Search

Background: Uganda's energy relies heavily on biomass sources. This dependence on biomass for household and commercial purposes, driven largely by population increase, poses pressure on natural resources, such as forests. This study investigates the usage of some of the country's largely produced agricultural wastes for the production of biofuels. Methods: Pineapple peels (PP), banana peels (BP) and water hyacinth (WH_Eichhornia crassipes (Mart.) Solms) were used for generation of both carbonized and uncarbonized briquettes. Physical properties and calorific values for the developed briquettes were determined through thermogravimetric analysis and using a bomb calorimeter. Results: Pineapple peel carbonized briquettes had the highest calorific value (25.08 MJ/kg), followed by a composite of banana peels and pineapple peels (22.77 MJ/kg). The moisture content for briquettes ranged from 3.9% to 18.65%. Uncarbonized briquettes had higher volatile matter (ranging between 62.83% and 75.1%) compared to carbonized briquettes (ranging between 22.01% and 24.74%). Uncarbonized briquettes had a shorter boiling time (ranging between 27 and 36 min for 2.5 L of water) compared to carbonized briquettes (ranging between 26 and 41 min). Bulk density was highest in uncarbonized BP briquettes (1.089 g/cm3) and compressive strength was highest with carbonized BP + PP (53.22 N/mm2). When using water hyacinth alone, the produced carbonized briquettes show low calorific values (16.22 MJ/kg). However, the calorific values increased when they were mixed with banana (20.79 MJ/kg) or pineapple peels (20.55 MJ/kg). Conclusions: The findings revealed that agricultural wastes could be used to augment the energy sources pool to protect the environment and create social stability in the community. [ABSTRACT FROM AUTHOR]

[Display omitted] • Growth in urban population has led to increased generation of fecal sludge (FS). • Production of briquettes from FS blended with food wastes was explored. • Blending fecal sludge with the wastes reduced its ash content between 43% and 87%. • The calorific values of the blended briquettes were between 11.7 and 17.9 MJ/kg. • Use of FS derived briquettes could save USD 620 per ton of wood charcoal foregone. This study explored the production and evaluation of briquettes made from dried fecal sludge mixed with fresh food waste as a dual strategy to solve energy poverty and poor sanitation problems in Ugandan slums. Cylindrical briquettes measuring 82 mm height by 76 mm diameter were produced from dried fecal sludge (FS) alone, and FS mixed separately with pineapple peels (FS + PP), charcoal fines (FS + CD), and bean husks (FS + BH) in a mix ratio of 50% FS: 50% biomass (wt/wt basis) using red soil as the binder. Physiochemical characteristics and fuel thermal efficiency of the briquettes were tested following ASTM standards and were compared to wood-derived charcoal and commonly traded briquettes on market in Uganda. The average moisture content was 5.1%. Bulk density was highest in FS briquettes (1.12 g/cm3) and lowest in FS + BH (0.847 g/cm3). Volatile matter (VM) was highest in FS + PP (39%) and lowest in FS alone (25.7%). The average ash content was 30.4%. FS + PP had the highest calorific value (17.92 MJ/kg) while FS alone had the lowest (6.19 MJ/kg). The highest burning rate was recorded in FS + CD briquettes (8 g/min) and was lowest in FS + PP (4 g/min). Based on the calculated burning rates and calorific values, the economic advantage calculations implied that blending one ton of dry FS with one ton of dry pineapple peels for fuel briquettes, and their use as a substitute could save consumers about USD 620 per ton of wood charcoal foregone. [ABSTRACT FROM AUTHOR]

Effects of alkaline surface modification and carbonization on biochemical properties of selected rice and coffee husk varieties in Uganda were studied. Alkali pre-treatment was done by washing the husks in NaOH at a 15:1 liquor ratio. Pre-treatment is used in biomass conversion to overcome chemical and structural difficulties. Carbonization resulted in production of bio-char. Results showed increased cellulose contents for both the husks and their bio-chars after pre-treatment with NaOH solution. Lignin and hemi-cellulose compositions were reduced after pre-treatment in NaOH solution. Bio-chars for all rice husk varieties showed an increase in lignin content after carbonization. Lignin contents for Robusta coffee husks also increased after carbonization. Cellulose content in bio-chars of both rice and coffee husks reduced drastically after carbonization. A simple regression model relating bulk density and biochemical composition was developed at an accuracy of 70%. Alkaline surface modification and carbonization effects on biochemical properties are due to their impact on the non-cellulosic material and hydrophobicity, respectively, on the fibers. [ABSTRACT FROM AUTHOR]

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 rated amidst continued increase in charcoal demand from the ever growing urbanization. This study therefore investigated burning performance and cost in affecting briquette use. A comparative performance analysis was carried out for locally purchased carbonized briquettes made from matooke 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 work will 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. [ABSTRACT FROM AUTHOR]

In Uganda, agro-processing of fruits produces large volumes of agricultural wastes, much of which are not utilized but disposed in the landfill. This study explored the possibility of producing biomass briquettes from mango waste (seed covers) that could be used for energy supply in small factories and for domestic cooking. Mangoes were selected because of their abundance throughout the country and its high fiber content which is a good property for a raw material for briquetting. Dried mango seed covers were crushed to particles of size 2 mm and bonded with three different binders; starch, starch-clay soil, and starch-red soil. The best mixing ratios for briquettes were; 4:1 (seed-cover: starch), 9:2:1 (seed cover: starch: clay soil), and 16:4:1 (seed-cover: starch: red soil). The formed briquettes were subjected to several standard methods to verify their suitability as fuels. The briquette properties tested were moisture content, volatile matter, ash content, fixed carbon content, calorific value, compressive strength, and gas emissions. Results showed that briquettes bonded with only starch had higher fuel properties (p≤0.05) with low: moisture content (11.9%), volatile matter (16.0%), ash content (2.8%) and emissions (0.178% CO, 0.0021% (CH)X, 1.14% CO2 and no NOx); higher fixed carbon (69.3%), breaking strength (maximum force, 34 N and compressive stress, 273 N/mm²) and calorific values (16,140 kJ/kg) compared to starch-red soil and starch-clay soil briquettes. But after a linear regression analysis, results further showed that maximum force (R² = 0.636) and ash content (R² = 0.520) were good indicators of energy content of a particular briquette. However, more research is needed on using other binder types rather than cassava starch which is considered as food. [ABSTRACT FROM AUTHOR]