In the quest for a circular, sustainable economy, agricultural residues into reliable energy sources hold enormous potential for reducing waste and providing alternative fuels in the quest for a circular, sustainable economy. This dissertation focuses on developing innovative and sustainable pathways to produce energy from sundried millet and sorghum straws from Nigeria’s arid and semi-arid regions. These underutilized biomasses offer a promising route toward reducing dependency on fossil fuels while contributing to energy resilience and environmental sustainability. This research explores thermochemical conversion techniques, particularly biomass torrefaction, fast pyrolysis, and gasification, to assess their efficacy in transforming millet and sorghum straws into high-quality, carbon-rich materials and syngas suited for energy production. Through detailed physical and chemical characterization, the study establishes the energy potential of these straws, pinpointing the most viable conversion process based on both technical feasibility and environmental considerations. Our findings indicate that torrefaction presents significant advantages. Further advances were made by gasifying torrefied biomass in an equilibrium-based entrained flow gasifier developed in Aspen Plus. Machine learning models were also developed to forecast critical elemental compositions in the biomass feedstock—specifically carbon, hydrogen, and oxygen—based on target syngas parameters, thus enhancing the predictability and customization of biomass-to-energy conversions. This work contributes to scientific understanding and practical advancements in renewable energy by investigating millet and sorghum residues' unique properties and conversion pathways.
