AN ESTIMATION OF AIRCRAFT EMISSIONS AT TURKISH AIRPORTS
We present the first estimates for aircraft landing and take-off (LTO) emissions at 40 Turkish airports in 2001, including the biggest airports: Ataturk International Airport in Istanbul (AIA), Antalya Airport in Antalya and Esenboga Airport in Ankara. The calculation model is based on flight data recorded by the State Airports Authority. The flight data include the type and number of aircraft, number of passengers, and cargo volume by date and time. For the emission calculations, we used the International Civil Aviation Organization (ICAO) Engine Exhaust Emissions Data Bank, which includes minimum and maximum values for both fuel flow rates and emissions factors. Total LTO emissions at Turkish airports are estimated to be between 7614 and 8338 tons per year. These results are comparable with U.S. airports on the average. Approximately half of the LTO emissions are, however, produced at the AIA. To predict future emissions, we estimated that an increase of 25% in LTO cycles might cause a rise of between 31% and 33% in emissions. The estimations show that a decrease of 2 minutes in taxiing time results in a decrease of 6% in LTO emissions. The model developed in this study was shown to perform well for airport environmental planning and expansion in the Turkish case.
The exhaust emissions from an aircraft are carbon dioxide (CO2), water vapour (H2O), nitrogen oxides (NO^sub X^), various sulphur oxides (SO^sub X^), carbon monoxide (CO), various non-methane (NM) hydrocarbons (HC), and other gases and particles. Aircraft engines produce such emissions in a sensitive area of the atmosphere within and above the troposphere. Emissions from aircrafts are important from an environmental point of view. Not only because of environmental aspects but also for health reasons, it becomes increasingly important to know the types and amounts of emissions from aircrafts. Near airports, for example, the produced SO^sub X^ and NO^sub X^ may contribute to smog, while CO is toxic and some HC and soot are suspected of being carcinogenic (Doeppelheuer, 2000). Smog and ozone formation in the vicinity of airports were the main environmental concern in the seventies and early eighties. Consequently, the emissions of unburned hydrocarbons (UHC) of aircraft engines were regulated. Emissions of NO^sub X^ were also controlled by similar standards (Westerberg, 2000).
Aircraft engines have two quite different requirements. The first is for very high combustion efficiency at low power, because of the large amounts of fuel burned during taxiing and ground manoeuvring. The primary problem here is the reduction of UHC. The main concern of the second requirement mentioned above is NO^sub X^ at take-off power, climb and cruise. ICAO sets standards on a worldwide basis, for both landing and take-off (LTO) cycles and also for cruise at high altitude; the first is concerned with air quality in the vicinity of airports and the second with ozone depletion in the upper atmosphere. It has been shown that for a modern twin-engine transport operating over an 800 kilometre range, approximately 25% of the emissions is produced during the LTO cycle, with the remainder during climb, cruise and descent; approximately 86% of the total emissions is NO^sub X^ (Saravanamuttoo, Rogers & Cohen, 2001).
At present, exhaust emissions from aircrafts are small compared to anthropogenic surface emissions. Nearly 6% of all petrol products are burned as aviation fuel. Relative to the total anthropogenic emissions of CO2, aviation contributes about 2.6%. With respect to NO^sub X^ the contributions from aviation is about 3% of all anthropogenic sources. Nevertheless, the unique location of aircraft emissions in the upper atmosphere and the predicted growth of air traffic require that particular attention is given to the effects of these emissions (Schumann, 2000).
Aircraft emissions are likely to have their greatest effect upon the atmosphere and climate when discharged near the junction of the troposphere and stratosphere. Research related to the atmospheric effects of aircraft emissions has become increasingly important and several experimental studies have been performed on contamination of the atmosphere by emissions from aircraft engines in cruise flight conditions, to establish and improve models of the physical and chemical processes which take place in the aircraft wake and in the general zone of air traffic corridors (Dedesh, Leut & Boris, 2001; Kjellstrom, Feichter, Sausen & Hein, 1999; Lee, Dilosquer, Singh & Rycoft, 1996; Schumann et al., 1998).
