Renewable Energy Alternatives

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A Review of the Current Trends in the Production and Consumption of Bioenergy
(Sami Publishing Company, 2021-02-01) Korir, Benjamin K.; Kibet, Joshua; Mosonik, Bornes C.
With the current traditional fossil fuels depleting at an alarming rate coupled with environmental degradation because of toxic emissions, there is a mounting desire in search of renewable and sustainable energy resources. In this regard, bioenergy is considered one of the greatest potential to address the global energy demands in order to foster confidence in energy security, economic sustainability, and environmental protection. Global use of biomass to generate electricity and enhanced green energy transport is expected to increase in the near future. Accordingly, the demand for renewable energy is aimed at minimizing energy poverty and mitigation against climate change. Bioenergy despite bioconversion challenges is one of the key solutions to the world’s current energy demands. Model bioenergy plant sources – Croton megalocarpus, palm oil, Jatropha, and soybeans are briefly discussed in this review as major sources of bioenergy. The increased focus on bioenergy has been necessitated by high oil and gas prices, and the desire for sustainable energy resources. Nonetheless, corrupt practices and lack of political goodwill has hampered efforts towards achieving the full utilization of bioenergy. Corruption has been widely cited as a major setback to bioenergy development in a range of global jurisdictions. In order to minimize environmental damage, carbon trade has been projected as a necessary action by developing countries to reduce carbon emissions. Generally, the analysis of the use of fossil fuels across the world shows a strong interrelationship involving energy utilization, degradation of air quality, and environmental health concerns.
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.
ASSESSMENT OF WIND CHARACTERISTICS AND POWER POTENTIAL AT KESSES LOCATION - UASIN-GISHU COUNTY, KENYA
(University of Eldoret, 2015) Cheruiyot, Wilkins
Wind energy is increasingly becoming popular all over the world as a green energy source for electricity generation since it is renewable and environmentally friendly. Pioneer wind turbines for electricity generation in Kenya were recently installed at Ngong Hills and Lake Turkana, and more is expected to be initiated in different parts of the country. Wind turbines extract the kinetic energy carried by the flowing wind and this energy is directly proportional to the cube of wind speed. Thus, the wind speed is the most important parameter to consider in designing and selecting an efficient wind energy conversion system. Meteorological Department (MET) and some learning institutions in Kenya have been collecting and storing climatic data for several years, including wind speeds and most of them have not been analyzed. Precise knowledge of availability of wind at any given location is a pre-requisite for the effective planning and implementation and speed analysis is useful for the assessment of wind characteristicsand power potential at a location. In this work, analyses of five years (2009-2013) wind speed data collected at a meteorological unit at Moi University, Kesses area, Uasin Gishu County- Kenya, was done. The station measures wind speed at a height of 2 m and were extrapolated to the standard height of measurements of 10 m and typical hub heights of 40 m, 70 m and 100 m for purposes of characterization and determination of energy potential respectively. The extrapolated results revealed that the average annual wind speed at the height of 10 m is 3.86 ms-1, meaning that the location wind speed can be classified as class IV with a maximum wind power density of 100 Wm-2. The average annual wind speed at the hub heights of 40 m, 70 m and 100 m were 5.48ms-1, 6.33ms-1and 6.93ms-1, giving corresponding power densities of 115.563Wm-2, 175.395Wm-2and 228.917 Wm-2respectively. Weibull distribution model was used in the analysis of wind speed distribution. The Weibull scale parameter range from 2.543 ms-1to a maximum of 3.046 ms-1. The Weibull shape parameter was peaked at 5.902 in the year 2012. Both cumulative and probability density function were assessed and graphically presented.Results showed that the site has potential for harnessing wind energy for electricity generation and both small and medium scale wind power turbines are recommended for installation at the site.
