Weekend reading: All of the above



Competition in the electrolysis space is intensifying. The International Energy Agency (IEA) expects 380 GW of hydrogen production capacity by 2030, so four different technologies are likely to emerge as demand peaks. We look at the market.

Converting all of today’s fossil-fueled gray hydrogen production to the green form of the energy carrier would require 950 TW of electrolyzer capacity. By 2050, electrolyzer capacity is expected to be four to five PW, so the European Patent Office and the IEA expect four different electrolyzer technologies to dominate the field.

Alkaline water electrolysis, which uses two electrodes made of a non-precious metal (typically nickel) operating in a liquid alkaline electrolyte solution, is the oldest technique. Introduced as a fuel cell technology in the 1960s, polymer electrolyte membrane electrolysis (PEM) contains a solid polymer electrolyte and has already been commercialized. Solid oxide electrolyzer cells (SOECs), which are in the pre-commercial demonstration stage, use a solid oxide – or ceramic – electrolyte to produce hydrogen gas. Finally, anion exchange membrane (AEM) technology is an evolution of alkaline water electrolysis and is currently undergoing a market entry phase.

Growing investments

Over the past decade, PEM electrolysis and SOEC systems have registered more published international patent families than alkaline water electrolysis. Triggered by carbon removal efforts and tight energy markets, electrolysis investments are accelerating and the focus is also shifting.

“The open grants for academic work focused more on increasing the efficiency of the cell and the right materials for the electrocatalyst and the membrane,” says Andras Perl, researcher from the “Entrance” (Energy Transition Center), Center of Entrance. Energy expertise at Hanze University of Applied Sciences in the Netherlands. “Now the focus is mostly on scaling up and eventually increasing the economics of electrolysis; how you can turn the process into something commercially viable, not just hydrogen. Hydrogen peroxide is an example.”

The primary investments are currently focused on cheaper materials, series production and increasing the automation of cell manufacturing. Industry observers expect costs to fall, but have refrained from making cost projections. At this point, radical innovations such as the production of hydrogen directly from the sun without electricity are expected to remain on the fringes of the electrolysis equipment market.

“I don’t see the industry adopting technology based on light-activated electrocatalysts at any point (soon),” says Perl. “It’s more of a university research focus.” The Hanze University researcher explains that scaling up the technology from the lab can be tricky, as achieving system stability can prove difficult.

PEM technology

European companies optimize their products, focusing primarily on their core business. “We are currently focusing on improving our PEM electrolyzer technology,” says Manuel Kuehn, Siemens Energy’s Sales Director for Sustainable Energy Systems. PEM electrolyzers operate at higher pressures and current densities, which means they take up less space than alkaline water electrolysis systems.

In the field of PEM electrolyzer production, as with the predecessor technology, the original equipment manufacturers are, at least for the time being, inventing a solution that suits everyone. They expect to optimize their products for local needs as the industry evolves.

“At the moment there is no order quantity or staff working on different system configurations yet,” says Kuehn. “However, at some point this will happen.” The projects are still relatively small, but practical experience in the field is being accumulated. “This is the only way to improve our confidence in the long-term functionality of technical solutions,” he adds. “With better data, we can support our customers in getting their projects financed.”

AEM technology

Hyter, part of the Italian Pietro Fiorentini gas group, is betting on AEM water electrolyzers (AEMWE). The company, placed in the commercial stage, manufactures and sells its AEMWE devices, all of which have their own stack chemistry.

“We are currently the company producing the largest AEMWE sizes on the market, with our Rigel stack producing 2 Nm3 (normal cubic meter)/h and the ambitious goal of developing our Sirius stack concept over the next few months, which would produce 50 Nm3/h of pure hydrogen,” says Massimiliano Masperi, Hyter’s product expert.

