AVIATION & THE ENVIRONMENT
Ian A. Waitz
Professor and Deputy Head
Department of Aeronautics and Astronautics
Massachusetts Institute of Technology
? 2003 Waitz 1
LECTURE OUTLINE
? Overview of environmental effects of aircraft
? Aircraft noise
– Impacts and regulatory issues
– Technology trends
? Aircraft pollutant emissions
– Impacts and regulatory issues
– Technology and emissions trends
? Summary and references
? 2003 Waitz 2
Noise
None applicable
Compatibility with nearby
land uses
Air quality
Most serious problem currently
Most serious problem in the future
Wetlands
29
AIRPORT
Noise
22
RANKING OF
ENVIRONMENTAL 12
Water quality
ISSUES
Water Quality
6
6
Air Quality
Current and Future
16
2
Compatibility with
Land-use limitations
4
1
None Applicable
0
0
Wetlands
2
0 5 10 15 20 25 30 35
Number of airports
Most serious problem currently
Most serious problem in future
Source: GAO’s survey of the nation’s 50 busiest commercial service airports.
? 2003 Waitz (GAO, 2000) 3
CHARACTERISTICS OF
NOISE AND EMISSIONS ISSUES
? Noise
– Local
– Persistence = minutes
– Well-established metrics
– Impacts: annoyance, sleep disturbance, domestic
animals?, endangered species?, health impacts?
? Emissions
– Local, regional, global
– Effluents: CO
2
, H
2
O, NO
x
, CO, VOC’s, soot, others
– Persistence = 1 day -1000 years
– Drastic change in public/scientific perception and
regulatory frameworks
– Impacts: human health, ecosystem health
? 2003 Waitz 4
AVIATION ENVIRONMENTAL IMPACTS
? “EXTERNALITIES”
– A large fraction of current aviation health and welfare
impacts are real costs to society but are not accounted
for by the providers or users of the service
“The government’s objectives for aviation are that…the
polluter should pay and aviation, like other industries,
should meet its external costs, including environmental
costs.”
(From UK Department of Transport, Aviation and the
Environment, Using Economic Instruments, March 2003)
? 2003 Waitz 5
EXTERNAL COSTS OF AVIATION
VALUATION SOCIAL INSTITUTIONAL
BASIS (industry + affected public) (regulatory policy)
Impact Area
(objective)
Total $ $ / capita Total $ $ / capita
% of Total $
addressed by
regulation
Noise $ 26B $ 2100 $ 2.9B $ 6000 11%
(quiet environs)
Air Quality $ 11B $ 140 $ 2.5B $ 30 22%
(safe air)
Climate Change ~$100B $ 345 $ 0.0B $ 0 0%
(stable climate)
TOTAL ~$137B $ 5.4B 5%
? Regulatory framework currently accommodates ~ 5% potential
internalization of external costs
? Noise cost per capita greater than emissions aligns with public
opinion and institutional attention
– Most vociferous opposition to noise, but air quality becoming
more of an issue (GAO 2000)
>>PRELIMINARY ESTIMATES ONLY<<
Lukachko, 2003
? 2003 Waitz 6
GROWTH IN MOBILITY PROVIDED BY U.S.
AVIATION INDUSTRY (DOT Form 41 data)
Fastest Growing Mode of Transportation (4-6%/yr)
Revenue Passenger Miles Performed by All Airlines Operating Aircraft with >60 Seats
8E+11
7E+11
6E+11
5E+11
4E+11
3E+11
2E+11
1E+11
0
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
? 2003 Waitz 7
AIR TRAVEL PROJECTED TO BE FASTEST GROWING
MODE OF TRANSPORTATION (4-6%/yr)
- DRIVEN BY POPULATION AND GDP GROWTH, AND AVAILABLE DAILY TRAVEL TIME -
Automobiles
Buses
Railways
Aircraft
1960 1990 2020 2050
5.5×10
12
RPK 23 ×10
12
RPK 54 ×10
12
RPK 105 ×10
12
RPK
Source: Schafer et al. (1998), GDP/cap growth rates from IPCC IS92a Scenario
? 2003 Waitz 8
MOBILITY AND THE ENVIRONMENT
“ Environmental issues are likely to impose the fundamental
limitation on air transportation growth in the 21st century. ”
U.S. National Science and Technology Council, 1995
72%
28%
25%
75%
Expansion Projects Delayed due to
Environmental Issues
Source: GAO (2000) survey of 50 busiest commercial
airports. N=33 for this question, 1 airport did not respond.
