Alternative Fuel Effects on Aircraft Emissions and Contrails
Dr. Bruce Anderson Senior Research Scientist NASA Langley Research Center Hampton Virgi
#SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. What are the Environmental Impacts of Aviation?
• Aerosol and gas-phase emissions effect air quality near airports • NOx emissions effect background Ozone concentrations at altitude • Aerosols affect air quality and influence cloud formation and radiative properties • Contrails, Black Carbon, Ozone
and CO2 can enhance climate impacts
Military accounts for >10% of U.S. Jet Fuel Consumption, is Partially Responsible for Impacts
2 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Military Aircraft have Special Emissions Problems
• Still using older engine technologies, such as turbo-jet engines shown above • Aircraft designed to optimize performance over economy and emissions--i.e., low-bypass engines with augmenters used on fighters and bombers • Many military fuels have special properties to meet mission requirements
3 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Inflight Measurements Show Fuel S and Afterburners are Large Sources of PM Emissions
17 10 8 6
4
2
16 10 8 6
4
nvPMEmissions (#/kg) 2
15 10 70 80 90 100 Engine Thrust (%) • Fighter aircraft emit 5-10 times more soot than commercial aircraft • Afterburner operations increase soot emissions by 10 to 20 • Fuel sulfur increases total PM emissions by 10 to 100
4 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. CO2 emissions a major concern for commercial aviation as air travel is growing 2-3% per year CO2 and Clouds from Aviation Already Account for 5% of Anthropogenic Climate Impacts
Bonus: Sustainable jet fuels should also produce lower soot and sulfate emissions
ICAO goal is to reduce aircraft
CO2 emissions 50% by 2050
5 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. U.S. Federal Agencies are Collaborating to Develop Alt Fuels
Economic and environmental sustainability analysis across entire supply chain
Feedstock Feedstock Conversion Fuel Testing/Approval Fuel Process Scale- Fuel Environment Enable End User/ Logistics Production Conversion up/Integration Performance Assmt Production Buyer
USDA ------ --- DOC ------ ---
DOE --- ---
DoD --- --- FAA, DOD and EPA ------ --- NASA Primarily Focusing on FAA ------ --- Aviation Fuels NASA ------ ------6 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. NASA is Leading Effort to Assess Alternative Fuel Effects on Emissions and Contrails
Year Project Location Test Article Fuels 2008 PW308 West Palm Pratt PW308 Jet A, FT, 50% FT
2009 AAFEX-1 Palmdale DC-8 Jet A, FT (gas), FT (coal), 50% blends
2011 AAFEX-2 Palmdale DC-8 Jet A, HEFA, 50% HEFA, FT (gas) 2013 *ACCESS-1 Palmdale DC-8 Jet A, 50% HEFA
2014 *ACCESS-2 Palmdale DC-8 Jet A, 50% HEFA
2015 CONEX Cleveland Honeywell APU Jet A, Alt Fuels, Blends
2015 *ECLIF-1 Manching DLR A320 2 Jet A ref fuels, 4 Blends
2018 *NDMAX ECLIF Ramstein DLR A320 Jet A ref fuels, 3 Blends
* Flight Projects with Ground Measurements 7 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Alternative Fuels Studied in NASA Tests, most obtain from AFRL
Coal FT Sasol Natural Gas FT Shell ~35% C10 & C11 Fuels Vary 0.4% ~60% C & C ~48% C9 & C10 12.0% 10 11 Considerably in 46.7% 87.6% i-paraffins 53.3% n-paraffins Hydrocarbon cycloparaffins i-paraffins Composition aromatics
High degree branching Mild degree branching Alternative Fuels contain < 0.5% Petroleum Animal Fat or Plant Oil JP-8 HRJ Aromatics and < 20 5% 15% ppm Sulfur 18.7% 19.0% n-paraffins n-paraffins i-paraffins 31.0% 31.3% i-paraffins cycloparaffins cycloparaffins aromatics 80%
