by Hydrogeit | Jan 15, 2025 | Development, Germany, Market, News
Nordrhein-Westfalen is further expanding its capacities in the H2 research sector. In September 2024, the expanded HyTechLab4NRW in Duisburg went into operation. Since then, the site of the Center for Fuel Cell Technology has provided even better conditions for research into fuel cells and electrolyzers thanks to its improved infrastructure.
As part of extensive renovation work, the HyTechLab4NRW, which opened in 2019, was brought up to the latest state of the art and better equipped, particularly in terms of media supply, so that larger systems can now also be tested. ZBT Operations Manager Bernd Oberschachtsiek was visibly relieved: “Our temporary facility was the ugliest container in the world. Now we finally have a fully equipped laboratory that is not only technically up to date, but is also visually impressive.”
ZBT CEO Dr. Peter Beckhaus explained: “Today we are talking about fuel cell drives for ships, aircraft and trucks, with outputs ranging from 300 kW to the megawatt range. We have now created the right infrastructure to further research these applications.” Silke Krebs, State Secretary in the NRW Ministry of Economic Affairs, explained: “Hydrogen is a growth market and is of central importance for NRW in particular as an industrial location. We need new technologies and research to shape this future.” Prof. Astrid Westendorf, Vice-Rector for Research at the University of Duisburg-Essen, added: ”This is a real gain for our research infrastructure.”
The first ZBT Hydrogen Days on February 4 and 5 will provide an opportunity to view the improved facilities.
by Ole Raubner-Wagner | Dec 13, 2024 | Development, hydrogen development, Hydrogen economy, Market, News
Recycling as a Key Factor for Resource Efficiency
The hydrogen economy as a crucial technology for replacing fossil resources is subject to high expectations in terms of sustainability. Hardly any other growth area is the subject of such controversial discussions about how ‘green’ it really is. In the context of resources, the hydrogen economy however is about more than just ideological considerations. Electrolysers and fuel cells contain rare and valuable raw materials, such as the precious metals iridium and platinum. From economic and strategic perspectives, they must be recovered after the end of their life. Recycling is a must—and should be considered from the outset, not only when the end of life of the plants and vehicles is reached. But where does the circular economy stand today in the context of hydrogen? We provide an overview using the example of PEM technology.
Many valuable raw materials go into the stacks of electrolysers and fuel cells. When considering the weight, one could almost overlook the value drivers. It is only when looking at the value of the raw material components of a PEM stack (Proton-Exchange-Membrane) that it becomes clear that the focus is primarily on the CCM (Catalyst Coated Membrane). It consists of an ionomer that is coated with precious metal.
Valuable and Rare: Raw Materials in the Hydrogen Economy
Even though the composition of the stacks is constantly being optimized and therefore these 2016 data no longer completely correspond to reality, the precious metals on the membrane remain the value driver.
Precious metals are not only valuable, some of them are also extremely rare. This is particularly true for iridium, which is indispensable in PEM electrolysis. In May 2022, the Hydrogen Council [1] spoke of announced 175 gigawatts of electrolyzer capacity by 2030. Since then, the goals have become even more ambitious. According to experts’ estimates, 40 percent of this is expected to be realized with PEM technology. Based on the average amounts of iridium currently used per gigawatt, this would require around 28 tons of iridium—more than will be available during the same period.
The experts at the precious metal specialist Heraeus Precious Metals in Hanau, whose core business includes trading, products, and recycling of precious metals, estimate that, out of the very low annual production quantities of iridium, a maximum of cumulative twelve tons can be used for the hydrogen economy by 2030.
Circular Economy as a Lever for Growth
The industry is primarily addressing this challenge with technological innovations. The experts at Heraeus are doing this with catalysts that require significantly less iridium, reducing the required amount to seven tons by 2030. This however clearly demonstrates how important the establishment of a circular economy for raw materials will be for further growth, as an increase in production quantities of iridium is not considered realistic from the experts’ perspective.
In addition to considerations regarding raw material supply, the value of precious metals naturally plays a significant role. Typically, the recovery of the installed precious metals is part of the plan from the outset because they represent a significant share of the investment costs (CapEx). Reuse reduces the total cost of ownership by supplying future systems. Furthermore, the CO2 footprint of recycled precious metals is up to 98 percent lower compared to primary materials [2].
