Caractérisation optique et microphysique des aérosols atmosphériques en zone urbaine ouest africaine : application aux calculs du forçage radiatif à Ouagadougou

In this thesis, we analyze the main characteristics of atmospheric aerosols on an urban site in West Africa: Ouagadougou. This analysis is followed by an assessment of the radiative forcing produced by this population of aerosols at the top of the atmosphere, in the atmospheric layer and at the Earth's surface. A climatological study of the optical properties (optical thickness, Angstrom exponent, single scattering albedo, asymmetry factor) and microphysical properties (particle size distribution, complex refractive index) was performed on basis of data obtained from photometric measurement and inversions of AERONET network. The analysis of these data allowed us to define the different variabilities of the properties studied at various time scales. These properties have highlighted the combined effects of human activity, the cycle production of mineral dust from the Sahara region, the seasonal succession and the climate dynamics known in this region of the earth. The composition of the aerosol plume was also deduced from the analysis of optical data, and the conclusions were found to be in good agreement with chemical analysis carried out at LSCE on samples obtained by sampling on filters at Ouagadougou. The radiation balance was assessed using the GAME model. This simulation showed a strong relationship of the radiative forcing with the succesion of wet and dry seasons, with extreme values in August (wet) and Mars (dry with maximum dust emissions). The results showed a cooling at the surface that can reach -41 W / m 2 in March, a warming of the atmosphere, ranging from 15 to 35 W / m 2 about and a cooling at the top of the atmosphere between -2 and -6 W / m 2 . The representation of the radiative forcing calculated as a function of the single scattering albedo showed a linear trend with a correlation coefficient reflecting relatively good reliability of our results (about 88%). The consistency of simulated values was also shown by a comparison with the results obtained in the West African region by other researchers using different techniques. Similarly, the representation of the radiative efficiency simulated as a function of the inverted AERONET one showed a very good agreement.Dans cette thèse, nous analysons les principales caractéristiques des aérosols atmosphériques sur un site urbain en Afrique de l’Ouest : la ville de Ouagadougou. Cette analyse est suivie de l’évaluation du forçage radiatif produit par cette population d’aérosols au sommet de l’atmosphère, dans la couche atmosphérique ainsi qu’à la surface terrestre. Une étude climatologique des propriétés optiques (épaisseurs optiques, exposant d’Angström, albédo de simple diffusion, facteur d’asymétrie) et microphysiques (distribution granulométrique, indice complexe de réfraction) a été effectuée sur la base des données de mesures et d’inversions photométriques du réseau AERONET. L’analyse de ces données a permis de définir à diverses échelles de temps les différentes variabilités des propriétés étudiées. Ces propriétés ont mis en exergue les effets combinés de l’activité anthropique, du cycle de production des poussières minérales d’origine saharienne, de la succession saisonnière et la dynamique du climat spécifiques à cette région de la terre. La composition du panache d’aérosols a également été déduite de l’analyse des données optiques, et les conclusions tirées se sont avérées être en bon accord avec des mesures chimiques effectuées au LSCE sur des échantillons obtenus par prélèvement manuel sur filtres. Le bilan radiatif a été évalué en utilisant le modèle GAME. Cette simulation a montré une forte corrélation du forçage avec la succession des saisons sèche et humide, avec des valeurs extrêmes au mois d’Août (humide) et de Mars (sec avec poussières maximales). Les résultats traduisent un refroidissement en surface pouvant atteindre -41 W/m 2 en Mars, un réchauffement de la couche atmosphérique qui va de 15 à 35 W/m 2 environ et un refroidissement au sommet de l’atmosphère compris entre -2 et -6 W/m 2 . La représentation du forçage calculé en fonction de l’albédo de simple diffusion a montré une tendance linéaire avec un coefficient de corrélation traduisant une fiabilité de nos résultats de l’ordre de 88%. La cohérence des valeurs simulées a été aussi montrée par une comparaison avec des résultats obtenus dans la région Ouest Africaine par d’autres chercheurs utilisant des techniques différentes. De même, la représentation de l’efficacité radiative simulée en fonction de celle inversée par AERONET a montré un très bon accord

Mapping the least-cost option for rural electrification in Burkina Faso: Scaling-up renewable energies

