HYCOMP

Enhanced Design Requirements and Testing Procedures for Composite Cylinders intended for the Safe Storage of Hydrogen

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 Obiettivo del progetto (Objective)

'Hydrogen storage is a key enabling technology for the use of hydrogen as an energy vector. To improve volumetric and gravimetric performance, carbon fiber composite cylinders are currently being developed. However, current standards governing the design, qualification and in-service inspection of carbon fiber composite cylinders do not allow cylinder design to be optimized. In particular, safety factors for cycle life and burst pressure ratios appear to be conservative, which results in the cylinders being overdesigned and thus costly. Furthermore, the requirements in these standards are often not based on degradation processes in composite materials but have been adapted from standards covering metallic cylinders.

To address these issues, HyCOMP will conduct pre-normative research on high-pressure type III and type IV composite cylinders for hydrogen storage and transport for automotive, stationary and transportable applications. The project will generate all the data necessary to develop a comprehensive scientific and technical basis for fully justifying as well as improving the full set of requirements defined for ensuring the structural integrity of the cylinders throughout their service life, covering design type approval, manufacturing quality assurance, and in-service inspection.

The outcome of the project will be recommendations gathering broad support for improving the applicable European and international standards and regulation on high-pressure hydrogen cylinders for automotive, transport and stationary applications, as well as defining a strategy for implementing these changes. These recommendations will include performance-based design requirements, and improved procedures for type testing, batch testing and in-service inspections.'

Descrizione progetto (Article)

Hydrogen storage is an important and challenging factor affecting the feasibility of using hydrogen gas (H2) to produce energy. H2 has high energy density by weight, but poor energy density by volume. To compensate, the most mature H2 storage technique to date uses high-pressure cylinders to store compressed H2. Such technology has been around for years to store industrial gases in metallic cylinders. However, in order to use H2 in mobile applications and to transport tanks by trailers, tank weight must be reduced while maintaining reliability.

Carbon fibre-based composites have light weight, high stiffness and high strength. Scientists initiated the EU-funded project Hycomp to evaluate the behaviour of the composite materials over their intended service lifetimes to fill an important gap in available data. Results will provide the scientific basis for development of regulations, codes and standards (RCS) for composite cylinders used to store compressed H2. They will also facilitate optimal materials usage and development of tests for manufacturing quality assurance and in-service inspection.

Scientists are developing acoustic emission (AE) methods to measure the level of damage relative to a critical state of damage. The latter is the point beyond which the structure becomes unstable due to sharp acceleration of the degradation process resulting in tank rupture. Experimental studies include investigations of the effects of pressure and environmental conditions on damage accumulation rate. In parallel, scientists are developing numerical models based on the experimental data. Both a multi-scale finite element method (FEM) model and a fractal-based procedure were able to correctly simulate damage accumulation to the critical point and are being used for cylinder design and optimisation. Finally, scientists are defining manufacturing quality assurance guidelines based on four selected process parameters affecting cylinder performance.

With a clear scientific understanding of damage accumulation in carbon fibre-composite H2 storage tanks, Hycomp expects to deliver recommendations improving European and international RCS for automotive, transport and stationary applications. Design tools will facilitate meeting standards while optimising material usage and cost.