Recycling of non-precious metal components, such as titanium, steel, or aluminum, also contributes to reducing the total cost of ownership, even if the material value is lower. A higher value is created when it is possible to reuse them, but many questions still remain unanswered.
Establishment of Structures and Processes
To establish a sustainable and efficient hydrogen economy, efficient and economically viable structures and processes are needed. In principle, the recycling value chain can be divided into four major areas: return structure, processing & pre-treatment, recycling & refining, reutilization. The benefits of the circular economy can only unfold when all four components of the value chain are effectively designed, organized, and implemented.
Various Steps of a Circular Economy
Step 1: Return Structure
The return structure includes the processes and infrastructure required to return electrolysers and fuel cells at the end of their life cycle. This involves collection, logistics, and also the tracking of materials. It is essential to develop a clear concept here before the materials enter circulation. Once they are lost sight of, it becomes difficult to ensure widespread return.
A central issue here is the uncertainty about how the recycling infrastructure will develop in the future. Who should be responsible and accountable for the return? The manufacturer? The operator? The recycler? To avoid missing the opportunity to regulate in a timely manner, close collaboration along the entire value chain and supporting regulatory requirements are needed.
Step 2: Processing and Pre-Treatment
Once the stacks have been successfully collected, the next step is to process and pre-treat them. This is essential because a good yield for the materials can only be achieved if they are as homogeneous as possible before recycling.
Science and industry are still searching for the best method for the efficient and scalable separation of materials. One option is disassembly. In this approach, the stack is dismantled and broken down into components, specifically those for which processes already exist. For instance, the MEA (Membrane Electrode Assembly) has been processed in existing recycling and refining processes at Heraeus Precious Metals for more than ten years.
However, this approach is associated with a high procedural effort and is limited in terms of scale effects. Therefore, methods for automated or semi-automated disassembly are being considered, similar to those already widely used in traction batteries from electric vehicles.
In particular, for fuel cells, there is also the option to crush them as a whole using industrial shredding facilities. However, the resulting material mixture must then be separated in downstream separation and sorting processes, requiring careful attention. The by far most valuable components are the fragments which are destined for precious metal recycling. When separating and sorting these, certain impurities that would lead to more complex treatment or poor yields should be removed.
Therefore, pre-treatment and subsequent recycling steps are ideally carried out by a single source.
Challenges for Pre-Treatment
Overall, many questions remain unanswered. A major challenge is posed by the different designs of the stacks, particularly with regard to the automation mentioned. Agreement on standards and consideration of the entire life cycle, including recycling, already in the design, would significantly contribute to the solution. For example, a screw connection is easier to detach than an adhesive surface or a weld seam. Manufacturers, policymakers, and associations should address this issue.
Furthermore, the different components enter very different post-processing streams with very different requirements. With precious metals and membranes, (raw) materials are recovered, while for other components such as bipolar plates, a possible reuse of the component itself is on the table. Such functional recycling goes far beyond material value. Currently, it is not yet clear what is possible and economically feasible. This also leads to a lack of requirements for reutilization, which could serve to adjust the disassembly processes so that the components are not damaged and reuse remains realistic.
Step 3: Recycling & Refining
For precious metals, well-established processes have existed for decades to recover the valuable material. Initially, the material is thermally treated to remove non-metallic residues and the water. Subsequently, the material is carefully homogenized, and a representative sample for material analysis is drawn before further processing. This so-called sample serves to analytically determine the precious metal content of the material and forms the basis for the calculation of the amount of precious metal that will be compensated. In hydrometallurgy and refining, the precious metal is then recovered and highly purified.
Materials from the hydrogen economy are some of the more demanding materials in precious metal recycling. Iridium is chemically challenging, and the thermal treatment of fluorinated membranes requires special care in the safe post-treatment of emissions. Precious metal specialist Heraeus Precious Metals is one of the few companies that can efficiently process these material streams for its customers. Iridium has been processed on a ton scale for years, and significant investments have been made in the necessary facilities for the hydrogen economy.
Platinum-containing material after incineration
Special Processes for Special Materials
For the ionomer membranes, there is another possibility. Ionomers are special fluoropolymers that, due to their unique properties, significantly contribute to the functionality of fuel cells and PEM electrolyzers. They are complex to manufacture and therefore expensive. In addition, their handling after end-of-life is currently the subject of controversial discussions in the EU due to a proposal to regulate PFAS (per- and polyfluoroalkyl substances). Therefore, increased efforts are being made to find solutions for their reutilization. Work is underway to chemically separate the ionomers from the precious metals and process them separately.
