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Biofuel blending reduces particle emissions from aircraft engines at cruise conditions


Aviation-related aerosol emissions contribute to the formation of contrail cirrus clouds that can alter upper tropospheric radiation and water budgets, and therefore climate1. The magnitude of air-traffic-related aerosol–cloud interactions and the ways in which these interactions might change in the future remain uncertain1. Modelling studies of the present and future effects of aviation on climate require detailed information about the number of aerosol particles emitted per kilogram of fuel burned and the microphysical properties of those aerosols that are relevant for cloud formation2. However, previous observational data at cruise altitudes are sparse for engines burning conventional fuels2,3, and no data have previously been reported for biofuel use in-flight. Here we report observations from research aircraft that sampled the exhaust of engines onboard a NASA DC‐8 aircraft as they burned conventional Jet A fuel and a 50:50 (by volume) blend of Jet A fuel and a biofuel derived from Camelina oil. We show that, compared to using conventional fuels, biofuel blending reduces particle number and mass emissions immediately behind the aircraft by 50 to 70 per cent. Our observations quantify the impact of biofuel blending on aerosol emissions at cruise conditions and provide key microphysical parameters, which will be useful to assess the potential of biofuel use in aviation as a viable strategy to mitigate climate change.

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Figure 1: Side and forward views of DC-8 contrails and the operational cruise curve.
Figure 2: Summary of particle emissions indices at all thrust and cruise conditions.
Figure 3: Size distributions of particle emissions at high-thrust and cruise conditions.

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We thank the flight crew of the NASA DC-8 and DLR Falcon, W. Ringelberg, D. Fedors, T. Asher, M. Berry, B. Elit, T. Sandon, P. Weber, R. Welser, S. Kaufmann, T. Klausner, A. Reiter, A. Roiger, R. Schlage and U. Schumann for providing meteorological forecasts, and B. Kärcher and P. Le Clercq for discussions. This work was supported by the NASA Advanced Air Vehicles Program, Advanced Air Transport Technology Project, the DLR Aeronautics Research Programme, the Transport Canada Clean Transportation Initiative, and the National Research Council Canada CAAFER Project (46FA-JA12). R.H.M. was supported, in part, by a NASA Postdoctoral Program fellowship. B.W. was supported by the Helmholtz Association (grant number VH-NG-606) and by the European Research Council grant agreement number 640458. C.V. and T.J. were supported by the Helmholtz Association (grant number W2/W3-060) and the German Science Foundation (DFG grant number JU3059/1-1).

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Authors and Affiliations



R.H.M., B.B., G.S., R.Y., A.B., H.S. and B.E.A. designed and carried out the flight experiment; B.B., J.B., R.M., D.R. and R.W. designed and assisted with the payload integration; R.H.M., K.L.T., B.W., D.S., E.D., J.K., M.L., M.S., D.B., T.J., C.V., E.W., L.D.Z., A.B. and B.E.A. made in-flight measurements and analysed the data; R.H.M. wrote the paper. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Richard H. Moore.

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The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Table 1 Mean fuel properties (±1 a.s.d.) for each of the three fuels investigated
Extended Data Table 2 Summary of cruise emissions index tables
Extended Data Table 3 Emissions indices for no. 2 engine under high-thrust and cruise conditions
Extended Data Table 4 Emissions indices for no. 3 engine under high-thrust and cruise conditions
Extended Data Table 5 Emissions indices for no. 2 engine under medium-thrust and cruise conditions
Extended Data Table 6 Emissions indices for no. 2 engine under low-thrust and cruise conditions
Extended Data Table 7 Emissions indices for no. 3 engine under low-thrust and cruise conditions
Extended Data Table 8 Fit coefficients for the number size distribution
Extended Data Table 9 Fit coefficients for the volume size distribution

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Moore, R., Thornhill, K., Weinzierl, B. et al. Biofuel blending reduces particle emissions from aircraft engines at cruise conditions. Nature 543, 411–415 (2017).

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