Alkaline electrolysers are the most established and widely deployed technology for electrolysis, providing a key source of industrial hydrogen production for over a century. As demand grows for low-cost, scalable, and reliable clean hydrogen, alkaline systems are an important technology that has been proven at the GW scale, while more advanced technology is still being tested at that scale. At a fundamental level, alkaline electrolysers operate using water electrolysis, the process in which electricity is used to split water into hydrogen and oxygen. In alkaline systems, an aqueous alkaline electrolyte enables ion transport, allowing for steady, high-volume hydrogen generation.
An alkaline electrolyser consists of an electrolysis stack made up of multiple cells. Water enters the system and, when electrical current is applied, hydrogen gas is produced at the cathode while oxygen is generated at the anode. Gases are separated by a diaphragm, enabling safe and continuous operation.
This design has made alkaline electrolysers a proven choice for industrial hydrogen production and other industrial electrolyser applications. As part of the broader category of hydrogen electrolysers, alkaline systems are often selected for large-scale electrolysis and centralized hydrogen plants where long operating hours are expected.
Modern hydrogen projects evaluate multiple electrolyser technologies depending on performance, cost, and application. To this point, AEM electrolysis is still in development for projects over 100MW, so PEM and Alkaline have been the preferred methods. In the ongoing comparison of PEM vs. alkaline electrolysis, alkaline systems are typically favored for lower capital cost and longevity, while PEM systems offer faster response times and higher power density.
Compared to proton exchange membrane (PEM) electrolysis, alkaline electrolysers operate at lower pressures and are less flexible under rapidly fluctuating loads. Emerging technologies such as AEM electrolysers and solid oxide electrolyser cell (SOEC) electrolysis aim to address some of these limitations by improving efficiency, operating temperature, or dynamic response. Across all types of electrolysers, alkaline technology remains the industrial reference point.
Alkaline electrolysers are valued for stable operation and competitive electrolysis efficiency, particularly when running continuously. Their mature supply chains and non-precious materials help reduce system costs, contributing to a lower LCOH (levelized cost of hydrogen) in many use cases.
Key characteristics that continue to make alkaline electrolysers attractive for industrial deployments include:
However, alkaline systems are less ideal for applications requiring rapid ramping or frequent start-stop cycles. This can limit their suitability for certain forms of distributed hydrogen production, though they perform well in predictable, high-utilization environments tied to renewable power generation or grid-connected energy assets.
Alkaline electrolysers play a growing role in hydrogen energy storage and long-duration energy storage strategies. By converting excess electricity into hydrogen, they support hydrogen grid integration and grid stabilization,helping balance renewable-heavy power systems.
Hydrogen produced via alkaline electrolysis can be stored in a hydrogen storage system using compressed gas, liquid hydrogen, or other hydrogen storage methods, depending on scale and application. These systems form a critical part of modern hydrogen infrastructure and the broader hydrogen supply chain. A leading example is the ACES Delta Project in Utah, which is using electrolytic hydrogen stored in underground salt caverns to provide large-scale, long duration clean energy storage for the power grid.
Thanks to their scalability and reliability, alkaline electrolysers are widely used across industrial hydrogen applications, including hydrogen for refining, chemicals, and steel.
As governments introduce hydrogen subsidies, incentives, and clean hydrogen tax credits, alkaline electrolysers remain a compelling option for organizations seeking low-cost hydrogen and proven performance.
While newer approaches such as AEM-based electrolysis and hybrid electrolysis continue to advance, alkaline electrolysers remain a cornerstone of today’s hydrogen economy. Their long track record, compatibility with large-scale infrastructure, and role in reducing the cost of clean hydrogen ensure they will remain relevant as hydrogen technology and global energy solutions continue to evolve.
If you're interested in learning more about electrolysis and the benefits of different electrolyser technologies, read our article on electrolyser types.