To develop cycles for such demanding materials as fluoropolymers, collaboration among manufacturers, users, and recyclers is necessary, as demonstrated in the H2Circ funding project of the US Department of Energy: In this consortium, companies along the entire value chain work on the recovery of materials, especially ionomers. [3]
Step 4: Reutilization
After the recovery process is completed, the material is ready to be reused. This is not a problem for precious metals, as recycling provides high-purity materials according to internationally certified standards, which do not differ in their properties from primary materials.
In contrast, for ionomers, there are neither established recycling processes nor defined requirements for the recyclate. Unlike with precious metals, the recycled material here differs from that produced in primary manufacturing. Therefore, it requires not only the development of recovery processes, but also applications and markets for consumption.
Similar to the functional reuse of components, the ecosystem faces a chicken-and-egg problem here: Before the requirements for the use of the recycled material are clarified, the recycling processes cannot be meaningfully developed, also with regard to a possible business model. This is because only when the value of the output is clear can the costs of the process be calculated to determine if they will be worthwhile.
Setting the Stage for the Future
The Hanau-based precious metal company, Heraeus Precious Metals, systematically employs collaboration. For example, the company works with manufacturers of fluoropolymers to establish closed cycles for ionomers. Heraeus begins considering the value chain, including recycling, in the early stages of development together with its customers. It is also working on developing holistic solutions in public projects such as the aforementioned Department of Energy research project.
Even though the recycling of fuel cells and electrolyzers is currently limited in volume, its importance for the development of the hydrogen economy and the promotion of a circular economy should not be underestimated. Experts anticipate significant amounts of precious metals from the hydrogen economy by the end of this decade. It is important to take advantage of this window of opportunity to develop efficient processes across all parts of the value chain and to build corresponding recycling capacities.
Autoren: Ole Raubner-Wagner, Gisela Mainberger, both Heraeus Precious Metals GmbH & Co. KG, Hanau
Sources:
- Hydrogen Council, Hydrogen Insights 2023 [L]
- International Platinum Group Metals Association e.V, 2022, The Life Cycle Assessment of Platinum Group Metals (PGMs), [L]
- American Institute of Chemical Engineers, 2024, AIChE Selected by DOE to Lead New Hydrogen Electrolyzer and Fuel Cell Recycling Consortium, [L]
- Stahl et al., Ableitung von Recycling- und Umweltanforderungen und Strategien zur Vermeidung von Versorgungsrisiken bei innovativen Energiespeichern, Umweltbundesamt, 2016 [L]
- Kalkulation durch Heraeus Precios Metals, basierend auf Materialanteilen basierend auf H. Stahl et al., Ableitung von Recycling- und Umweltanforderungen und Strategien zur Vermeidung von Versorgungsrisiken bei innovativen Energiespeichern, Umweltbundesamt, 2016
by Monika Roessiger | Dec 13, 2024 | Development, Germany, hydrogen development, Market, News
Patented process as a cost-effective alternative to electrolysis
The course to success of Siqens began with special methanol fuel cells. Then came the electrochemical hydrogen separation (EHS) in addition, based on the self-developed HT-PEM-FC stacks. With their help, hydrogen can be separated from natural gas or waste gases from industry and waste incineration with a high degree of purity. The manufacturer also sees EHS in combination with its own fuel cells as a solution to the last mile problem.
Whether in the South American jungle or at an altitude of 3,000 meters in the Swiss mountains, in a research station in the Antarctic or at a border post in northern Scandinavia – in all these places HT-PEM fuel cells from Siquens are in use, which supply electricity for radio and measuring stations or cameras, as Thomas Klaue, managing director of the company founded as a startup in Munich in 2012, states.
The special methanol fuel cells are also, however, in less exotic places: For example, they serve in the lighting of German highway construction sites or aviation obstruction lighting of wind parks. The “Ecoport” FC systems consist of fuel cell stacks with a high-temperature polymer electrolyte membrane (HT-PEM) and a reformer. “In the reformer, pure hydrogen is obtained from methanol,” according to engineer and doctor of business administration Klaue. “This hydrogen then passes through the HT-PEM fuel cell. Our system works with industrial methanol, however, at a fraction of the cost compared to high-purity methanol.”
