• Energy Research

The fast-economic development and population growth in Nigeria have resulted in huge quantities of air pollutants emission which have implications on the environment. Detailed sectoral emission inventory to serve as the basis for policy formation to mitigate the condition is still lacking. This study builds detailed sectoral emission inventory using the emission factor approach to estimates various pollutant emissions from different sources. Five major sources of pollutant emissions were identified which include transportation, energy, municipal solid waste, wood fuel, and agricultural sectors. An increasing trend in emissions from 1980 to 2020 was observed for total emission of CO, NOx, PM2.5, PM10, SO2, NH3 and NMVOC in Nigeria that increased from 1 736-6 210; 143-338; 126-551; 171-717; 19-60; 4-28; and 471-1 587 Gg, respectively. Wood fuel, transportation, and municipal waste sectors are the major sources that contributed to 63%, 16%, and 15% of the total CO emission. Three mitigation scenarios for emission reduction for the future were analyzed. CO emission reductions of 38%, 24%, and 38% will be obtained from the liquefied petroleum gas (LPG) intervention, waste to energy (WTE) technology, and vehicle inspection and maintenance (VIM) policy scenarios, respectively, through to the year 2050.

The fast-economic development and population growth in Nigeria have resulted in huge quantities of air pollutants emission which have implications on the environment. Detailed sectoral emission inventory to serve as the basis for policy formation to mitigate the condition is still lacking. This study builds detailed sectoral emission inventory using the emission factor approach to estimates various pollutant emissions from different sources. Five major sources of pollutant emissions were identified which include transportation, energy, municipal solid waste, wood fuel, and agricultural sectors. An increasing trend in emissions from 1980 to 2020 was observed for total emission of CO, NOx, PM2.5, PM10, SO2, NH3 and NMVOC in Nigeria that increased from 1 736-6 210; 143-338; 126-551; 171-717; 19-60; 4-28; and 471-1 587 Gg, respectively. Wood fuel, transportation, and municipal waste sectors are the major sources that contributed to 63%, 16%, and 15% of the total CO emission. Three mitigation scenarios for emission reduction for the future were analyzed. CO emission reductions of 38%, 24%, and 38% will be obtained from the liquefied petroleum gas (LPG) intervention, waste to energy (WTE) technology, and vehicle inspection and maintenance (VIM) policy scenarios, respectively, through to the year 2050.

Road dust is a principal source and depository of polycyclic aromatic hydrocarbons (PAHs) in many urban areas of the world. Hence, this study probed the spatial and seasonal pattern, sources, and related cancer health risks of PAHs in the road dusts sampled at ten traffic intersection (TIs) of a model African city. Mixed PAHs sources were ascertained using the diagnostic ratios and positive matrix factorization (PMF) model. The results showed fluctuations in mean concentrations from 36.51 to 43.04 µg/g. Three-ring PAHs were the most abundant PAHs with anthracene (Anth) ranging from 6.84 ± 1.99 to 9.26 ± 4.42 µg/g being the predominant pollutant in Ibadan. Benzo(k)Fluoranthene (BkF) which is a pointer of traffic emission was the most dominant among the seven carcinogenic PAHs considered, varying from 2.68 ± 0.43 to 4.59 ± 0.48 µg/g. Seasonal variation results showed that PAH concentrations were 20% higher during dry season than rainy season. The seven sources of PAHs identified by PMF model include the following: diesel vehicle exhausts, gasoline combustion, diesel combustion, coal tar combustion, gasoline vehicle exhausts, coal and wood (biomass) combustion, and emissions from unburnt fossil fuels. Employing the incremental lifetime cancer risk (ILCR) model, the city's cancer risk of 5.96E-05 for children and 6.60E-05 for adults were more than the satisfactory risk baseline of ILCR ≤ 10-6 and higher in adults than in Children.

Road dust is a principal source and depository of polycyclic aromatic hydrocarbons (PAHs) in many urban areas of the world. Hence, this study probed the spatial and seasonal pattern, sources, and related cancer health risks of PAHs in the road dusts sampled at ten traffic intersection (TIs) of a model African city. Mixed PAHs sources were ascertained using the diagnostic ratios and positive matrix factorization (PMF) model. The results showed fluctuations in mean concentrations from 36.51 to 43.04 µg/g. Three-ring PAHs were the most abundant PAHs with anthracene (Anth) ranging from 6.84 ± 1.99 to 9.26 ± 4.42 µg/g being the predominant pollutant in Ibadan. Benzo(k)Fluoranthene (BkF) which is a pointer of traffic emission was the most dominant among the seven carcinogenic PAHs considered, varying from 2.68 ± 0.43 to 4.59 ± 0.48 µg/g. Seasonal variation results showed that PAH concentrations were 20% higher during dry season than rainy season. The seven sources of PAHs identified by PMF model include the following: diesel vehicle exhausts, gasoline combustion, diesel combustion, coal tar combustion, gasoline vehicle exhausts, coal and wood (biomass) combustion, and emissions from unburnt fossil fuels. Employing the incremental lifetime cancer risk (ILCR) model, the city's cancer risk of 5.96E-05 for children and 6.60E-05 for adults were more than the satisfactory risk baseline of ILCR ≤ 10-6 and higher in adults than in Children.