There are several studies to estimate the aircraft emissions at airports. In a study of airport-related emissions in the U.S., airports are estimated with a projection to the year 2010 (EPA, 1999). Perl, Patterson and Perez (1997) estimate the cost of air pollution from aviation at Lyon-Satolas airport for the years 1987, 1990 and 2015 by linking environmental assessment techniques that yield an emission inventory for aircraft operations with economic cost evaluations of air pollution from ground based sources in Lyon. Stefanou and Haralambopoulos (1998) used an inventory calculation system for air traffic to determine annual fuel consumption and emissions. They used airline data on routes, hours of flights, density of traffic, fleet mix, and ratings of engine manufacturers for an airline company in Greece. They calculated annual environmental loads and showed that significant amounts of pollutants are received in areas around airports. In a previous study based on data from the State Airport Authority (DHMI) environmental effects of aircraft engine exhaust gases around Ataturk International Airport was studied by Sen (1997).
Studies estimating present and future aircraft emissions have been performed recently. Dameris et al. (1998) present a global three-dimensional dynamic-chemical model to estimate present and future subsonic and supersonic aircraft NO^sub X^ emissions on ozone. Grooss, Bruehl and Peter ( 1998) performed a study investigating the impact of air-traffic-induced NO^sub X^ and H2O emissions on the chemical composition of the global troposphere and stratosphere for 1991 and a future scenario for 2015. Kalivoda and Kudrna (1997) present a study on the future development of air traffic and the expected changes and improvements in specific fuel consumption and air pollutant emissions for 2010 and 2020. Vedantham and Oppenheimer (1998) give long term scenarios for aviation through to the year 2100.
This paper deals with estimating aircraft LTO emissions at 40 Turkish airports in 2001 including the biggest airports: AIA in Istanbul, Antalya Airport in Antalya and Esenboga Airport in Ankara. The calculation model is based on flight data recorded by State Airports Authority. The flight data includes type and number of aircraft, number of passengers, and amount of cargo by day, time of day and date as recorded by the State Airport Authority (DHMI, 2002). For the emission calculations the ICAO Engine Exhaust Emissions Data Bank is used. Additionally, the effect of taxiing time on the aircraft emissions is estimated. Finally, the future aircraft emissions are estimated using peak day emissions at the AIA.
CALCULATING AIRCRAFT EMISSIONS
Aircraft emissions at airports are calculated for the LTO cycle consisting of four operation modes: approach, taxi, take-off and climb. A typical LTO cycle described by ICAO is shown in Figure 1 (Penner, Lister, Griggs, Dokken & McFarland, 1999). ICAO defines the climbing as the interval between the end of take-off and the moment the plane exits the atmospheric boundary layer (ABL). ICAO’s norms therefore take air traffic emissions into account from the surface to the top of the ABL, whose height is defined to be 915 meters (3000 feet) by default.
Fuel flow and emission rates and times in each operation mode of the LTO cycle vary. These depend on the aircraft type, meteorological conditions and operational considerations at the airport. In this study, the times for approach, taxi, take-off and climb are taken from a standard LTO cycle; that is, 4 minutes for approach, 26 minutes for taxi, 0.7 minutes for take-off and 2.2 minutes for climb (Penner et al., 1999). Fuel consumption and emission indexes of an aircraft for each operation mode are taken from the ICAO Engine Exhaust Emissions Data Bank (ICAO, 1995). A comparison shows that the calculation method based on emission indexes underestimate, for example, NO^sub X^ emissions by about 12% on average (Penner et al., 1999). As mentioned above, there is an obstacle for the calculations of emissions from aircrafts due to the fact that some aircraft engines have various fuel flow rates and emission factors as listed in the data bank. This obstacle is removed by calculating two estimations of aircraft LTO emissions at Turkish airports through the use of the minimum and the maximum values from the data bank: that is, minimum and maximum estimations. This methodology was developed and used by Woodmansey and Petterson (1994). Since this methodology gives minimum and maximum estimations of aircraft emissions, an error analysis is not necessary.