Bio-alkanol gel fuel for rural households in the Lake Victoria Basin
(2019) Nyambega, Benson
The clean energy potential in eastern Africa is sufficient to develop a strong economic, social and environmentally beneficial supply that can exceed regional energy needs, make significant progress in increasing energy access, and do so in a way that achieves environmental sustainability and a more diverse and vibrant private sector.The Lake Victoria basin which is a significant water resource for the region is characterized by high rates of deforestation. Only 6% of rural households around the lake basin rely on modern fuels with the majority predominantly using solid fuel such as charcoal and firewood for their primary cooking needs. The resulting degradation of the catchment areas of Lake Victoria basin is a major threat to these resources and livelihoods. Moreover, firewood and paraffin which are popularly used by the rural households are a major source of indoor air pollution and are known to cause numerous respiratory ailments such as pneumonia, asthma and lung cancer among others.To minimize reliance on wood-based fuel and paraffin, the project will commercialize a renewable biofuel known as ‘bio-alkanol gel’ made from fruit waste. The bio-alkanol gel also has the potential to repel mosquitoes that cause malaria. An enterprise will be established through which the gel will be commercially produced, and sustainable business models developed to scale the product to benefit rural household communities in the Lake Victoria basin, youth and women among others
Biogas Technology in Kenya
(KIRDI, 2021-06-15) Lumadede H.M.*, Wangai L., Kwach S., Khalifa J. and Mbithi V.
Research into biogas production and sustainability in Kenya is in progress at Kenya Industrial Research and Development Institute (KIRDI) through its biogas laboratory. Biogas production is one of the renewable energies which we use in Kenya. Biogas importance, development, opportunities and the economical and sustainability in Kenya are discussed. The full exploitation of Kenya ‘s agricultural potential will yield a lot of biomass through which innovative use of the available bio waste from maize, cotton, tea and sugarcane can be utilized. Present and emerging biogas technologies convert these biowaste into renewable energy, thereby replacing the expensive fossil energy sources, and reducing dependency on fossil fuels. Other substrates like water hyacinth and molasses distillery waste have been found to be a good source of biogas. This review examines the energy potential of biogas production from crop residues. The findings will promote biogas addition to the energy mix Kenya needs as well as providing approaches, achievements, lessons learnt and other relevant aspects of domestic biogas programmers. It aims to achieve a greater, more effective use of biogas and contributes to the process by providing knowledge of biogas use in Kenya and its potential. Development partners are supporting the implementation of market-based domestic biogas programmers in Kenya with a view to establish a commercially viable biogas sector.
Characterization of Local Nano-Heat Transfer Fluids for Solar Thermal Collection
(Advances in Materials Science and Engineering, 2020-07-07) Millien, Kawira
Performance of organic oils in solar thermal collection is limited due to their low thermal conductivity when they are compared to molten salt solutions. Extraction of organic oils from plants can be locally achieved. The purpose of this study was to investigate the effect of use of copper nanoparticles in some base local heat transfer fluids (HTFs). Addition of volume fraction of 1.2% of the copper nanoparticles to oil-based heat transfer fluids improved their thermal conductivity as deduced from the thermal heat they conducted from solar radiation. The oil-based copper nanofluids were obtained by preparation of a colloidal solution of the nanoparticles. Impurities were added to increase the boiling point of the nano-heat transfer fluids. Stabilizers were used to keep the particles suspended in the oil-based fluids. The power output of the oil-based copper nano-heat transfer fluids was in the range of 475.4 W to 1130 W. The heat capacity of the steam in the heat exchanger was 93.7% dry and had a thermal capacity of 5.71 × 103 kJ. The heat rate of flow of the oil-based copper nano-heat transfer fluids was an average of 72.7 Js−1·kg−1 to 89.1 Js−1·kg−1. The thermal efficiency for the oil-based copper nano-heat transfer fluids ranged from 0.85 to 0.91. The average solar thermal solar intensity was in the range 700 Wm−2 to 1180 Wm−2. The heat exchanger used in this study was operating at 4.15 × 103 kJ and a temperature of 500.0°C. The heat transfer fluids entered the exchanger at an average temperature of 381°C and exited at 96.3°C and their heat coefficient ranged between 290.1 Wm−2°C and 254.1 Wm−2°C. The average temperatures of operation ranged between 394.1°C and 219.7°C with respective temperature efficiencies ranging between 93.4% and 64.4%. It was established that utilization of copper nanoparticles to enhance heat transfer in oil-based local heat transfer fluids can mitigate energy demand for meeting the world’s increasing energy uses, especially for areas inaccessible due to poor land terrain.
