Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
The potential to improve the mobility efficiency of air transport is discussed in Section 8.3.1. The consequences for the aviation transportation system of avoiding
specific areas at particular times and at particular altitudes and the resultant impact on fuel consumption are described in Section 8.3.2. Section 8.3.3 compares CO2 emissions from various transport modes. Section 8.3.4 then discusses ground-based, aircraft-related emissions. Section 8.3.5 provides concluding remarks.
8.3.1. Aircraft Performance
This section describes potential reduction of fuel consumption by optimizing the operational use of an aircraft. Issues discussed include improving aircraft capacity
utilization, reducing the operational weight of an aircraft, and optimizing the speed of an aircraft. In general, however, these variables have already been optimized by
airlines, largely because of economic pressures and the requirement within the industry to minimize operational costs.
8.3.1.1. Aircraft Capacity Utilization
The energy required per passenger-km depends on the distance travelled and the load factor, where the load factor is defined as the ratio between the transported
payload and the maximum payload. Increasing payload improves fuel efficiency, as illustrated by the effect of payload on fuel burn for a Tupolev-154 (see Table 8-3).
The Tupolev-154 is an older aircraft with lower fuel efficiency than modern aircraft that is frequently used in the Eastern part of Europe and the former Soviet Union.
The effect of load factor on fuel efficiency for modern aircraft is similar (see Table 8-4); fuel efficiency of modern aircraft is greater at all payloads (Table 8-4 and
Section 8.3.3). For a discussion of trends in fuel efficiency over different generations of aircraft and levels of technology, see Chapter 7.
Table 8-4: Effect of configuration on fuel consumption in Boeing 747-400 aircraft.*
Length of Flight
(km)
1000
2000
4000
6000
8000
10000
12000
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B747-400 Long-Range
Configuration (262 Seats)
Fuel
Consumption
0.049
0.042
0.040
0.040
0.042
0.043
0.045
MJ per Seat-km
2.1
1.8
1.7
1.7
1.8
1.8
1.9
B747-400D High-Density
Configuration (568 Seats)
Fuel
Consumption
0.023
0.020
0.019
MJ per Seat-km
1.0
0.9
0.8