28% (9 airports) with
no impact
projects delayed
at 72% (23 airports)
Expansion Projects Cancelled or Indefinitely
Postponed due to Environmental Issues
25% (12 airports) with at
least 1 project affected
no impact at
75% (36 airports)
Source: GAO (2000) survey of 50 busiest commercial
airports. N=50 for this question, 2 airports with no projects
planned.
? 2003 Waitz 9
AIRPORTS ARE REACHING CAPACITY LIMIT
Figure 2: Anticipated Date for Airports to Reach Capacity
Number of airports
14
13
11
5
2
8
7
4
0
1
2
3
4
5
6
7
8
9
10
11
12
13
Already 1-2 years 3-4 years 5-6 years 7-9 years 10 or Other
at or more
above years
capacity
Estimated time to reach capacity
Source: GAO’s survey of the nation’s 50 busiest commercial service airports.
? 2003 Waitz 10
DOD ENCROACHMENT
? External factors such as urbanization, increasing
environmental restrictions, and competition with civilian
demands on airspace, land, seaspace, and radio frequencies
“The overall trends are adverse because the number of external inputs is
increasing, and the readiness impacts are growing. Future testing and
training needs will only further exacerbate these issues, as the speed and
range of test articles and training scenarios increase…” (DOD Sustainable
Ranges Outreach Plan, SROC)
Examples: JSF basing, Oceana operations, Navy in Japan
? Senior Readiness Oversight Council (SROC) action plans:
– Endangered species, ordnance, frequency encroachment, the
maritime sustainability, airspace restrictions, air quality, airborne
noise and urban growth
? House of Representatives proposal (2002): National Security
Impact Statement with all Environmental Impact Statements
? 2003 Waitz 11
REGULATIONS: BALANCING PUBLIC GOALS
? Economy and Mobility vs. National Security vs. Environment
? State vs. National interests and control
? Federal Noise Control Act + local noise restrictions
– Commercial yes
– Military no (Nat. Sec. Exemption, but NEPA EIS)
? Federal Clean Air Act + State Implementation Plans
– Military yes (General Conformity Rule)
– Commercial “no” (Interstate Commerce & Trade exemption)
? Endangered Species and Marine Mammal Protection Acts
– Military “yes” (Nat. Sec. Exemption, but never used)
– Commercial yes
? 2003 Waitz 12
GROWTH OF ENVIRONMENTAL REGULATION
Reflects increasing environmental impacts and
increasing valuation of the environment
Materiel Developer’s Guide for Pollution Prevention,
Cumulative Number of Federal
Environmental Laws
World-wide Civil Aircraft
Noise Restrictions
NAP
Charges
Quotas
Budgets
CH2 PO
CH2 Rest.
CH3 Rest.
1970
0
50
100
150
200
250
300
350
400
1980 1990
Year
Number of Restrictions
2000
Curfews
Levels
Army Acquisition Support Office, 1994
www.boeing.com
? 2003 Waitz 13
AIRCRAFT REGULATIONS
- Local , National, International -
? Noise
– Certification
standards
– Phase-outs
– Curfews
– Flight control
– Landing fees
– Ticket taxes
? Emissions
– Certification
standards
– Phase-outs
– Limited local rules in
place
? 2003 Waitz 14
LECTURE OUTLINE
? Overview of environmental effects of aircraft
? Aircraft noise
– Impacts and regulatory issues
– Technology trends
? Aircraft pollutant emissions
– Impacts and regulatory issues
– Technology and emissions trends
? Summary and references
? 2003 Waitz 15
AIRCRAFT NOISE GENERATION
AIRFRAME
NOISE
ENGINE
NOISE
SONIC
BOOM?
