Chapter 4: Large Auxiliary Power Units for Vessels and Airplanes Check Access

Electricity requirements in mobile applications are increasing in nearly all forecasts for the future by electric devices for more comfort and a guaranteed energy supply during idling mode. Today combustion engines and turbo jet engines were applied as auxiliary power units (APU) on-board of air planes and ocean-going vessels. Fuel cells are envisaged as an environmental friendly and high efficient energy conversion system for future systems. The ideal energy carrier for fuel cells is hydrogen. The availability of hydrogen is a prerequisite for the use of fuel cells in mobile and stationary applications. However, an infrastructure for hydrogen as a future energy carrier does not yet exist. It is therefore essential that hydrogen be produced from readily available energy carriers. Usually for logistical reasons, APUs should use the same fuel as the main engine. This will be kerosene or JET A-1 for air planes and diesel or marine gas oil for vessels.

This contribution will show the requirements of for aeronautic and maritime applications and will give an overview about today's developments in fuel cell technology and fuel processing. The targeted power class of large APUs for these applications is higher than 400 – 500 kW_e. Especially for aeronautic applications two system concepts were compared for long and short range missions with hydrogen and JET A-1 as fuel. The application of kerosene-based fuel cell APUs for long-range missions could be preferable due to the lower volume required for the complete multifunctional system, the usage of the existing infrastructure, a short- to medium-term CO₂ reduction and a gradual switch to biofuels. Short-range missions require a low system mass which lead to the preference of hydrogen-based HT-PEFCs.