Dispersion of gas flaring emissions in the Niger delta: Impact of prevailing meteorological conditions and flare characteristics

An understanding of the dispersion and level of emissions source of atmospheric pollutants; whether point, area or volume sources, is required to inform policies on air pollution and day-to-day predictions of pollution level. Very few studies have carried out simulations of the dispersion pattern and groundlevel concentration of pollutants emitted from real-world gas flares. The limited availability of official data on gas flares from the oil and gas industries makes accurate dispersion calculations difficult. Using ADMS 5 and AERMOD, this study assessed the sensitivity of dispersion and ground-level concentration of pollutants from gas flares in the Niger Delta to prevailing meteorological condition; fuel composition; and flare size. Although, during the non-WAM (West African Monsoon) months (November and March), the simulated ground-level concentrations of pollutants from a single flare are lower, the dispersion of pollutants is towards both the inland and coastal communities. In the WAM months, the ground-level concentrations are higher and are dispersed predominantly over the inland communities. Less buoyant plumes from smaller flares (lower volume flow rates) and/or flaring of fuel with lower heat content results in higher ground-level concentrations in areas closer to the flare. Considering the huge number of flares scattered around the region, a mitigation of the acute local pollution level would be to combine short stacks flaring at lower volume flow rates to enhance the volume flow rate of a single exhaust, and hence, the buoyancy of the plume exiting the stack.