Truck-manufacturers are demanding pressure vessels made of composite materials as substitutes for vessels of steel, which is heavy and prone to corrode, or aluminium, which is expensive. For compliance with European car-recycling regulations, it is preferable to use recyclable composites, i.e. composites with a thermoplastic matrix. The vessels must have a modular design so that they can be produced in different volumes while retaining the same diameter Until now, no design of composite pressure vessels has complied with all the specifications set by truck manufacturers. To fulfil all the requirements concurrently, the Darmstadt University of Technology Germany, developed a completely new design concept.