The purpose of this paper is the analysis of different powertrain options with respect to their emissions. To ensure a holistic approach, not only operational emissions are taken into account, but also the emissions caused by the production of the powertrain components and the production of the energy carriers. As a baseline, the Tecnam P2006T is used and a design mission is defined, which represents a typical thin-haul air taxi route. Biofuels, battery-powered, parallel-hybrid, series-hybrid and fuel cell driven powertrains with liquid and gaseous hydrogen are compared to the fossil fuel reference. The total emissions are expressed in g CO_2_(eq)/RPK. The key findings are the following: Biofuels can achieve great reductions of up to 42% of the carbon footprint, depending on the method of production. Due to their lower calorific value, the the vehicle is heavier and might require a more powerful engine. However, the problem of vapor bubbles at higher altitudes prevent their use until now. Battery-powered aircraft are currently not able to perform the design mission due to the low gravimetric energy density of the batteries. Future battery cells have the potential to reduce the carbon emissions by 227%, or even up to 70%, if global electricity production shifts towards nuclear power and/or renewable energy sources. Hybrid-electric powertrains can be designed in a multitude of different ways. The ones examined in this work add weight and complexity to the vehicle, yet fail to significantly reduce emissions. Parallel-hybrids are superior to series-hybrids in that respect, but limit the design freedom substantially. The environmental footprint of fuel cell driven powertrains is highly dependend on the production method of hydrogen. While steam reforming using coal would almost double emissions, production through electrolysis with renewable energy can reduce it by 91%. The technology is already available today, with liquid tanks being superior to gaseous tanks on a vehicle level.
展开▼
