Elaboration and outlook for metal hydride applications in future hydrogen-powered aviation

Hydrogen is a promising energy carrier to decarbonise aviation. However, many challenges regarding its storage or handling still have to be solved to successfully utilise hydrogen in aircraft and at airport infrastructures. The increasing use of hydrogen also generates opportunities for disruptive improvements, like the possibility to integrate metal hydrides (MHs) into the hydrogen powertrain and its infrastructure. Besides their ability to store hydrogen, MHs enable a wide range of potential secondary functions such as high-power thermal applications or compression. This way, MHs may contribute to achieve the goal of sustainable hydrogen-powered aviation. Hence, potential MH application options and their current state-of-the-art are presented. Based on that overview, the following seven use cases for aviation are selected for evaluation: 'hydrogen emergency storage', 'cabin air-conditioning', 'thermal management of fuel cells', 'gas gap heat switches', 'hydrogen boil-off recovery', 'onboard hydrogen compression' and 'hydrogen safety sensors'. Four of these use cases are investigated to achieve comparable degrees of detail to avoid misevaluations in the subsequent weighted point rating. The results reveal the high potential of MHs for 'hydrogen boil-off recovery', 'hydrogen safety sensors' and 'cabin air-conditioning'. For the three most promising use cases, outlooks to their potential future implementation are provided in order to outline the ability of MHs to empower sustainable aviation. These investigations highlight the huge potential of MHs for boil-off treatment.