Environmental Engineering Reference
In-Depth Information
The global fuel and NO
x
data for 1991/1992, 2015 and 2050 are given in Table
5.1. The estimated global emission of NO
x
(as NO
2
) from civil and military avia-
tion for the base year of 1991/1992 is 1.81teragrams (10
6
tonnes) of nitrogen diox-
ide per year (Tg NO
2
yr
-1
) and the fuel burned 131Tg yr
-1
. Military emissions,
although more uncertain than the civil estimates, are approximately 11 per cent of
the total, and for climate effects other than CO
2
, are less important as most emis-
sions are at much lower altitudes than those from civil aircraft. The spatial and verti-
cal structure of emissions is shown in Figures 5.4 and 5.5, respectively. It can be seen
that much of the emissions occur in the Northern Hemisphere and at altitudes of
between 10km and 12km.
Ta b l e 5 . 1
Fuel, NO
x
and emission index (EI) for NO
x
for 1991/1992, 2015 and
2050 gridded data sets
Data set
Fuel
Tg yr
-1
NO
x
(as NO
2
)
Tg yr
-1
EI for NO
x
Reference
ANCAT/EC2 -
1991/1992
131.3
1.81
13.8
Gardner et al, 1998
ANCAT/EC2 -
2015
286.9
3.53
12.3
Gardner et al, 1998
DTI - 2050
633
4.43
7
Newton and Falk, 1997
Fa1 - 2050
471.0
7.2
15.2
FESG, 1998
Fa2 - 2050
487.6
5.5
11.4
FESG, 1998
Fc1 - 2050
268.2
4.0
15.0
FESG, 1998
Fc2 - 2050
277.2
3.1
11.3
FESG, 1998
Fe1 - 2050
744.3
11.4
15.3
FESG, 1998
Fe2 - 2050
772.1
8.8
11.4
FESG, 1998
By 2015, it is forecast that emissions of NO
x
(as NO
2
) from civil aviation will have
grown by a factor of nearly 2, to 3.53Tg NO
2
yr
-1
with a fuel burn of 287Tg yr
-1
. It
is important to discriminate between forecasts and scenarios. Here, we adopt a defi-
nition of a forecast as a situation that is the result of extrapolation of current and
foreseen technologies and aviation growth. For scenarios, the assumptions are greater
and the approach, while similar in some respects, tends to be driven 'top down'.
For 2050, the most commonly used gridded data sets are those generated by the
forecasting and economic subgroup of ICAO (FESG, 1998). These scenarios were
based upon a relationship between revenue passenger kilometres and gross domestic
product (GDP). The GDP scenarios were the IPCC 'IS92a, c and e' scenarios (Leg-
gett et al, 1992).
1
In addition, two technology scenarios for fuel and NO
x
were assumed:
one ambitious, one less so, giving six scenarios in total. The nomenclature adopted
was, by example, Fa1 -
F
ESG IS92
a
Te c h n o l o g y S c e n a r i o
1
. Fuel usages ranged
from 268 to 772Tg yr
-1
and NO
x
emissions from 3.1 to 11.4Tg NO
2
yr
-1
; these
estimates equate to factors of approximately 2 to 6 on fuel and NO
x
emissions over
early 1990s data.