These systems therefore differ significantly from direct methanol fuel cells (DMFCs), in which a liquid methanol-water mixture is passed through the FC. For that, the methanol has to be as pure as for medical purposes, which is correspondingly expensive, explains Klaue, who has been CEO of Siqens since the end of 2019. The efficiency and power range of DMFCs are comparatively low, and they do not tolerate low temperatures well. Other indirect methanol fuel cells with PEM and reformer are available in both the low and high temperature range, but these would require manufacturer-specific methanol-water mixtures with lower energy density, according to Klaue. With a consumption of 0.6 liters per kilowatt-hour of electricity, Siqens is the market leader in efficiency. The Ecoports, according to Klaue “our bread and butter business,” have a peak electrical output of 800 or 1,500 watts (continuous operation: 500 or 1,000 watts).
FC as a replacement for diesel generators
Methanol, which has long been used in industry, like other liquid fuels, can be transported and stored cost-effectively. Because of this, (methanol) fuel cells are particularly suitable for areas without a connection to an electricity grid and where an uninterruptible power supply must be guaranteed, for example in the emergency power supply for critical infrastructure. Up to now, this function has mostly been performed by diesel generators, but these will little by little be replaced by fuel cells in the future – and not only because of their significantly lower CO2 emissions: They also work more quietly and are free of particulate matter and nitrogen oxides.
Ecoport 800
Demand for the patented systems, with which the southern German company has been on the market since 2019, is rising. For example, agencies, companies and operators of telecommunications systems are interested in the methanol fuel cells from Siqens, which according to Klaue are robust and reliable and can also be used far away from civilization. This applies to all climate zones, from minus 20 to plus 50 degrees Celsius. What’s more, the operating costs are around 75 percent lower than those of diesel generators. This year, the Munich-based company, which employs around 30 people, expects to sell several hundred of its HT-PEM fuel cell systems.
That the need to use hydrogen and fuel cell technologies for reasons of climate protection is increasing is beyond question today. The Siqens CEO stressed however: “We are convinced that the hydrogen economy will only be a success with price-competitive solutions, especially when it comes to last-mile distribution.”
FC as a replacement for diesel generators
In addition to fuel cells, the company has been offering a very special technical solution for producing pure hydrogen since 2022: electrochemical hydrogen separation (EHS). In this patented process, the feed gas flows through an HT-PEM stack, which is also used in the Ecoport, states Klaue. “The stack with the MEAs is comparable to a sieve that, under tension, is only permeable to the hydrogen molecules that have been reduced to protons on the anode side. On the cathode side, the protons get the electrons back. The product is highly pure hydrogen.” With this method, hydrogen can be separated, purified and processed from very different media. This can be natural gas or exhaust gas that is produced in industrial processes or from waste incineration. The hydrogen can also be obtained from natural reservoirs such as natural gas deposits.
And because methanol is a good hydrogen carrier, the EHS system can also avoid the last mile problem: From the methanol transported via the natural gas network, hydrogen is produced directly on site at the consumer’s premises CO2-free. “In 10 liters of methanol, approximately one kilogram of hydrogen is chemically bound,” calculates Thomas Klaue. This is more than in a standard 70-kilogram compressed gas cylinder that contains 50 liters of hydrogen compressed to 200 bar. The yield with that is only 0.8 kilograms. Instead of transporting hydrogen in bundles of heavy steel bottles or in pressure tanks by trailer, as was previously the case, a lot of money can be saved through the employment of methanol fuel cells.
Transport and storage costs currently make up the largest percentage of the hydrogen price. “This is even more true if the deployment location can only be reached by helicopter,” added Klaue. “The ratio of transport weight to useful H2 weight is for methanol ten to one versus one hundred to one for compressed gas cylinders.”
1 kg hydrogen for less than two euros
During EHS, likewise to water electrolysis, electricity is used. However, the energy requirement is significantly lower: Per kilogram of hydrogen, only three to five kilowatt hours of electricity would be needed; so around ten percent of the electricity required for electrolysis. “This produces hydrogen in fuel cell quality at a price of less than two euros per kilogram,” states Klaue. The technology is flexible, scalable and can be adapted to a wide range of gases. Such a system, which only takes up an area of one to two square meters depending on its capacity, can be connected directly to the gas network.
The EHS process could produce a good 100 kilograms of hydrogen per day with three stacks, which is enough for an H2 refueling station, according to Thomas Klaue. The modular design also allows several tonnes per day to meet the needs of an industrial company. “Electrochemical hydrogen separation is definitely an attractive alternative to other H2 technologies, as it consumes comparatively little energy and has a high selectivity for hydrogen,” according to the CEO.