AIR TRAFFIC AT TURKISH AIRPORTS
There are forty commercial airports in Turkey which serve domestic and international flights with an aircraft capacity of 2,076,100, although only 18% of this capacity was used in 2001. Table 1 shows aircraft movements and capacity of Turkish airports for 2001 (DHMI, 2002). The distribution of aircraft types at Turkish airports in 2001 is shown in Figure 2. Boeing 737s comprise 35% of the aircraft movements at Turkish airports.
Because of a large mixture of aircraft types at Turkish airports approximately 92% of Instrument Flight Rule (IFR) flights are taken into consideration for the estimation of aircraft emissions. The IFR ratios for AlA, Antalya and Esenboga are 96%, 96% and 83 %, respectively.
RESULTS FOR TURKISH AIRPORTS
The total aircraft fuel consumption for LTO cycles at Turkish airports is estimated at approximately 174,000 tons in 2001. Dividing the total we find that the fuel consumption percentages during take-off, climb-out, taxi and approach are 11, 29, 42 and 18, respectively. Comparing this fuel consumption to total primary energy consumption in Turkey (MENS, 2004), shows that the fuel consumed by aircrafts in LTO cycles is approximately 0.23 %.
The amounts of minimum and maximum estimations of the aircraft LTO emissions at Turkish airports are listed in Table 2. Despite the fact that the AIA comprise only 43% of total LTO cycles at all Turkish airports, aircraft LTO cycles at the AIA produce half of the total emissions at all Turkish airports, as shown in Table 2. The distribution of aircraft emissions for different operation modes in Figure 3 shows that the taxiing mode has the biggest portion of LTO emissions, at around 72%. The second biggest portion belongs to the climb-out mode, at around 15%.
A projection up to the year 2020 gives the emission estimations throughout Turkey (Kaygusuz, 2003). Comparing the aircraft LTO emissions at Turkish airports to the total amount of emissions in Turkey for 2001, it can be stated that the aircraft LTO cycles produce 0.3% of NO^sub X^ and 0.25% of CO in Turkey.
Effect of taxiing time
Taxiing time is necessary for an aircraft to access the terminal area, the runways, fixed based operators, and their home hangar or tie-down area. From an environmental point of view improved taxiways reduce emissions at the airport by providing quicker and more direct taxi routes with fewer stops, turns, and runway crossings. Aircraft engines produce more emissions per unit of fuel while taxiing than other phases of airport operation. Consequently, taxiing aircrafts are a significant source of HC and CO emissions since the emission indexes of such emissions are the highest during the taxiing and idle phase, when engines operate at low power.
In order to show the effect of taxiing time on emissions, the time for taxiing is varied from 20 minutes to 26 minutes and the results are shown in Figure 4.
A decrease of 2 minutes in taxiing mode results in a decrease of approximately 6% in the amount of LTO emissions and a decrease of approximately 8% in the amount of emissions in taxiing mode. That means that the taxiing mode will have a portion of 65% of total LTO emissions if time for taxiing is reduced from 26 minutes to 20 minutes. This reduction of 23% in taxiing time results in a decrease of approximately 16.5% in the amount of the aircraft emissions. This result is comparable to that reported by Daniel (2002). He reports the benefits from reduced taxiing time, improved airport access, increased safety, decreased emissions, and reduced noise at the New Castle Airport in Delaware. He found that a reduction of 25% in taxiing time results in a decrease of up to 16% in aircraft emissions. This information is very useful for airport expansion programs including projects involving environmental protection related to aircraft emissions.
