Browsing by Author "Kihedu, Joseph H."

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    Assessment of Hydropower Potential of Un-Gauged Myombwe River Based nn Hydrological Data
    (International Journal of Innovative Research in Technology & Science(IJIRTS), 2014-09-30) Mrope, Hamis A.; Kihedu, Joseph H.
    Assessment of hydropower potential is necessary in evaluating energy generation based on hydrological data for hydropower systems. A study was done at Magunguli waterfalls along the un-gauged Myombwe River with an aim of assessing and analyzing hydropower potential. Hydrological data collections and analysis covered flow rate for gauged Ruaha River and area ratio method to obtain the flow rate for Myombwe River based on catchment area analysed by ArcView GIS. Based on the available resources and data analysis; a hydraulic head of 636 m was realized through GPS techniques, flow rate of 1.979 m3 /s was estimated using area ratio method and flow duration curve. The selected turbine was Pelton turbine which has an efficiency range of 80 - 90%. Based on the hydrological data a Power potential of 9,388.69 kW was realized which is viable for development of mini hydro scheme. To enhance and sustain development of hydropower projects in Tanzania; extensive utilization of acquired data, extended assessment of un-gauge rivers in parallel with impact assessment for the potential hydropower schemes should be done.
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    Contribution of Volatile Interactions during Co-gasification of Biomass with Coal
    (Life science Global, 2013) Kihedu, Joseph H.; Yoshiie, Ryo; Nunome, Yoko; Naruse, Ichiro
    Thermo-gravimetric behavior during steam co-gasification of Japanese cedar and coal was investigated. The difference between co-gasification behavior and the average gasification behavior of cedar and coal indicates two synergetic peaks. The first peak occurred between 300 °C and 550 °C while the second peak was observed above 800 °C. The first peak coincides with volatile release and therefore associated with volatile interactions while the second peak is linked with catalytic effect of alkali and alkaline earth metal (AAEM). Acid washed cellulose and Na rich lignin chemicals were used as artificial biomass components. In reference to Japanese cedar, mixture of cellulose and lignin i.e. simulated biomass, was also investigated. Co-gasification of cellulose with coal and co-gasification of lignin with coal, demonstrates contribution of volatile interactions and AAEM catalysis respectively. Morphology of partially gasified blends, shows hastened pore development and physical cracking on coal particles. Brunauer−Emmett−Teller (BET) surface area of the charred blend was lower than the average surface area for charred biomass and coal.
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    Conversion Synergies during Steam Co-Gasification of Ligno-Cellulosic Simulated Biomass with Coal
    (Scientific Research, 2012-12) Kihedu, Joseph H.; Yoshiie, Ryo; Nunome, Yoko; Ueki, Yasuaki; Naruse, Ichiro
    Lignin and cellulose chemicals were used as artificial biomass components to make-up a simulated biomass. Alkali and Alkaline Earth Metal (AAEM) as well as volatile matter contents in these chemicals were much different from each other. Co-gasification of coal with simulated biomass shows improved conversion characteristics in comparison to the average calculated from separate conversion of coal and simulated biomass. Two conversion synergetic peaks were observed whereby the first peak occurred around 400℃ while the second one occurred above 800℃. Although co-gasification of coal with lignin that has high AAEM content also shows two synergy peaks, the one at higher temperature is dominant. Co-gasification of coal with cellulose shows only a single synergy peak around 400℃ indicating that synergy at low temperature is related with interaction of volatiles. Investigation of morphology changes during gasification of lignin and coal, suggests that their low reactivity is associated with their solid shape maintained even at high temperature.
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    A Cost Effective Model of Electrifying Low Cost Residential Houses in Remote Locations
    (2006-10-11) Kihedu, Joseph H.; Karsten, A.; Kimambo, C. Z. M.
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    Counter-flow air gasification of woody biomass pellets in the auto-thermal packed bed reactor
    (Sciencedirect, 2014-01) Kihedu, Joseph H.; Yoshiie, Ryo; Nunome, Yoko; Ueki, Yasuaki; Naruse, Ichiro
    Counter-flow packed bed gasification was carried out featuring a combination of downdraft and updraft operation modes. A column reactor of inside diameter 102 mm and 1000 mm height was used. Downdraft and updraft air supply were varied while the total air supply was maintained constant. Counter-flow gasification with downdraft air supply at 12 L/min and updraft air at 4 L/min offered optimal conditions, producing syngas with 4.28 MJ/m3 N LHV and 5.84 g/m3 N tar content. Under similar operating conditions, cold gas efficiency was about 77% while carbon conversion reached 88%. Increasing the updraft air flow resulted in reduced tar generation and increased carbon conversion, however, the syngas LHV and cold gas efficiency were affected adversely.
