- Within the scope of the project, SAG Group is working on the construction of the LH2 tank system and will assist in its installation at Milan-Malpensa Airport.
The ALRIGH2T project represents a significant advancement in sustainable aviation, focusing on the demonstration of Liquid Hydrogen (LH2) direct refuelling processes at an airport level for aircraft. Central to this innovative initiative is the participation of SAG Group (Salzburger Aluminium Group), a recognized leader in the aluminum industry and a prominent member of the European project consortium. The SAG LH2 tank system plays a pivotal role in this endeavour, serving as a critical component for the effective and safe refuelling of hydrogen-powered aircraft.
In the context of the project, SAG Group is involved in conducting real-life tests with LH2 and establishing a digital twin. This will enhance the thermodynamic models used to predict the behaviour of LH2 tank systems, ultimately optimizing development efforts for future applications in the aviation sector.
SAG Group, pioneering cryogenic tank solutions for CO2-free transportation
The mission of SAG Group is to develop technologies for the storage of alternative fuels for applications in road, rail and air transportation and thus make a significant contribution to CO2-free transportation. Since 2011, SAG has been involved in the development and manufacture of cryogenic tank storage systems for alternative fuels (LNG, LH2). These developments have been in the automotive sector and are based on stainless steel recently. The company has developed and refined the cryotank concept for heavy duty vehicles with a maximum capacity of 40kg LH2, which also makes it suitable for small aircraft applications.
SAG’s solutions have undergone rigorous testing and trial runs, and as of July 2024, they have been in daily operation on the roads with trucks owned by end customers. Alongside these operational milestones, the company possesses substantial expertise in conducting approval tests for liquid hydrogen storage. They have collaborated closely with certification authorities and partner research institutes to develop new testing protocols, as these had not been previously executed.
To date, SAG has developed three generations of LH2 storage systems for trucks, bringing them to a mature phase supported by an extensive testing program. Throughout this process, the SAG ALRIGH2T team has played a crucial role. The project benefits from the extensive expertise of the team, which is further enriched by their diverse educational backgrounds in engineering, rooted in university-level training.
The research team is led by Dr. Thomas Stepan (Senior Cryogenic Engineer), supported by Christian Eder (Project Manager) and Johannes Thaler (Cryogenic Design Engineer). Additionally, the cryogenics department at SAG has access to internal experts in simulation, testing, electronics, prototyping, and process technology, ensuring that all tasks in the project are effectively fulfilled. This collaborative approach enhances the team’s capability to address the project’s complex challenges.
SAG Group technicians at the company facilities.
Key contributions driving ALRIGH2T forward
SAG Group is at the forefront of Work Package 4 of the project, which aims to develop technologies for the direct refuelling of aircraft with LH2. A primary objective of this work package is to create a specialized tank designed specifically for this purpose.
To this end, SAG produced the first ready-to-use LH2 tank system for trucks, demonstrating a safe refuelling procedure for aircraft as well. This innovative system features advanced instrumentation that enables testing under real-world conditions. Additionally, the development of a digital twin will facilitate the simulation of structural loads and LH2 behaviour, ensuring maximum safety for future aerospace applications.
Building on SAG’s sLH2 tank system, which provides safe storage for liquid hydrogen and supports long hold times along with refuelling mass flows of up to 800 kg/h, a fully instrumented tank is being developed in collaboration with ALRIGH2T partners. This enhanced tank design incorporates numerous temperature sensors and stress gauges to accurately monitor the thermodynamic state of the hydrogen, allowing for precise comparisons with the test results from the fully instrumented system.
In partnership with project collaborators, a digital twin of the tank system is being created. This model will be validated against the test results from the fully instrumented tank, with the goal of limiting discrepancies in the thermodynamic states of LH2 between the real tank and the digital model to within 5%.
The construction of the complete tank system, including control units, will occur at the SAG Technology Centre, where trial operations using liquid nitrogen (LN2) will also take place in collaboration with ALRIGH2T partners from Work Package 4. The company will support the installation of the tank system at Malpensa Airport, as well as the refuelling process with LH2 or sLH2. The results of these operations will be compared with the digital twin model to further enhance the system’s accuracy.
However, the SAG team faces several challenges in executing these initiatives successfully. First, sensor technology suitable for cryogenic applications below LN2 temperatures is available only to a limited extent on the market. This technology will need to be adapted by the work package partners for the project. Ultimately, it is essential that the integration of this additional sensor technology minimally impacts the thermodynamic behaviour of the LH2 tank system.
Johannes Thaler: “Further improving the knowledge about our LH2 tank system with regards to future aircraft applications is an exciting technical challenge, with which we can do pioneering work again, as we did with our previous cryogenic tank projects. ALRIGH2T is another key project for us with high impact on the future of sustainable mobility”.
Christian Eder: “We are very pleased that we may contribute with our expertise in the development of cryogenic tank systems for trucks to the aviation sector as part of the ALRIGH2T project. A task that we were happy to accept and implement consistently”.
