##### Estimation of Hourly Clearness Index and Diffuse Fraction Over Coastal and Sahel Regions of Nigeria Using NCEP/NCAR Satellite Data

Journal of Energy Research and Reviews, Page 1-18
DOI: 10.9734/jenrr/2021/v7i430195

In this paper, daily satellite data of global and diffuse irradiances obtained from the archives of National Centre for Environmental Prediction (NCEP) and National Centre for Atmospheric Research (NCAR) covering a period of ten years (2005-2014) have been employed to study clearness index (KT) and diffuse fraction (KD) distributions over six carefully selected meteorological stations in Nigeria. These stations are Port Harcourt, Akure and Enugu in the coastal region; Kano, Maiduguri and Bauchi in the sahelian region. Results have shown that while global irradiance show double peaks in its mean annual daily variation at both regions, diffuse radiation only show this in the sahelian region. In the coastal region, its values are almost uniform throughout the year .In observing the synoptic hourly distribution of clearness index and diffuse fraction, it was found that while clearness index exhibits minima values at hours close to sunrise and sunset, the reverse is the case for diffuse fraction. Also that in the coastal region, clear sky condition is prevalent in Akure and Enugu at both seasons whereas in Port Harcourt, it seldomly occurs. In the sahelian region, on the other hand, clear sky condition is prevalent at both seasons. Using ANOVA method, empirical models were developed for KT. All the models at the stations and regions gave good and significant coefficient of determination R2. During the dry season months, it ranges between 0.98 and 0.99 while during the rainy season, it is 0.89 and 0.95. To further test the efficiencies of the developed models, the Mean Bias Error (MBE) and Root Mean Square Error (RMSE) were computed. Values obtained for both MBE and RMSE for most of the stations are low and positive. These are desirable results for good and significant models. It shows that these models can be used to predict clearness index KTwith high accuracy in the selected stations and proximateones.

##### Experimental Study of the Thermal Behavior of a Watercress Planted Roofed Cubic Cell to be Watered with Domestic Wastewater

Dominique Morau, Ives Abel Fetra Andriatsitohaina Rabesah, Hery Tiana Rakotondramiarana

Journal of Energy Research and Reviews, Page 19-30
DOI: 10.9734/jenrr/2021/v7i430196

One of the virtues of watercress is its ability to grow in wastewater. This work aims at experimentally studying the thermal behavior of a watercress planted roofed cubic cell. To do this, the temperatures of various components of the cell and the solar radiation received by this cell were measured in order to compare the watercress roof performance with that of the conventional concrete roof. Then, the influence of the opening applied on the door of the studied cell was analyzed. As results, the fluctuation amplitude of the indoor ambient temperature of the concrete roofed cell is wider than that of the green roofed cell. Moreover, the last opening applied to the facades of the cell was the optimum area that the ambient temperature indoor was more attenuated. The LAI’s crop was worth 1.2. In addition, the low value of the canopy apparent thermal conductivity revealed that this layer plays a role of thermal insulation. The rooftop greening allows energy savings of about 85% compared to the consumed energy with conventional roofing. An extension of this work could be the energy performance analysis of a system using renewable energy for pumping domestic wastewater produced in or around green roofed housing.

##### Design and Modelling of PV Power Plant for Rural Electrification in Kayonza, Rwanda

Alexis Bakundukize, Maurice Twizerimana, Dushengere Bernadette, Bizabakoraho Jean Pierre, Nsekambabaye Theoneste

Journal of Energy Research and Reviews, Page 31-55
DOI: 10.9734/jenrr/2021/v7i430197

Aims: This study aimed to design and model an off-grid SPV power plant with a storage system to meet the load required in Rwisirabo village.

Study Design:  PV modules, inverter, charge controller, and Batteries have been designed, reproduced/simulated, and optimized for the rural area of Rwisirabo village in Kayonza district, Eastern Province, Rwanda.

Place and Duration of Study: The experiment has been done in the University of Rwanda/ African Centre of Excellence in Energy Studies for Sustainable Development (UR/ACE-ESD) High E-Tech Smart Grid Laboratory, Kigali, Rwanda between October 2020 and February 2021.

Methodology: Different methodologies have been applied to address the objective of this work. The site was identified, problems of the community were clearly stated, data required for the work was collected through various data collection mechanisms, and different literature was reviewed to identify the way to do this work. The data were collected from different sources and were analysed using a software tool (HOMER software) and simulated for getting a solution for the problems and challenged accordingly. An Off-grid Solar Photovoltaic Power Plant was established in Rwisirabo village in Kayonza District, Rwanda. This site has been chosen because, in the Mwiri sector, Kageyo cellule in Rwisirabo (Rwisirabo II) village is listed by National Electrification Plan (NEP) as the site to construct an off-grid solar PV Power Plant.

