TANK2ZERO completes the development of a cryogenic carbon-fibre hydrogen tank for zero-emission aviation

The TANK2ZERO project (Hydrogen Storage Technologies to Enable the Operation of Zero-Emission Aircraft) has concluded following the completion of its research programme. The consortium, led by CITD Engineering & Technologies and comprising King Marine, PROSIX and SUPRASYS, achieved significant progress in developing a tank made from carbon-fibre-reinforced polymer (CFRP) intended for hydrogen storage under cryogenic operating conditions.

The work spanned the full development chain: the selection of fibres, resins and adhesives; the design of demonstrators at different scales; and the validation of system performance against permeability and thermal phenomena through the CFRP under cryogenic conditions. These stages made it possible to document the behaviour of the materials and design solutions under the demands of liquid-hydrogen storage.

TANK2ZERO was funded by the Aeronautical Technology Programme (PTAP), with a grant from the Centre for the Development of Industrial Technology (CDTI) under the 2023 call, through the Recovery, Transformation and Resilience Plan, with European Union funding via the Next Generation programme.

The project’s main objective was to raise the technology readiness level of the cryogenic hydrogen tank concept in carbon-fibre-reinforced composite for commercial aviation. This concept had previously been developed under the Aeronautical Technology Plan 2021, within the ZERO project — led by a consortium headed by Airbus — in which CITD contributed to defining the tank structure up to a maturity level of TRL2-3. TANK2ZERO built on those results in order to demonstrate the viability of the solution and to investigate the open questions identified in the previous phase.

Storing hydrogen on board an aircraft poses specific challenges. Hydrogen delivers more energy per unit of mass than aviation kerosene, but less energy per unit of volume. This limitation constrains its use on long-range flights: the viable option in terms of volume is cryogenic liquid-hydrogen storage, which maximizes energy density. As a reference, four litres of liquid hydrogen are roughly equivalent to one litre of conventional fuel. Hydrogen also allows two propulsion routes — combustion engines and electric propulsion via a hydrogen fuel cell — both constrained by the same technical barrier: on-board storage.

To address the critical points identified in the earlier development, the project worked along three lines of enabling technologies. The first was the investigation of new materials with optimised resins, assessed against criteria of low permeability and manufacturability. The second was the definition of aeronautical thermal-insulation solutions ensuring low conductivity and vacuum-based insulation. The third was the design of industrializable solutions for the complete integration of the tank system, including the vessels, the interfaces and the subsystems required for the safety and management of cryogenic hydrogen.

Validation of these concepts was framed through a test pyramid aimed at raising the technology to TRL4: coupon-level tests for the materials, demonstrator-level tests for the new interface solutions, and full-tank-level tests to verify system integration and the structural integrity of the vessel.

The consortium brought together complementary capabilities. CITD contributed aeronautical structural engineering, the design of hydrogen tanks in advanced materials, and the integration and definition of aeronautical systems. PROSIX contributed the manufacturing and assembly of high-strength aerospace structures, together with its prior experience in the space sector and in lightweight solutions using novel materials. SUPRASYS contributed its expertise in high vacuum and cryogenics, with robust solutions already deployed in the scientific industry.

King Marine took on the industrialization of novel carbon-fibre solutions and the handling of large-scale structures. Its involvement focused on translating the engineering developments into scalable manufacturing processes — one of the conditions required for the CFRP cryogenic tank concept to advance from the research phase towards industrial applications.

The combined result is a cryogenic carbon-fibre tank conceived to meet the zero-emission objective of commercial aviation. With the project now concluded, the consortium consolidates a technological foundation on which to support future development phases for liquid-hydrogen storage in aircraft.