The aviation industry is increasingly focused on the development of sustainable alternative fuels to augment and diversify fuel supplies while simultaneously reducing its environmental impact. The impact of airport operations on local air quality and aviation related greenhouse * Corresponding author, e-mail address: plobo@mst.edu 2 gas emissions on a life cycle basis have been shown to be reduced with the use of alternative fuels. However, the evaluation of incremental variations in fuel composition of a single alternative fuel on the production of non-volatile particulate matter (nvPM) emissions has not been explored. This is critical to understanding the emissions profile for aircraft engines burning alternative fuels and their impact on air quality and climate change. A systematic evaluation of nvPM emissions from a GTCP85 aircraft auxiliary power unit (APU) burning a 16 different blends of Used Cooking Oil (UCO) derived Hydroprocessed Esters and Fatty Acids (HEFA) type alternative fuel with a conventional Jet A-1 baseline fuel was performed.The nvPM number-and mass-based emission indices for the 16 fuel blends and neat 100% UCO-HEFA were compared against those for the baseline Jet A-1 at the three APU operating conditions. Fuel composition was found to influence nvPM production. The reductions in nvPM were found to be greater with increasing fuel hydrogen content (higher proportion of UCO-HEFA in the fuel blend). For a 50:50 blend of UCO-HEFA and Jet A-1, which would meet current ASTM specifications, the average reduction in nvPM number-based emissions was ~35%, while that for mass-based emissions was ~60%. The nvPM size distributions were found to narrow and shift to smaller sizes as the UCO-HEFA component of the fuel blend increased. This shift has a greater impact on the reduction in nvPM mass compared to the overall decrease in nvPM number, when comparing the blends to the baseline Jet A-1.
Aviation is an important contributor to the global economy, satisfying society’s mobility needs. It contributes to climate change through CO2 and non-CO2 effects, including contrail-cirrus and ozone formation. There is currently significant interest in policies, regulations and research aiming to reduce aviation’s climate impact. Here we model the effect of these measures on global warming and perform a bottom-up analysis of potential technical improvements, challenging the assumptions of the targets for the sector with a number of scenarios up to 2100. We show that although the emissions targets for aviation are in line with the overall goals of the Paris Agreement, there is a high likelihood that the climate impact of aviation will not meet these goals. Our assessment includes feasible technological advancements and the availability of sustainable aviation fuels. This conclusion is robust for several COVID-19 recovery scenarios, including changes in travel behaviour.
Growing concern over emissions from increased airport operations has resulted in a need to assess the impact of aviation related activities on local air quality in and around airports, and to develop strategies to mitigate these effects. One such strategy being investigated is the use of alternative fuels in aircraft engines and auxiliary power units (APUs) as a means to diversify fuel supplies and reduce emissions. This paper summarizes the results of a study to characterize the emissions of an APU, a small gas turbine engine, burning conventional Jet A-1, a fully synthetic jet fuel, and other alternative fuels with varying compositions. Gas phase emissions were measured at the engine exit plane while PM emissions were recorded at the exit plane as well as 10 m downstream of the engine. Five percent reduction in NO(x) emissions and 5-10% reduction in CO emissions were observed for the alternative fuels. Significant reductions in PM emissions at the engine exit plane were achieved with the alternative fuels. However, as the exhaust plume expanded and cooled, organic species were found to condense on the PM. This increase in organic PM elevated the PM mass but had little impact on PM number.
This study evaluates the relationship between the emissions parameters of smoke number (SN) and mass concentration of nonvolatile particulate matter (nvPM) in the exhaust of a gas turbine engine for a conventional Jet A-1 and a number of alternative fuel blends. The data demonstrate the significant impact of fuel composition on the emissions and highlight the magnitude of the fuel-induced uncertainty for both SN within the Emissions Data Bank as well as nvPM mass within the new regulatory standard under development. Notwithstanding these substantial differences, the data show that correlation between SN and nvPM mass concentration still adheres to the first order approximation (FOA3), and this agreement is maintained over a wide range of fuel compositions. Hence, the data support the supposition that the FOA3 is applicable to engines burning both conventional and alternative fuel blends without adaptation or modification. The chemical composition of the fuel is shown to impact mass and number concentration as well as geometric mean diameter of the emitted nvPM; however, the data do not support assertions that the emissions of black carbon with small mean diameter will result in significant deviations from FOA3.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.