Creating livelihoods through clean energy and agriculture
(The International Journal Of Rural development, 2020-06-26) Shirley, Rebekah
Just 35 per cent of the African population have access to electricity, with rural access rates at less than one-third of urban communities. Not only could decentralised renewable energy technologies help in meeting energy demand in rural areas in a climate-friendly manner, and promoting innovations in the agri-food sector, they are also an important potential driver of local job creation and the formalisation of labour – provided that the skills gaps hindering the sector’s growth can be closed.
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.
EMERGING TRENDS FOR ENERGY CONSUMPTION WITHIN ICT DEVICES
(International Journal of Engineering Applied Sciences and Technology, 2020) Chitechi, Kadima Victor; Odoyo, Collins Otieno
The information and communicationtechnology (ICT) is closely related to the future ofglobal energy consumption, not only because theICT equipment itself increasingly consumesenergy, but also because it is a general-purposetechnology, which may affect energy use of almostall sectors. The growing demand for ICT devicesand services outpaces the efficiency gains ofindividual devices. Previous studies had alludedthat cumulated potentials for ICT-induced savingsis several times larger than the entire energyconsumption of ICT itself. More studies on ICTrelated energy consumption do exist, and anincreasing number of studies looking at ICTinduced energy efficiency. The few studies,however, considering both aspects, typically do soindependently, without relating the two aspects.Moreover, in the energy efficiency discourse, ICTis usually treated as a monolithic block oftechnologies – only the application areas that areexpected to benefit from it being differentiated. Itis only by consequently following low energyconsumption targets for technologies with a lowenergy efficiency potential, while at the same timenot suffocating technologies with a high-energyefficiency potential through restrictiveconsumption targets, this paper will discuss thevarious emerging trends in energy consumptionswithin ICT devices.
Environmental Science Biogas Technology in Kenya: A Review
(Journal of Environmental Science, Computer Science and Engineering & Technology, 2021-07-22) Mudoga, Humphrey Lumadede; Wangai, Lucy; Kwach, Sarah; Mbithi, Victor; Khalifa, Joan
Research into biogas production and sustainability in Kenya is in progress at Kenya Industrial Research and Development Institute (KIRDI) through its biogas laboratory. Biogas production is one of the renewable energies which we use in Kenya. Biogas importance, development, opportunities and the economical and sustainability in Kenya are discussed. The full exploitation of Kenya 's agricultural potential will yield a lot of biomass through which innovative use of the available bio waste from maize, cotton, tea and sugarcane can be utilized. Present and emerging biogas technologies convert these biowaste into renewable energy, thereby replacing the expensive fossil energy sources, and reducing dependency on fossil fuels. Other substrates like water hyacinth and molasses distillery waste have been found to be a good source of biogas. This review examines the energy potential of biogas production from crop residues. The findings will promote biogas addition to the energy mix Kenya needs as well as providing approaches, achievements, lessons learnt and other relevant aspects of domestic biogas programmers. It aims to achieve a greater, more effective use of biogas and contributes to the process by providing knowledge of biogas use in Kenya and its potential. Development partners are supporting the implementation of market-based domestic biogas programmers in Kenya with a view to establish a commercially viable biogas sector.
High-performance organic solar cells utilizing graphene oxide in the active and hole transport layers
(Elsevier Ltd, 2018-06-22) Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.