ATMOSPHERIC PROPAGATION
SPECTRUM, MAGNITUDE, DIRECTIVITY, DURATION
FREQUENCY OF OCCURENCE, TIME OF DAY, LOCATION
HUMAN ANNOYANCE
? 2003 Waitz 16
NOISE EFFECTS ON PEOPLE
(FICON, 1992)
? 2003 Waitz 18
Effects Hearing Loss Annoyance
Day-
Night
Average
Sound
Level in
Decibels
Qualitative
Description
% of
Population
Highly
Annoyed
Average
Community
Reaction
General Community Attitude
Towards Area
75 and
above
May begin to
occur
37% Very Severe
Noise is likely to be most
important of all adverse aspects of
the community environment
70
Will not likely
occur
22% Severe
Noise is one of the most adverse
aspects of the community
environment
65 Will not occur 12% Significant
Noise is one of the adverse aspects
of the community environment
60 Will not occur 7%
Moderate to
slight
Noise may be considered an
adverse aspects of the community
environment
55 and
below
Will not occur 3%
Moderate to
slight
Noise considered no more
important than various other
environmental factors
COMMERICAL AIRPORT NOISE EXPOSURE MAP
(DNL levels)
(INM, 1999)
? 2003 Waitz 19
NOISE IMPACT TRENDS
?Phase-out
–55% of U.S. fleet
–94% reduction in impact
–During 6X mobility growth
–$10B US cost
–
–TECHNOLOGY foundation
?$1B/yr in US for sound abatement
–
–Low cost effectiveness
$43/person/DNLdB
$960/person/DNLdB
? 2003 Waitz 20
COMMERCIAL AND MILITARY NOISE IMPACTS
Norfolk Intl.
Airport
210 TO/day
Oceana
121 TO/day
7 FCLP/day
Fentress
20 TO/day
354 FCLP/day
http://www.norfolkairport.com, http://www.nasoceana.navy.mil/aicuz
? 2003 Waitz 21
AIRCRAFT NOISE TECHNOLOGY TRENDS
? 2003 Waitz 22
AIRCRAFT NOISE SUMMARY
? Difficult connection between human annoyance and physics
– Public becoming more sensitive to aviation noise
– Relatively mature regulatory history
? Step changes in fleet unlikely
? Increased commercial certification stringency likely but
probably within current technological capabilities
? Growing problem for the military
? Local restrictions make noise a product differentiator
– For GE-90 powered B-777 (-6EPNdB cumulative relative
to other engines) twice as many t/o and landings allowed
at Heathrow
– Manufacturers willing to trade 2% fuel burn for 2 dB
(A380)
? 2003 Waitz 23
LECTURE OUTLINE
? Overview of environmental effects of aircraft
? Aircraft noise
– Impacts and regulatory issues
– Technology trends
? Aircraft pollutant emissions
– Impacts and regulatory issues
– Technology and emissions trends
? Summary and references
? 2003 Waitz 24
EMISSIONS IMPACTS
? Local air quality (NO
x
, CO, UHC, PM)
– Focus of current regulations
? Regional/global atmospheric effects
1) Stratospheric ozone depletion (time-scale=10 years)
– Largely a concern for supersonic aircraft (NOx)
2) Climate change (time-scale = 100-1000 years)
– Subsonic and supersonic aircraft
– CO
2
and H
2
O
– NO
x
through ozone production
– Particulates (SO
x
and soot) through heterogeneous
chemistry and cloud nucleation
? 2003 Waitz 25
AIRCRAFT ENGINE EXHAUST
? Composition
– Reservoir and primary combustion products
CO
2
, H
2
O, N
2
, O
2
: O(10000-100000) ppmv
– Secondary products and pollutant emissions
CO, NO
x
, HC, soot: O(1-100) ppmv
– Trace species constituents
NO
y
, SO
x
, HO
x
: O(0.0001-0.1) ppmv
? Most constituents play some role in atmospheric processes
– e.g. If 100% of SO
2
in engine oxidizes to SO
3
it may double
stratospheric ozone depletion
– Primary and secondary species relatively well-understood
– Relative magnitudes and engine/operations effects on trace
species poorly characterized
? 2003 Waitz 26
LOCAL AIR QUALITY
? Approx. 1% of US mobile source NO
x
emissions are from aircraft
? NO
x
, particulate matter, VOCs, CO -- ozone
– Lung function, cardiovascular disease, respiratory infection
? 2003 Waitz 27
28? 2003 Waitz
PM-10
Lead
CO
Ozone
SO2
Notes: Incomplete data, not classified, and Section 185(a) areas are not shown. Ozone nonattainment areas on
map based on pre-existing ozone standard. Nonattainment designations based on revised 8-hour ozone standard
will not be designated until 2000. PM-10 nonattainment areas on map are based on pre-existing PM-10 standards.