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    Gasification characteristics of woody biomass in the packed bed reactor
    (Sciencedirect, 2011) Ueki, Yasuaki; Torigoe, Takashi; Ono, Hirofumi; Yoshiie, Ryo; Kihedu, Joseph H.; Naruse, Ichiro
    Gasification technology is recognized as one of the possibilities for utilizing biomass effectively. This study focused on woody biomass gasification fundamentals, using a bench-scale packed-bed reactor. In this experiment, pellets of black pine were gasified, using air as the oxidizing agent. Gasification tests were carried out under both updraft and downdraft conditions. Temperature distributions and compositions of syngas inside the gasifier were continuously monitored during gasification experiments at several ports on the wall of the reactor. The syngas at the exit of the gasifier was also sampled to estimate the amount of tar. Lower heating values of the syngas under updraft and downdraft conditions were 4.8 and 3.8 MJ/m3N, respectively. It was easier to control the height of the packed bed under the downdraft condition than under the updraft condition. Under the updraft condition, a bridging phenomenon occurred. Tar generation under the downdraft condition was lower than that under the updraft condition. This is because tar passes through a partial combustion zone or higher temperature zone in the downdraft gasifier.
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    Impacts and Challenges of Solar PV Projects: Home Systems, Battery Charging and Water Pumping
    (College of Engineering, Design, Art and Technology (CEDAT), Makerere University, 2014-07) Kihedu, Joseph H.; Raymond, J.; Kimambo, C. Z. M.
    Assessment was conducted on the impacts and challenges on solar PV projects in Bagamoyo District and in Uzi Island, Tanzania. The projects covered include Solar Home Systems, Solar Battery Charging Stations and Solar Water Pumping Systems. Despite wider range of positive socio-economic impacts resulting from Solar PV projects; awareness, technology management and market development issues pose challenges on implementation and operation of such projects. As a result of installed solar PV systems around the study area, there has been an impact on the uptake of solar home systems. However, about 20% of solar home systems installed were found to be inoperative. Among the inoperative systems, public ones constituted a majority share. At least 67% of the solar systems users are satisfied with the solar PV system as the sole source of power for their energy needs. Capacity of users and village technicians towards solar PV systems maintenance was observed to be moderate; therefore the need for service of technicians from outside the villages remained low. Higher cost of replacement for system parts and repeated sabotage, leave vandalized public systems abandoned. About 96% of solar home system users indicated that solar PV systems are still unaffordable despite the existing tax exemption on solar PV equipment. Capacity building for local technicians need to be considered and sense of ownership among beneficiaries of public solar PV projects should be cultivated. Impacts of tax reduction implementation should also be assessed and micro-credit systems be set up to accelerate uptakes of solar PV systems.
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    A Low Cost Delivery Mode of Solar Powered Electricity for Low Income Households
    (Institution of Engineers Tanzania (IET), 2008) Kimambo, C. Z. M.; Kihedu, Joseph H.
    Housing and shelter adequacy are among the basic essentials of human beings. Only 10% of households are connected to the commercial electricity supply in Tanzania. In rural areas, where the great majority of the population lives, the percentage of the population that is supplied with electricity is less than 2%. Renewable energy sources such as solar energy are viable options. Sustainable uptake of such technology depends to a large extent on availability of proven appropriate delivery modes for the energy sources. This paper describes an alternative electricity delivery mode for low income households that are not connected to power utility grid and cannot afford Solar Home Systems (SHS). The paper is based on an electrification project in Uzi Island in Zanzibar using Solar Battery Charging Stations (SBCS) that the authors implemented with financial support of a German Non-governmental Organisation, Deutsch-Tansanische Partnersschaft e.V (DTP). The work involved a feasibility study that covered technical, environmental and socio-economical aspects; design and installation of the systems; setting up a management system for the project and monitoring. The project is run by villagers via a Village Committee. Each household pay monthly fees of less than US$ 2 to cover the costs operation, maintenance, replacements and expansion of the project. The monthly fee is lower than costs that would have been incurred for the other viable alternatives. The project has had very positive social, environmental and economic impacts on the island and the surrounding communities resulting in expansion of the project in terms of the number of households involved and new independent solar home systems. This delivery mode of electricity has proved to cost effective on the part of the electricity suppliers and affordable by the low income households in Tanzania. It is thus recommended for widespread adoption.
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    Mass And Energy Balance For Fixed Bed Incinerators A case of a locally designed incinerator in Tanzania
    (JMEST, 2015-10) Omari, Arthur; Njau, Karoli N.; John, Geoffrey R.; Kihedu, Joseph H.; Mtui, Peter L.
