Browsing by Author "Kombe, Godlisten"

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    Biowastes as a potential energy source in Africa
    (IntechOpen, 2021) Kazawadi, Deodatus; Ntalikwa, Justin; Kombe, Godlisten
    High population and industrialization have brought the need for a reliable and sustainable source of energy and protection of the environment. Although Africa has a low energy consumption capacity (3.4% of the global share in 2019), its high population growth rate and industrialization predict high energy demand in the future. Reliable and available energy resources are required to protect the environment and create energy dependency. Despite Africa’s low energy consumption capacity (3.4% of global consumption in 2019), its rapid population growth rate and industrialization indicate future significant energy demand. The current high production of biowastes with high energy content and their low utilization provides an opportunity for energy dependency, crop value addition, creation of jobs, and protection of the environment. The chapter has identified that the African population of 1.203 billion in 2017 consumed 928 Mtoe of energy and this demand is expected to increase in years to come. The energy mix has been identified to depend on fossil fuels with little consideration of biowastes. The biowaste is reported to contain 20.1 TWh in 2025. Biowaste is currently underutilized, and there are few conversion methods available. Government and non-government investments have been reported to be making efforts to improve bioenergy and biowaste usage. The prevailing challenges have been low proven technologies, poor energy policy, low population knowledge, and poor investments. Biowastes use can be increased when environmental laws and legislation are tightened, energy policy strengthened and enforced, cheap and appropriate technologies are introduced, and the population Education is provided. It is expected that when biowastes are well utilized, energy will be available even in disadvantaged (remote) areas at an affordable price for the developing continent of Africa.
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    Co-pyrolysis of cashew nut, coconut shells, and rice husk waste: kinetic and thermodynamic investigations
    (Tylor and Francis, 2022) Kazawadi, Deodatus; Ntalikwa, Justin; Kombe, Godlisten
    Co-pyrolysis of low ash content of coconut shell (CNS) and cashew nuts shells (CCS), and high ash content rice husk (RH) blends was performed using thermal gravimetric analysis (TGA). RH was blended with both CCS and CNS at 0, 30, 60, and 100% RH by mass. Results showed that CCS and CNS have low ash contents of 2.7 and 1.5%, respectively, while RH has high ash content of 26.7% on dry basis. TGA under nitrogen gas study was carried out at three heating rates of 10, 15, and 20 K/min. It was observed that the increase of CCS/CNS increased decomposition rates of blends. For example, RH increased from 6 to 7.7%/min when CNS was added. Furthermore, addition of low ash content leads to high decrease of maximum decomposition rates compared to high-high or low-low ash blends. Synergistic analysis has found out that a positive effect is observed when CNS/CCS is added to RH. The decrease of maximum decomposition temperature of 60–63°C compared to other studies of 10°C for all low and 40° for all high ashes is of great advantage. Flynn-Wall-Ozawa (FWO), Kissinger-Akahra-Sunose (KAS), and DAEM kinetic model analysis for 0.1 ≤α≤ 0.75 were used between 315 and 840°C. FWO model gave activation energy of 85, 70, and 75 kJ/mol, for RH, CNS, and CCS, respectively. Addition of low ash content biomass reduced activation energy of RH, activation energy of RH was reduced from 85 to 72 kJ/mol when CNS was added. RH requires high energy than the rest, example, RH needed 66.29 kJ/mol of energy compared to 51% of CNS and 56 kJ/mol for CCS. The entropy results were negative which implies a different orientation of molecules from origin samples properties. The Gibbs-free energies were positive and thus non-spontaneous process. Empirical models generated using SB model indicated that kinetics depends on reaction order and acceleration mechanism rather than diffusion and nuclei growth. Kinetically, the blending of high and low ash content biomass leads to high decrease of operating temperature and activation energy compared to low-low or high-high ash content blends. It has been recommended to further study on quality and quantity of product from such blends and the possibility of pre-treatment methods such as microwaves to improve pyrolysis of such blend
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    A review of intermediate pyrolysis as a technology of biomass conversion for coproduction of biooil and adsorption biochar
    (Hindawi, 2021) Kazawadi, Deodatus; Ntalikwa, Justin; Kombe, Godlisten
    The agenda to utilize and efficiently convert biomass has been raised to alleviate environmental problems and pressure on the reliance on fossil fuel. Intermediate pyrolysis has the ability to treat different biomasses and coproduction of biooil and adsorption biochar. This review article aims to evaluate the appropriateness of intermediate pyrolysis for the coproduction of biooil and adsorption biochar. It was observed that coproduced biooil is of high quality, stable, and miscible that can be used directly to existing engines or be easily blended. The biochar coproduced is good for adsorption but is not stable for microbial attack and hence unsuitable in soil treatment but for hydrometallurgy. Since the process is capable of treating waste biomass, it is an opportunity for further investigations in areas where wastes are plenty and less utilized. To increase the effectiveness of this technology for coproduction, optimizing parameters, design of efficient reactors, and use of catalyst must be worked upon