Nonattainment designations based on revised PM-10 standards have not yet been made. Source: U.S. EPA,
National Air Quality and Emissions Trends Report, 1997.
LOCATION OF “NON-ATTAINMENT” AREAS FOR CRITERIA
POLLUTANTS AS OF SEPTEMBER, 1998
(Chang, 1999)
% reg mobile source emiss
AIRCRAFT CONTRIBUTION TO REGIONAL MOBILE SOURCE NO
X
EMISSIONS AT SELECTED US CITIES IS ESTIMATED TO INCREASE
Estimated commercial aircraft contribution to regional mobile source
emissions of NOx
12
10
8
6
4
2
0
LA DC
Atlanta Boston
Charlotte
Chicago
Houston
NY
Phila.
Phoenix
1990
2010
Source: Table 4-2, EPA 420-R -99-013, "Evaluation of Air Pollutant Emissions from Subsonic
Commercial Jet Aircraf t," April, 1999
(Chang, 1999)
? 2003 Waitz 29
30? 2003 Waitz
AIRCRAFT AND OZONE
(NOAA, NASA, UNEP, WMO, “Scientific
Assessment of Ozone Depletion: 1994”)
? Aircraft: NEGATIVE
EFFECT AT ALL
ALTITUDES
– Subsonics: +0.9% total
column ozone (global
warming)
– Supersonics (1000, <
5% of fleet): -1.3% total
column ozone
– Combined fleet: -0.4%
total column ozone
(IPCC, 1999)
SCIENTIFIC UNDERSTANDING IN 2003 vs. 1999
Green bars are
updated values,
with arrows
updated
uncertainty.
? 2003 Waitz 32
NOTES ON CLIMATE CHANGE IMPACTS
? Burning a gallon of fuel at 11km has about double the radiative
impact of burning a gallon of fuel at sea-level
? Burning a gallon of fuel at 19km has about 5 times the impact
at sea-level
? CO
2
is not the biggest global concern (potential impacts from
contrails and cirrus clouds are greater).
? Large imbalance between northern and southern hemisphere
? Improving engine efficiency tends to make NOx and contrails
worse
? High uncertainty
? 2003 Waitz 36
THE ROLE OF TECHNOLOGY:
CHARACTERISTICS OF AVIATION SYSTEMS
? Safety critical
? Weight and volume limited
? Complex
? 10-20 year development times
? $30M to $1B per unit capital costs
? 25 to 100 year usage in fleet
? Slow technology development and uptake
? 2003 Waitz 37
TECHNOLOGY
CHOICES: BOEING
“Boeing is focusing its product development efforts on a super efficient airplane. This is the
airplane that airline customers around the globe agree will bring the best value to an industry in need of
improved performance. The advanced technologies that allowed the Sonic Cruiser configuration to
provide 15 to 20 percent faster flight at today’s efficiencies now will be used to bring 15 to 20 percent
lower fuel usage at the top end of today’s commercial jet speeds. Boeing believes that in the future
airlines will again be interested in faster flight and we will be ready with a concept and technologies to
meet this need.” (www.boeing.com, March, 2003)
? 2003 Waitz 38
COMMERCIAL vs. MILITARY FLEET TRENDS
? Demand growth for civil aviation (3.8%/year in US)
? Military fleet contraction
? Ops tempo (4.3/day commercial, 0.35/day military)
Number of Aircraft
Flights/day
? 2003 Waitz 40
FUEL CONSUMPTION TRENDS
Aircraft responsible for 2%-3% of U.S fossil fuel use
? 2003 Waitz 41
COMMERCIAL AIRCRAFT EFFICIENCY
Average Age = 13 yrs
? 2003 Waitz 42
MILITARY AIRCRAFT FUEL BURN
Average Age
21 yrs
? 2003 Waitz 43
ENERGY EFFICIENCY
? Function of performance of entire system
– Aircraft technology (structures, aerodynamics, engines)
– Aircraft operations (stage length, fuel load, taxi/take-
off/landing time, flight altitude, delays, etc.)
