a leader in FID projects, representing 40% of global FIDs ², this is largely attributed to its established strength in mass manufacturing of clean energy technologies, reminiscent of its historical role in solar PV and battery production.⁸ However, it is noteworthy that in 2023, approximately 90% of global coal consumption for hydrogen production occurred in China, indicating a continued reliance on unabated fossil fuels for its current hydrogen supply.¹ This situation highlights that China is simultaneously a leader in scaling up green hydrogen manufacturing and a major consumer of high-emissions hydrogen. Its manufacturing prowess is expected to drive down electrolyzer costs globally ⁸, offering significant benefits for the worldwide energy transition. However, its domestic energy mix for hydrogen production still poses a substantial decarbonization challenge. International collaboration and policy alignment will be critical to ensure that this manufacturing scale translates into truly green hydrogen deployment on a global scale.

VI. Outlook: The Path to Widespread Green Hydrogen Adoption

The green hydrogen industry, particularly the PEM electrolysis sector, is currently experiencing unprecedented momentum. This surge is propelled by continuous technological advancements, robust policy support, and an escalating global commitment to decarbonization.⁵ Significant progress is evident in reducing the reliance on precious group metals, developing advanced membrane and component designs, and rapidly scaling up manufacturing capabilities.¹⁸

Despite this positive trajectory, substantial challenges persist. The primary hurdles revolve around achieving full cost competitiveness with conventional hydrogen production methods, enhancing long-term durability under demanding dynamic operating conditions, and establishing a robust and scalable supply chain for all critical components.⁶ The notable gap between announced projects and those that have reached Final Investment Decision (FID) underscores the urgent need for clear market signals and effective financial de-risking mechanisms to unlock the full potential of the pipeline.¹

The successful widespread adoption of green hydrogen produced via PEM electrolyzers depends on several critical factors:

• Continued Research and Development: Sustained investment in both fundamental and applied research is indispensable for driving further breakthroughs in materials science, electrochemistry, and system integration. This is particularly crucial for the development of cost-effective non-PGM catalysts and more durable, environmentally benign membranes.¹²
• Industrialization and Automation: The rapid scale-up of manufacturing through the establishment of gigafactories and the implementation of advanced automation processes will be paramount to achieving economies of scale and significantly driving down Capital Expenditures (CapEx).²
• Policy and Regulatory Support: The existence of clear, consistent, and long-term policy frameworks, including incentives for green hydrogen production, mechanisms for demand creation, and supportive regulations for grid-serving operation, is essential to de-risk investments and accelerate deployment.¹
• Cross-Industry Collaboration: Fostering strong collaboration among research institutions, technology developers, manufacturers, and end-users across the entire hydrogen value chain—from production to delivery and utilization—is vital for optimizing the ecosystem.²

The journey towards widespread green hydrogen adoption is a complex, multi-faceted undertaking where progress in one area often depends on, or enables, advancements in others. Technical breakthroughs in materials and design are necessary, but their impact is amplified by economic factors, which are, in turn, profoundly shaped by supportive policy and regulatory environments. This interconnectedness means that the success of PEM electrolyzers is not merely a technological challenge but a systemic one. Bottlenecks in any single area can significantly impede overall progress, underscoring the necessity for integrated planning and coordinated efforts across governments, industry, and academia.

PEM electrolyzers are unequivocally poised to play a central role in the global energy transition. By continuously pushing the boundaries of performance, cost-effectiveness, and durability, and by fostering a supportive ecosystem that addresses the interconnected technical, economic, and policy dimensions, green hydrogen produced via PEM technology can become a cornerstone of a sustainable, carbon-neutral future. The ongoing innovations and the burgeoning global project pipeline indicate a strong trajectory towards widespread adoption, promising to transform industries and contribute significantly to global climate action.²

