Project Description
Key information
Project title: THERMODYNAMICS-DRIVEN CONTROL MANAGEMENT OF HYDROGEN POWERED AND ELECTRIFIED PROPULSION FOR AVIATION
Project in the Spotlight: E23015
Funding: This project has received funding from the European Union’s Horizon Europe Research and Innovation programme under grant agreement No 101138960, project TRIATHLON.
| 8 | 6 | 48 | EUR 4.00M |
|---|---|---|---|
| Partners | Countries | Months | Budget |
Run time: 2024-2028
Market: Circularity/sustainability
Written by M2i Program Manager: Andrew den bakker
Outline of the project
Aviation is under increasing pressure to reduce its carbon footprint. Hydrogen, with its potential for zero-emission propulsion, has emerged as a frontrunner in the race toward climate-neutral flight. But turning this vision into viable aircraft technology requires far more than replacing fuel tanks and engines. That’s where TRIATHLON comes in.
Now at its midway point, the TRIATHLON project is demonstrating how a coordinated, systems-level approach can overcome the complex interdependencies of hydrogen aviation. Funded under the Horizon Europe programme and supported by M2i, the project brings together advanced materials science, fluid dynamics, thermodynamics, and propulsion expertise to redesign the aircraft powertrain from the ground up.
At its core, TRIATHLON is a rethink of how hydrogen can be stored, conditioned, and converted into thrust at system level. The project’s multi-disciplinary effort spans from tank to turboprop and advanced fuel technology. Its progress so far has already yielded significant innovations.
Rethinking Aviation Powertrains
Figure 2: Right image: The figure shows the main layers of the tank, the flow of hydrogen in and out, and the paths through which heat enters from the surroundings or leaves the tank during operation. Left images: One tank supplies fuel to the aircraft, while a second tank can exchange hydrogen through a controlled valve.
One key challenge is how to store hydrogen efficiently and safely. TU Delft, TU Dresden and Cryomotive are looking into this challenge. The project’s multi-state storage concept combines different hydrogen phases — gaseous, liquid, and cryo-compressed — within a single tank system. TU delft developed a flexible modelling tool to simulate and compare tank configurations across an entire flight cycle, without being tied to any specific layout. This allows engineers to virtually test different combinations of tank types, control strategies, and mission profiles in early design stages, a crucial step for down selecting viable hydrogen architectures.
Material behaviour under cryogenic and high-pressure conditions is another vital piece of the puzzle. TU Dresden has designed and built a cryogenic test rig to study how composite materials behave when exposed to extreme conditions typical of hydrogen storage. The setup enables measurement of gas permeability and thermal conductivity at low temperatures, essential for assessing safety and durability. Of particular interest is the formation of microcracks in all-composite vessels, which could allow hydrogen leakage. Understanding and managing these mechanisms will help optimize composites for predictable permeation and structural integrity.
Figure 3: Test rig assembly with “dry cryostat” and periphery components at TU Dresden
Figure 4: Above: Coupon gyroid – 65% porosity; CAD drawing. Below: Coupon printed: gyroid – 65% porosity, aluminum oxide, sintered.
Beyond storage, the TRIATHLON team is also addressing thermal management. Lithoz and Ergon Research are designing high-performance ceramic heat exchanger coupons. The coupons were designed and manufactured using Lithography-based Ceramic Manufacturing (LCM). These were tested to compare structures such as gyroid, offset, and straight fins. Aluminium nitride and aluminium oxide ceramics were evaluated for their thermal conductivity, structural behaviour, and suitability for high-temperature applications. These experiments feed into system-level redesigns of fuel cell heat exchangers and hydrogen pre-conditioning units.
Another front of innovation lies in the fuel cell system itself. Ergon Research is building system-level models using Simscape to simulate the performance of high-temperature PEM fuel cells. These digital twins allow engineers to explore trade-offs in system sizing, water recovery, thermal integration, and overall efficiency across different flight phases. They also help anticipate the interaction between fuel cells and hydrogen-powered combustors using water injection to reduce NOx emissions.
Figure 5: Notional sketch of hydrogen-powered hybrid-electric powertrain system based on fuel cells and gas turbines.
Figure 6: Rich-Quench-Lean Trapped Vortex Combustor sketch, with NOx values at the outlet extracted from detailed CFD simulations in Take-off-like conditions
Meanwhile, advanced combustion work led by TU Delft focuses on a 100% hydrogen-fuelled trapped vortex combustor. Using Large Eddy Simulations, the team is optimizing the geometry and air-fuel injection strategies to stabilise the flame while controlling emissions. Initial results showed excellent flame stability and combustion efficiency under dry conditions. More recently, water injection strategies were modelled, revealing that injecting water in the rich cavity region significantly reduces NOx formation due to thermal dilution. These findings help inform smart hydrogen temperature conditioning strategies that balance combustion stability, emissions, and system efficiency.
As a midpoint milestone, TRIATHLON recently completed a successful midterm review—a key vote of confidence in both the technical direction and the collaborative strength of the project. Dissemination efforts, lead by AMIRES, have ramped up accordingly: the consortium has presented its progress at major events including ILA Berlin, the EASN Conference, ASME Turbo Expo, and Vienna Aviation Days, and continues to engage in European clustering through the ClimAvTech initiative.
Figure 7: TRIATHLON represented by Lithoz during the Vienna Aviation Days 2025
Looking to the future of TRIATHLON
Looking ahead, the final phase of TRIATHLON will focus on system-level integration and validation. The project partners are already synthesizing the diverse technical workstreams into a unified hybrid powertrain model, combining air and hydrogen flow control, fuel cell and combustion modules, and propulsion components. The goal: to produce a roadmap that outlines how these enabling technologies can converge into certifiable, scalable, and efficient aviation solutions.
Figure 8: Team photo during the M24 Consortium meeting at Ergon Research in Florence, Italy.
Technical Lead of the project, Julien van Campen:
“We are at the halfway point of the TRIATHLON-project and all the separate building blocks are really starting to come together. I am confident that the technologies developed in TRIATHLON will contribute to the realization of a disruptive hybrid hydrogen-electric powertrain for megawatt class aircraft.”
For more on this project or to explore collaboration opportunities, contact M2i. Join us in shaping the future of sustainable aviation.
