Renewable Energy Alternatives

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2013 ISES Solar World Congress Promotion of PV Uptake and Sector Growth in Kenya through Value Added Training in PV Sizing, Installation and Maintenance
(Science Direct, 2014) Justus Simiyu; Sebastian M. Waita; Alex Ogacho; Robinson Musembi
Sub-Saharan Africa, and more specifically the East African region, has the lowest rates of access to electricity in the world. On average, at most 15% of the rural population has access to electricity. Rural households and remote institutions use traditional energy sources such as charcoal, firewood, kerosene and diesel for generator sets, batteries and dry cell batteries. On the other hand, the region is one of the most promising in the world in economic development with growth levels being high and market saturation is a far away future problem. This growth has however been hampered by several factors with lack of energy being one of them. Kenya being one of the countries in the region faces a similar problem with the traditional sources of hydro facing weather related challenges. The situation is more wanting in the rural setting having only achieved electrification rates of between 5 and 10%. The rural being where the majority of low-income earning groups reside is further compounded with large geographical imbalance in electricity demand and supply. The main challenge to adopting pv utilization however, is lack of local capacity to handle the uptake all the way from solar home systems to grid connected and hybrid systems. According to Kenya Renewable Energy Association (KEREA), it is estimated that between 800 and 1000 pv technicians have been in practice since this sector started in Kenya in the late eighties, majority of them having the basic skills but no formal training to provide the service. They however have been offering necessary service to end-users and are hence an important aspect in the pv sector as a whole. Currently the pv (mainly SHS) comprise an over the counter trade system which provides loopholes when it comes to quality of products and installation. To safeguard the quality and safety of installations, formal training has to be incorporated in the system.
A Simple Low Cost Solar Panel/cell Characterization Experiment for Senior Undergraduate Students
(ISES, 2015-11-11) Sebastian Waita*, Justus Simiyu, Alexander N. Kiragu, Vivian Imali and Bernard Aduda
A simple low cost solar cell characterization experiment has been developed for senior undergraduate students in the Department of Physics, University of Nairobi. Experiments were conducted with solar panels (also called solar modules/photovoltaic modules) rated 20 W and 40 W peak power on different sunny days on the roof top of Physics Department, University of Nairobi. It was observed that the current- voltage (I-V) curves obtained for all the measurements for each panel were comparable. The fill factor (FF), short circuit current (Isc), open circuit voltage (Voc), current at maximum power point (Im) and voltage at maximum power point (Vm) were within acceptable margins when compared with the manufacturer’s rated values, an indication of the reliability and accuracy of the method. The method eliminates the need for expensive characterization equipment like solar simulators, unaffordable by many developing country institutions. The experiment is recommended for senior undergraduate students with an interest in renewable energy as one way of introducing them to renewable energy. The experiment may also help in arousing the learner’s interest in solar energy.
Adoption of Improved Cookstoves in the Peri-urban Areas of Nairobi: Case of Magina Area, Kiambu County, Kenya
(Research Gate, 2019-02-04) Kong'ani, Lilian Sarah; Ang'u, Cohen; Muthama, Nzioka
Concerted efforts have been made to enable communication and adoption of improved cookstoves by diverse development organizations in Kenya. However, their adoption remains low. This study sought to examine levels of adoption and use of improved cookstoves in Magina, Kiambu County and determine factors affecting their adoption and use. Results demonstrate that 93% of the households received the cookstoves from developmental programmes, among these 50% were making use of them but only 14% of the 50% had fully adopted them as main cookstoves. Efficiency and suitability, socio-cultural practices, economic capacity, limited capacity to appreciate the improved cookstoves concept and governance considerations were the cited limiting factors to adoption and use. There is need for an enabling policy and strategies to implement the bottom-up approach in the design and implementation of improved cookstoves to facilitate the upscaling of the adoption and use of improved cookstoves to conserve the forests in the country for sustainable development.
Effects of TiO2 Blocking Layer on Photovoltaic Characteristics of TiO2/Nb2O5 Dye Sensitized Solar Cells
(Springer Nature, 2020-09-13) Owino, Brian O.; Nyongesa, Francis W.; Ogacho, Alex A.; Aduda, Bernard O.; Odari, Benjamin V.
This study reports on the effect of introducing TiO2 compact layer on the photovoltaic characteristics of TiO2/Nb2O5 composite dye sensitized solar cell. The compact layer was deposited by spray pyrolysis technique. It was observed that introduction of 60 nm thick compact layer improved the short circuit current density Jsc,Open circuit voltage Voc, and efficiency of the cell from 4.9 mA/cm2 to 8.2 mA/cm2, 6.8×10-1 V to 7.2×10-1 V and 1.9 % to 3.4 % respectively compared to traditional cell prepared without compact layer. Electrochemical impedance spectroscopy confirmed an increase in recombination resistance from 5.5×101 Ω.cm2 for bare DSSC to 9.0×101 Ω.cm2 for DSSC with compact layer thereby improving electron lifetime of the cells from 2.5×10-4 s to 386.9×10-4 s.
