"The plastics industry is H2-ready."

Interview with Dr.-Ing. Kai Fischer, Scientific Director at the Institute of Plastics Processing (IKV) at RWTH Aachen University

Dr. Fischer coordinates the area of hydrogen technologies at IKV. In 2021, he and his team conducted a twelve-month consortium study to identify potential cooperation between the plastics industry and the hydrogen economy. The resulting network became the Hydrogen Business and Technology Forum in 2022. Today, more than 20 well-known producers and users of hydrogen technologies are in close dialog with the plastics industry. In this interview, Dr. Fischer reveals why the exchange between the industries is essential for the hydrogen ramp-up.

gwf: Dr. Fischer, are plastics important for hydrogen technologies?

Dr. Fischer: Two points: Mass production and adaptability. Plastics are predestined materials for scaling up technical applications cost-effectively. In other words, where high volumes and high efficiency are required, plastics are indispensable. This is the case in all technical sectors, such as the automotive industry. In addition, plastic products can be adapted very well to different application requirements. That's why we say: If the hydrogen economy also requires high volumes one day, there will be no getting around plastic.

gwf: Has there been too little exchange between the hydrogen and plastics industries so far?

Dr. Fischer: We think so. It starts with production: green hydrogen, which is so popular due to its positive climate footprint, is produced in electrolysis. Today, however, only 4% of all hydrogen production takes place via electrolysers. One reason for this is that they contain many expensive stainless steel components - pipes, containers, etc. They would be much cheaper with plastic components, especially for the upscaling required to produce green hydrogen. Incidentally, there are formulations for all common plastics - PP, PE, PA and so on - that meet the requirements of hydrogen.

gwf: You mentioned it: There is no such thing as "the" plastic, but a whole range of different materials. And if you use plastic instead of metal, you have to be familiar with them and be able to combine them.

Dr. Fischer: Exactly! And that's what the plastics industry does, but now it also has to understand the individual elements in the systems of the hydrogen economy. That is our mission: to make the requirements of hydrogen system manufacturers known to the plastics industry so that they can propose solutions suitable for plastics in order to make the systems more performant, more durable and cheaper. Don't get me wrong - we don't want to and can't replace all steel. But we think that hydrogen systems will have just as significant a share of plastic components in the future as other technical applications with high cost pressure.

gwf: So the main driver for replacing metal with plastic is cost reduction?

Dr. Fischer: Definitely. It's always about costs; the systems are already efficient. Many already contain plastic core components, such as the PEM membrane. But a lot of metal is still used in the periphery. Here, plastic can replace many metal components - and in very large quantities. At the beginning of November, we launched a project to produce cheaper media line systems for electrolysers and fuel cells from plastic. We are cooperating with the manufacturers of these systems in order to precisely understand their requirements. Different media, such as deionized water, come into contact with the technical parts in the systems. It is important that the plastics are not damaged by these media, but also that the plastics do not transfer any contaminants that would impair their functionality.

gwf: Does plastic also have weaknesses?

Dr. Fischer: Yes, for example in terms of temperature resistance. We can't replace components that work at 300-400 °C. But there are very many components that operate in a range of 100-120 °C - no problem for plastics with the right design and choice of material.

gwf: There are public discussions about the sustainability of plastics, for example in the recycling of plastic packaging.

Dr. Fischer: That's true, but the technical plastic parts for hydrogen systems are clearly traceable in terms of their composition and recycling options. Without the complexity of the mixed fractions in the Yellow Bag, they can be recycled very well after use, i.e. returned to the cycles for high-quality mechanical recycling. Incidentally, we are talking about an operating life of around 30 years for an electrolyser. Fuel cells, tanks and other components are also designed for a long service life.

gwf: What about the CO2 balance? The use of green hydrogen falls under the buzzword "decarbonization", plastics are petroleum-based. By using plastics, aren't we buying carbon back in through the back door?

Dr. Fischer: The carbon footprint is an important aspect for us. It is probably clear to everyone that the production of plastic-based materials - as with all materials - emits CO2. However, the plastics industry is striving for defossilization. One method for this is mass balancing, in which waste gases from production are fed back into the production cycle. Another lever for improving the carbon footprint of today's hydrogen systems is the functional integration typical of technical plastic parts, in which many individual parts are replaced by a single part. This saves material and therefore automatically reduces CO2 emissions. In addition, functionally integrated parts often contribute to increasing the efficiency of systems - hydrogen production and hydrogen use also have an ecological price tag that is determined by system efficiency.

gwf: So far, we have mainly associated the combination of plastic and hydrogen with the distribution network.