    An estimation of mass and energy balance of an incinerator is an important consideration toward the design and operation of the incineration process. This paper is aimed to study the mass and energy balance of a locally made fixed bed incinerator. The results shows that the total mass rate of 49 kg/h of municipal solid waste and 9.75 kg/h of diesel consumed 458.9 kg/h of air. The incineration process generates 379,287.14 kJ/h with ash and flue gases emissions at a total mass rate of 528.51 kg/h.
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    Performance indicators for air and air–steam auto-thermal updraft gasification of biomass in packed bed reactor
    (Sciencedirect, 2015-08-08) Kihedu, Joseph H.; Yoshiie, Ryo; Naruse, Ichiro
    Auto-thermal updraft gasification of biomass pellets in a packed bed reactor was conducted by using air and air–steam mixture. Air–steam gasification produced syngas with slightly improved lower heating value of 4.5 MJ/mN3 in comparison to 4.4 MJ/mN3 produced during air gasification. The corresponding tar generation for air gasification and air–steam gasification was 21.2 g/mN3 and 26.2 g/mN3, respectively. Cold gas efficiency for air gasification and air–steam gasification was realized to be 91% and 91.4%, respectively. Carbon conversion during air–steam gasification reached about 91.5% while carbon conversion during air gasification was limited to 84.3%.
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    Reaction Characteristic of Woody Biomass with CO2 and H2O
    (J Stage, 2010) Naruse, Ichiro; Ueki, Yasuaki; Isayama, Tsutomu; Shinba, Takanori; Kihedu, Joseph H.; Yoshiie, Ryo
    Objective in this study is to elucidate the fundamental gasification characteristics for carbonaceous resources. Effects of temperature and gaseous agents on the gasification characteristics of carbonaceous materials were experimentally and theoretically studied by the gasification of woody sawdust, using an electrically heated drop tube furnace. Results of the co-gasification of CO2 with H2O were compared by the gasi- fication by a single gaseous agent such as CO2 or H2O. As a result, H2 and CO concentrations increased with an increase of temperature. CO concentration under the co-gasification condition produced more than that under the single gasification condition. The H2 formation showed the opposite tendency to the CO formation during the co-gasification. This synergy effect was also elucidated theoretically by the simulation of reaction kinetics. The simulated temperature indicating the maximum synergy effect on CO formation agreed well with that obtained by the experiments.
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    Technology Management Challenges Facing Wind Pumping Projects in Tanzania
    (2008) Kihedu, Joseph H.; Kimambo, C. Z. M.
    Wind energy resources provide a renewable energy, which is friendly to the environment and decentralized. There exist adequate wind energy resources in Tanzania; however technological base of supporting institutions is weak. Local commercial manufacturing attempts have so far failed and support to existing wind energy technology users remain low, therefore majority of wind energy systems installed have failed. Only 40% of installed systems are operational with poor management, inadequate maintenance and lack of spare parts contributing to this situation. As part of technology development oriented research project aiming at integrating water pumping and electricity generation applications, a study on issues affecting the diffusion of the technology was conducted. The issues include technical and socio-economic issues. A technology assessment model was used in assessing the fitness of the technology in relation to the pertaining situations. Primary data was collected in Kongwa District, Dodoma region. The study has revealed a big potential of wind energy applications and factors that hinder its wide spread. It also gives possible ways to overcome the barriers.
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    Torrefaction and Combustion of Ligno-Cellulosic Biomass
    (Sciencedirect, 2015) Kihedu, Joseph H.
    Torrefaction of biomass and ligno-hemicellulosic compounds followed by combustion of torrefied samples was conducted by using a TGA. Cellulose exhibited highest thermal stability during torrefation at 473 K. Hemicellulose attained 48% decompositionafter torrefaction at 523 K while lignin decomposition was limited to 65% after torrefaction at 573 K. Co-torrefaction ligno-hemicellulosic compounds followed a similar trend for torrefaction behavior of biomass samples. Morphology changes in torrefied cellulose and biomass were notable on fiber shrinkage basis while hemicellulose disintegrated into smaller. However, no significant morphology change was observed on lignin. HHV increased with the increase in torrefaction temperature however torrefaction at 573 K resulted into decrease in HHV for biomass and co-torrefied ligno-hemicellulosic compounds. Optimal torrefaction temperature was observed to be 523 K where average mass loss of 34% resulted in energy yield of 75%. Torrefied samples exhibited slightly slower combustion than pyrolyzed samples. Combustion reactivity of torrefied biomass, hemicellulose, cellulose and lignin were realized to be 15%/min, 21%/min, 18%/min and 14%/min, respectively.