H2-Flex – Process and Plant Development of Geometrically Flexible Hydrogen Pressure Tanks using a Bio-Based Resin System

Climate change is the greatest societal, safety, and financial risk that the world is facing today. Hydrogen is one of the few zero-emission fuels and sustainable source of energy with a promising potential for scalable use for longer distances and larger energy needs in transportation. Attention on hydrogen technologies as a fuel in transportation is growing. Industries such as automotive, train, aircraft and aerospace industries are increasing investment in hydrogen solutions.

Hydrogen (H₂) is the smallest molecule. It has a wide flammability range and ignites easily. Pure hydrogen can be stored either as a liquefied gas at very low temperature (-253 °C) and slight overpressure (typically 1–10 bar) or as a compressed gas at very-high pressure (typically 250–700 bar). Due to the low volumetric energy density of hydrogen (1.3 kWh/l at 700 bar and 20°C) compared to fossil fuels such as gasoline (8.8 kWh/l), optimal use of hydrogen tanks is essential.

The aim of this H2-Flex project is the process and plant development for the production of a novel, cost-effective, geometrically highly flexible lightweight-hydrogen-tank. It can be manufactured as fiber-reinforced plastic composite construction with carbon fiber and bio-based resin system in order to make a significant contribution to minimizing the consumption of resources.

The starting point of the work in the H2-Flex project are the design of a new type of lightweight-hydrogen-pressure tank and manufacturing process are developed at IVW on TRL-3 level. The novel design provides maximum lightweight construction quality, because -due to its structure with purely axial (0°) and circumferentially applied fibers (approx.90°). Subsequently, together with the project partner Automation, Steeg and Hoffmeyer, a plant will be designed and built on the basis of this manufacturing process. Hydrogen tank can also be manufactured with a very small cross-section. In order to improve the eco-balance of the pressure tanks, bio-based resin system is being developed by the project partner Schill and Seilacher.

The load is transferred layer by layer from the axial layers in the cylindrical area of the pressure vessel by using the "IVW force introduction" patented at IVW. The project partner Karl Wolf Präzisions³ will determine suitable materials and surface treatments and manufacturing of the metallic parts. The cyclic loads acting on the tank during operation generate a tribological load on the joints between the materials used (aluminum-/-aluminum, aluminum-/-FRP), which is investigated experimentally at IVW with the aim of surface optimization.

The project "H2-Flex: Process and plant development for the production of a novel, cost-effective, geometrically highly flexible lightweight hydrogen tank construction using carbon fibers and bio-based resin system" is funded by the Federal Ministry for Economic Affairs and Climate Protection -on the basis of a resolution of the German Bundestag (funding code: 03LB3100E).