We have successfully synthesized and employed graphene oxide (GO) to boost photons harvesting and charge transport process in thin film organic solar cells (TFOSCs). The graphene oxide was inlayed in both the P3HT:PCBM-based photoactive medium of the device, as well as, a dopant in PEDOT:PSS hole transport buffer layer (HTL). The parameters of the solar cells produced with the inclusion of GO in the HTL and the active layer results in high short-circuit current densities (Jsc), which translated into high power conversion efficiencies (PCEs). GO in the HTL facilitates charge transport, selective electron blocking and hole injection at the interface for enhanced device performance. On the other hand, the use of GO in the active layer remarkably improves the optical absorption leading to high charge carriers photogeneration requisite to efficient OSCs. Similarly, effective exciton dissociation is energetically favoured in the GO modified active layer devices which corroborated with improved conductivity of the medium that assisted charge carriers transport processes. Enhanced photocurrent has been recorded, as high as 18 mA cm−2, from the TFOSCs by the inlay of GO in the active layer. Consequently, increased PCE of up to 40% and 120% is achieved by the inclusion of GO in the HTL and photoactive layers, respectively.
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.
Numerical Study of Copper Antimony Sulphide (CuSbS2) Solar Cell by SCAPS-1D
(Heliyon, 2023-07-27) Obare, Nancy; Isoe, Wycliffe; Nalianya, Amos; Mageto, Maxwell; Odari, Victor
Copper antimony sulphide has ability in applications on photovoltaics since it is a promising, less toxic, earth abundant absorber material. In this study, the photovoltaic characteristics of copper antimony sulphide (CuSbS2) photovoltaic cell were simulated and studied by one dimensional solar cell capacitance simulator (SCAPS-1D) to improve their operations. This study investigated the impact of modifying the thicknesses of fluorine-doped tin oxide (FTO), cadmium sulphide (CdS), carbon(C), and CuSbS2 absorber layer, Also the amount of doping and the number of defects on CuSbS2 photoactive layer, the structure of the solar cell is made up of glass, FTO, n-CdS, p-CuSbS2, C, and Au. The optimum parameters of the designed photovoltaic cell yielded 0.9388 V of open-circuit voltage (Voc), the short-circuit current density (Jsc) was 28.31 mA/cm2, the fill factor (FF) of 60.8%, and the solar cell efficiency of 16.17%. The ideal thickness was discovered to be 300 nm for the CuSbS2 solar cell. The defect density increment led to a decrease in carrier lifetime resulting also to decrease in diffusion length and the optimum absorber layer doping concentration was found to be 1018 cm-3
Numerical study of lead free CsSn0.5Ge0.5I3 perovskite solar cell by SCAPS-1D
(Elsevier, 2021-12) Nalianya, Milimo Amos; Awino, Celline; Barasa, Henry; Odari, Victor; Gaitho, Francis; Omogo, Benard; Mageto, Maxwell
Lead free perovskite solar cells (PCS) are becoming a distinctly predominant area of study due to the toxicity and stability hurdles of the lead halide perovskite. Current lead-free perovskites are also plagued with low efficiency. This work is concerned with the design and analysis of CsSnGeI3 that is a viable competitor to lead based perovskites by SCAPS-1D simulator (ver.3.3.08). The primary solar cell’s structure is FTO/PCBM/ CsSn0.5Ge0.5I3 / spiro-OMeTAD/Au which achieved a power conversion efficiency (PCE) of 7.11% [1]. To enhance device performance, the effect of optimizing absorber layer defect density (1 × 1015 cm−3) and thickness (700–800 nm), doping concentration of absorber layer (1 × 1015 cm−3), variation of Electron Transport Material (ETL) and Hole Transport Material (HTL) parameters (effect of CBO and VBO and doping concentration) and potential material options for ETL and HTL are studied. The results of the simulation are as follows; maximum power conversion efficiency (PCE) 18.79%, short circuit current density (Jsc) 27.05 mA/cm2, open circuit voltage (Voc) 0.87 V and fill factor (FF) 79.25%. By choosing appropriate material parameters, improving fabrication and encapsulation processes, CsSn0.5Ge0.5I3 proves to be an environmentally friendly solar cell with high efficiency.
