Doctoral Theses

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    Biomass gasification using a horizontal entrained-flow gasifier and catalytic processing of the product gas
    (Cardiff Insitute of EnergyCardiff University, 2012) Legonda, Isack Amos
    A novel study on biomass-air gasification using a horizontal entrained-flow gasifier and catalytic processing of the product gas has been conducted. The study was designed to investigate the effect of catalyst loading on the product gas. The use of a horizontal entrained-flow gasifier reactor was used toassess the effect of the gasifier reactor orientation on the gasification process. Both experimental and computational fluid dynamics (CFD) approaches were employed. The gasification tests were conducted at 800oC and equivalence ratio of 0.23 while the product gas was catalysed at 350-400oC and a gas hourly space velocity (GHSV) of 8000h-1. Preparation and characterisation of wood powder and catalysts were performed using classical methods. Moreover, the syngas and tar composition were analysed using a gas chromatograph (GC) and GC-mass spectrometer (GC-MS) respectively. The research findings showed that maximum fuel conversion and cold gas efficiency using a horizontal entrained-flow gasifier were 99% and 70%respectively. The gasifier length can also be reduced from the common 1000-2000 mm to 500 mm. The catalysis study showedthat pumice and kaolin have limited catalytic effect on the product gas.However,doping with CeO2, ZrO2, CuO and NiO improved the syngas heating value, coking resistance and tar conversion. A notable increase in syngas LHVwas achievedusing ceria doped pumice (8.97MJ/Nm3) and copper doped pumice (8.66MJ/Nm3) compared to6.67 MJ/Nm3of non-catalytic test. For the tested catalysts, CeO2doped pumice exhibited highest coking resistance. Furthermore, catalytic tar conversion was mainly through cracking and partial oxidation reactions. The lowesttar yield was found to be 3.55g/Nm3using kaolin-ceria-zirconia catalystcompared to 14.92 g/Nm3of non-catalytic gasification. Tar reduction usinguntreated pumice was through adsorption and ranged4-6 g/Nm3.In general, the results of this study suggest that there exist a sensitivity to the gasifier orientation on the overall gasification process. It has also shown that metal oxides have both beneficial and detrimental effects of syngas composition. Although syngas heating value increased with increasing catalyst loading, H2showed a decreasing trend highlighting that further catalyst modification is required. Furthermore, pumice and kaolin can be utilised as catalyst support in the gasification technology. However, further experimental investigation on doping various catalytic metals and testing at different operating conditions are hereby proposed.
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    Determining the level of economic efficacy of mandatory and supplementary schemes in the post-retirement period
    (Springer, Cham., 2022) Mujwahuzi, L. S.; Maselle, Ana E.
    Purpose: This paper presents the investigation on the level of economic efficacy due to mandatory and supplementary schemes in the post-retirement period among National Social Security Fund (NSSF) beneficiaries taking Morogoro as a case for study. The main argument is that once the reasonable level of economic efficacy is achieved it is likely to decrease the direct national economic losses relative to global gross domestic product. Design/Methodology/Approach: Purposive sampling technique was used to select 100 respondents under the condition that they should be NSSF retired beneficiaries. Descriptive statistics were used to analyze quantitative data which enabled researchers to generate frequencies and percentages under the objectives of the study. The level of economic efficacy was measured through Economic Efficacy Summated Index (EESI). Findings: Findings revealed that the economic efficacy level due to NSSF services to the retired population was at a moderate level. This was pre-determined by lack of significant association between background characteristics of respondents and a monthly income as well as low extent under which NSSF serve its clients at the time of disbursing terminal benefits. Research Limitation/Implications: The study’s target population was retired officials who some of them were not found in Morogoro region. This forced a researcher to use telephone interviews which have many shortfalls in social science research. Practical Implication: The knowledge generated from this study will inform Social Security employees on empowering more Tanzanian workers so that the benefits they give them may positively contribute to decreasing the direct national economic losses relative to global gross domestic product.
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    Household reliance reliance on environment income and wildlife-induces cost of living adjacent to protected areas in western Serengeti, Tanzania
    (The University of Dodoma, 2020) Kyando, Moses Titus
    Huge pressures on protected areas (PAs) in the Serengeti ecosystem in Tanzania are increasing through the extractive use by surrounding communities and human wildlife-related conflicts, which undermine conservation objectives and human welfare. The study examined household reliance on environmental income and wildlife-induced costs due to crop raiding and livestock depredation along the gradient of distance from Serengeti National Park (SNP) boundary in the western Serengeti. Data were collected through a semi-structured questionnaire in 150 households, randomly selected in three villages (Robanda, Rwamkoma and Kowak). The study also involved focus group discussions, physical observation and archive data. Results indicate that environmental cash-income varies from 21.3% to 45.2% of the total annual cash income. This reliance is associated with distance from SNP boundary, household wealth rank and absolute income from off-farm activities. Environmental income derived from inside PAs accounted for 14.7% and 31.2% of the total household income and total household environmental income, respectively. Households in the closest village accrued the highest income from inside PAs than households in a distant village. Moreover, income-poor households derived the highest relative income from inside PAs than medium-income and rich-income households. In addition, results revealed that household annual relative cost due to crop raiding was inversely related to distance from SNP boundary, but increased with the increase of income wealth of households. Nevertheless, the estimated relative household annual economic costs due to livestock depredation was inversely related to the increase of wealth of a household, although increased with the increase of distance from SNP boundary. The study recommends promotion of off-farm activities, improved wood fuel stoves, electricity and alternative sources of fuels, enhanced law enforcement to reduce pressure on PAs.