https://ir.cut.ac.zw/xmlui/handle/123456789/68 2026-07-16T23:22:52Z https://ir.cut.ac.zw/xmlui/handle/123456789/815 Microwave-assisted pyrolysis of pine sawdust (Pinus patula) with subsequent bio-oil transesterification for biodiesel production Makepa, Denzel Christopher; Chihobo, Chido Hermes; Musademba, Downmore This study aims to thermochemically convert pine sawdust to crude bio-oil via the microwaveassisted pyrolysis technique with subsequent bio-oil transesterification. American Society for Testing and Materials (ASTM) standards were followed in the characterization of the feedstock and pyrolysis products. The thermal degradation behaviour of pine sawdust was studied using thermogravimetric analysis. The components in the bio-oil organic phase were upgraded to fatty acid methyl esters via the transesterification process. The composition of the organic phase and the fatty acid methyl esters was analysed using gas chromatography–mass spectrometry (GC-MS) and Fourier transform infrared (FT-IR). The thermal degradation behaviour of pine sawdust showed three distinct phases of weight loss. These were the drying stage (30–200 C), the devolatilization stage (200–450 C), and the char formation stage (>450 C). The process yielded 42.28wt.% of bio-oil, constituting 24 and 76wt.% of the organic and aqueous phases, respectively. GC-MS and FT-IR compositional analysis identified various organic compounds and functional groups, with phenolics contributing a greater percentage. Transesterification improved the bio-oil properties by converting the organic acids and oxygenated compounds to methyl esters with a concentration of 510.05mg/L. The bio-oil has proven to be a promising sustainable raw material for the production of biofuels and value-added biochemicals 2023-08-04T00:00:00Z https://ir.cut.ac.zw/xmlui/handle/123456789/740 Synthetic biology-enhanced microalgae for biofuel production: a perspective Makepa, Denzel Christopher; Chihobo, Chido Hermes The development of microalgae-based biofuels has emerged as a promising solution to address the pressing global challenges of climate change, resource scarcity, and the need for renewable energy sources. Microalgae possess unique capabilities that make them an attractive feedstock for biofuel production, including their ability to capture and sequester carbon dioxide, their efficient use of water and land resources, and the potential for them to utilize waste streams as nutrient sources. This paper provides a comprehensive overview of the environmental and economic implications of microalgae-derived fuels, highlighting the key benefits and remaining challenges. The integration of synthetic biology to enhance microalgae strains, optimize cultivation and processing, and diversify revenue streams is explored as a means to address the economic barriers to large-scale commercialization. As research and development in this field continue to progress, the future prospects of microalgae-based biofuels are discussed, underscoring their potential to reshape the global energy landscape towards a more sustainable and economically viable future. © 2024 Society of Industrial Chemistry and John Wiley & Sons Ltd. 2024-09-07T00:00:00Z https://ir.cut.ac.zw/xmlui/handle/123456789/704 14 - Carbon emissions reduction assessment via biogas production and resource recovery: the IPCC methodology Makepa, Denzel C.; Chihambakwe, Zviemurwi J. This chapter looks into the assessment of carbon emissions reductions from biogas production and resource recovery, employing the robust Intergovernmental Panel on Climate Change methodology. Through guidelines, calculation methods, and tiered approaches, stakeholders can evaluate biogas initiatives’ environmental impacts and sustainability implications. Key metrics such as carbon dioxide equivalent and global warming potential provide a comprehensive framework for quantifying emissions reductions and identifying areas for improvement. The displacement of fossil fuels, nutrient recycling, soil carbon impacts, and lifecycle assessments of digestate uses are crucial in evaluating broader environmental benefits. The case study of New Horizons Energy’s biogas plant in Cape Town exemplifies the significant potential of biogas projects in reducing carbon emissions, promoting sustainable waste management, and supporting the transition to a low-carbon economy. This research contributes to climate change mitigation strategies, aligns with international agreements and sustainable development goals, and emphasizes the pivotal role of biogas initiatives in achieving environmental sustainability. 2025-01-01T00:00:00Z https://ir.cut.ac.zw/xmlui/handle/123456789/703 Lifecycle assessment and techno-economic analysis of biofuel production from lignocellulosic biomass Makepa, Denzel Christopher; Chihobo, Chido Hermes; Musademba, Downmore This chapter examines life cycle assessment (LCA) and techno-economic analysis (TEA) for evaluating biofuel production from lignocellulosic biomass. LCA considers environmental impacts across cultivation, conversion and utilization by establishing goals, inventorying flows, assessing impacts and interpreting results. TEA assesses economic viability by estimating capital, operating costs and production costs. Case studies apply these analyses to thermochemical and biochemical pathways using various biomass feedstocks. Challenges with biomass conversion include data availability and quality issues, uncertainty and boundary definitions. Standardized methods and technological advances are addressing these challenges to improve assessment consistency and accuracy. Integrating LCA and TEA can provide deeper insights through broader sustainability metrics. These analytical tools can help optimize biomass conversion technologies and inform policies by identifying environmental hotspots and costs. As biomass conversion methods advance alongside supporting policies, LCA and TEA will continue facilitating realization of sustainable biofuels at commercial scale from lignocellulosic biomass. 2025-01-01T00:00:00Z