This report describes the current status and limitations of the power sector in Burkina Faso and develops a new methodology that through spatial analysis processes aims to provide a possible pathway for universal electricity access through a sustainable energy mix. Two percent of the rural population in Burkina Faso has access to electricity and supply is lacking at many social structures such as schools and hospitals. Energy access achievements in Burkina Faso are still very modest. The rural electrification strategy for Burkina Faso is scattered in several electricity sector development policies: there is a need of defining a concrete action plan. Planning and coordination between grid extension and off-grid electrification programmes is essential to reach a long-term sustainable energy model and to avoid high unnecessary infrastructure investments. This report describes the development and the results obtained with a dynamic planning tool to support national government and development partners in defining an alternative electrification plan. Currently, the common national policy for electrification is dominated almost exclusively by grid extension with the government subsidising fossil fuel electricity production. However, the results of our analysis suggest that an electrification plan mainly based on further grid extension becomes inefficient and unsustainable in order to reach the national energy access targets. Our results also suggest that Burkina Faso’s rural electrification strategy should be driven by distributed minigrids powered by local renewable resources. We find that this approach would connect more people to power more quickly, and would reduce imported fossil fuel dependence/consumption that would otherwise be necessary for grid extension options.JRC.C.2-Energy Efficiency and Renewable

Optical and microphysical characterization of atmospheric aerosols in west african urban site : Application to the calculation of radiative forcing over Ouagadougou

Dans cette thèse, nous analysons les principales caractéristiques des aérosols atmosphériques sur un site urbain en Afrique de l’Ouest : la ville de Ouagadougou. Cette analyse est suivie de l’évaluation du forçage radiatif produit par cette population d’aérosols au sommet de l’atmosphère, dans la couche atmosphérique ainsi qu’à la surface terrestre. Une étude climatologique des propriétés optiques (épaisseurs optiques, exposant d’Angström, albédo de simple diffusion, facteur d’asymétrie) et microphysiques (distribution granulométrique, indice complexe de réfraction) a été effectuée sur la base des données de mesures et d’inversions photométriques du réseau AERONET. L’analyse de ces données a permis de définir à diverses échelles de temps les différentes variabilités des propriétés étudiées. Ces propriétés ont mis en exergue les effets combinés de l’activité anthropique, du cycle de production des poussières minérales d’origine saharienne, de la succession saisonnière et la dynamique du climat spécifiques à cette région de la terre. La composition du panache d’aérosols a également été déduite de l’analyse des données optiques, et les conclusions tirées se sont avérées être en bon accord avec des mesures chimiques effectuées au LSCE sur des échantillons obtenus par prélèvement manuel sur filtres. Le bilan radiatif a été évalué en utilisant le modèle GAME. Cette simulation a montré une forte corrélation du forçage avec la succession des saisons sèche et humide, avec des valeurs extrêmes au mois d’Août (humide) et de Mars (sec avec poussières maximales). Les résultats traduisent un refroidissement en surface pouvant atteindre -41 W/m 2 en Mars, un réchauffement de la couche atmosphérique qui va de 15 à 35 W/m 2 environ et un refroidissement au sommet de l’atmosphère compris entre -2 et -6 W/m 2 . La représentation du forçage calculé en fonction de l’albédo de simple diffusion a montré une tendance linéaire avec un coefficient de corrélation traduisant une fiabilité de nos résultats de l’ordre de 88%. La cohérence des valeurs simulées a été aussi montrée par une comparaison avec des résultats obtenus dans la région Ouest Africaine par d’autres chercheurs utilisant des techniques différentes. De même, la représentation de l’efficacité radiative simulée en fonction de celle inversée par AERONET a montré un très bon accord.In this thesis, we analyze the main characteristics of atmospheric aerosols on an urban site in West Africa: Ouagadougou. This analysis is followed by an assessment of the radiative forcing produced by this population of aerosols at the top of the atmosphere, in the atmospheric layer and at the Earth's surface. A climatological study of the optical properties (optical thickness, Angstrom exponent, single scattering albedo, asymmetry factor) and microphysical properties (particle size distribution, complex refractive index) was performed on basis of data obtained from photometric measurement and inversions of AERONET network. The analysis of these data allowed us to define the different variabilities of the properties studied at various time scales. These properties have highlighted the combined effects of human activity, the cycle production of mineral dust from the Sahara region, the seasonal succession and the climate dynamics known in this region of the earth. The composition of the aerosol plume was also deduced from the analysis of optical data, and the conclusions were found to be in good agreement with chemical analysis carried out at LSCE on samples obtained by sampling on filters at Ouagadougou. The radiation balance was assessed using the GAME model. This simulation showed a strong relationship of the radiative forcing with the succesion of wet and dry seasons, with extreme values in August (wet) and Mars (dry with maximum dust emissions). The results showed a cooling at the surface that can reach -41 W / m 2 in March, a warming of the atmosphere, ranging from 15 to 35 W / m 2 about and a cooling at the top of the atmosphere between -2 and -6 W / m 2 . The representation of the radiative forcing calculated as a function of the single scattering albedo showed a linear trend with a correlation coefficient reflecting relatively good reliability of our results (about 88%). The consistency of simulated values was also shown by a comparison with the results obtained in the West African region by other researchers using different techniques. Similarly, the representation of the radiative efficiency simulated as a function of the inverted AERONET one showed a very good agreement