AIR TRAFFIC AT THE AIA
The AIA, located southwest of Istanbul, is the biggest airport in Turkey, which is a connection point for international flights between the continents of Europe, Asia, Africa, Australia and America. Table 3 shows the aircraft movements at the AIA in the year 2001. Its annual capacity of aircraft and passengers is 350,400 and 21.5 million, respectively. The AIA served approximately 13 million passengers in 2001. Consequently, the use of capacity of aircraft and passenger is 46% and 59%, respectively (DHMI, 2002). The monthly distribution of aircraft movements at the AIA is shown in Figure 5.
The AIA has a large mixture of aircraft types. Figure 6 shows distribution of aircraft types at the AIA in 2001. Boeing 737s comprise half of the aircraft movements at the AIA. As listed in Table 3, there were more than 80,000 LTO cycles at the AIA in 2001.
RESULTS FOR THE AIA
The minimum and maximum estimations of total LTO emissions from aircrafts at the AIA are shown both in Table 4 and in Figure 7. As seen in Table 4, the amount of total aircraft emissions are estimated to be between 3778 and 4254 tons per year and the rate of the estimated maximum total emissions to the estimated minimum total emissions is around 1.17. Both estimations in Table 4 show that the international flights cause around 67% of the amount of emissions from all flights.
The distribution of aircraft emissions for different operation modes shown in Figure 7 shows that the taxiing mode has the biggest portion of LTO emissions, which is around 72%. The second biggest portion of around 15% belongs to the climb mode, which is found to be the same for all other Turkish airports.
The distribution of emissions from each type of aircrafts is shown in Figure 8. As mentioned above half of the aircraft movements at the AIA are with a Boeing 737. Despite this, movement of Boeing 737s has a smaller fraction of total emissions of between 31% (maximum) and 35% (minimum). Using the emission estimations in Turkey (Kaygusuz, 2003) it can be said that the aircraft LTO cycles at the AIA produce 0.15% Of NO^sub X^ and 0.13% CO in Turkey.
ESTIMATING FUTURE EMISSIONS: PEAK DAY EMISSIONS AT THE AIA
Emissions from aircrafts contribute to pollution of the atmosphere. Although that pollution is a relatively small part of global human pollution (less than 3% in 1990), further emission reductions need to be achieved by the air transport community, since air traffic has a growth (3% to 5% per year), which exceeds the technology improvement rate. The longer-term prospects for the aeronautics industry are very promising. Market projections indicate that 15,000 to 16,000 new aircraft will be delivered over the next twenty years, significantly in excess of the number required to simply replace ageing air transport. Pollutants from air traffic are emitted at high altitudes, in the upper troposphere/lower stratosphere (8 to 12 kilometres), where they are of greater influence than those emitted at ground level. In spite of the aircraft engine industry having achieved 40% CO2 emission reduction without degrading of NO^sub X^ emissions during the last forty years, further technological improvements are needed. Increasing engine efficiency of modern gas turbines with higher turbine inlet pressure and temperature conditions tends to increase the quantity of NO^sub X^ generated per unit of fuel burn.
Aviation fuel production grew by about 2.6% annually from 1981 to 1997. For the future, global passenger air travel, as measured in revenue per passenger-kilometre, is expected to grow by about 5% per year between 1990 and 2015, whereas total aviation fuel use, including passenger freight, and military, is projected to increase by 3% per year, over the same period (Schumann, 2000).
A projection to estimate the number of aircraft movements at the Turkish airports from 2001 to 2006 shows that the air traffic at the AIA will grow by about 25% (SPO, 2001). To estimate the amount of aircraft emissions at the AIA for 2006 the following approximation is used. As mentioned above, around 80,000 LTO cycles (220 LTO cycles daily on average) occurred at the AlA in the year 2001. These LTO cycles cause a total amount of emissions of 10.35 tons at minimum and 11.66 tons at maximum on an average day. To estimate future emissions, this average per day result is compared with the peak day emissions in the year 2001. The peak day was August 30, 2001, and on this day 275 LTO cycles occurred. This value corresponds to an increase of 25% in LTO cycles.
