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How does Smoltek's hydrogen business division compare with other PEM electrolyzer players? Smoltek Hydrogen’s president, Ellinor Ehrnberg, attended the 244th ECS meeting in Gothenburg and has the answer. In this interview, she also talks about the challenges of the industry and ways to deal with them.
In early October 2023, The Electrochemical Society (ECS) held its 244th meeting in Gothenburg. Smoltek Hydrogen was there with both a speaker at the conference and a booth at the exhibition. The purpose was mainly to meet potential partners and customers. But it was also an excellent opportunity for Smoltek to benchmark itself against some of the world’s leading researchers from industry and academia.
Smoltek wasn’t alone at the ECS 244th meeting. More than 3,400 researchers and industrialists participated.
“Many came from the USA, which is the home of ECS,” says Ellinor Ehrnberg. “But a surprising number came from Asia, especially Japan and Korea. I think it’s great because there are two giant LNG countries.”
LNG-countries? What does it mean?
“Just as coal has been an important energy source for the industry in Germany, liquefied natural gas, LNG, is an important energy source for the industry in Japan and Korea,” Ellinor Ehrnberg explains.
“Both countries import large amounts of LNG. Their industries need to replace natural gas with something more climate-friendly. As they are used to handle energy gas, hydrogen is a natural alternative ”, says Ellinor Ehrnberg, and uses Toyota as an example:
“Toyota dares to develop a mid-size hydrogen fuel cell vehicle while the rest of the automotive industry solely focuses on battery-powered cars. I believe the confidence to go their way comes partly from Japan’s experience with LNG.”
It’s not because Ellinor Ehrnberg is a proponent of fuel cells that she is happy to see many from Japan and Korea at the conference and on the exhibition floor.
“Proton-exchange membranes are used in both fuel cells and electrolyzers. This means that many technological advances made in the research and industrialization of membranes for fuel cells are directly transferable to PEM electrolyzers and vice versa,” says Ellinor Ehrnberg.
The ECS 244th meeting attracted many top talents in the industry, many of whom are from Asia, giving Ellinor Ehrnberg and her team a unique opportunity to benchmark their technology with others.
“Much research and development of proton-exchange membranes is done without publishing results. But, most people tend to be outspoken and share information at an event like this. So, we need to participate to learn more about others’ approaches and results.”
Before we examine the approaches taken by different companies and labs and the results they have achieved, we must understand the problem that fuel cell and electrolyzer manufacturers are trying to solve.
A membrane is at the center of the magic, where water is split into hydrogen and oxygen. It blocks electrons but allows protons to pass through – hence the name Proton Exchange Membrane (PEM).
On both sides of the membrane are electrodes. An electrode is a fancy term for an electrical conductor in contact with a nonmetallic part of a circuit (in this case, water). One of the electrodes is connected to the positive terminal of a power source and is called the anode. The other is connected to the negative terminal of the same power source and is called the cathode.
The power source wants to push out electrons at the cathode and pull in an equal number at the anode. However, this is not possible because the membrane blocks electrons. And here comes the trick:
We add water between the anode and the membrane. For the power source to draw electrons at the anode, water molecules (H2O) must split into two hydrogen atoms (2H) and one oxygen atom (O). The two hydrogen atoms then give up their single electron (2e-) and become two hydrogen ions (2H+).
(There is always a but in any good story.)
The oxygen atom fights back. It doesn’t want to let go of the hydrogen unless it makes a new friend. Oxygen atoms prefer to stick together in pairs (O2). However, this requires two water molecules to split up virtually simultaneously and close to each other, which doesn’t happen very often. So, to speed up the process, something is needed for the oxygen atoms to hold hands with while they look for a mate to merge with.
What do oxygen atoms like as much as themselves? Metal. Oxygen loves metal so much that it forms an oxide with it. If the metal is iron or steel, we call this oxide rust. And trust me, rust is not desirable in a PEM electrolyzer.
