Analysis of the potential of metal hydride‑based range extenders for electric commuter aircraft

Abstract

Using alternative fuels such as hydrogen in electrifed propulsion systems presents one potential approach for reducing aircraft emissions. The development of a safe hydrogen storage with acceptable energy densities introduces an essential challenge. Metal hydrides enable inherently safe, reliable, and sustainable hydrogen storage. While ofering high volumetric storage densities, they achieve only low gravimetric storage densities. These properties make the use of metal hydrides unfavorable for primary hydrogen storage solutions in aviation. Nevertheless, their application may still be benefcial for secondary hydrogen storage devices. This paper analyzes the applicability of hydrides for the range extension of a commuter aircraft to facilitate diversion to an alternate airport. Therefore, various hydride types, such as complex hydrides, hydride slurry, and metal hydrides combined with compressed hydrogen storage, are evaluated and compared with conventional means of storage solutions. This analysis assesses the potential of these diferent technologies and identifes future research needs. Although the results of the evaluation show that hydride range extenders can be benefcial from the safety point of view, their application as a range extender for the diversion would entail a reduction of the aircraft range or payload.