– Airline operations (load factor)
? Each component of system can be examined independently
for reduced fuel burn and impacts on local air quality and
regional/global atmospheric effects
? 2003 Waitz 44
??
??
RANGE EQUATION
Technology and Operations
Stage Length
VLD
g SFC
W
W W W
fuel
payload structure reserve
=
( )
?
+
+ +
?
?
?
?
?
?
ln 1
= Technology
= Operations
Efficiency
W StageLength
W
ASK
kg
Stagelength seats
payload
fuel
fuel
W
g
f
∝
=
,
#
Use data to separate
effects and understand
influences of technology
? 2003 Waitz 45
TRENDS IN LOAD FACTOR
Load Factor
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Regional Jets
Turboprops
Large Aircraft
1965 1970 1975 1980 1985 1990 1995 2000
Year
Babikian, Raffi, The Historical Fuel Efficiency Characteristics of Regional Aircraft From Technological, Operational, and Cost
Perspectives, SM Thesis, Massachusetts Institute of Technology, June 2001
? 2003 Waitz 46
FLIGHT AND GROUND DELAYS
Ratio
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Airborne to Block Hours
Minimum Flight to Airborne Hours
Mininum Flight to Block Hours
1965 1970 1975 1980 1985 1990 1995 2000
Year
? 2003 Waitz 47
HISTORICAL TRENDS
Aerodynamic Efficiency
L/D
max
25
20
15
10
5
0
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
abikian et al. (2002)
Data Unavailable For:
EMB-145 FH-227
BAE RJ85 SA-226
CV-600 DHC-7
Turboprops
CV-880 Nihon YS-11
Regional Jets
Beech 1900 DHC-8-100
Large Aircraft CV-580 L-188
DHC8-300
D328
J41
ATR42
BAE-ATP
ATR72F27
BAC111-200/400
B767-200/ER
S360
J31
SA227
S340A
F28-1000 F28-4000/6000
BAE146-100/200/RJ70
B727-200/231A
BAE-146-300
B757-200
F100
B747-400
RJ200/ER
B777
B707-100B/300 B707-300B
B737-100/200
L1011-1/100/200
A300-600
DC9-30
B737-300
DC10-40
MD11
B737-400
A320-100/200
A310-300
DC10-30
L1011-500 B767-300/ER
B747-100/200/300
DC10-10 MD80 & DC9-80
EMB120
B737-500/600
B
Year
? 2003 Waitz 48
HISTORICAL TRENDS
Engine Efficiency
TSFC (mg/Ns)
30
25
20
15
10
5
0
B707-300
B720-000
B727-200/231A
F28-4000/6000BAC111-400
DC9-40
BAE146-100/200/RJ70
CV880 F28-1000
BAE-146-300
F100
RJ85
B737-100/200DC9-30
DC9-10
DC9-50
MD80 & DC9-80
B737-300
D328
EM170
RJ200/ER
F27
CV600
DC10-30
DC10-40
L1011-500
B767-200/ER
MD11
B747-400
B737-400
B737-500/600
A300-600
B767-300/ER
B757-200
L1011-1/100/200
B747-100
B747-200/300
DC10-10
EMB145
EMB135
RJ700
J31L188A-08/188C
A320-100/200A310-300
B777
D328
J41
ATR72
DHC7
S360
B1900
CV580
SA226 SA227
EMB120
ATR42
DHC8-300
BAE-ATP
DHC8-100
DHC8-400
Turboprops
S340A
bikian et al. (2002)Ba
Regional Jets
Large Jets
New Regional Jet Engines
New Turboprop Engines
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