So, are there any metals that attract oxygen without perishing in the relationship?
Yes, you guessed it: Iridium.
Iridium is a safe place for oxygen atoms to land while waiting for a new partner. When two oxygen atoms land next to each other, they let go of the iridium and combine to become oxygen (O2).
Thus, we have the following reaction on the anode side in a PEM electrolyzer:
2H2O → 4H+ + 4e- + O2
On the other side of the membrane, the cathode spouts out electrons. The hydrogen ions (H+) are attracted to these excess electrons, so they migrate through the membrane. (Remember that a hydrogen atom is just a proton with an electron, so when the electron is gone, the hydrogen ion is a proton, which can pass through the membrane.)
Once on the other side, each hydrogen ion joins with an electron to become a hydrogen atom. Then, the hydrogen atoms join together in pairs to form hydrogen gas (H2).
And just like that, we have produced hydrogen gas from just water and electricity.
Of course, it’s not that simple.
Water has to flow around the iridium for the reaction to take place. The iridium should be in contact with the membrane to allow the hydrogen ions to cross over to the other side. The iridium must be electrically connected to a power source to pull the electrons in. And the oxygen gas has to be dissipated. All this happens only on the anode side of the membrane.
On the cathode side, the membrane must be in contact with the cathode so that the hydrogen ions can combine with electrons to form hydrogen atoms, which must then be transported away to be utilized.
Another thing to consider is that the more iridium in contact with the membrane, the more water can be broken down into hydrogen and oxygen. However, you can’t just cover one side of the membrane with iridium because it would block the hydrogen ions from passing through the membrane.
The solution is to build a stack called Membrane Electrode Assembly (MEA). Ellinor Ehrnberg describes how a typical MEA is built:
“Small grains of iridium are mixed in a solvent, and the result is used as ‘ink’ to make screen prints on the anode side of the membrane. The result is called a Catalyst Coated Membrane.”
“On top of the catalyst coating, a layer of electrically conductive and porous material is added to conduct electricity and water to the membrane and allow oxygen to escape. This is called the porous transport layer or PTL. Another PTL is added on the other side of the membrane to allow hydrogen to escape.”
“Finally, the whole thing is firmly pressed together to ensure that the membrane, the iridium, and the porous transport layer come into contact with each other,” Ellinor Ehrnberg concludes the explanation.
This sounds like an elegant solution. But there is a catch.
“The surface of the porous transport layer is… porous. It is not smooth. When everything is pressed together to make contact, its roughness can damage the catalyst coating, breaking the conductive path necessary for electron flow,” explains Ellinor Ehrnberg.
The solution is to apply several layers of catalyst coating on top of each other. But this is a significant waste of iridium because most grains of iridium end up inside the layer. They don’t come into contact with water and the membrane and don’t contribute to hydrogen production.
This would not be a problem if iridium were not so rare.
Iridium is extremely rare; only seven to eight tons can be extracted annually. This limited availability contributes to the metal’s high cost. As of October 2023, iridium’s market price exceeds USD 160,000 per kilogram.
Each PEM-electrolyzer doesn’t use much iridium. Catalyst-coated membrane uses about two milligrams of iridium per square centimeter (2 mg/cm2). But it adds up to a lot, and with the rapidly growing demand, it will soon cause the demand for iridium to exceed the supply.
So, something must be done.
Part of the solution is recovering iridium from end-of-life PEM electrolyzers. But that alone is not enough. To meet demand and keep the use of virgin iridium at an acceptable level, the amount of iridium per square centimeter of the membrane must be reduced to one-twentieth of the current amount.
That’s why 0.1 milligrams of iridium per square centimeter membrane (0.1 mg/cm2) is the industry’s holy grail.
Smoltek Hydrogen’s technology actually makes it possible to get as low as 0.1 milligrams of iridium per square centimeter in the near future.
