Dear reader,
As we reach the end of October 2025, the OVERLEAF project officially concludes, marking the culmination of over three years of pioneering research, collaboration, and innovation. Over these years, OVERLEAF has tried to tackle one of aviation’s greatest technological challenges by developing a novel, low-pressure cryogenic liquid hydrogen storage system, and has set a new benchmark for the future of clean, sustainable flight.
Throughout this journey, our consortium, led by Aciturri and composed of 11 partners from 6 countries, has transformed an ambitious vision into a tangible set of results that will continue to shape European aviation and beyond. From advanced bio-based composites and insulation foams to cutting-edge safety sensors, simulation tools, and design methodologies, OVERLEAF’s legacy extends far beyond its original objectives, offering Europe a defendable technological position in hydrogen storage and safety.
Tank achievements: the cornerstone of OVERLEAF’s innovation
At the heart of OVERLEAF lies its innovative cryogenic hydrogen tank concept: a fully composite, multi-layer system designed to optimise weight, safety, and efficiency. Despite the technical challenges faced during the final demonstrator phase, including a structural failure that halted full-scale testing, the project generated a robust portfolio of results that secure Europe’s leadership in hydrogen storage technologies.
Among these, the most significant tank-related achievements include:
– The patented OVERLEAF tank design (EP 4283182 B1), protecting the multi-layer architecture and its passive evaporator concept.
– A comprehensive safety case and failure database, now serving as a pre-certification knowledge base for future hydrogen demonstrators.
– An extensive body of validated know-how on tank behaviour, materials, and integration, crucial for de-risking the next generation of cryogenic systems.
– The definition of heat exchanger characteristics that will support further testing and system integration under upcoming programmes such as Clean Aviation 2.
Together, these assets not only consolidate ACITURRI’s industrial leadership but also ensure that the knowledge gained through OVERLEAF will guide future aviation and hydrogen infrastructure projects for years to come.
Beyond the project: sustaining impact and exploiting results
The conclusion of OVERLEAF does not mark an end, but rather a transition toward sustained exploitation and dissemination. OVERLEAF partners will continue to develop, scale, and apply the project’s results across multiple sectors.
– In aviation, results will feed directly into new European demonstrators under Clean Aviation 2, targeting TRL 6 readiness by 2028.
– In non-aviation domains, the same technologies will find early application in mobility, energy storage, refuelling infrastructure, and cryogenic logistics, ensuring faster market impact.
– Partners such as AIMPLAS, ARKEMA, CANOE, AIMEN, TU Delft, NTNU, UdG, and ICSI will continue leveraging their innovations, from bio-based composites and s-CO₂ foams to safety sensors and simulation tools, through new research collaborations and industrial partnerships.
Cross-sector transferability, an essential pillar of OVERLEAF’s exploitation logic, ensures that the project’s legacy endures: creating value in multiple industries, fostering innovation ecosystems, and supporting Europe’s decarbonisation ambitions.
A Collective Achievement
As the project draws to a close, we take this opportunity to extend our heartfelt thanks to all partners, researchers, and stakeholders who have contributed to this remarkable journey. Their expertise, dedication, and collaborative spirit have been the driving forces behind OVERLEAF’s success.
The project’s achievements demonstrate not only what can be accomplished through interdisciplinary European research but also the transformative potential of hydrogen as a clean energy carrier for aviation and beyond.
Here is a final statement from our project coordinator, Emma Celeste Lope Retuerto: “OVERLEAF comes to an end, but not the need to keep driving forward the technologies developed during these three and a half years. Clean aviation is possible , but it demands teamwork, perseverance, and the courage to face the challenges that come with changing the world.”
The OVERLEAF project team