? 2003 Waitz 49
HISTORICAL TRENDS
Structural Efficiency
OEW
/
MTOW
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
DC9-40
B737-100/200
B727-200/231A
DC9-10
DC10-10
BAC111-200
F28-1000
BAC111-400
F27
FH227
CV600
L188A-08/188C
DC10-40
DC9-50
MD80 & DC9-80
B767-200/ER
B777
B747-400
B737-400
B737-500/600
A320-100/200
A300-600
A310-300
B767-300/ER
B737-300
B757-200
L1011-1/100/200
B747-200/300
F28-4000/6000
BAE146-100/RJ70
BAE146-200
BAE-146-300
F100
RJ85
RJ200/ER
EMB145
DHC8-300
D328
J41
BAE-ATP
ATR72
DHC7
S360
B1900
J31
DHC8-100
SA226
SA227 EMB120
S340A
ATR42
DC9-30
CV880
L1011-500
DC10-30 MD11
B747-100
Turboprops
B707-300B
bikian et al. (2002)Ba
Regional Jets
Large Aircraft
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Year
? 2003 Waitz 50
EFFICIENCY
Regional Jets Versus Turboprops
6
Energy Usage (MJ/ASK)
5
Regional
BAC111-400
Jet Fleet
Regional
4
CV880 Aircraft Fleet
BAC111-200
CV600
3
RJ200/ERB1900
F28-1000
L188A-08/188C
BAE146-100 RJ85
F28-4000/6000
F27
J31
DHC7
SA226
S360
SA227
BAE-146-300
F100 EMB145
2
J41
D328
Turboprop
BAE146-200
DHC8-300
Fleet
DHC8-100
ATR72
S340A
Babikian et al. (2002)
EMB120
1 ATR42 BAE-ATP
Turboprops
Regional Jets
0
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
? 2003 Waitz 51
ENERGY USAGE
Total Versus Cruise
0
1
2
3
4
5
MJ/ASK
E
U,CR
Large Aircraft
Total E
U
Large Aircraft
E
U,CR
Regional Aircraft
Total E
U
Regional Aircraft
Babikian (2001)
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Year
52 ? 2003 Waitz
COMMERCIAL AIRCRAFT ENERGY INTENSITY TRENDS
? New technology energy intensity has been reduced 60% over last 40
years (jet age)
– 57% due to increases in engine efficiency
– 22% due to increases aerodynamic performance
– 17% due to load factor
– 4% due to other (structures, flight time efficiency, etc.)
– Structural efficiency constant (but traded for aero, passenger
comfort, noise and SFC)
– Flight time efficiency constant (balance of capacity constraints and
improved ATM)
? Fleet average energy intensity has been reduced 60% since 1968
– Lags new technology by 10-15 years
? 2003 Waitz 53
SHORT HAUL AIRCRAFT
Facing Increasing Scrutiny
E
U
(MJ/ASK)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
Jets
Turboprops
Aircraft introduced during or after 1980 only
(Babikian, 2002)
0 1000 2000 3000 4000 5000 6000 7000 8000 9000
Stage Length (km)
Royal Commission on the
Environment (2002)
the prospect of continuing
rapid increases in air
transport, particularly an
increase in short haul
flights…”
government should divert
resources...encouraging
and facilitating a modal
shift from air to high-
“…deeply concerned at
“It is essential that the
speed rail.”