Results: Based on the load assessment and the design of the SPV system, the primary AC load of the village was 551,718 kWh/day with a peak load of 85.10 kW, the deferrable load was about 9.99 kWh/day and a deferrable peak load of 2.00 kW with the cost of energy (COE) $0.200/kWh were involved during optimization of the power plant. It also found that the peak demand of the community occurs from 18:00 to 20:00 hours because most of the household members would expect to be at their homes. The system items such as PV module, batteries, and inverter size have been found as an optimum system with 220 kW, 860 BAE PVS 210 batteries, and 110 kW respectively with a lifespan of 25 years of the project. The total net present cost (NPC), initial capital, operating cost, and Levelized COE for this off-grid SPV system were$903,829, $517,000,$17,522, and $0.200/kWh respectively. The monthly results of power generation in kW obtained after stimulation with software showed that the solar radiation is high in March, July, August, and September which brings more electric power generation. However, all months the power electricity remain generated. Results from simulation showed that this system generated mean power output of 220 kW and total production of 297,291 kWh/year. It approved that the system converter contributed the lowest NPC with$52,888.25 (6%), followed by PV modules that cost $244,284.28 (27%) and battery bank the first for this SPV system with a cost of$606,656.60 (67%). This optimal system uses 100% renewable energy.

Conclusion: It found that the implementation of an SPV system with battery storage in residential, commercial, and institutions in the area where the solar irradiance is concentrated across a country will reduce the cost of electricity and power interruption on the national grid. Therefore, further work is needed to optimize this system for rural electrification as well by integrating with other renewable sources available in the country and also extend the electrification to another area that is detached from the national grid.

##### Investigating Road Pavement Failure in Oworonshoki, Kosofe Area of Lagos, Using Geophysical and Geotechnical Methods

O. J. Airen, K. K. Oboshenure

Journal of Energy Research and Reviews, Page 56-67
DOI: 10.9734/jenrr/2021/v7i430198

An assessment of the immediate causes of persistent road pavement failure in Oworonshoki, Koshofe area of Lagos, Nigeria using geophysical and geotechnical methods was carried out. Six traverses were occupied in the study area along the alignment of the road. Electrical Resistivity Imaging (ERI) data using the Wenner array were acquired along the six traverses. These were followed by six (6) Vertical Electrical Sounding (VES) data along the traverses. On traverse 1 are VES 1 and 2, on traverse 2 are VES 3 and 4, on traverse 3 are VES 5 and 6. One boring and three Cone Penetration Testing (CPT) were conducted along traverse 6 while the three CPTs were carried out on traverse 3, 4 and 5 respectively. The inverted 2D results reveal that resistivity values vary from 6.74 – 1333 Ωm in the study area. Four resistivity structures are delineated which are peat, clay/sandy clay, clayey sand and sand. The peat has resistivity values ranging from 6.74 – 17.7 Ωm, clay/sandy clay (20.9 – 86.9 Ωm), clayey sand (96.3 – 194 Ωm) and sand (245 – 1333 Ωm). The peat is laterally extensive and occurs from the surface to a depth of 25 m. The peat is underlain by the clay which is fairly extensive across the area of study with a thickness of 2.5 – 20 m in most location. The Cone Penetration Tests (CPT) reveal cone resistance values that progressively varies from 0 – 101 kg/m2 from the surface to a depth of 17 m, indicating dense earth materials at deeper depth while at near surface, they are incompetent soft clayey earth materials. The laterally extensive peat and clay units underlying the road pavement, extending up 30 m depth as revealed from the 2D ERI, the geoelectric investigation and the borehole are suspected to be responsible for the persistent settlement, rutting and pitting of the road pavement. The thickness of the peat/clay and the lateral extent may not be economically admissible for excavation during construction. Pile foundations to the dense gravely sand at 40 m depth along the stretch of the road is therefore recommended for stable road pavement.

##### Utilization of Annona senegalensis as a Sorbent for THE Removal of Crude Oil from Aqueous Media

B. J. Dimas, S. A. Osemeahon

Journal of Energy Research and Reviews, Page 68-82
DOI: 10.9734/jenrr/2021/v7i430199

In the present study, the efficiency of Annona senegalensis fiber to remove crude oil from aqueous solution was evaluated. The crude Annona senegalensis (CAS), retted Annona senegalensis (RAS) and bleach Annona senegalensis (PFAS) were subjected to sorption studies to optimize their sorption capacity. The results revealed that the efficiency of sorbent to remove crude oil from water is related to the sorbent weight, contact time, initial oil concentration and temperature of sorption. It was found out that increase in sorbent weight led to increase in sorption capacity from 3.99-5.25g/g, 5.51-7.12g/g, and 5.01-6.72g/g in CAS, RAS and PFAS respectively. Increased in Initial oil concentration also increased the oil sorption capacity by 20-21% until it reach equilibrium. Sorption time was varied from 10, 20, 30, 40, 50, 60 and 70 minutes and the highest sorption capacity was recorded at 30 minutes before a gradual decreased was observed. Sorption capacity decreased with increased in temperature above 400C. The sorbent exhibited good reusability after 8 cycles, with less than 50 % reduction in sorption capacity. The kinetics of crude oil sorption onto CAS, RAS and PFAS follow the second- order model with correlation coefficients higher than 0.99. The results obtained revealed that crude oil adsorption onto the Annona senegalensis fiber can be used as an effective adsorbent to oil spill cleanup in water bodies.