Works cited

1. Hydrogen - IEA, accessed July 12, 2025, https://www.iea.org/energy-system/low-emission-fuels/hydrogen
2. Securing the Supply: Electrolyzers for Green Hydrogen | WRI India, accessed July 12, 2025, https://wri-india.org/perspectives/securing-supply-electrolyzers-green-hydrogen
3. Status and perspectives of key materials for PEM electrolyzer - SciOpen, accessed July 12, 2025, https://www.sciopen.com/article/10.26599/NRE.2022.9120032
4. Dynamic modelling of a PEM Electrolysis System: optimal ... - POLITesi, accessed July 12, 2025, https://www.politesi.polimi.it/retrieve/c4e3275e-4a65-4b42-bbd8-dd9368d61215/Tesi_Molho_Simone.pdf
5. PEM Electrolyzer Market is Gaining Strong Momentum Ahead - TimesTech, accessed July 12, 2025, https://timestech.in/pem-electrolyzer-market-is-gaining-strong-momentum-ahead/
6. Proton Exchange Membrane (PEM) Water Electrolysis: Cell-Level ..., accessed July 12, 2025, https://pubs.acs.org/doi/10.1021/acs.chemrev.3c00904
7. Electrolysers - Energy System - IEA, accessed July 12, 2025, https://www.iea.org/energy-system/low-emission-fuels/electrolysers
8. Executive summary – Global Hydrogen Review 2024 – Analysis - IEA, accessed July 12, 2025, https://www.iea.org/reports/global-hydrogen-review-2024/executive-summary
9. Technical Targets for Proton Exchange Membrane Electrolysis ..., accessed July 12, 2025, https://www.energy.gov/eere/fuelcells/technical-targets-proton-exchange-membrane-electrolysis
10. Investigation of the Degradation Phenomena of a Proton Exchange ..., accessed July 12, 2025, https://pubs.acs.org/doi/full/10.1021/acssuschemeng.4c07358
11. Proton exchange membrane electrolysis - Wikipedia, accessed July 12, 2025, https://en.wikipedia.org/wiki/Proton_exchange_membrane_electrolysis
12. Jan 17, 2024 Development of non-fluorinated ... - Funding & tenders, accessed July 12, 2025, https://ec.europa.eu/info/funding-tenders/opportunities/portal/screen/opportunities/topic-details/horizon-jti-cleanh2-2024-05-02
13. H2NEW: Hydrogen (H2) from Next-Generation ... - Publications, accessed July 12, 2025, https://www.nrel.gov/docs/fy24osti/89648.pdf
14. Design of a Proton Exchange Membrane Electrolyzer - MDPI, accessed July 12, 2025, https://www.mdpi.com/2673-4141/6/2/30
15. Grid-serving integration of electrolysers - VDE, accessed July 12, 2025, https://www.vde.com/resource/blob/2238464/1a45861506354b372b42f5faaab27d79/discussion-paper-grid-serving-integration-of-electrolysers-data.pdf
16. PTL for Water Electrolysis Market Disruption: Competitor Insights and Trends 2025-2033, accessed July 12, 2025, https://www.datainsightsmarket.com/reports/ptl-for-water-electrolysis-243401
17. Electroconductive and Durable Ceramic Supports for Low-Loaded, accessed July 12, 2025, https://ecs.confex.com/ecs/248/meetingapp.cgi/Paper/212373
18. Fraunhofer ISE Demonstrates Ultrafine Transport Layers for ..., accessed July 12, 2025, https://www.ise.fraunhofer.de/en/press-media/press-releases/2025/fraunhofer-ise-demonstrates-ultrafine-transport-layers-for-electrolyzers.html
19. Clean Energy Trends for 2025 ... - North American Clean Energy, accessed July 12, 2025, https://www.nacleanenergy.com/alternative-energies/clean-energy-trends-for-2025-advancements-in-electrolyzer-technology
20. Anion exchange membrane electrolysis - Wikipedia, accessed July 12, 2025, https://en.wikipedia.org/wiki/Anion_exchange_membrane_electrolysis
