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

The level of oxides of nitrogen (NOx) in the stack gases is controlled through
the use of a dry low NOx burner in all of the above gas turbine models.
Furthermore, the level of carbon monoxide (CO) in the stack gases will be
controlled by mixing natural gas with air, and will be controlled by the gas
turbine control system. There is also the potential for emissions of hydrogen
sulphide (H 2S) to the air which will be dependent on the quantity of sulphur
in the gas supplied to the power station. Natural gas normally contains
negligible quantities of sulphur. The gas receiving station will contain
scrubbers in order to control the amount of sulfur present in the fuel stream.
A summary of the overall air emissions from the four gas turbines (open cycle
operations) and exhaust parameters including stack height, diameter, flow
rate and temperature are all provided in Table 3.2 below.
Table 3.2
Emissions to Air from Four GE 9E Gas Turbines (OCGT)
Summary of Emissions to Air from the Azura-Edo IPP
Parameter Emission from one unit Emission from the power
station
Number of stacks 1 4
Estimated height of the stacks (m) 50 50
Temperature of release ( 0 C) 543 543
Stack diameter (m) 7 7
Actual flow rate (kg/s) 418 1,672
Actual flow rate (m 3 /s) 995 3,980
Efflux velocity at stack exit (m/s) 26 26
Emission concentrations
NO x (ppm) 20 20
CO (ppm) 30 30
H 2S Trace Trace
Carbon Dioxide (tonnes/yr) 545,000 2,178,000
Source: Azura Power, 2011
The key point sources of emissions from the power plant will originate from
the four gas turbine stacks, and the black start diesel engine stacks and will
include approximately 20 ppm NOx, 30 ppm CO and trace amounts of H 2S.
Approximately 2,178,000 tonnes of carbon dioxide is expected to be released
per annum as a result of the operation of the power station. Supplementary
design measures in order to increase efficiency were considered, including
conversion to CCGT technology. Azura Power will convert the power plant to
CCGT if and when this is found to become economically viable.
Sulphur hexafluoride, a potent greenhouse gas is contained in transformers.
On decommissioning, measures should be taken such that this is not be
released to the atmosphere, but be reclaimed for use if possible.
Noise Emissions
Noise emissions will result from a variety of sources including the gas
turbines. The key noise sources during construction phase will be from the
mobile machinery and plant. Auger piling will be used to drive in the
AZURA EDO IPP
3-11
DRAFT EIA REPORT