The calculated amount of LTO emissions for the peak day is listed in Table 5. It can be seen from Table 5 that an increase of 25% in LTO cycles causes an increase in emissions of around 31% to 33%. This increase in emissions can also be expected for emission estimation at the AIA in 2006.
It could be roughly estimated that motor vehicles in Istanbul emitted 71,181 tons of NO^sub X^ in 1994 (Istanbul Research Department, 1995). In comparison, the amount of NO^sub X^ emissions from aircrafts at the AIA is only approximately 1.8% of NO^sub X^ emissions from motor vehicles in Istanbul in this same period. On the other hand, Kesgin and Vardar (2001) estimate that ships at Istanbul Strait emitted 7,064 tons of NO^sub X^ in 1997. In comparison, the aircrafts at the AIA emit only 18% as much NO^sub X^ as do the ships at Istanbul Strait. These results are comparable to the values in the literature (IPCC, 1990; Perl et al., 1997; Schumann, 2000). Schumann (2000), for example, reports that aviation contributes only about 2% of total NO^sub X^ emissions.
The estimation of exhaust gas emissions of aircraft LTO cycles at Turkish airports has not been presented before. This study is based on the flight data, which includes the type and number of aircraft, number of passengers, and cargo volume by date and time. For the emission calculations, we used the ICAO Engine Exhaust Emissions Data Bank, which includes minimum and maximum values for both fuel flow rates and emissions factors. The minimum and maximum values from the data bank allowed us to estimate the minimum and maximum amount of emissions. The estimations of emissions were investigated for all Turkish airports including the biggest airports, that is, AIA, Antalya Airport in Antalya and Esenboga Airport in Ankara.
As a result, we draw the following conclusions from this study:
1. Total LTO emissions from aircrafts at Turkish airports are estimated to be between 7,614 and 8,338 tons per year. Approximately half of these amounts will be produced at the AlA.
2. Total aircraft LTO emissions at the AlA are estimated to be between 3,778 and 4,254 tons per year.
3. International flights at the AlA emit 67% of total LTO emissions from aircraft.
4. A decrease of 2 minutes in taxiing time results in a decrease of approximately 6% of LTO emissions.
5. It has been estimated that an increase of 25% in LTO cycles might cause 31 to 33% more emissions.
Dameris, M., Grewe, V., Koehler, I., Sausen, R., Bruehl, C., Grooss, J. U., & Steil, B. (1998). Impact of aircraft emissions on tropospheric and stratospheric ozone. Part II: 3-D model results. Atmospheric Environment, 32(18), 3185-3199.
Daniel, J. I. (2002). Benefit-cost analysis of airport infrastructure: The case of taxiways. Journal of Air Transport Management, 8, 149-164.
Dedesh, V., Leut, A., & Boris, S. (2001). Aircraft emission research within ISTC project. Air & Space Europe, 3(3-4), 244-246.
DHMI (State Airports Authority). (2002). Istatistik Yilligi 2001 [Annual Statistics for 2001J. Yesilkoy, Istanbul: Devlet Hava Meydanlan Isletmesi Genel Mudurlugu.
Doeppelheuer, A. (2000). Aircraft Emission Parameter Modelling. Air & Space Europe, 2(3), 34-37.
EPA (Environmental Protection Agency). (1999). Evaluation of air pollutant emissions from subsonic commercial jet aircraft: Final report. Report no. EPA A420-R-99-013. Ann Arbor, MI, USA: Engine Programs and Compliance Division, U.S. Environmental Protection Agency.
Grooss, J. U., Bruehl, C., & Peter, T. (1998). Impact of aircraft emissions on tropospheric and stratospheric ozone. Part 1: Chemistry and 2-D model results. Atmospheric Environment, 32(18), 3173-3184.
ICAO (1995). Engine exhaust emissions data bank. Document no. 9646-AN/943. Montreal, CA.
Instanbul Research Department. (1995). Cevre Rapom [Report of Environment]. Istanbul: Municipality of Istanbul, Research Department.
