AbstractThe invention presents a hydrogen fuel gauge for metal hydride tanks based on an optical fibre. It offers a means to directly detect the amount of hydrogen in a solid state storage device. This direct measurement is particularly advantageous for intermittent release of hydrogen, like in applications for mobility or household. Swiss research institute is looking for partners in automotive and sensor industry for licence agreements and further development.
DetailsHydrogen storage in metal hydride is a safe and reliable alternative to hydrogen stored in high-pressure vessels. Promising application of such storage devices is long-term energy storage in e.g. stationary hydrogen storage for self-sufficient housing using hydrogen as seasonal energy storage (autarkic living cell see picture 1), or for boats, submarines, etc.
Picture 1 shows the self-sufficient accommodation unit (SELF) using hydrogen stored in metal hydrides as seasonal energy storage.
Such tanks will have to be equipped with a hydrogen fuel gauge, i.e. an indicator of the actual amount of hydrogen stored in the metal hydride tank. Although there is a physical relation between the equilibrium pressure and the amount of hydrogen in a metal hydride, the pressure - like in pressure vessels - cannot be directly used to indicate the amount of hydrogen. Thus, other methods to measure the amount of hydrogen in a tank are needed. State-of-the-art is the bookkeeping of released and absorbed hydrogen by measuring the in- and outgoing hydrogen flux. However, leaks, the uncertainty of the flux measurement, and possible data storage losses may falsify the total amount of hydrogen stored significantly.
Picture 2 shows the technology, using optical fibres measuring the change of the optical properties of the surrounding hydrogen storage material. To quantify the hydrogen content in the hydrogen storage material, we make use of the optical changes and thus refractive index upon hydrogen intercalation in the material.
- A direct measurement of the amount of hydrogen is a better alternative because measurement errors do not add up.
- The accuracy of this method is significantly higher than the state-of-the-art methods.