Following an initial pilot project in Australia, there is now a second one in Germany: In the Unterfranken city of Haßfurt, hydrogen is being obtained from the natural gas grid using EHS. The municipal utilities of the city are known as pioneers, because they have been relying on renewable energies since the 1990s: photovoltaics, wind power and biogas from farmers in the region. Since 2016, they have had an electrolyzer to generate hydrogen from surplus wind power.
Now, with the help of EHS technology from Siqens, they are tapping into the municipal gas grid as a source of hydrogen. This is done in cooperation with the Helmholtz-Institut Erlangen-Nürnberg and the Institut für Energietechnik of the university Ostbayerische Technische Hochschule Amberg-Weiden. The hydrogen separated from the natural gas is compressed and stored and, as needed, converted into electricity via a fuel cell.
As many gas network operators want to add green hydrogen to their natural gas in the future, such solutions for separating and processing climate-neutral gas could soon become more significant. “By separating the gases using EHS at the point of consumption, the end customer can be supplied directly with high-purity ‘green’ hydrogen,” says Thomas Klaue. In other words, hydrogen of the quality required for industrial processes or fuel cell vehicles. For this reason, Klaue also argues vehemently in favor of maintaining the gas grids.
In February of this year, he publicly appealed to the German economy ministry to reconsider the dismantling plans; for cost reasons alone. “In addition, the planned H2 core grid will not be able to supply the entire country with green energy for a long time without great effort,” he says. However, because the nationwide gas network is largely suitable for hydrogen, the infrastructure should be used for the future transportation of green hydrogen, to supply industry and communities with climate-friendly energy.
by Jörg Steger | Dec 12, 2024 | Development, Germany, Market, News
Atmospheric plasma coating of polymer bipolar plates
In times of global sensitization to economic and especially ecological issues, awareness of energy-efficient whole solution strategies across the entire value chain and the sustainable use of available resources is also growing. Before profitable mass production of bipolar plates can begin, a whole series of developments and preliminary investigations are necessary in the product creation process, to determine the optimum efficiency depending on the design and execution. As this cannot be done with the help of simulations alone, experimental investigations are indispensable.
With the coating processes currently available on the market, prototype, pre-series and small series production is very time-consuming and cost-intensive. This is where the approach investigated by the research institute ITW Chemnitz comes in, to provide an easily moldable and cost-effective base material with a suitable coating, to carry out preliminary and small series tests in an energy-, time-, cost- and material-efficient way.
With the help of the combination of low-cost additive base material production and universally applicable coating technology implemented in this project, it is possible to manufacture different bipolar plate designs flexibly and cost-effectively, without neglecting the required industrial parameters. As a result, the envisaged versatile production technology should make it possible to produce prototypes as well as pre-series and small series in an energy-, time-, cost- and material-efficient manner and thus even out the path for industrial practice.
Coating technology plays a major role
In the course of the investigations, a low-energy plasma was used, into which the coating material used was definably fed in the form of microparticles. This enables a firm bond between the coating material and the substrate (see Fig. 1). Due to the technologically dependent low thermal load on the substrate to be coated, it is possible to create material combinations that seem at first glance unrealistic (in the context presented, a polymer as substrate and copper powder as coating material). Another advantage of the process used is the application under atmospheric conditions. In contrast to comparative processes such as physical or chemical vapor deposition, a prior evacuation and working in a vacuum are not necessary. Furthermore, the high degree of flexibility and the possibility of partial coating should be positively highlighted.
Search for suitable substrate material
When searching for and selecting a suitable substrate material, various challenges had to be accounted for:
- the required temperature resistance (should be oriented toward the operating temperatures of PEM fuel cells of about 110 °C),
- easy and variable processing (base structure should be producible using selective laser sintering, to ensure high design flexibility),
- the good as well as cost-effective availability of the raw material.
Several potential substrate materials were examined in more detail and tested for their suitability for coating. For this, variants available on the market were also modified so that they were optimized for the planned application. After a comprehensive series of tests, consisting of coating trials, optical analyses, surface measurements, simulative studies and thermal post-treatment tests with regard to temperature resistance, the choice fell on a glass fiber-modified polybutylene terephthalate (PBT). This material was modified by the targeted addition of glass fibers such that all the required technical parameters were achieved. In addition, the modified PBT has the best coating properties.