Optical and Electrical Properties Dependence on Thickness of Screen-Printed TiO2 Thin Films
(Springer, 2016) Domtau, D. L.; Simiyu, J.; Ayieta, E. O.; Muthoka, B.; Mwabora, J. M.
Abstract Effect of film thickness on the optical and electrical properties of TiO2 thin films were studied. Thin films of different thicknesses were deposited by screen printing method on fluorine doped tin oxide coated on glass substrate. The film thickness was determined by surface profile measurement. The thicknesses were 3.2, 8.2, 13.5 and 18.9 µm. Transmittance, reflectance and absorbance spectra were studied using UV-VIS-NIR spectrophotometer in the photon wavelength range of 300-1500 nm for transmittance and reflectance and 350-1200 nm for absorbance. Band gap and refractive index of the films were determined using these spectra. It was found that reflectance, absorbance, band gap and refractive index increased with film thickness while transmittance decreased with increase in thickness. I-V characteristics of the films were also measured by a 4- point probe. Electrical resistivity (𝜌𝜌) and conductivity (σ) where calculated from the I-V values. Resistivity was found to increase with thickness while conductivity decreased with increase in film thickness. Keywords: TiO2 thin films, thickness, optical and electrical properties, screen printing
Polymer solar cells with reduced graphene oxide–germanium quantum dots nanocomposite in the hole transport layer
(Journal of Materials Science: Materials in Electronics, 2018-02-19) Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.
Reduced graphene oxide–germanium quantum dots (rGO–Ge QDs) nanocomposite has been successfully employed in modifying poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the hole transport layer (HTL) in the preparation of a P3HT:PCBM-based polymer solar cell (PSC). The effect of the surface morphology and the optical transmittance of the PEDOT:PSS/rGO–Ge QDs HTL on the devices’ photovoltaic performance is examined. A significant improvement of up to 50% in the power conversion efficiency is achieved by the incorporation of the composite in the HTL. The modified HTL devices exhibited higher short-circuit current density values which resulted from better transportation and collection of photo-generated charge carriers. The synergistic effect of the high electrical conductivity of the composites and the formation of good ohmic contact at the interface between the anode and the active layer not only facilitates charge carrier transport but also impairs their recombination to yield better photovoltaic performance.
POTENTIAL USE OF ALGAE FOR NUTRIENT REMEDIATION OF WASTEWATER AND PRODUCTION OF CLEAN ENERGY
(University of Eldoret, 2014) Rono, Mary
The reliance on fossil fuels as a source of energy has led to environmental degradation and a myriad of health problems leading to a need for renewable source of energy that is economical and sustainable. Likewise, eutrophication of water bodies is a matter of concern because it disturbs normal functioning of such an ecosystem. The release of improperly treated wastewater is one major cause of this problem. The objective of this study was to utilize nutrients present in wastewater for algal growth and later produce biofuel from the harvested biomass of the algae. Individual algae cultures of locally dominant genera Spirogyra, Oedogonium and Zygnema, collected in Kesses area of Uasin Gishu County were grown in laboratory conditions at Moi University. A 10g portion of the algae were grown in 250 ml Erlenmeyer flasks containing 100ml of sewage in an incubator set at 260C with continuous light provided by a 5 W fluorescent tube. The flasks were stirred once daily to prevent settling of algal cells. 0.05 mg of CO2 was bubbled to the flasks once. The control consisted of algae grown in Bold Basal media. Algal growth was monitored for seven days using daily measurements of chlorophyll a. Daily uptake of nitrate from the wastewater by the algae was also determined through automated hydrazine reduction method. After the seven days, the algae were harvested and dried. Lipids were obtained from the dried biomass by Soxhlet extraction using a mixture of hexane and ethanol, and weighed in grams. The quantities of starch were estimated using enzymatic-colorimetric method and given as a percentage of the sample. The lipids obtained were utilized to determine the calorific value of the fuel using a bomb calorimeter. All the data obtained were statistically analyzed using the SPSS program. Friedman test was utilized to check whether there was a statistical difference exhibited by