“Both projects are about hydrogen,” says Othon Moultos of ME’s Department of Process and Energy (P&E) “because this is what brought us all together,” referring to his Cohesion partners, Poulumi Dey of the Department of Materials Science and Engineering (MSE) and Carey Walters of the Department of Marine and Transport Technology (MTT). Moreover, the success of this first Cohesion project ‘Multi-scale Modelling of Hydrogen Embrittlement’ led to a second collaboration between Moultos and Dey: a 4-year PhD project involving computational discovery of hydrogen storage materials.
“The idea for the first project came together quickly,” explains Dey, “because we knew that we wanted to tackle the problem of Hydrogen embrittlement.” This is the phenomenon of degradation of materials, particularly steels, in the presence of hydrogen that can cause cracks in a pipeline or a bridge: “Hydrogen embrittlement has been a problem for decades but it’s still unresolved because we don’t understand what the mechanisms are - partly because it happens at different scales. So we decided we wanted to get a fundamental understanding of what was happening at every scale and that’s why we wanted to work together because I work at the atomistic level, Otto at one scale higher, the molecular level, and then Carey’s higher again, at the actual structural levels.”
Bridge of scales
“It was really this bridge of scales, so going from the fundamental to the more applied, that was important to understanding how the structural integrity of a pipeline, for instance, will hold in the presence of hydrogen,” says Moultos. “So at Carey’s scale, he can answer the question of where the pipeline breaks, at my scale I can answer the question of how fast hydrogen diffuses through the pipeline, and at the atomistic scale, Poulumi can tell you how strongly the hydrogen binds to other materials.”
Gas and oil pipelines in the Netherlands
With Energy Transition becoming a huge issue right now, and hydrogen emerging as a cleaner and more sustainably produced alternative to fossil fuels, understanding the mechanisms behind Hydrogen Embrittlement has become an even greater priority, both worldwide and here in the Netherlands: “This country has been producing its own oil and gas since the ‘80s, using an extensive network of steel pipelines to distributing it nationwide. Now, with the Dutch government’s new hydrogen agenda, they’re thinking about using this same network to transport hydrogen.” So of course it’s important to understand how Hydrogen Embrittlement could affect existing pipelines so we know whether or not they are structurally suitable for the distribution hydrogen. Poulumi: “One problem with hydrogen is that it’s an extremely small molecule that penetrates materials much more than other gases with larger molecules such as methane, or natural gas.”
That's the good thing about Cohesion projects - to be able to do this kind of exploratory research projects, use your imagination and blend your expertise - and I think it works beautifully.
New software and the ‘right to play’
One year, two post-doctoral researchers and three partners later, the first Cohesion project has ended - with much to show for it. Walters: “We’ve published two papers - both of which have given us a good basis of understanding how hydrogen is distributed within steel, and that’s important to understanding how steel fails in the presence of hydrogen.” The project’s also produced some important infrastructure, software, and what Walters calls the ‘right to play’: “We have a reputation now as being a group of people who are doing good things on hydrogen and that has helped us all considerably.”
Borophene and hydrogen storage
Meanwhile Moultos and Dey are collaborating on a second Cohesion project entitled ‘Computational discovery of hydrogen storage materials.’ Dey: “The question is how can hydrogen be stored efficiently and within a reasonable volume? We already know that some materials are in principle good for storage, but the hydrogen binds so strongly you need to add things to get it back. So we’re wondering how we can ‘tune’ the properties of the material at the atomic or molecular level for more efficient hydrogen storage.”
Graphene for instance looks to be a promising contender, particularly ‘defective graphene,’ which is engineered to have ‘defects’ or vacancies where hydrogen can bind more tightly. But Dey and Moultos are now focussing on a new boron-based material called borophene, which like graphene is composed of a layer that is just one atom thick. “This project is a bit more ‘blue sky’, so beyond state-of-the-art, which you can’t normally do,” says Moultos. “And that’s the good thing about Cohesion projects - to be able to do this kind of exploratory research projects, use your imagination and blend your expertise - and I think it works beautifully.”