DEVELOPMENT OF PERMEATION BARRIER COATINGS FOR STEELS IN HYDROGEN APPLICATIONS
.jpg)
Steel industry emissions must fall by at least 55% within 2030 to contribute to the European Green Deal final goal of making EU carbon neutral by 2050. The most promising mitigation approach to tackle the problem is the hydrogen transition, capable to reduce direct emissions by 48%. In the present scenario, a crucial role in this mitigation approach is played by repurposing gas pipelines and building of new hydrogen pipelines. Not all of them are “hydrogen ready” or “hydrogen-embrittlement-free” or their weld zones, the more susceptible to failure, raise concerns of possible serious incidents due to the hazardous nature of H2, thus application of HPB coatings will solve this issue. Commercial products are present but not tested or applicable to the internal walls of a hydrogen pipeline.
MITHRIL Project aims to develop durable hydrogen permeation barriers (HPB) coatings with 5 technologies (Gel, Pack Cementation, Sol-Gel, PECVD, electroless plating).
Thanks to its tailored coating technologies and instruments (there is PECVD specifically designed for this scope), MITHRIL solutions will fill this gap by developing, upscaling, validating at TRL5, and diffusing guidelines of HPB coatings to impart embrittlement-resistance and increase the steel ductility of at least 20%, allowing the repurpose or application of non-hydrogen-ready pipelines and thus boosting the EU hydrogen transition. MITHRIL will also study transferability of its solutions to other hydrogen-relevant sectors (e.g., nuclear, automotive, domestic storage).
MITHRIL CONTEXT
The hydrogen infrastructure involves hydrogen production, storage, and distribution, and different fields: pipelines, domestic, automotive, nuclear. Hydrogen ingress into structural materials, such as steel, can be detrimental due to corrosion and embrittlement, a phenomenon that describes the early failure of materials due to their reduction in strength and/or ductility in the presence of hydrogen. Considering hydrogen is flammable in the presence of oxygen, any material failure in hydrogen pipes can lead to serious incidents. Hydrogen barriers are crucial to prevent these phenomena to occur, thus prolonging the lifetime of the structural materials, avoiding costly replacements, and preventing or reducing the severity of possible accidents (especially in nuclear applications). While commercial coatings with barrier properties exist, they lack sufficient mechanical strength (and thermal resistance, if the application requires it) and thus durability to really impart the barrier property to be viable in real operating conditions. One of the crucial points of the hydrogen infrastructure is represented by its delivery. Assuredly, cost-efficient hydrogen distribution is essential for establishing an economically feasible hydrogen economy. Pipeline transmission is by far the most technologically ready and scalable method and the possibility of using existing natural gas pipelines for hydrogen transport would greatly reduce the investment.
Despite the economic appeal of using hydrogen in existing natural gas infrastructure, the differing properties of hydrogen and methane pose numerous challenges across the value chain, requiring substantial retrofits and replacements. Even if technical and economic barriers are overcome, serious safety and environmental risks remain. According to a new study funded by the EU-backed Clean Hydrogen Partnership, without the option to transport H2 through either retrofitting or new pipelines, there is a significant increase in costs and 20% CO2 emissions. There are about 91 planned hydrogen pipeline projects in the world, totalling 30,300 km and due to come online by 2035. Currently, more than 4,300 km already exists for hydrogen transportation with more than 90% located in Europe and North America. Globally, Europe is at the forefront of efforts to produce and import green hydrogen and its attention is now turning to building the necessary infrastructure to get it to demand centers. The presence of its extensive gas grid would make switching infrastructure from gas to hydrogen possible and cost effective, provided hydrogen embrittlement is prevented.
Pipeline industries are already checking the hydrogen readiness of their gas transmission systems, e.g., FGSZ (Hungary) in January 2022, APA (Australia) in May 2023, SGN (UK) in June 2023. In July 2023, TenneT (DE) issued a statement pushing for the repurposing of Germany natural gas pipelines to carry hydrogen, in August 2024 Germany revealed a project to set up a 9,700-kilometre hydrogen network by 2032, with 60% of the network being repurposed natural gas pipelines. Additionally, new pipelines for hydrogen transport are already being subjected to EU approval: in May 2023, Italy, Germany and Austria agreed to support the development of a 3,300-km hydrogen-ready pipeline between North Africa and Europe, led by Snam, Trans Austria Gasleitung, Gas Connect Austria and Bayernets, in July 2023 Greek grid operator DESFA has passed the EU technical approval for 540-km hydrogen pipeline, in July 2023 RINA and AFRY have jointly performed an initial feasibility study on the possibility of exporting to Europe low-carbon hydrogen produced in the Middle East could be exported through a new pipeline under the Mediterranean Sea, in September 2023 Snam has contracted Corinth Pipeworks to supply longitudinally submerged arc-welded steel pipes for transporting gas from an FSRU at the port of Ravenna, eastern Italy (The 26-inch pipeline will be certified to transport up to 100% hydrogen, and Corinth Pipeworks is devising solutions for hydrogen certification of new pipelines.), in November 2023 Società Gasdotti Italia has commissioned Corinth Pipeworks to produce over 80 km of 100% hydrogen ready pipelines, in July 2024 Corinth Pipeworks was awarded €27 million contract for hydrogen-ready pipeline in Greece, in August 2024 RINA has awarded Saipem two certifications for the performance qualification methodology of materials used in assembling subsea pipelines for transporting gaseous hydrogen, in the same month ArcelorMittal announced its HyMatch® new steel grades for hydrogen transportation.
The pipe materials are still being decided. Mid-strength steel grades API5L-X42 and X52 are known to be safe to carry hydrogen at 7 MPa at constant pressure/low pressure cycling, and they are being tested at 13 MPa. Yet, to guarantee a stable and consistent delivery, transmission efficiency needs to be increased and so higher pressures of hydrogen are required. To accommodate such pressures, investigations on the suitability of using higher-grade pipeline steels, such as API 5 L X60, X70, and X80 are in progress. However, high-strength pipeline steels are more susceptible to hydrogen embrittlement (HE) than mid-strength steels. Literature points to hydrogen permeation barrier (HPB) coatings to overcome HE (a) in steels being considered for new pipelines and (b) in steels used in gas pipelines that currently cannot be repurposed for hydrogen. The concept of HPB coatings is to prevent or delay permeation and diffusion of hydrogen without changing the desirable attributes of the base materials. Noteworthily, there is a third field – often disregarded by coatings literature – where HPB coatings will play a crucial role: hydrogen pipeline welds.