IPCC. (1990). IPCC first assessment report. Vol. 3: WGIII Formulation of response option strategies. Washington, D.C.
Kalivoda, M. T. & Kudrna, M. (1997). Methodologies for estimating emissions from air traffic: Future emissions. Report no. MEET Project ST-96-SC.204. Vienna, Austria: Perchtoldsdorf-Vienna.
Kaygusuz, K. (2003). Energy policy and climate change in Turkey. Energy Conversion and Management, 44, 1671-1688.
Kesgin, U. & Vardar, N. (2001). A study on exhaust gas emissions from ships in Turkish Straits, Atmospheric Environment, 35, 1863-1870.
Kjellström, E., Feichter, J., Sausen, R. & Hein, R. (1999). The contribution of aircraft emissions to the atmospheric sulphur budget. Atmospheric Environment, 33, 3455-3465.
Lee, H., Dilosquer, M. L., Singh, R., & Rycoft, M. J. (1996). Further considerations of engine emissions from subsonic aircraft at cruise altitude. Atmospheric Environment, 30(22), 3689-3695.
MENS (Ministry of Energy and Natural Sources). (2004). 1990-2001 Yillari icin Birincil Enerji Tuketimi [Primary energy consumption for 1990-2001]. Ankara, Turkey. Available: http://www.enerji.gov.tr/birincilenerjituketimi.asp
Penner, J., Lister, D. H., Griggs, D. J., Dokken, D. J., & Farland, M.(1999). Aviation and the global atmosphere: A special report of the intergovernmental panel on climate change. Cambridge: Cambridge University Press.
Perl, A., Patterson, J., & Perez, M. (1997). Pricing aircraft emissions at Lyon-Satolas Airport. Transportation Research Part D, 2(2), 89-105.
Saravanamuttoo, H. I. H., Rogers. G. F. C., & Cohen, H. (2001). Gas Turbine Theory. Harlow: Prentice Hall.
Schumann, U. (2000). Effects of aircraft emissions on ozone, cirrus clouds, and environmental climate. Air & Space Europe, 2(3), 29-33.
Schumann, U., Schlager, H., Arnold, F., Baumann, R., Haschberger, P., & Klemm, O. (1998). Dilution of aircraft exhaust plumes at cruise altitudes. Atmospheric Environment, 32(18), 3097-3103.
Sen, O., (1997). The effect of aircraft engine exhaust gases on the environment. Int. J. Environmental and Pollution, Vol. 8, No. 1A, 148-157.
SPO (State Planning Organization). (2001). Ulastirma Özel Ihtisas Komisyonu Rapont, Hava YoIu Ulastirmasi Alt Komisyon Raporu [Eight Five-Year Development Plan: Transportation special impression commission report, air transportation sub-commission report]. Report no. DPT:2585-O1K:596. Ankara, Turkey: Devlet Planlama Teskilati. Available: http://www.ekutup.dpt.gov.tr
Stefanou, P. & Haralambopoulos, D. (1998). Energy demand and environmental pressures due to the operation of Olympic airways in Greece. Energy, 23(2), 125-136.
Vedantham, A. & Oppenheimer, M. (1998). Long-term scenarios for aviation: Demand and emissions of CO2 and NO^sub X^. Energy Policy, 26(8), 625-641.
Westerberg, J. (2000). Air transport system sensibilities. Air & Space Europe, 2(3), 38-40.
Woodmansey, B. & Petterson, J. (1994). New methodology for modelling annual aircraft emissions at airports. Transportation Engineering, 120, 339-357
Yildiz Technical University
Ugur Kesgin is an Associate Professor at Yildiz Technical University in Istanbul, Turkey. He completed his BSc and MSc degrees in marine engineering studies at Yildiz University and received his PhD degree from the Institute for Internal Combustion Engines and Thermodynamics at the Technical University Graz, Austria. The author thanks the State Airports Authority in Istanbul for their help in obtaining the statistics and other official documentation.
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