From the idea to industry-oriented flow field design
One of the major challenges within the investigations was the development of an industry-oriented flow field design taking into account the material-specific and technological limits of the processes used. This involved working out and defining the manufacturing limits of selective laser sintering, taking into account the material and the target application, as well as the technological limits of the subsequent coating process. To this end, various parameter and geometry studies were carried out on industrially used flow field designs. In the end, a meandering flow field structure with the following dimensions was realized:
| Effective area |
Channel width |
Web height |
Web width |
| 100 cm² |
1.5 mm |
1.5 mm |
0.6 mm |
Tab. 1: Realized flow field structure
The four wing-shaped hold-down devices (see Fig. 2) are required for fixation during the coating process and can be easily removed afterwards.
Developed polymer base body (left) and coating result (right)
To counteract any distortion, a metallic sample holder was used. This test setup ensures a targeted removal of the applied temperature and thus an optimum coating result. Both optical surface analyses and adhesion tests based on the cross-cut test in accordance with DIN EN ISO 2409 yielded satisfactory results and reveal a high potential for the abovementioned prototype, pre-series and small series production.
The studies were supported with funding from the German ministry for economic affairs and climate protection.
by Anette Weingärtner | Dec 11, 2024 | Development, Germany, hydrogen development, News
New catalyst releases H2 from ammonia
To facilitate and accelerate the recovery of hydrogen from ammonia, researchers from the institute for inorganic chemistry of the university Christian-Albrechts-Universität zu Kiel (CAU) have developed, in its project AmmoRef (duration 04/2021-03/2025), a more active and cost-effective catalyst together with its cooperation partners. The results of this work are retained in the hydrogen lead project (Wasserstoff-Leitprojekt) TransHyDE of the Germany ministry for education and research (BMBF). AmmoRef is one of ten TransHyDE projects that are funded by the BMBF. In it, existing technologies for hydrogen transport are to be improved.
The ability to store energy from wind or solar power is playing a central role in the clean energy transition. “The storage of energy in the form of chemical compounds such as hydrogen has many advantages. The energy density is high, and the chemical industry also needs hydrogen for many processes,” says Malte Behrens, professor for inorganic chemistry at CAU Kiel and subproject manager in AmmoRef. In addition, green hydrogen can be produced through electrolysis using electricity from renewable energy sources, without producing CO2.
Importing hydrogen from regions where wind and solar power is cheap is, however, not easy. One possibility is the chemical conversion of hydrogen into ammonia, which itself already contains a relatively large amount of hydrogen. For the transport of ammonia over long distances, a mature infrastructure already exists. “Ammonia can easily be liquefied for transport. It is already being manufactured on a megatonne scale and shipped and traded worldwide, and is therefore interesting for us,” says chemist Dr. Shilong Chen, scientist in the Kiel AmmoRef subproject of TransHyDE. Together Chen and Behrens are exploring how hydrogen can be released from ammonia after transport.
Image taken with a transmission electron microscope: nanoscale structure of the iron-cobalt catalyst. The many bimetallic particles, visible here as dark spots, are separated from each other at the nano level by the carrier material and thus contribute to a large active surface of the catalyst.
Source: Franz-Philipp Schmidt, Thomas Lunkenbein, adaptiert: Shilong, C.et al. Nature Communications (2024), https://creativecommons.org/licenses/by/4.0/
When hydrogen is transformed into ammonia, less gas is lost than with other processes. Ammonia allows itself, according to Behrens, to be liquefied already at a pressure of eight bar. Tankers could easily be filled with it. “A major advantage over other chemical processes, such as LOHC, is that hydrogen in liquid ammonia has a very high storage density,” says Behrens.
The problem for the scientists at the start of the project was to develop a catalyst that would allow ammonia to be quickly converted into hydrogen at the target location. “Large systems are required for this,” explains Behrens. However, there is currently no industrial application for reforming ammonia on this scale.
Cobalt for the activation of iron
The researchers’ goal was to find the cheapest possible materials for the catalysis. In addition, the expected application of the catalyst should be scalable. The material ruthenium is currently the benchmark in research. Iron is, according to Behrens, however, the most cost-effective metal used. “The problem, however, is that inexpensive iron catalysts suffer from low activity due to too strong iron-nitrogen binding energy compared to more active metals such as ruthenium. However, this limitation can be overcome by adding cobalt,” he explains. By combining two base metals – iron and cobalt – which creates highly active, bimetallic surfaces with a lower metal-nitrogen binding energy and other properties that are otherwise only known from much more expensive precious metals, the catalyst, which has a metal content of more than 70 percent, is not only highly active but also affordable.