8 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Alternative Aviation Fuel Experiment (AAFEX-1) Multi-Agency Collaboration to Study Fischer-Tropsch Fuels
Huge Reductions in nvPM Number, Mass and Particle Size seen when Burning Alternative Fuels Objectives • Create gaseous and particulate emission profiles as a function of fuel-type and engine power; • Investigate the factors that control volatile aerosol formation and growth • Establish aircraft APU emission characteristics and examine their dependence on fuel composition
9 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Systematic Tests with APU Show Soot Emissions Vary Directly with Fuel Aromatic Content, Inversely with %H
15 4.0x10 500
3.5 400 3.0 300 2.5 200 2.0
1.5 100 nvPMNumber EI (#/kg) Red=SAK; Green=AR100; Blue=AFBlend nvPMMass EI (mg/kg) Red=SAK; Green=AR100; Blue=AFBlend 1.0 0 0 5 10 15 20 25 0 5 10 15 20 25 Percent Aromatic Additive Percent Aromatic Additive
• Added different SAKs to pure alternative fuel (Sasol) • Varied SAK percentage from 0 to 24% • nvPM (soot) number, mass and size increased directly with aromatics, inversely with %H content • nvPM emissions increase with naphthalene fraction
10 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Motivation for Flight Experiments
14 13 12 • Almost 90% of Jet fuel burned during flight 11 10 9 • Cruise-level power settings are very poorly simulated in 8
7 ground tests 6 Fuel Burn
Altitude (km) 5 4 • Particle emission parameters are very temperature 3 2 dependent--ground-level tests cannot replicate the cold, dry 1 0 5 10 15 20 25 30 conditions present at flight altitudes % Fuel Consumption • Emission impacts on contrails cannot be assessed at ground 14 13 12 level 11 10 • Very little data available to relate ground-based PM emission
Altitude (km) Altitude 9 8
7 NOx parameters to cruise altitude emissions; data for black carbon 6
Altitude (km) 5 Emissions mass/number emissions are particularly lacking 4 3 2 • Very little data available to relate aircraft PM emissions to 1 0 5 10 15 20 25 30 contrail formation and microphysical characteristics % NOx Emissions 11 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Sampling Platforms
DLR Falcon 20 ACCESS-II, ECLIF-1 Falcons slow, but can sample up close; DC-8 fast, but has to sample >5 km NASA Falcon HU-25C ACCESS-I, ACCESS-II
NASA DC-8 NDMAX/ECLIF
12 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Source Aircraft
DLR A320 Advanced Technology Research Aircraft V2527-A5 engines 26,600 lbs thrust ECLIF-1, NDMAX/ECLIF
NASA DC-8-72 CFM56-2C Engines 22,000 lbs thrust each AAFEX-1, AAFEX-2, ACCESS-I, ACCESS-II
13 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Sample Platforms Equipped with Probes and Inlets
Gas/Aerosol Inlets Measured aerosols and trace gases CVI Inlet using cabin-mounted instruments; Cloud particles measured with open-path sensors on wings Counter-Flow Virtual Trace-Gas Impactor Inlet Inlets H2O(v) Inlet
FFSSP Cloud Probe Aerosol Inlets
#SerdpEstcp2018 DISTRIBUTION A. Approved for14 public release: distribution unlimited. Example Research Flight from ACCESS-2
15 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Time Series for Typical Set of ACCESS-2 Maneuvers
16 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Combined Mission Accomplishments
ACCESS-II, 2014 • 8 flights, 25 hours, 3 fuels • Near-field emissions, very few contrail observations • 1 ground test, 3-hour DC-8 runtime
