This field of competence is focussed on the safety properties of components and systems for hydrogen technologies. Component testing, taking into account aging mechanisms with regard to component integrity and service life, even under dynamic load profiles, plays an important role. BAM has special expertise in the field of hydrogen storage, from the characterization of microcracks to the testing of accident loads and the statistical evaluation of failure probability up to structural health monitoring, and in the field of wind energy in the strength analysis, production and non-destructive testing of foundation structures and rotor blades.

Selected examples of our work are described below. Detailed information can be found in our brochure "Hydrogen: Our contribution to safety" (PDF) .

Compressed gas storage vessels — an official task and research focus at BAM

Currently, hydrogen is predominantly stored in gaseous form and for weight reasons, mostly in pressure vessels made from fibre-reinforced composites. In order to achieve the highest possible storage densities necessary for hydrogen vehicles travelling great distances, the hydrogen is usually stored under very high pressure. Pressure vessels must be designed in such a manner that they can safely endure the various loads that may occur during their operational life. For this purpose, pressure vessels must undergo intensive tests before placing on the market and later on when they are in service.

In addition to internal pressure loads at very high and low temperatures, these tests also include fire and drop 20 Unser Beitrag zur Sicherheit von Wasserstoff tests, acid tests and puncture tests. This aims to ensure that the vessels remain safe even under maximum operating

Compressed gas storage vessels — departmental advice and legal development

Issues concerning the safe storage of gaseous energy carrier such as propane/butane, natural gas/biogas and hydrogen affect everyday life and public safety more often than one might first perceive. This ranges from the local approval of the operation of systems relevant for hazardous incidents, the regional approval of corresponding vehicles, to the worldwide transport of dangerous goods.

The associated rules and the organisations managing the work on these legal and technical standards are equally as diverse. The United Nations (UN) plays a central role in relation to the safety of pressure vessels during their transport and storage.

Additionally, there are specific regulations such as the ADR (European Agreement concerning the International Carriage of Dangerous Goods by Road). This is all accompanied and supported by standardization work, some of which is undertaken on behalf of the German Government and is then also reflected in national bodies.

Glass storage vessels — an unusual material for high pressure storage

In order for hydrogen to be effectively manageable, suitable storage materials for hydrogen were looked for since years. Unusual materials such as glass are also being used. Glass has out-standing properties, including three times higher tensile strength compared to steel with a significantly lower material density. This makes potentially lighter storage units possible compared to conventional storage. For these properties to be effective, however, the glasses must be in capillary form and the hydrogen must be stored in its cavities. Depending on the shape and size of the capillaries, glass is able to withstand pressures above 1,500bar, so that storage pressures from 700 to 1,000 bar appear realistic.

Within the scope of an international research project with partners C.En (Switzerland) and INCOM (USA), BAM scientists have developed a system whose storage capillaries – bundled into tubes made up of millions of individual capillaries – can be assembled in different sizes. In order to demonstrate the viability of this system, the first prototypes were integrated into an e-bike and an e-scooter. In other projects, BAM was looking for protection for the sensitive glass surfaces in order to be able to implement permanent hydrogen storage.

Project DELFIN — How to make the storage of hydrogen safer and easier

Today, anyone who wants to drive an emissions-free car mostly does so in an electric one powered by batteries. The biggest weaknesses of these vehicles are the long charging times, their heavy weight, limited service life and the very high costs. An alternative: hydrogen-powered electric vehicles. In the fuel cells of these cars, gaseous hydrogen is converted into electricity, which then powers an electric motor. The hydrogen storage systems required for this purpose can be filled just as quickly as the tanks of petrol or diesel vehicles. At the moment, however, hydrogen storage systems remain very heavy and are therefore expensive to manufacture.

With the launch of the DELFIN project, research has commenced for a particularly light, inexpensive and safe hydrogen tank made of carbon fibres and a plastic liner. This began in 2018 and will run until 2021. BAM, as a safety expert for gas cylinders, is working with an array of car manufacturers and developers of composite pressure vessels. The research at BAM focuses on the so-called impact loading of hydrogen storage vessels. BAM has designed a special new test bench for adjusting the load of the storage units with and without gas load.

Project TAHYA — Using carbon fibres to make particularly efficient and safe hydrogen tanks

The TAHYA research project (Tank Hydrogen Automotive) aims to develop a particularly efficient and safe hydrogen tank for the automobile industry using carbon fibres and a plastic liner. The materials should be easy to wrap, material-saving and therefore cost-effective to manufacture; the tanks must have thin walls, be space-saving and light.

A further important area TAHYA is focusing on is the analysis of existing standards and approval regulations with the help of BAM’s Monte-Carlo Approach as well as the processing of improvement proposals in order to be able to meet the safety requirements suitably with the current knowledge about composite materials. BAM is concentrating on the verification of the vessel design through destructive tests such as fire, burst and load cycle tests.

Project GW4SHM — Structural Health Monitoring for hydrogen pressure vessels

Could the integrity of a highly loaded hydrogen pressure vessel be assessed during operation of the component so that a catastrophic failure can be avoided? The answer to this question is Structural Health Monitoring (SHM). This approach delivers up-to-date information about the degradation of the component. The SHM enhances non-destructive testing by applying adapted measurement equipment permanently to the structure under test. Appropriate signal Versuchsaufbau mit Demonstrator Lab demonstrator 46 Unser Beitrag zur Sicherheit von Wasserstoff processing algorithms evaluate information about the current state of the component or the growing of small cracks in the wall of the pressure vessel.

To further develop this method, the EU project GW4SHM (Guided Waves for Structural Health Monitoring) coordinated by BAM brings together more than 20 European partners from academia, research and industry to develop new approaches in all aspects of SHM.