Influence of Pore Size on the Optical and Electrical Properties of Screen Printed
(Hindawi Publishing Corporation, 2016-09-27) Domtau, Dinfa Luka; Simiyu, Justus; Ayieta, Elijah Omollo; Asiimwe, Godwin Mwebeze; Mwabora, Julius Mwakondo
Influence of pore size on the optical and electrical properties of TiO2 thin films was studied. TiO2 thin films with different weight percentages (wt%) of carbon black were deposited by screen printing method on fluorine doped tin oxide (FTO) coated on glass substrate. Carbon black decomposed on annealing and artificial pores were created in the films. All the films were 3.2 µm thick as measured by a surface profiler. UV-VIS-NIR spectrophotometer was used to study transmittance and reflectance spectra of the films in the photon wavelength of 300–900 nm while absorbance was studied in the range of 350–900 nm. Band gaps and refractive index of the films were studied using the spectra. Reflectance, absorbance, and refractive index were found to increase with concentrations of carbon black. There was no significant variation in band gaps of films with change in carbon black concentrations. Transmittance reduced as the concentration of carbon black in TiO2 increased (i.e., increase in pore size). Currents and voltages () characteristics of the films were measured by a 4-point probe. Resistivity () and conductivity () of the films were computed from the values. It was observed that resistivity increased with carbon black concentrations while conductivity decreased as the pore size of the films increased.
Isolation of Actinomycetes from Geothermal Vents of Menengai Crater in Kenya
(International Journal of Molecular Biology, 2017-07-20) Waithaka, Paul Njenga; Mwaura, Francis; Wagacha, John M.; Gathuru, Eliud Mugu
The current study was carried out to isolate actinomycetes from the geothermal vents of Menengai crater. Soil samples were collected from vents A and D in sterile polythene papers and transported to Egerton University, Department of biological sciences laboratories. The samples were air dried on the benches for one week. To kill vegetative bacteria, the soil samples were heat in a hot air oven for 1h before serial dilution to 10-6. The samples separately plated on Starch casein agar, Luria Bertani agar and starch nitrate agar in which nystatin and nalidixic acid had been added to reduce the growth of fungi and other types of bacteria. Incubation was carried out at 30 o C for up to a period of one Month. The isolated actinomycetes were characterized by cultural, morphological and biochemical means. There was no significant difference in the number of actinomycetes isolated between vents A and vents D(P=0.439). However, the number of actinomycetes isolated using the three isolation media varied significantly (F=37, P=0.03). Totally, 16 actinomycetes were isolated from the vents. It is recommended that the isolates be tested for antagonism against pathogenic microorganism.
Optical Properties and Analysis of OJL Model’s Electronic inter-band Transition Parameters of TiO2 Films
(Path of Science, 2018-07-31) Musila, Nicholas; Munji, Mathew; Simiyu, Justus; Masika, Eric; Nyenge, Raphael; Musila, Nicholas; Munji, Mathew; Simiyu, Justus; Masika, Eric; Nyenge, Raphael
Titanium dioxide is a wide band gap semiconductor responsible for the bright white appearance in most substances. This material has many unique properties due to its extra-ordinary chemical stability. TiO2 has a conduction band that closely matches the excited energy level of organic dyes hence it is used in fabrication of photo-anode electrode of dye sensitized solar cell. However, the optical properties and the density of states of TiO2 thin films determine the performance of dye sensitized solar cell fabricated from TiO2 photo-anode electrode. For this reason, the purpose of this study was to investigate the optical properties and the OJL electronic inter-band transition analysis of TiO2 nanoparticle thin films. Under the OJL model, the expressions of density of states were specified for the optical transition from the valence band to the conduction band. The TiO2 nanoparticles were prepared using sol-gel and hydrothermal methods and deposited on a conductive glass substrate by screen printing and spray pyrolysis techniques. SEM analysis revealed that TiO2 nanoparticles were spongy and had unevenly sphere-shaped profile while TiO2 nanotubes had a skein-like morphology with abundant number of nanotubes intertwined together. This study showed that TiO2 thin films have both direct and indirect band-gaps. The OJL Gap energy (E0) values were observed to be between 30273.2356 and 31072.0000 wavenumbers which translated to band-gap energies between 3.744 and 3.843 eV. From these findings showed that TiO2 films prepared could be used in the fabrication of high performing dye-sensitized solar cell.
Power loss reduction in the distribution system with a wind based distributed generation.
(University of Nairobi Research Archive, 2022-11-23) Musau, Peter M.
Distribution system operating environments are changing rapidly due to the integration of the intermittent renewable in to the power grid at the distribution side of the power system. Therefore, with increasing number of wind based distributed generators (DFIGs) being installed within distribution systems, the traditional methods for distribution system modeling, DFIG placement & sizing, network reconfiguration needs to be reviewed and better practical ones developed to cater for the intermittent renewable power. The combined participation factors, realized by the Newton Raphson method, capture network parameters, load distributions and DFIG capacities (sizes) and locations have been formulated considering real and reactive power. A distributed slack bus model taking into consideration network sensitivity is proposed in the research as compared to the distributed slack bus models based on the DFIG capacity, DFIG domains and the single slack bus model. DFIG placement and sizing using a particle swarm optimization method (PSO) and a hybrid of GA and PSO (HGAPSO) and by load flow method are compared. With simulated results, the optimal location of the DFIG is the primary distribution system, with the HGAPSO giving improved results as compared to the ordinary PSO and the load flow. The active distribution network reconfiguration problem with an objective function of reducing real and reactive power losses in the presence of DFIG and uncertain loads proves the practicability of such a method in reducing power losses and in improvement of the voltage profile .Here an hybrid method of bacterial foraging and differential evolution (HBFDE)is applied. The proposed methods, as applied to the IEEE 33 Bus Radial distribution system ,are found to be effective in the power loss reduction in the power system wind based distributed generation.

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