ECLIF-1, 2015 • 9 flights, 35 hours, 6 fuels • Near-field emissions, good contrail observations • 10 ground tests, 8-hour A320 runtime
NDMAX/ECLIF, 2018 • 8 flights, ~40 hours, 4 fuels • 1 Emission survey flight, 6 hrs • Very good contrail observations • 9 ground tests, 10-hour A320 runtime
17 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. ACCESS-2 Results Show that 50% Blends Reduce nvPM Emissions by 30 to 70% at Cruise
Blend nvPM emissions are also smaller, and more spherical in shape
Moore et al., NATURE, 2017
18 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. ECLIF A320 Ground Emissions Consistent with APU Test Results
15 500 7x10 14.6 FuelContent Hydrogen 14.6 FuelContent Hydrogen Engine 2 6 Number 400 14.4 14.4 5 Soot number, 14.2 14.2 300 4 mass and size 14.0 14.0 200 3 decrease with 13.8 13.8 100
2 BCMass EI (mg/kg) increasing nvPMNumber EI (#/kg) MassEngine 2 1 0 alternative- 20 30 40 50 60 70 80 20 30 40 50 60 70 80 Thrust (N1) fuel fraction Thrust (N1) Schripp et al., Environ. Sci. Technol. 2018, 52, 4969−4978
50 100 14.6 %Hydrogen Content %Hydrogen
14.6 Content Hydrogen % 45 90 14.4 14.4 40 14.2 14.2 80 35 14.0 14.0 70 30 13.8 13.8 Engine 2 Number-Size 60 25 MassEngine-Size 2
20 Volume MeanDiameter (nm) 50 Geometric MeanDiameter (nm) 20 30 40 50 60 70 80 20 30 40 50 60 70 80 Thrust (N1) 19 Thrust (N1) #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. NDMAX Confirms that Soot Regulates EI_ice
4E+15 4E+15
3E+15 3E+15 Data Courtesy -1 -1 of C. Voigt, DLR
/ kg / 2E+15 kg / 2E+15
ice ice
EI EI
1E+15 1E+15
0E+00 0E+00 Blend 1 Blend 2 Ref 3 Blend 1 Blend 2 Ref 3 24/01/2018 23/01/2018 29/01/2018 24/01/2018 23/01/2018 29/01/2018 Results very preliminary Median RHi 116 % 107 % 111 % Median RHi 109 % 108 % 111 % StdDev RHi 9.9 % 7.0 % 13.1 % StdDev RHi 8.8 % 6.9 % 8.5 %
Flight Level 380, Mach Number 0.76 Flight Level 380, Mach Number 0.8
20 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Summary of Results So Far
Aircraft performance at cruise not affected by burning 50% Alt fuel blends
No discernable difference in NOx and CO emissions between fuels, even for pure Alt fuels versus standard Jet A nvPM number and mass emissions and particle size varies linearly with fuel C:H ratio, inversely with %H 50% blends reduce nvPM number and mass emissions by ~30 to 80% on ground and at cruise Contrail ice concentrations proportional to soot emissions-- may be possible to greatly reduce contrail visibility and lifetime using pure alt fuels or engines with lower PM emissions Note: U.S. Air Force has reached goal of certifying their aircraft to burn 50% blends of alt fuels
21 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. Questions?
22 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited. What are the Benefits of Burning Alternative Fue
• Fuels can be produced from renewable feed stocks, can reduce GHG accumulation in the atmosphere and acidification of oceans • Fuels can be designed to burn much cleaner, can mitigate AQ problems in EPA non- attainment areas • Fuels can be produced domestically, reduce dependence on foreign suppliers • Possible that fuels can be produced at costs competitive with petroleum, could give US economy time to transition to other more efficient, less environmentally damaging energy sources • For aircraft, lower soot- and sulfuric acid-producing fuels may reduce condensation trail formation and decrease aviation climate impacts. U.S. Air Force has already reached goal of certifying all their aircraft to burn 50% blends of alt fuels
23 #SerdpEstcp2018 DISTRIBUTION A. Approved for public release: distribution unlimited.