Electrolyzer Manufacturing and ABB Robots

People have split water with electricity for more than two centuries, yet electrolyzer manufacturing at factory scale is only a few years old. A stack is a pile of thin plates, membranes and seals, and building them by the thousand is repetitive, precise work that suits robots. This post goes from the first lab experiments and Norway's hydro-powered plants to the automated lines Nel and Siemens Energy opened in 2022 and 2023. It also covers September's news about De Nora's gigafactory near Milan, the ABB arms that already work on one of these lines, and why electrolyzers are still expensive to build.

A worker guides an electrolyzer stack held by a lifting frame at Siemens Energy's factory in Berlin. Photo: Siemens Energy

How water splitting moved from lab glass to power stations

The first experiments were small. In 1789 the Dutch chemists Jan Rudolph Deiman and Adriaan Paets van Troostwijk split water with an electrostatic machine and gold electrodes in a Leyden jar. In 1800, a few weeks after Alessandro Volta invented his pile, the English scientists William Nicholson and Anthony Carlisle used it to do the same. Later in the century the glass Hofmann voltameter, with three upright tubes, became the usual way to show students that water gives two volumes of hydrogen for every one of oxygen. Chemistry classes still use it.

A Hofmann voltameter for splitting water into hydrogen and oxygen, at the Deutsches Museum. Photo: Mattes / Wikimedia Commons (CC BY-SA 3.0)

Cheap electricity turned the experiment into an industry. Zénobe Gramme's dynamo of 1869 made electrolysis an affordable way to produce hydrogen, and in 1888 the Russian engineer Dmitry Lachinov worked out a method for making hydrogen and oxygen by electrolysis on an industrial scale. Chemical plants then built whole halls of cells. A photo of the electrolysis room at a chemical works in Ústí nad Labem, in what is now the Czech Republic, taken around 1920, shows long rows of open tanks with cables hanging above them. Each cell was its own tank, so more output meant more tanks and more floor space.

The electrolysis room of a chemical works in Ústí nad Labem, around 1920. Photo: unknown author via Wikimedia Commons (public domain)

Norway had cheap hydropower and used it for some of the biggest electrolysis plants of the century. Norsk Hydro opened the Vemork power station in 1911 to supply a fertilizer factory. From December 1934 the site also made heavy water by electrolysis, which is why saboteurs blew up the heavy water section in 1943. Norsk Hydro started its hydrogen business in 1927, and the company Nel traces its roots to that work. For decades electrolyzers were built in modest numbers for fertilizer plants, laboratories and industry, with no need for anything like a gigafactory.

The Vemork power station in Norway, built by Norsk Hydro and opened in 1911, photographed in 1972. Photo: anonymous / Wikimedia Commons (CC BY-SA 3.0)

Electrolyzer gigafactories and the robots inside them

The first highly automated plants opened only recently. On 20 April 2022 Nel opened its factory at Herøya in Norway, which it called the world's first fully automated electrolyser production facility, with 500 megawatts a year of capacity for alkaline stacks. A second line later doubled that to about one gigawatt. At the opening, Nel's CEO Jon André Løkke said half of the savings the company needed would come from scale and more efficient production. In November 2023 Siemens Energy started series production of PEM stacks in Berlin, in a factory run with Air Liquide, with plans to reach three gigawatts a year.

ABB robot arms on the electrolyzer stack line at Siemens Energy in Berlin. Photo: Siemens Energy

Since then the rush has slowed. On 21 September 2026 De Nora said Italy's ministry of enterprise had cut public funding for its electrolyzer gigafactory in Cernusco sul Naviglio, near Milan, to 50.3 million euros in a decree dated 10 September. The earlier grants were worth about 63 million euros. De Nora started reviewing the project in March 2025 because of how the green hydrogen market was developing, and in July 2026 it adopted a plan with volumes matched to current demand. The plant, a project with the gas company Snam, had been planned for up to 2 GW.

A worker checks parts on the stack production line in Berlin, September 2023. Photo: Siemens Energy

Inside these factories robots do the work that is hardest to repeat by hand. In Berlin, coating machines put platinum on one side of each membrane and iridium on the other, cameras check the coating, and robots handle the fragile coated material. Siemens Energy's own photos of the line show ABB arms lifting and placing stack parts. ABB sells robot cells for fuel cell stacks, which are built in a similar way, covering coating, welding and sealing with its Integrated Dispensing Function Package. A large arm such as the IRB 6700 could carry heavy end plates, and lines like these are usually laid out and tested in RobotStudio before installation.

Engineers work beside an ABB robot in the Berlin electrolyzer factory. Photo: Siemens Energy

What it will take to make electrolyzers cheap

Cost is still the main problem. When Herøya opened, Nel said capital costs had to fall to about a quarter of the level at the time for green hydrogen to reach 1.5 dollars per kilogram. Automation lowers labor and scrap per stack, but only when the line runs near full. The De Nora decision shows the risk. A factory sized for fast growth sits underused if hydrogen buyers do not sign contracts, and a robot cell is an expensive asset in a half-empty plant.

A coated membrane for a PEM electrolyzer cell, the fragile part robots have to handle. Photo: Siemens Energy

For factories, the path may look like EV battery assembly a decade ago: bigger and more standard cells, and lines that switch between stack types without new tooling. Vision-guided robots would place plates and membranes, and software would track every layer for quality. Electrolyzers in homes are a long way off. Small units exist, such as the one from the UK's first hydrogen refuelling station, which is now in London's Science Museum, but the stacks coming off the lines in Herøya and Berlin are meant for industrial sites.

An electrolyser from the UK's first hydrogen refuelling station, now in the Science Museum, London. Photo: The wub / Wikimedia Commons (CC BY-SA 4.0)

The people side is unfinished too. A Siemens Energy staff member quoted in the company's own story put it simply: it is one thing for robots to handle parts in the car industry, and much harder when they handle sensitive membranes with ultrathin layers. Plants need technicians who understand both the robots and the electrochemistry. Safety adds work as well, because finished stacks run on high current and produce hydrogen. A gigafactory needs that mix of skills on every shift before its robots can run at full speed.

An ABB robot with a large gripper above a pile of stack plates in Siemens Energy's Berlin factory. Photo: Siemens Energy

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