the various taxa in amounts of nitrates reduced, as well as in the accumulation of chlorophyll a. Wilcoxon test was employed to check whether there was a statistical difference in the amounts of lipids, starch and calorific values between those algae that grew in sewage and those that had been grown in the growth medium. Results showed that all the algae genera grew better in Bold Basal Medium than on sewage. For all the genera that were grown on sewage, growth declined after the fourth day and Zygnema showed the highest growth in sewage. On nitrate removal from the wastewater, the length of contact time between the algae and wastewater was of paramount importance. After four days the studied Spirogyra decreased the quantities of nitrate in 100 mL sewage by 90.7%, Oedogonium by 89.48% and Zygnema by 83.84%. On lipid productivity, results obtained showed that growth of algae on sewage led to accumulation of higher quantities of lipid. Spirogyra increased lipid quantities when it was cultured on sewage by 73.99%, Oedogonium by 91.38 and Zygnema by 89.04%. However, those results acquired from estimation of starch illustrated that growth of the algae on sewage led to accumulation of less amounts of starch. Growth of Zygnema on the sewage reduced the quantities of starch by 82.11%, 79.63% in Spirogyra, and 58.13% in Oedogonium. In Spirogyra and Zygnema, lipids obtained from algae that grew in sewage had higher calorific values than those that had grown in the growth medium. From the results of this study, it can be concluded that sewage may be used as an alternative growth media for algae. The problem of eutrophication can also be counteracted using local genera of algae. The results also illustrate that sewage grown algae can produce biomass suitable for production of biofuel.v
Solar Radiation Prediction Models Analysis for Varying Climatic Conditions
(International Journal of Engineering and Technology, 2017-07) Wainaina, Patrick M.; Owino, George O.; Musa, Njue R.
This study has investigated global solar predictive models, modiﬁed, validated and compared ﬁve models, for prediction of monthly daily mean solar radiation in four different locations of Kenya that represents the four major climatic conditions. The input variables to the models Were; latitude, day length, sunshine hours, relative sunshine hours, temperature, and precipitation. Solar radiation data from 2000 to 2013 was used to obtain the monthly daily mean global solar radiation, to analyze, validate and compare the performance of the models. The predicted and measured data was simulated using MATLAB. Statistical indicators, MBE, RMSE, t-test and R, were performed to determine the models performance. The results showed that sunshine hours based models predicted global solar radiation with higher accuracy in wet and cold, wet and warm climatic conditions, while the temperature and precipitation models were accurate in solar radiation prediction in hot and dry climatic conditions. Key words: Global solar radiationl, Sunshine hours2, Day length3
Theoretical analysis of the electrical characteristics of lead-free formamidinium tin iodide solar cell
(Wiley, 2023-09-14) Katunge, Elizabeth K.; Njema, George G.; Kibet, Joshua K.
Green energy transition and climate change have gathered significant momentum in the world because of the rising population and increased clean energy demands. For this reason, renewable energy alternatives such as inexhaustible photo energy from the sun appear to be the ultimate solution to the world's energy needs. Formamidinium tin tri-iodide (HC(NH2)2SnI3)-based perovskites are found to be more efficient and stable than their methylammonium tin tri-iodide (MASnI3) counterparts because of its wider bandgap and better temperature stability. A device simulation of FASnI3-based solar cell is numerically performed using solar cell capacitance simulator (SCAPS-1D). The focus is to investigate the effect of changing working temperature, metal back contact, absorber thickness, defect density, and doping concentration on the performance of the proposed solar cell device. The optimised solar cell parameters of the proposed solar cell were: short-circuit current density (Jsc) of 28.45 mAcm−2, open-circuit voltage (Voc) of 1.0042 V, fill factor of 63.73%, and power conversion efficiency of 18.21% at 300 K, thus, paving the way for novel perovskite solar cells which are environmentally benign because they are lead-free, have better absorption efficiency, and can be injected into the production work flow for commercial applications.

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