Investigating the Effect of Inclination Angle of Magnetic Field Vector on Silicon PV Modules

In earlier studies, we have shown theoretically and experimentally that magnetic fields (MFs) have negative impact on silicon PV module (photovoltaic module). A noticeable decline in photocurrent with a slight increase in photovoltage was observed. Also, how those fields affected other key module’s parameters was also studied. These studies concluded that an increase in the magnitude of the MF resulted in the decrease of the efficiency of the silicon PV module. The previous experimental studies assumed that the MF vector formed zero angle of inclination with respect to the photosensitive face of the module. They did not factor in any effect that could be observed when the field vector is inclined. The present experimental work is an attempt to fill that gap. The characteristic curves of the PV module were plotted in the same system of axis for different values of the inclination angle of the MF vector. Correspondingly, the characteristic values (Pmax, Imax, Vmax, Isc, and Voc) of the PV module were also determined. These parameters then allowed the calculation of the efficiency of the module, its fill factor, and the equivalent circuit series and shunt resistances. It is observed that the module efficiency increases with the inclination of the MF vector, indicating that the effect of the MF on the PV module is reduced when its vector aligns towards a direction that is perpendicular to the base of the module. For example, when α moves from 0 to 90°, the power output and consequently the efficiency of the PV module relatively increase of 14%

The Radiative Forcing of Aerosols in a West Africa Sahelian Urban City: Case Study of Ouagadougou

International audienc

Diurnal Variability of the Radiative Impact of Atmospheric Aerosols in Ouagadougou, Burkina Faso: A Seasonal Approach

International audienc

Law and Policy Review on Green Hydrogen Potential in ECOWAS Countries

This paper aims to review existing energy-sector and hydrogen-energy-related legal, policy, and strategy documents in the ECOWAS region. To achieve this aim, current renewable-energy-related laws, acts of parliament, executive orders, presidential decrees, administrative orders, and memoranda were analyzed. The study shows that ECOWAS countries have strived to design consistent legal instruments regarding renewable energy in developing comprehensive legislation and bylaws to consolidate it and to encourage investments in renewable energy. Despite all these countries having a legislative basis for regulating renewable energy, there are still weaknesses that revolve around the law and policy regarding its possible application in green hydrogen production and use. The central conclusion of this review paper is that ECOWAS member states presently have no official hydrogen policies nor bylaws in place. The hydrogen rise presents a challenge and opportunity for members to play an important role in the fast-growing global hydrogen market. Therefore, these countries need to reform their regulatory frameworks and align their policies by introducing green hydrogen production in order to accomplish their green economy transition for the future and to boost the continent’s sustainable development

Effect of Reverse Polarisation of an Electromagnetic Field on the Performance of a Silicon PV Cell

This paper investigated, by one-dimensional modelling, the effects of reverse polarisation of an electromagnetic field, generated by an amplitude modulation radio antenna, on the efficiency of a silicon PV cell. Through a simulation, the effects of both the incidence angle and the electromagnetic field magnitude on the power output of the PV cell are analyzed. The power output curves against the junction dynamic velocity are used to find the junction dynamic velocity at the equilibrium, the maximum power output, and the efficiency of the PV cell. The results have shown that the presence of important electromagnetic fields in the neighborhood of a silicon PV cell decreases its performance