Hydrogen is particularly well suited to use as a chemical energy store. “Green hydrogen”, produced using renewable electricity, is therefore seen as a key component in the energy transition. The gas also comes with significant risks, however: In low concentrations it is flammable, and in higher concentrations it can even be explosive. As a result, any future hydrogen infrastructure must be subject to continuous monitoring to ensure that even the smallest leaks of H₂, and the transport gas ammonia (NH₃), are detected immediately. The hydrogen sensors available today fail to meet the stringent requirements for measurement accuracy, service life and cost effectiveness imposed here. In the TransHyDE project, researchers from Fraunhofer IPM are collaborating closely with metrology specialists from Endress + Hauser and from RMA Rheinau to develop and test innovative measurement approaches that will enable accurate leak detection, H₂ gas quality measurements, and the analysis of gas components in hydrogen gas mixtures.

Small leak, high risk: Hypersensitive, reliable H₂ sensor measurements are a must

In future, a low maintenance, self-testing sensor is set to provide continuous monitoring of large-scale facilities. This compact sensor will detect hydrogen based on its specific sound velocity and its high degree of thermal conductivity compared to other gases. By combining two measurement principles, the sensor is designed to meet the exacting functional safety standards required. A compact, cost-effective optical measurement system will likewise be employed to continuously detect hydrogen through Raman scattering. Instead of a costly spectrometer, however, a more inexpensive detector is destined to evaluate the scattered light.

Laser spectroscopy and infrared imaging will enable NH₃ leaks to be detected at a range of several meters. Here, a demonstrator will be constructed and tested for contactless, remote, imaging-based detection.

In future, colorimetric sensors should further enable the invisible gases H₂ and NH₃ to be discernable with the naked eye. This will be achieved thanks to a special paint, applied to pipelines and fittings, that changes color on contact with the gas. Such color-changing sensors are particularly useful during construction and installation works.

Determining purity: Fuel cells need H₂ without additional gas components

Hydrogen purity plays a key role in operations such as fuel cell function. Even low concentrations of impurities here can reduce service life or even cause a complete breakdown. Fraunhofer IPM’s close collaboration with Endress+Hauser as part of this project is developing a compact, robust, photoacoustic sensor system to continuously identify trace gases in hydrogen.

Determining calorific value: How much hydrogen is in natural gas?

If the existing gas grid is to be used to transport hydrogen, it must be possible to determine the precise composition of natural gas mixtures with a high H₂ content. The proportion of “green” hydrogen (produced by eco-friendly means) in natural gas is what ultimately determines its calorific value, and thus the actual cost of energy for consumers. To permit precise determination of the composition and H₂ content of natural gas, Fraunhofer IPM is collaborating closely with partners RMA Rheinau, Thüga, and Energie Südbayern to equip a natural gas analyzer with an H₂ thermal conductivity sensor that can achieve the most accurate, drift-free determination of natural gas composition possible.

In addition, the group is working on concepts for the design and evaluation of materials and components that have direct contact with H₂ gas. This research centers on the suitability of materials and components for safe, long-term use in realistic conditions within actual H₂ infrastructure.