The exergy analysis and air pollutants emission estimation from the kiln system of a major cement manufacturing plant located in Nigeria were conducted with a view to improve the level of performance of the production unit and minimize environmental effects. Material balance and exergy analysis were carried out on the system to determine the exergetic efficiency and exergy destruction rate. Pollutants emission was estimated using bottom-up emission factor approach. The physical and chemical exergy output obtained were 9.07×107 and 1.46×08 kJ/h, respectively. The exergy efficiency of the kiln system was 27.35%. The measure of entropy generation (6.53×108 kJ/h) represented a huge potential for energy savings for the unit. CO2 emission represented about 99.04% of the total criteria air pollutants emission from the kiln and an estimate of 0.90 tonnes of CO2/tonne of clinker produced was obtained. To improve the exergy efficiency and reduce pollutants emission from the kiln system, possible heat recovery options and CO2 mitigation approaches were suggested.

The exergy analysis and air pollutants emission estimation from the kiln system of a major cement manufacturing plant located in Nigeria were conducted with a view to improve the level of performance of the production unit and minimize environmental effects. Material balance and exergy analysis were carried out on the system to determine the exergetic efficiency and exergy destruction rate. Pollutants emission was estimated using bottom-up emission factor approach. The physical and chemical exergy output obtained were 9.07×107 and 1.46×08 kJ/h, respectively. The exergy efficiency of the kiln system was 27.35%. The measure of entropy generation (6.53×108 kJ/h) represented a huge potential for energy savings for the unit. CO2 emission represented about 99.04% of the total criteria air pollutants emission from the kiln and an estimate of 0.90 tonnes of CO2/tonne of clinker produced was obtained. To improve the exergy efficiency and reduce pollutants emission from the kiln system, possible heat recovery options and CO2 mitigation approaches were suggested.

Abstract Cement manufacturing contributes to the elevation of air pollutants in the atmosphere and thus impact on the nearby communities. This study assessed air quality in a major Cement Plant in Ibese Ogun State, Nigeria, through an ambient air quality monitoring and air emission dispersion modelling. Particulate Matter (PM) and gaseous pollutants were measured using portable samplers and AERMOD View was used for the emission dispersion modelling. Combustion products including SO2, NO, NO2, CO and VOCs were the gaseous pollutants detected along the complex fenceline and in the receptor environments. Pollutants measurements were undertaken at 23 locations within the fence line and receptor locations. The daily SO2 and NO2 Federal Ministry of Environment - Nigeria (FMEnv) limits were exceeded in ten (10) and five (5) locations along the fenceline, respectively. Particulates were detected in all the locations along the fenceline and in the communities. The cumulative gaseous pollutants resulting from simultaneous operations of all the identified plant air emission point sources are 0.01–276.13% of their respective 24-h limits along the fenceline, with 1-h SO2 within the threshold limit at all fenceline locations, but 1-h NOX exceeds the threshold limit at all locations 16–21 times. The 24-h CO and VOCs are within their limits at all fenceline locations; however the 24-h SO2 and NOX are breaching the limits at some locations 30–34 times (0.34–0.39% of the investigation period) and 44–87 times, respectively. Daily and Annual averaging concentrations of PM10 was 14.32–31.54% and 4.90–52.60% of their respective limits. Process facilities are the major point sources of atmospheric emissions identified in the factory. Several fugitive emission sources were also identified during the field work. Comprehensive evaluation of the fugitive emission sources should be carried out in the cement plant for immediate attention.

Abstract Cement manufacturing contributes to the elevation of air pollutants in the atmosphere and thus impact on the nearby communities. This study assessed air quality in a major Cement Plant in Ibese Ogun State, Nigeria, through an ambient air quality monitoring and air emission dispersion modelling. Particulate Matter (PM) and gaseous pollutants were measured using portable samplers and AERMOD View was used for the emission dispersion modelling. Combustion products including SO2, NO, NO2, CO and VOCs were the gaseous pollutants detected along the complex fenceline and in the receptor environments. Pollutants measurements were undertaken at 23 locations within the fence line and receptor locations. The daily SO2 and NO2 Federal Ministry of Environment - Nigeria (FMEnv) limits were exceeded in ten (10) and five (5) locations along the fenceline, respectively. Particulates were detected in all the locations along the fenceline and in the communities. The cumulative gaseous pollutants resulting from simultaneous operations of all the identified plant air emission point sources are 0.01–276.13% of their respective 24-h limits along the fenceline, with 1-h SO2 within the threshold limit at all fenceline locations, but 1-h NOX exceeds the threshold limit at all locations 16–21 times. The 24-h CO and VOCs are within their limits at all fenceline locations; however the 24-h SO2 and NOX are breaching the limits at some locations 30–34 times (0.34–0.39% of the investigation period) and 44–87 times, respectively. Daily and Annual averaging concentrations of PM10 was 14.32–31.54% and 4.90–52.60% of their respective limits. Process facilities are the major point sources of atmospheric emissions identified in the factory. Several fugitive emission sources were also identified during the field work. Comprehensive evaluation of the fugitive emission sources should be carried out in the cement plant for immediate attention.