For over a century, alkaline water electrolysis (AWE) has formed the backbone of industrial hydrogen production, dominating the landscape of electrolyser capacity globally. Despite its long-standing presence, the fundamental principles and operational paradigms governing AWE have remained largely static, confined by traditional assumptions of near-atmospheric pressure, relatively low current densities, and steady-state operating conditions. However, a provocative new perspective from Liu et al. challenges this status quo, revealing that the technology’s perceived limitations are not inherent to the alkaline chemistry itself, but rather arise from these conventional operating regimes and system configurations. This insight invites a paradigm shift, reimagining AWE through the lens of industrial realities and technological innovation to reclaim its position as a flexible, high-performance player in the hydrogen economy.
The historical dominance of AWE is well understood. Electrolysers using alkaline solutions, typically concentrated potassium hydroxide (KOH), have been favored for their relative material abundance, robust long-term operation, and cost-effectiveness. Yet, in recent decades, proton exchange membrane (PEM) systems have eclipsed alkaline designs, boasting higher power densities, faster dynamic response, and more compact footprints. These advantages translate into better system efficiencies and flexible integration with renewable energy sources, driving their rapid adoption despite higher capital costs. The persistent “performance gap” between AWE and PEM electrolyzers has been treated as a consequence of fundamental electrochemical kinetics and membrane limitations intrinsic to alkaline chemistry.
Contrary to this widely held belief, Liu and colleagues argue that it is not alkaline chemistry but rather the operational and engineering constraints applied to conventional AWE that impose these performance ceilings. Near-atmospheric pressure operation constrains gas purity and energy efficiency, as gaseous hydrogen and oxygen evolve at low partial pressures, increasing the work needed for compression and purification downstream. Operating at low current densities further caps throughput and energy conversion efficiency since electrode reactions are not driven hard enough for optimal kinetics. Constant, steady-state operation ignores the pressing need for modern systems to respond dynamically to fluctuating electricity inputs typical of renewable sources, further limiting their industrial relevance.
A detailed, hierarchical analysis affirms that the performance gap emerges from an interplay of multiple loss mechanisms spanning scales from the electrode surface to entire plant operations. At the microscopic level, kinetic and ohmic losses arise within the electrodes and the separators immersed in concentrated KOH. These contribute significant voltage drops and heat generation, reducing faradaic efficiency and increasing the parasitic power consumption needed to maintain the electrolyte at elevated temperature. Meanwhile, macroscale losses in bipolar stack manifolds result in shunt and reverse currents that siphon off power and degrade overall stack performance. Beyond the stacks, at the plant level, additional inefficiencies manifest in power conversion electronics, mechanical compression of gases, and thermal management systems, aggregating into a substantial energy penalty.
To bridge this gap and revive alkaline electrolysis as a competitive, industrially viable technology, Liu et al. advocate for a coordinated and holistic approach that simultaneously targets material innovation, electrolyser design, power electronics, and system integration. Advances in electrode materials must prioritize catalytic activity and corrosion resistance in high alkalinity and elevated temperature environments, with novel nanostructured catalysts and improved conductive supports promising significant gains. The separator, traditionally a thick diaphragm ensuring ionic conductivity and gas separation, requires reengineering to minimize resistance while maintaining chemical and mechanical stability under harsher operating conditions.
Equally important, the architecture of bipolar stacks—the fundamental unit of electrolyser modules—needs transformation. Optimizing flow fields and electrical manifolds to suppress parasitic shunt currents and improve hydraulic conditions will mitigate energy losses and prolong component lifetimes. Integrating advanced power electronics capable of rapid load modulation and energy recovery will enable the electrolyser system to respond flexibly to variable power supplies, a trait indispensable for coupling with renewable energy sources such as wind and solar. Thermal management systems must also evolve to efficiently recycle process heat and maintain optimal temperature profiles that maximize reaction kinetics without compromising durability.