“Highly active” means that it has a very high conversion speed. “Our catalyst reaches over 90 percent that of ruthenium and is around 20 percent more powerful than our nickel benchmark,” says Behrens. The researchers have also developed a special manufacturing method that allows a very high metal load. Up to 74 percent of the material consists of active metal particles. These alternate with carrier particles, so that cavities in the nanoscale range are created between them – like a porous, metallic nano-sponge. The structure is stable enough to withstand the high temperatures of around 600 °C associated with the decomposition of ammonia.
Previous result
By alloying iron with cobalt, the nitration of iron, which led to weak binding energy and thus lower activity, was suppressed and the nitrogen binding energy additionally influenced in such a way that the binding energies move closer to the peak of the activity volcano, which leads to a highly active and catalytic performance. It was also shown that alloying iron with other metals with weak nitrogen adsorption energy provides a simple and general approach to producing a highly active and nitride-free catalyst for the ammonia decomposition reaction.
Fig. 3: Prof. Malte Behrens and Dr. Shilong Chen in their Kiel laboratory in front of a test stand for new catalysts
Source: Julia Siekmann, Uni Kiel
Ammonia synthesis and decomposition
The production of ammonia using the Haber-Bosch process changed the world, as it enabled the production of fertilizers on an industrial scale. In 2021, 235 million tonnes of ammonia were produced, making it the highest-volume chemical produced. This production could be further increased in the near future, because ammonia due to its high hydrogen content and energy density as well as favorable infrastructure for transport and storage, as a carrier and storage material for regeneratively produced hydrogen, could help mitigate the climate crisis. In this scenario, hydrogen could be released from ammonia through its decomposition.
In contrast to ammonia synthesis, its reverse reaction, ammonia decomposition, has not found a comparable large-scale industrial application, but has been used primarily academically for over half a century to study the reaction mechanism of ammonia synthesis at ambient pressure on catalysts designed for the ammonia synthesis reaction. The most active catalysts for this synthesis are ruthenium-based, but the commercial aspect makes the less active but much cheaper iron catalysts appear more attractive. The reason for their moderate activity is the nitration. The present AmmoRef subproject was able to show how nitration can be suppressed and nitrogen binding energy, similar to ruthenium, can be achieved by alloying iron with cobalt.
The current challenge is to reduce the cobalt content. This is necessary on the one hand for cost reasons, but also because of the current political conditions under which cobalt is extracted. The prerequisites for upscaling are already there, but further measures need to be identified. In addition, it must be determined what still needs to be done to further increase the stability and activity of the catalyst. The addition of promoters, substances that increase the activity of a catalyst, is being considered.
Synthesis efforts are currently being transferred from the 1-liter to the 100-liter scale. The catalyst will now be further investigated and transferred from basic research to application. The scientists’ goal is to achieve an industrial scale for the catalyst.
by Niels Hendrik Petersen | Dec 9, 2024 | Development, Germany, Market, News
Hydrogen through photocatalysis
The startup Yellow SiC from Berlin is working on an innovative technology that does not require electrolyzers to produce green hydrogen. Yellow cells made of silicon carbide generate hydrogen directly on their surface. They utilize a broader spectrum of sunlight in this than other solar cells. Depending on the location, the production of “golden hydrogen” could be significantly cheaper than the production of green hydrogen from solar power. In this way, 6 cents per kWh could be achieved, even at our latitudes.
The H2 color palette is already quite extensive to the point of being dizzying. Now another variant is being added with “golden hydrogen.” At least that’s what Yellow SiC from Berlin have named their future product. The startup has developed its own technology: The innovative HydroSiC-Zelle splits water into hydrogen and oxygen in a one-step process. In this direct photocatalysis (more precisely photochemical water splitting), high-purity silicon carbide (3C-SiC) serves as a catalyst.
The 3C refers to the cubic crystal structure. This semiconductor material is yellow, which explains the name of the young company. Its solar cell does not require any electrical cables and consists solely of a 3C-SiC plate surrounded by water, which is exposed to sunlight from one side. This multi-junction solar cell utilizes a broader spectrum of sunlight than other solar cells – and that increases the efficiency. So there is no need for an electrolyzer. Instead, solar cells on the roof could produce green hydrogen directly.