21. Non-precious metal hydrogen catalyst in commercial ... - OSTI.GOV, accessed July 12, 2025, https://www.osti.gov/servlets/purl/1576567
22. R&D 100 of the day: PGM-free OER Catalyst as Replacement of ..., accessed July 12, 2025, https://www.rdworldonline.com/pgm-free-oer-catalyst-as-replacement-of-iridium-for-pem-water-electrolyzer/
23. Critical and strategic raw materials for electrolysers, fuel cells, metal hydrides and hydrogen separation technologies - ResearchGate, accessed July 12, 2025, https://www.researchgate.net/publication/381079864_Critical_and_strategic_raw_materials_for_electrolysers_fuel_cells_metal_hydrides_and_hydrogen_separation_technologies
24. Self‐Enhancement of Perfluorinated Sulfonic Acid Proton Exchange ..., accessed July 12, 2025, https://www.bohrium.com/paper-details/self-enhancement-of-perfluorinated-sulfonic-acid-proton-exchange-membrane-with-its-own-nanofibers/964343466848944132-2016
25. Ion Exchange Membranes 2025-2035: Technologies, Markets, Forecasts - IDTechEx, accessed July 12, 2025, https://www.idtechex.com/en/research-report/ion-exchange-membranes/1089
26. Hydrocarbon Membranes in Fuel Cell and Electrolyser Market Size ..., accessed July 12, 2025, https://www.industryarc.com/Research/Hydrocarbon-Membranes-in-Fuel-Cell-and-Electrolyser-Market-800736
27. Hydrogen and Fuel Cell Technologies Office Multi-Year Program Plan - Department of Energy, accessed July 12, 2025, https://www.energy.gov/sites/default/files/2024-05/hfto-mypp-fuel-cell-technologies.pdf
28. Advanced Bipolar Plates for the Next Generation PEM Water ..., accessed July 12, 2025, https://www.researchgate.net/publication/387254962_Advanced_Bipolar_Plates_for_the_Next_Generation_PEM_Water_Electrolyzers_Flow-Field_Design_Fabrication_and_Optimization
29. Physical vapor deposition maximizes performance of PEM ..., accessed July 12, 2025, https://www.materion.com/en/insights/blog/physical-vapor-deposition-maximizes-performance-of-pem-electrolyzers-for-hydrogen-fuel-production
30. Hannover Messe 2025: Bosch embraces hydrogen production ..., accessed July 12, 2025, https://www.bosch-presse.de/pressportal/de/en/hannover-messe-2025-bosch-embraces-hydrogen-production-274816.html
31. PEM Electrolyzer Market Size, Growth Outlook 2025-2034, accessed July 12, 2025, https://www.gminsights.com/industry-analysis/pem-electrolyzer-market
32. SMM Survey: Weekly Review of the Electrolyzer Industry, 2025-2024, accessed July 12, 2025, https://news.metal.com/newscontent/103297200/SMM-Survey:-Weekly-Review-of-the-Electrolyzer-Industry-2025-2024
33. Hydrogen Electrolyzers Market Report 2025 - Global Growth Insights, accessed July 12, 2025, https://www.globalgrowthinsights.com/market-reports/hydrogen-electrolyzers-market-100639
34. Electrolyzer Ancillary Services → Term - Prism → Sustainability Directory, accessed July 12, 2025, https://prism.sustainability-directory.com/term/electrolyzer-ancillary-services/
35. Pem Electrolyzer Market Size, Growth, Trends, Report 2034, accessed July 12, 2025, https://www.marketresearchfuture.com/reports/pem-electrolyzer-market-24929
36. Proton Exchange Membrane Electrolysis Benchmarking - Publications, accessed July 12, 2025, https://docs.nrel.gov/docs/fy25osti/94212.pdf
37. Green Hydrogen Basics - From Electrolyzers to Industry Impact - YouTube, accessed July 12, 2025, https://www.youtube.com/watch?v=1_Mmn6hTinY