? 2003 Waitz 55
IMPACT OF NASA TECHNOLOGY SCENARIOS
Global CO
2
Emitted per Year
Billion Kg
Effect of Proposed Environmental CO
2
Goals
2000
1750
1500
1250
1000
750
500
250
0
1990 2000 2010 2020 2030 2040 2050
No Improvement Beyond 1997 Technology
25% Reduction Introduced in 2007
50% Reduction Introduced in 2022
Zero CO2 Emission A/C Introduced in 2027
Zero CO2 Emission A/C Introduced in 2037
+340%
+140%
+230%
+40%
Change Relative to 1990:
Emission inventories
U.S. DOE reported fuel use
1990-5% Level
-20%
( - GA and Military Emissions based on Boeing forecast
- IPCC IS92a based ICAO demand model
- No retrofit of technologies)
Kyoto Protocol
Timing For Reductions
Year
J. E. Rohde, NASA 1999
? 2003 Waitz 56
IMPACTS OF MISSION REQUIREMENTS (NOx & Noise)
? Range/payload ~ fuel efficiency (commercial and military)
High pressures and
– Thermal efficiency
temperatures
High NO
x
– Propulsive efficiency
velocity change
Large mass flow with small
Low Noise
? Maneuverability (military)
High energy conversion per
– High thrust-per-weight,
unit volume (high
small compact engine
temperatures and
pressures)
High NO
x
? Supersonic flight (military)
velocity change
– Low drag, small compact
engine
Small mass flow with large
High Noise
? 2003 Waitz 57
NO
x
EMISSIONS TECHNOLOGY TRENDS
? 2003 Waitz 58
NO
x
EMISSIONS TRENDS
? 2003 Waitz 59
HISTORICAL FLEET CRUISE EMISSIONS PER
PASSENGER PER KILOMETER
1.0
Relative Emission / P
ass-km
0.5
0
1975 1980 1985 1990 1995
NO
x
CO
2
,
H
2
O
CO
HC
Year
(DuBois, Boeing)
? 2003 Waitz 60
TECHNOLOGY AND EMISSIONS
? Improvements will not keep up with growth
? Aircraft typically have greater impact per unit of fuel burned
? “Solutions” for global climate will require unprecedented action
(demand management/regulations, electric vehicles, contrail avoidance,
etc.)
? Current understanding is that hydrogen makes problem worse
? High uncertainty relative to global impacts
? Engine efficiency improvements exacerbate NO
x
and contrails
? Significant improvements in structural efficiency, aero and operations
are possible
– Improvements in these areas do not exacerbate other problems
? 2003 Waitz 61
SUMMARY
? Broad range of environmental impacts from aircraft
– Social costs of same order as industry profits
– Currently not internalized
– Current technology path and regulations not aligned
with social costs
? Strong growth in demand
? Increasing public concern/regulatory stringency
? High uncertainty
? Many competing trades
– Environmental impacts
– Design, operations
? 2003 Waitz 62
SELECTED REFERENCES
? Babikian, R., Lukachko, S. P. and Waitz, I. A. "Historical Fuel Efficiency Characteristics of
Regional Aircraft from Technological, Operational, and Cost Perspectives,” Journal of Air
Transport Management, Volume 8, No. 6, pp. 389-400, Nov. 2002
? Lee, J. J., Lukachko, S. P., Waitz, I. A., and Schafer, A., “Historical and Future Trends in
Aircraft Performance, Cost and Emissions,” Annual Review of Energy and the
Environment, Volume 26, 2001. (Available on Waitz web page)
? Waitz, I. A., Lukachko, S. P., and J. J. Lee, "Military Aviation and the Environment:
Historical Trends and Comparison to Civil Aviation," AIAA-2003-2620, invited contribution
to AIAA/ICAS International Air and Space Symposium and Exposition, Dayton, Ohio, July
14-17, 2003.
? Marks, D. H., et al., "Mobility 2001", World Business Council for Sustainable Development,
Switzerland, 2001. (Available on Waitz web page)
? Miake-Lye, R.C., Waitz, I.A., Fahey, D.W., Kolb, C.E., Wesoky, H.L., and Wey, C.C., “Aviation
and Climate Change,” Aerospace America, September, 2000. (Available on Waitz web page)
? Penner et al., United Nations Environment Programme, Intergovernmental Panel on
Climate Change (IPCC), Special Report on Aviation and the Global Atmosphere, 1999.
(Summary for Policy Makers available on Waitz web page)
? RCEP, “The Environmental Effects of Civil Aircraft In Flight,” Royal Commission on
Environmental Pollution (RCEP), England, December, 2003
? Waitz web page: http://web.mit.edu/aeroastro/www/people/iaw/bio.html
? 2003 Waitz 63