First pilot plant in Osnabrück
There are currently various prototypes that show that photocatalysis works with the test material. “At the moment, we are mainly working on improving the material properties,” states cofounder and managing director Dr. Christopher Höfener. For a pilot plant, the electrodes that are currently produced on a laboratory scale still need to be produced in larger quantities. “We are now working on scaling up the manufacturing processes for the electrodes,” says the physicist and mechanical engineer.
Prototype cell: Photocatalysis with the test material works. Source: Yellow SiC
The young company has ambitious goals: As early as 2025, Yellow SiC wants to produce the golden hydrogen in a first pilot plant for H2 generation on the site of a paper mill in Osnabrück, Niedersachsen. “Electrolysis for H2 production is a thing of the past,” former investment banker Höfener is convinced. In his view, a two-stage procedure is simply too inefficient. This conviction is also underpinned by his financial commitment: Of the more than 8 million euros of the development costs raised, a significant part comes from his own assets.
Cofounder and CTO of the company Prof. Siegmund Greulich-Weber acquired his expertise in silicon carbide at the University of Paderborn. He has been working full-time for the startup for several years and leads the development team in Berlin.
The cost per kg of H2 ultimately depends on the efficiency of the material achieved:
“In contrast to silicon, where there is a physical limit for efficiency of around 33 percent, this limit for doped 3C-SiC silicon carbide is 63 percent – and thus achieves almost twice as many percentage points in the conversion,” says Greulich-Weber. He and his team assume that efficiencies of around 25 percent can be achieved for this so-termed solar-to-hydrogen process.
Hydrogen for 2 cents per kwh
The cost of conventional green hydrogen from electrolysis is currently between 4.5 and 6.7 US dollars per kilogram, or around 16 US cents per kWh. The young company forecasts the price of its product at 0.75 to 2 US dollars per kg – depending on the solar radiation per square meter. That would be less than a third of the current costs. This would result in costs of around 6 euro cents per kWh at our latitudes in Central Europe or 2 cents per kWh in North Africa. “Converted to the cost per kg of hydrogen, this amounts to 2 euros or 0.75 euro,” calculates Höfener.
The main advantage of the new technology lies in the lower costs and the smaller space requirement compared to a combination of photovoltaics and electrolysis. “The cost advantage arises because everything occurs in one step” stresses Höfener. This eliminates the high investment costs for the electrolyzer and the efficiency losses caused by the electrolysis process.
The next step for Yellow SiC is the demonstration of a prototype that shows the achievable efficiency on an area of a few square meters. Another important technical task is further optimization of the material. For this purpose, the electrodes produced will now be characterized using various methods.
2,000 °C and the highest purity
There are, however, still a few hurdles to overcome: Because the production of the material requires very high temperatures of around 2,000 °C – which entails a whole series of technical challenges. In addition, the process may only be carried out under the highest level of purity. More precisely: Out of one million atoms, only a maximum of one atom may be a foreign atom (1 ppm), is the company’s own stipulation. At the same time, attention must be paid to the correct doping and surface structure of the material.
That is a complex process. “The challenges are somewhat less when the material is used in electrolysis,” compares Höfener. Yellow SiC has already achieved interesting results in the tests: This way, the company was able to replace platinum and iridium in PEM electrolysis.
Another challenge is the search for skilled workers, because the team intends to continue to grow. Needed are mainly engineers, physicists and chemists, especially with experience in the fields of PEM/AEM electrolysis and the production of high-temperature ceramics. All in all, therefore very specialist topics. Berlin-Adlershof, where the startup is located, offers with partners from industry and research such as Helmholtz-Zentrum Berlin (HZB) an excellent environment for this.
Prototype cell, Source: Yellow SiC
The technology strengthens decentralized H2 production and thus fits in with the energy transition and the millions of photovoltaic systems on the roofs of private homes. However, the first applications will be for the chemical industry and steelworks, thinks Höfener. The company, founded in 2020, will start looking for new investors again at the end of the year.
At the beginning of last year, Conenergy from Essen already invested: “We were very impressed by the product, business idea and management of the company,” chairman Niels Ellwanger explains the decision of Conenergy to acquire a stake in the Berlin-based company. The task now is to bring further venture capitalists on board. For the new pilot plant, about 10 million euros of fresh money must come in.
