Azura-Edo Independent Power Plant Environmental Impact ... - IFC

AERMOD is considered to be appropriate for this type of assessment as the
model is well recognised within the air quality and impact assessment practice
by numerous organisations including the IFC, the USEPA and the UK
Environment Agency.
Model Inputs
Table 7.4 sets out the model inputs used in this assessment while Table 7.5 sets
out the values used in the model relating to emissions arising from the plant.
Table 7.4
Model Inputs
Building Co-ordinates Length
(m)
Power Plant 5.681176 E, 6.409856 N 395 330
Width (m)
Height (m)
25 (assumed
worst case)
Criteria Emission parameters – engines Units Value
Source Location 1 (Stacks 1, 2, 3 and 4)
Latitude,
Longitude
5.681176 E,
6.409856 N
Stack height m 50
Stack diameter (effective) 1 m 14
1: The four stacks are co-located adjacent to one another and modelled here as a single stack.
This is reflected in model input values and the effective diameter is based upon 4x 14 m
diameter stacks
Table 7.5
Power Plant Emissions Values
Fuel type Units Value
Emission flow rate Am 3 /s 3980
Emission temperature Celsius 543
CO mg m -3 37.5
NO x mg m -3 27.5
CO g/s 50
NO x g/s 36.6
Meteorological Data
In line with best practice, five years of hourly sequential meteorological data
were obtained and processed through the USEPA AERMET program to
generate files suitable for use in the air dispersion model. Data from the
Bohicon meteorological station, approximately 400 km west of Benin City was
selected. Although the use of meteorological from a site some 400 km distant
does limit the assessment, in the absence of a station closer to the site that
monitors all the relevant parameters the use of this data was necessary. Data
from a number of meteorological sites in West Africa was reviewed including
Bohicon, Lagos, Cotonou and Lome. The Bohicon station is the closest site for
which complete years of data are available for all the required parameters and
is also not coastal (unlike nearer meteorological stations) and therefore is more
likely to be representative of this inland site. In addition, a review of the data
AZURA EDO IPP
7-13
DRAFT EIA REPORT