To achieve the stated climate goals and prevent increased global warming, all countries should reduce the use of fossil fuels as soon as possible in their energy mix budget.
There is an increasing focus on hydrogen technologies as a sustainable alternative – especially in the industrial production and mobility sectors. Where hydrogen is used, stored, transported and transferred, appropriate safety precautions must be taken into account.
Although hydrogen is non-toxic, it weighs less than air, and thus rises upward: dangerous situations can occur: in fact, if the hydrogen concentration in the air exceeds the four percent limit, it will occur quickly if there is sufficient pressure.
Fraunhofer Gesellschaft writes in this press release that if a hydrogen tank or chamber is not properly ventilated, a small combustion source, a single spark, is sufficient to induce an explosion.
Small, smooth to combine and with out a inherent protection risk
A prospective approach is needed to prevent this, and Dr. Frauenhofer, a senior scientist at HHI. Gunter Flachenecker, knows how to go about this. In the Fraunhofer HHI Fibre Optical Sensor Systems Branch Lab section at Goslar, physicists and their team have developed new techniques for detecting hydrogen using glass fibre sensors: Supplies are needed.
In the worst case scenario, both variants serve as a source of ignition, and they can trigger an explosion that must be prevented if the equipment or power supply lines are defective, “Flachenecker explains. Can be without problems incorporated into diverse structures.
Optical fibres are virtually predefined for sensor applications in a safety-related environment because they are robust and have a diameter of only a quarter of a millimetre. To become an optical fibre hydrogen sensor, it needs to be modified in several places.
To do this, the laser is first used to print certain structures to the fibre optic core, known as fibre Bragg grating – periodic refractive index modulation to ensure that light is reflected at a given frequency.
Functional coating around the sensor.
To ensure that the glass fibre responds specifically to hydrogen, a special functional coating is applied around the sensor part of the glass fibre: “We work with catalytic layers, such as palladium or palladium alloys,” Flachnecker says.
Palladium is able to soaking up hydrogen like a sponge. As soon as the two substances meet, the hydrogen breaks into its atomic fragments, and the released hydrogen atoms penetrate the crystalline structure of the palladium. This results in length in the optical fibre, which can be readily measured as a change in reflected light signals by the built-in fibre Bragg grating. As soon as the hydrogen concentration in the air is lowered again, hydrogen is released from the palladium. This means there is no damage to the coating and the sensor can be reused.
Flachenecker emphasises that the process described here only works because hydrogen atoms are so small. Other materials do not penetrate the palladium layer in this way.
Potential for a extensive variety of applications
However, this is not the only method the researchers tested. For example, hydrogen can be detected with glass fibres, its fibre cladding inscribed, or by a thin layer of nanoparticles applied to the glass fibre surface.
“It’s a great playground, and there’s a lot of things we want to try,” Flachnecker says. “It is important that we discover approaches to locate hydrogen that responds sufficiently rapid and reliably withinside the required variety of sensitivity to save you accidents. In that regard, we are definitely making good progress at this time.
2M EngineeringFiber optic sensor(s) for gas, water & hydrogen leakage detection
Hydrogen sensor networks to become reality.
In practice, for example, new fibre optic sensors can become an integral part of hydrogen-powered vehicles and can be used to monitor hydrogen refuelling stations, auto repair shops, or electrolyzers. Based on this technology, a large sensor network can be easily measured, which monitors the hydrogen infrastructure at multiple levels simultaneously. Electronics to record measurement data, such as a spectrometer for optical evaluation of fibre optic sensors, can be installed in a safe location at any distance from the sensors.
If the specific concentration of hydrogen is exceeded and the sensor picks it up, a warning management system for a related application is triggered and specific actions such as an acoustic warning signal, valves closing or opening windows can be initiated. In just a few seconds.