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Browsing Doctoral by Subject "Bioethanol and Bioelectricity Production"

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    Integrated Bioethanol and Bioelectricity production from Ghanaian Seaweed Biomass
    (2021-07-12) Offei, Felix; ;
    This study investigated the potential of integrating bioethanol and bioelectricity production technologies as an efficient means of maximising seaweed biomass utilization. It particularly sought to examine optimal conditions for the production of bioethanol from selected seaweeds, the bioelectricity potential of seaweed residue using microbial fuel cells and the sustainability of the integrated bioethanol and bioelectricity technologies on seaweeds. The motivation for this work is the growing concerns over the dire food securities issues that could occur from the continued use of edible biomass such as maize, cassava and sugarcane in commercial bioethanol production. The study was conducted through the screening of pretreatment methods, optimisation of dilute acid and enzymatic hydrolysis, screening of yeasts strains and screening of ethanol production pathways with seaweeds as substrates. It also included the evaluation of power generation, internal resistances and substrate consumption from microbial fuel cells fed with seaweed bioethanol residue and; an Energy Return on Investment analysis of various seaweed bioenergy production scenarios. The study established that the optimal ethanol yields for Ghanaian seaweeds, U. fasciata, H. dentata and S. vulgare were 5.06, 2.44 and 3.69% dry matter, respectively. This was obtained via the SHF pathway through enzymatic hydrolysis with an optimal cellulase dosage of 8 filter paper unit/g dry biomass and fermentation with S. cerevisiae SI17, C8T17 or PT17 yeast strains. The study also found residues from seaweed bioethanol production to be efficient substrates for use in microbial fuel cells since, it yielded power densities between 0.46 and 0.50 W/m3 which were comparable to sodium acetate by up to 52.62%. The integrated approach to seaweed biomass utilization was considered successful since waste generation was reduced to as low as 24.43% from a potential 79% from seaweed bioethanol production alone. It further established that the production of both bioethanol and bioelectricity from Ghanaian seaweeds would be sustainable based on the Energy Return on Investment value of 4.2 obtained after a Life Cycle Assessment of the bioenergy processes. The study further established that the production of bioethanol alone from seaweeds would not be sustainable commercially despite a net gain in energy from its Life Cycle Assessment.