Masperi says that like other AEMWE developers, Hyter had technical difficulties with a few prototypes, but has now finalized the design concept. “Disregarding the balance of the plant, we achieved 4.3 kWh per Nm3 of the amount of hydrogen produced with an output pressure of 25 bar and a high purity of 99.95% without a purification unit,” says Masperi, explaining that AEM technology is on the rise for three reasons.

The type of electrolyzer achieved reaction efficiencies “that are very competitive with all other technologies,” says Masperi. At the same time, by using a lower alkaline electrolyte concentration, Aemwe does not require precious metals for the cells. It also benefits from cells that can withstand up to 25 bar working pressure, so the first compression step is skipped. “So in the end, the levelized cost of hydrogen between AEMWE and other technologies will be lower when they are comparable in size and dimensions,” he adds.

Perl, a researcher at Hanze University, says the biggest drawback of AEM technology is the design and balance of the plant, which require additional work. Hyter disagrees.

Alkaline electrolyzers

A 2018 paper by Karim Ghaiba and Fatima-Zahrae Ben-Fares found that alkaline electrolyzers have operating efficiencies – electricity to hydrogen – of 62–82%, compared to 67–82% for PEM systems. The efficiency of the solid oxide has yet to be determined.

PEM and AEM technologies can rise and fall faster than alkaline electrolyzers, but the difference, although significant in the laboratory, is less apparent in large installations. The units take some time to adapt to the energy input in both PEM and alkaline systems, as the additional components around the stack require time.

Ulf-Steffen Bäumer, Head of Innovation Center, Service and Digitization at German electrolyser manufacturer ThyssenKrupp Nucera, says: “When you use renewable energy in 5 GW applications, this does not vary in a fraction of a second. These fluctuations can last for minutes. So the difference between PEM and alkaline is limited in real applications. PEM and alkaline both have their strengths.” ThyssenKrupp focuses on alkaline technology.

Bäumer says that the company has been doing chloralkali electrolysis since the early 1980s. In this case, the cathode side, hydrogen production, is the same. “This is a significant advantage in large projects,” he says. “The industrial supply chain exists. So we already have a supply chain of 1 GW, which will grow to 5 GW in the following years.

Also, like AEM systems, chloralkali electrolysis uses a limited amount of precious metals.

ThyssenKrupp Nucera designs and sells standardized 20 MW modules. “Each one consists of electrolyzers, a stack and some core equipment that closes the electrolytes of the liquid electrolytic cycle and gives off hydrogen gas that has been reduced along with the water,” adds Bäumer. “This is the case in all geographies. Minimal adjustments are required.”

Alkaline water electrolysis technology tends to raise the temperature, but ThyssenKrupp considers raising the temperature to be a topic for the future, not the target of current optimization efforts. – We use chloralkali electrolyzers at 90 C, which is already quite high, says Bäumer.

SOEC technology

From a thermodynamic point of view, the electrolysis process has a higher electronic efficiency at higher temperatures. The system needs less electricity, but requires a heat source. Experts agree that SOEC technology has an advantage in this regard, as it operates at a temperature of 600 to 800 C. Service providers are now focusing on increasing the stability of this temperature range.

“I don’t see a lot of solid oxide electrolyzers,” says Perl. “I saw more work on solid oxide fuel cells.”

Industry insiders say that in the long term there will be room for different electrolysis technologies, as the demand will be so great that no single technology or a limited number of companies will be able to satisfy the appetite for green hydrogen devices. At the same time, mergers and acquisitions are expected.

“Many new players are developing: new companies from start-ups to companies from fields unrelated to chemical plants will enter this sector,” says Thyssenkrupp’s Bäumer. “It’s a very dynamic environment. From a business perspective, consolidation will happen, as it is happening now. Still, there will be big players, but also local players.

David is a passionate writer and researcher who specializes in solar energy. He has a strong background in engineering and environmental science, which gives him a deep understanding of the science behind solar power and its benefits. David writes about the latest developments in solar technology and provides practical advice for homeowners and businesses who are interested in switching to solar.

Read More

Related Articles


Please enter your comment!
Please enter your name here