“We’re not quite there yet, but we’re well on our way,” says Ellinor Ehrnberg and continues: “In the lab, we have reached 0.5 milligrams per square centimeter and expect to reach 0.1 milligrams soon.”
But how far have others come? This was the question that Ellinor Ehrnberg and her team sought to answer during the 244th ECS meeting in Gothenburg.
The most common route is to replace the solid grains of iridium with solid grains of cheaper materials and put iridium on the outside, either as a shell or particle by particle.
With this technique, labs can reduce iridium to 0.3 milligrams per square centimeter membrane (0.3 mg/cm2). But that’s about as far as it goes, according to Ellinor Ehrnberg:
“The coating must still have a certain thickness, which inevitably means that grains inside the layer cannot come into contact. So, even if you have reduced the amount of iridium by replacing the core with cheaper materials, you are still wasting a lot.”
Although 0.3 milligrams is a radical improvement, albeit so far only in laboratories, Smoltek’s goal is still three times more ambitious. With Smoltek’s technology, producing three times as much hydrogen for the same amount of iridium will be possible.
So, while the current technology can be greatly improved, Smoltek’s technology will still have a significant competitive advantage.
Is there no one else who can reach the same low level as Smoltek? Truth to be told, there is.
Los Alamos National Lab – perhaps best known for the atomic bomb – has chosen the same path as Smoltek. Instead of trying to improve a flawed idea – the Catalyst Coated Membrane – both have chosen a completely different route.
The idea is to create fibers that run like spikes between the porous transport layer and the membrane. The fibers are coated with platinum to protect them from the corrosive environment. Nanoparticles of iridium are attached to the outside of the platinum surface of the fibers. In this way, each particle comes into contact with water and contributes to hydrogen production.
“They have chosen the same path as us, and for me, that proves we are doing the right thing,” says Ellinor Ehrnberg.
Oh dear. Same solution. That cannot be good for Smoltek Hydrogen.
“There are crucial differences,” assures Ellinor Ehrnberg.
Unlike Smoltek, Los Alamos National Laboratory has chosen to create the fibers in the same material as the membrane. These fibers are “pulled out” of the membrane and bent at the top so that they touch each other. This creates two problems, according to Ellinor Ehrnberg:
“First, when a membrane electrode assembly is manufactured, the porous transport layer is pressed with great force against the membrane. That’s no problem for Smoltek’s strong carbon nanofibers, but it may be challenging for Los Alamos fibers. They are made of nafion, a soft polymer that readily bends under pressure.”
“Second, Los Alamos fibers must be bent at the tips to make electrical contact, which can impair water flow and oxygen dissipation.”
But perhaps the most important competitive advantage, according to Ellinor Ehrnberg, is Smoltek’s head start.
“My team is working in two parallel tracks. We are refining our technology to achieve 0.1 milligrams of iridium per square centimeter. And at the same time, we are developing an industrial manufacturing process. Our plan is to combine the two tracks in a pilot plant to be completed in 2025.”
Los Alamos National Laboratory is not working on industrialization at all. On a direct question from an employee at Smoltek, Jacob S. Spendelow, who presented the results from Los Alamos National Laboratory during the ECS 244th meeting, answered that they “wish” for a partner to industrialize the technology.
To summarize, Ellinor Ehrnberg is delighted with what she and her team learned during the ECS 244th meeting in Gothenburg.
She feels confident that Smoltek has chosen the right path. The classic route – adding layer upon layer of iridium grains – will always waste the scarce metal. To reach the holy grail – 0.1 milligrams of iridium per square centimeter (0.1 mg/cm2) – manufacturers must follow Smoltek’s path.
Although others are looking at the same path, Ellinor Ehrnberg is convinced that Smoltek is ahead of the game.
“We don’t know of any company that has come as far as us,” she confidently assures. “Others struggle with reducing iridium, obtaining sufficient lifetime, or scaling up.”What are your thoughts on Smoltek Hydrogen’s future? Leave your comments on LinkedIn.