Impact of Hydrogen in Aviation

Abstract

Aviation accounts for about 4% of the total anthropogenic effective radiative forcing (ERF), resulting from aircraft operations since the 1940s. Thereby more than half of the aviation induced ERF is very likely caused by non-CO2 effects, such as contrails and NOx emissions. One measure to potentially reduce both CO2 and non-CO2 effects from aviation is the use of green hydrogen. Different applications of hydrogen such as direct burn or the use of hydrogen in fuel cells for electric propulsion are developed by the aviation industry, with the promise to decarbonize aviation. Still, the impact of the non-CO2 effects on climate from these propulsion systems is unquantified as direct measurements were missing until recently and model capabilities need to be enhanced. DLR in collaboration with industry and academic partners investigates the effects of hydrogen on the formation of contrails and NOx emissions and their effect on climate in internally and industry funded projects as well as using funding by German and European funding sources. These research activities are flanked by emission and contrail measurements from new lean burn technologies which provide a reference of current technologies for the low-soot regime. As the industry is transitioning to the use of hydrogen, projects on the impact of hydrogen leakages and their effect on climate forcing agents have also been launched.