Zero/Low Emission Commercial Aircraft Powered by Solid Oxide Fuel Cell Turbogenerator Hybrid Cycle

Trevor Kramer, September 26, 2023

Introduction of high efficiency power generation methods to the commercial aviation industry can lead to the reduction of carbon emissions and other environmental impacts. Aircraft are estimated to consume 9% of the transportation energy in the US and 12% of the carbon emissions.  The US Energy Information Administration (EIA) projects commercial air travel in terms of seat miles to increase > 60% by 2050.  Therefore, there is a strong drive for zero-emissions aircraft or low emission aircraft to off-set the potential increase in emissions. Hybrid electric aircraft provide a path for achieving zero/low-emissions, and the choice of fuel and system architecture is very important. An SOFC combustor hybrid turbogenerator power generation cycle can provide a method for high efficiency power generation that can significantly lower fuel burn and carbon emissions. This paper describes the simulated steady state modeling of the SOFC-C-TG SWaP (size, weight, and power) utilizing the flight conditions and the power requirements of a Boeing 737 class narrow body aircraft which needs a peak power of approximately 30MW. It was found that the SOFC-C-TG is a promising solution for the power generation needs of a fully electric zero/low emission commercial passenger aircraft. The modeling of the dynamics in the thermal fluid interactions used to capture the integrated system behavior is discussed in detail. The system performance of the SOFC-C-TG is also discussed when applied to the flight conditions of a 737-class commercial fully electric aircraft. It was found that the proposed power generation method could be applicable to the power requirements of said fully electric aircraft as well as having comparable range and passenger payload as the typical flight of the 737-class aircraft.    The SOFC Combustor (SOFC-C) concept allows for precise thermal management of the SOFC stack which is a critical requirement of an SOFC hybrid system. The SOFC-C allows for the removal of cathode heat exchangers, high temperature valves, and other high thermal mass and slow thermal actuators that have been present in traditional SOFC hybrids. The SOFC-C can do this by utilizing the unspent fuel in the anode-off gas in a combustion process that is then used to maintain the SOFC stack in the desired temperature range. Dynamic simulations of the SOFC-C-TG display the ability to successfully thermally manage the SOFC stack in conjunction with the turbogenerator load to control airflow. The SOFC combustor is designed for increased power density but also allows for a decrease in system complexity.