Dr. Fischer: Plastic pipes are particularly relevant for today's distribution networks for gas and, in the future, also for hydrogen. Today, these are very heterogeneous networks with a wide variety of pipes and components such as fittings and seals. At IKV, we focus on technical applications, for example in the periphery and core components of electrolyser and fuel cell systems.

gwf: Does hydrogen embrittlement occur in plastics, as it does in steel?

Dr. Fischer: Hydrogen is also absorbed by plastics at high pressures. However, we are not aware of any negative long-term consequences. It may only be that rapid decompression events - sudden changes in pressure - lead to damage caused by the hydrogen absorbed in the component. However, this can be avoided by using suitable materials and material combinations. It is therefore important that plastics experts recommend the right composition and construction method so that manufacturers of hydrogen systems can design their systems to be suitable for plastics and not use "just any" plastics.

gwf: In addition to components for electrolysers and fuel cells, you also deal with plastic pressure vessels.

Dr. Fischer: Exactly. These so-called "Type IV" tanks are made entirely from plastic, or more precisely from liners that are wrapped in carbon fibers. They can be operated at up to 700 bar. Several companies are already producing them. These tanks are very durable and significantly lighter than metal tanks, making them ideal for mobile applications. Another application is to combine the type IV tanks in containers with a medium double-digit number of tanks. This increases the storage volume, which is interesting for large end users, filling stations or intermediate storage in the gas network.

gwf: What is the focus of your research in this area?

Dr. Fischer: We are making the production of tanks even more economical. We use 20-30 kg of carbon fiber reinforced plastic (CFRP) in one tank, and considerably more in large ones. CFRP is a very expensive material. Our approach is to study the mechanical behavior and make the production processes even more reliable in order to avoid oversizing and thus reduce costs.

gwf: What is the typical use case for type IV containers?

Dr. Fischer: In addition to the container solutions I mentioned, heavy-duty mobility: buses, trucks, trains, ships. These can only rarely be efficiently powered by battery electricity, which is why hydrogen is the ideal alternative for a climate-neutral drive. And with hydrogen, there is currently no alternative to type IV containers, as the vehicles would otherwise be far too heavy. In truck traffic, a pressurized container has an operating life of around 100,000 operating hours. For safety reasons, they are subject to extremely strict inspections and meet the highest requirements.

gwf: Can the type IV containers also be recycled?

Dr. Fischer: Absolutely. Carbon fiber recycling is an important topic. There are several approaches to recovering the fibers, such as pyrolysis. However, returning them to the original products is actually the last choice, as the same pressure vessel can be used for different applications. If it can no longer withstand high pressure, it can be used for another application with lower pressure. All you need to know is the exact condition of the container. We are also researching this: If you continuously observe the functionality of a pressure vessel via structural health monitoring, you can not only operate it for as long as possible in one field of application, but also estimate for which it can be used again or reused later.

gwf: Do you see an overall increase in hydrogen activities in research?

Dr. Fischer: Definitely. RWTH Aachen University has the Center for Sustainable Hydrogen Systems, which brings together and coordinates all of the university's research activities. There are over 100 hydrogen projects there alone - from production and bacteria to transportation in tanks and use in vehicles. We see the same in the international environment. The assumption everywhere is that hydrogen is an important element of a defossilized energy supply. But there is still a lot to do because the upscaling has not yet taken place.

gwf: And this is where plastic comes into play, which would be the decisive piece of the puzzle for the ramp-up of the hydrogen economy?

Dr. Fischer: We and our partners from industry are firmly convinced of this. And the challenges are manageable. But we need to know which functions are required in the various components and assemblies of hydrogen systems. Then we can develop plastic-compatible designs with the materials that are already available today. The plastics industry is H2-ready, now it needs to exchange ideas with the hydrogen industry as well as the quantities and requirements. Then it will be able to offer new, more cost-effective and CO2-efficient solutions in a short space of time.

gwf: Dr. Fischer, thank you very much for the interview!