Jet aircraft non-volatile particulate matter characterization and estimation

Jet engine aircraft exhaust contains combustion byproducts and particulate matter in the form of nonvolatile particulate matter (nvPM), black carbon (BC) is used synonymously for nvPM throughout this paper. Aircraft cruise emissions are the only direct source of anthropogenic BC particles at altitudes above the tropopause.¹ Black carbon aerosols are strong solar radiation absorbers and have long atmospheric lifetimes.² Therefore, BC results in positive radiative forcing and is believed to be the second largest contributor to climate change.³ Additionally, upper troposphere and lower stratosphere BC particles contribute to climate forcing indirectly by acting as ice nucleation sites and cloud activators.^4-6 With regards to human health, a link between cardiopulmonary diseases and carbonaceous black particulate matter has recently been suggested.7 As concern for human health risks and environmental impacts caused by aviation BC emissions increases, emission reduction strategies will need to be implemented. An ambitious carbon, solid and gaseous, emission reduction goal of 50% reduction by 2050 as compared to 2000-2005 levels have already been defined by the International Air Transport Association and Advisory Council for Aviation Research and Innovation in Europe.⁸ Meeting these goals will require significant engineering advancements requiring a long implementation period. However, in the near term, alternative jet fuels with reduced aromatic content are an attractive solution for reducing BC emission.^9-12 Alternative aviation fuels containing synthetic blend components with near zero aromatic content (synthetic paraffinic kerosenes, SPKs) such as those synthesized via the Fischer-Tropsch (FT-SPK) process and hydrotreated esters and fatty acids (HEFA-SPK) overall contain highly reduced aromatic content compared to conventional fuel and thus significantly reduce aircraft engine BC emissions.^9-12.