SAE AIR7765

The scope of this joint EUROCAE/SAE report is to compile the considerations relating to airborne application of hydrogen fuel cells. This document provides a comprehensive analysis of the use of hydrogen as a fuel by describing its existing applications and the experience gained by exploiting fuel cells in sectors other than aviation. The use of hydrogen fuel cells in aircraft can help in meeting aviation environmental targets (including noise pollution) and can be vital to achieving efficient electrically propelled air vehicles. The experience gained with mature fuel cells in terrestrial applications and the handling of other gases in aviation, as presented herein, will help in alleviating safety concerns and in demystifying the usage of hydrogen in aviation. Hydrogen is the most abundant chemical element. One of the most valuable uses of hydrogen is in the hydrogen fuel cell. A fuel cell is used to combine hydrogen and oxygen to produce electricity and water. This use of hydrogen is becoming increasingly important, given the imperative to store and use energy without producing any greenhouse gasses. Fuel cells are being used in every sector of mobility (trains, cars, buses, ships, submarines, forklifts, even bicycles, etc.) except in civil aviation. Yet, fuel cells can be used to replace secondary power systems such as auxiliary power units and main engine-driven generators. Successful demonstrations of operating fuel cells in commercial airplanes and general aviation have already been performed. The hydrogen fuel cell is a key technology for reaching the goals for climate change prevention and for energy security in several commercial sectors, including transport, industry, and power generation/distribution. In addition, connecting different hydrogen-using sectors with transmission and distribution networks will increase the operational flexibility of the future low carbon energy economy. This SAE Aerospace Information Report will provide the needed comprehensive reference, background information, and potential benefits, aiming to promote the use of hydrogen-powered fuel cell systems in airborne applications.