Browsing by Author "Gandure, Jerekias"

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    A comparative performance analysis of carbonized briquettes and charcoal fuels in Kampala-urban, Uganda
    (Energy for Sustainable Development, 2016) Tumutegyereize, Peter; Mugenyi, Ronal; Ketlogetswe, Clever; Gandure, Jerekias
    As a result of the rising energy needs and environmental concerns, carbonized briquettes have been looked at as a possible substitute source of energy for charcoal in most of the developing regions. However their use and adoption in Uganda cannot be ratedamidst continued increase in charcoal demand fromthe ever growing urbanization. This study therefore investigated burning performance and cost in affecting briquette use. A comparative performance analysiswas carried out for locally purchased carbonized briquettes made frommatooke peels plus other household wastes and charcoal fuel denoted as A, B, C, and D, using a nested design. Calorific value, ash content, moisture content, burning time, and time of boil as well as cost per kilogram and per energy output, were the parameters compared. Results showed that gross calorific values were comparable for the two fuel types in the range of 4663–6517 kcal/kg. However, the average cost per energy output of briquettes as received was more than twice that of charcoal. This implies that briquettes are not worth their price since their calorific values are comparable to those of charcoal. The least expected was that shape and size of briquettes did not have influence on burning time and time of boil, an indication of briquette adulteration. Therefore further research needs to look at how the cost per energy output of briquettes can be reduced to be comparable to that of charcoal without compromising the quality. This workwill contribute to monitoring policies and promote efficient briquette production methods to reduce the cost of briquettes in order to create a competitive edge against charcoal. But at the moment, charcoal users may not be attracted to briquettes due to their high cost per energy output, calling for an alternative path of household waste utilization to provide sustainable energy.
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    Effect of Temperature Fluctuation, Substrate Concentration, and Composition of Starchy Substrates in Mixture and Use of Plant Oils as Antifoams on Biogas Production
    (Environmental Progress & Sustainable Energy, 2019) Tumutegyereize, Peter; Ketlogetswe, Clever; Gandure, Jerekias; Banadda, Noble
    This work investigated the effect of temperature fluctuations, substrate concentration and composition on foaming in anaerobic co-digestion of matooke, cassava, and sweet potato peels for biogas production as well as the use of plant oils as antifoams. In general, obtained results show that temperature fluctuations from mesophilic (≥25 C) to psychrophilic range (<25 C) is the major factor behind foaming in anaerobic digestion. Specifically, at concentrations of 6 and 9 g VS/L with methane yield of 1228.69 and 735.55 Nml CH4/g VS, respectively, for 2:0:1 ratio, there was no foaming until after 7.6 days compared with the other ratios where foaming generally started after 3.5 days. This indicated that, apart from high substrate concentration, foaming is also a function of substrate composition. Plant oils were found to suppress foaming only if temperatures were above 25 C, indicating temperature fluctuations to be the main factor in foaming even in the presence of antifoams.
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    Effect of Variation in Co-Digestion Ratios of Matooke, Cassava and Sweet Potato Peels on Hydraulic Retention Time, Methane Yield and Its Kinetics
    (Journal of Sustainable Bioenergy Systems, 2016) Tumutegyereize, Peter; Ketlogetswe, Clever; Gandure, Jerekias; Banadda, Noble
    This paper presents the results of batch anaerobic co-digestion of matooke, cassava, and sweet potato peels and vines. These agricultural wastes and others form the biggest portion of household wastes in developing countries. However, they have remained an unexploited resource amidst the ever increasing needs of clean energy and waste disposal challenges. Efforts to use them individually as biogas substrates have been associated with process acidification failure resulting from their fast hydrolysis. The aim of this work was to exploit agricultural wastes is co-digestion among themselves and assess their effect on methane yield and its kinetics, pH and hydraulic retention time (HRT). Sixteen ratios of Matooke peels (MP), cassava peels (CP) and sweet potato peels (SP) were assessed in duplicate. Methane yield and its kinetics, pH and HRT demonstrated dependence on the proportion of substrates in the mixture. Depending on the ratio mixture, HRT increased to 15 days compared to less than 5 days for single substrates, hydrolysis rate constant (k) reduced to a range of 0.1 - 0.3 d−1 compared to single substrates whose k-values were above 0.5 d−1, pH was maintained in the range of 6.38 - 6.43 and CH4 yield increased by 15% - 200%. Ratios 2:1:0, 2:0:1, 0:1:2, 1:1:1 and 1:1:4 were consistent all through in terms of model fitting, having a positive synergetic effect on HRT, hydrolysis rate constant, lag phase and methane yield. However, more research is needed in maintaining the pH near the neutral for process stability assurance if household wastes are to be used as standalone substrates for biogas production without being co-substrates with livestock manure.
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    Substrate Mixture Optimization of Nutrients Needed for Methane Yield
    (Journal of Biosystems Engineering, 2019) Tumutegyereize, Peter; Ketlogetswe, Clever; Gandure, Jerekias; Banadda, Noble
    The twofold aim of this study was to optimize nutrients important for methane yield in substrate mixtures and to assess the effect of the optimized nutrients on methane production. Method Augmented simplex lattice design was used on three substrates, i.e., matooke peels (MPs), cassava peels (CPs), and sweet potato peels (SPs) wherein 16 ratio combinations were assessed for their macro- and micronutrient compositions and methane production potential. Experimental data was simulated using canonical polynomial models to determine mixture combinations with optimal nutrients stimulatory to methane yield. Results Six optimization solutions with the global optimal having a desirability of 0.93 and a ratio of 0.611:0.375:0.015 were observed to be localized over the design space. Biomethane experiments were in agreement with the optimized mixture ratios as ratios that gave the highest methane yield of 0.3 Nm3 CH4/kg VS and above lay in the optimized design region. Conclusion Therefore, charts showing optimized regions of different substrate mixtures in terms of their nutrients can be a tool in biogas digester operations.
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    Technical Evaluation of Uptake, Use, Management and Future Implications of Household Biogas Digesters—A Case of Kampala City Peri-Urban Areas
    (Computational Water, Energy, and Environmental Engineering, 2017) Tumutegyereize, Peter; Ketlogetswe, Clever; Gandure, Jerekias; Banadda, Noble
    The purposes for which biogas technology was introduced at household level were multiple but the major and direct one was to provide a clean and sus- tainable energy, thereby reducing the reliance on wood fuel. From the so- cio-economic studies that have been carried out, biogas end-users and techni- cians continue to be blamed for technical factors hindering its adoption and use. However, the ways these factors hinder biogas adoption and use plus the linkage between them seem not well understood right from policy to end- users. A technical survey was carried out on household biogas digesters to evaluate the adoption, use and management factors and their implications on the future of household digesters. Over-designed digesters in relation to fami- ly size yet not producing enough biogas, dependence on cow dung as the feedstock, 75% of users not being sure of loading rate and mixing ratios, not feeding the digesters daily by all households were found to be the main causes of why biogas was not enough for 87.5% of the respondents and digesters were abandoned in Kampala, Uganda. All surveyed digesters were characte- rized by starvation-overfeeding problem. Wood fuel was found still dominat- ing in these households with biogas. Given that end-users had no options of digester types from which to select, but handed-over with over-size fixed dome digesters, there is need for all biogas stakeholders to come together as the reality on ground reveals that right from inception to management, eve- ryone is to blame for the technical failures.