Operating under industrial-relevant conditions—elevated pressure, higher temperature, and concentrated alkalinity—combined with dynamic load profiles that mimic realistic renewable energy feedstocks, is crucial to validating these advances. Such testing moves beyond the standardized, steady-state performance metrics prevalent today and reveals the true potential and limitations of next-generation alkaline electrolysers. By embracing this comprehensive, multi-scale perspective, researchers and developers can generate new insights that unlock performance improvements once deemed unattainable.
The implications of revitalizing alkaline water electrolysis are far reaching. Given the global imperative for low-carbon hydrogen production as a key vector for decarbonizing industry, transportation, and power sectors, a cost-effective, scalable, and reliable electrolyser technology is paramount. Since alkaline systems use relatively abundant materials and avoid precious metals that limit PEM scalability, advances in AWE could democratize access to green hydrogen production worldwide, reducing dependence on limited material supply chains and expensive manufacturing processes.
Emerging research further explores innovative configurations such as pressurized AWE cells enabling direct output of hydrogen at elevated pressures, minimizing or eliminating recompression steps. Coupling electrolyser stacks with smart grid and energy management systems allows optimized energy flow and cost reductions, harnessing the variability of renewable generation instead of being impeded by it. A new generation of electrolysing plants designed with integrated heat exchangers, power electronics, and advanced control algorithms could fundamentally redefine the operational economics and environmental footprint of hydrogen production.
Far from an obsolete relic, alkaline water electrolysis appears poised for a renaissance driven by bold rethinking and cross-disciplinary innovation. By abandoning dogma and embracing realistic industrial contexts, the technology can evolve from tradition-bound designs to agile, efficient, and sustainable hydrogen workhorses. The work by Liu et al. charts a visionary roadmap that invites the global research community to reengage with AWE, unlocking its neglected potential to serve as a cornerstone of the emerging hydrogen economy.
As the urgency of global decarbonization intensifies and renewable energy capacities expand, the importance of flexible, cost-efficient electrolyser technologies capable of high-throughput, dynamic operation cannot be overstated. Rethinking alkaline water electrolysis through fundamental reconsideration of operating conditions, materials, stack design, and system integration opens a new frontier. This frontier promises to make green hydrogen production more accessible and scalable, accelerating the transition to a net-zero future.
Crucially, realizing these advances will require not only breakthroughs in electrochemical materials science but also innovations in engineering design, systems control, and industrial process integration. Collaborative efforts spanning academia, industry, and government will be essential to translate laboratory insights into commercial-scale implementations. Pilot projects demonstrating performance under true industrial conditions—including fluctuations in power input, elevated pressure and temperature, and integrated thermal and energy management—will provide critical validation and de-risk scale-up.
Looking ahead, alkaline water electrolysis serves as a compelling example of how revisiting and refining mature technologies in light of evolving industrial needs and scientific understanding can yield transformative outcomes. Rather than defaulting to newer but costlier alternatives, the hydrogen sector stands to gain substantially by revitalizing alkaline systems through modern innovations. The resulting flexible and efficient electrolyser platforms promise to underpin a resilient, low-carbon hydrogen economy powering a sustainable energy future.
In conclusion, the century-old technology of alkaline water electrolysis is not constrained by chemistry but by convention. Liu et al.’s insightful analysis reframes these constraints as opportunities for radical innovation across materials, system design, and plant engineering. By embracing higher pressure, elevated temperature, concentrated alkali, and dynamic operation, the industry can reinvent alkaline electrolysis as a versatile, efficient, and economically competitive solution for green hydrogen production at scale. This reinvention has the potential to reshape the hydrogen landscape and accelerate the global clean energy transition in the years to come.
Subject of Research: Alkaline water electrolysis technology and its performance under industrial operating conditions.
Article Title: Rethinking alkaline water electrolysis under industrial conditions.
Article References:
Liu, C.P., Pagliaro, M., Semenova, A. et al. Rethinking alkaline water electrolysis under industrial conditions. Nat Rev Electr Eng (2026). https://doi.org/10.1038/s44287-026-00302-w
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