City Research Online

Abstract

Nigeria faces concurrent challenges of energy poverty, inadequate waste management, and socio-economic instability. This research investigates the sustainable feasibility of utilising biomass, particularly municipal solid waste (MSW), as a resource for decentralised combined heat and power (CHP) generation. Three waste-to-energy (WtE) system configurations were conceptualised: System A (anaerobic digestion + gasification + Organic Rankine Cycle), System B (anaerobic digestion + gasification + agricultural drying and cooling), and System C (anaerobic digestion + gasification + greenhouse urban farming). A comprehensive Life Cycle Sustainability Assessment (LCSA) framework was applied, incorporating Environmental Life Cycle Assessment (E-LCA), Life Cycle Costing (LCC), and Social Life Cycle Assessment (S-LCA) methodologies.

Technical performance modelling assessed system efficiencies and energy outputs, while the E-LCA evaluated environmental impacts across global warming potential (GWP), acidification, eutrophication, particulate matter formation, and resource depletion categories. The LCC quantified capital expenditure (CAPEX), operating expenditure (OPEX), and levelised cost of energy (LCOE), and the S-LCA employed stakeholder-informed indicators across community, worker, and societal dimensions. Across the three configurations, System C (anaerobic digestion + gasification with greenhouse urban farming) consistently delivered the strongest overall performance. With efficient internal-combustion prime movers (e.g., Wärtsilä 9L34DF/12V34DF), System C achieved an overall CHP utilisation of approximately 80 percent (with heat used in the greenhouse) and produced about 1.376 MWh of electricity per tonne of MSW, while a 1,000 m² greenhouse demand was fully met and still left sizeable surpluses (1.24–4.66 GWh yr⁻¹ of usable heat and 177–240 GWh yr⁻¹ of electricity at the city-scale throughput). Economically, System C achieved the lowest life-cycle cost (LCC) more than 60% lower than the worst-case turbine configuration, for example the SGT-400 exceeded $80 million in System C. It also achieved the most favourable Levelised Cost of Electricity (LCOE), reaching below $0.05 kWh⁻¹ in the most favourable engine cases. For comparison, System A (with ORC) recorded $0.46 kWh⁻¹ for the SGT-50 and $0.31 USD kWh⁻¹ for the SGT-400, while System B (drying and cooling) remained below about $0.08 USD per kWh with efficient engines. Socially, System C ranked highest on the weighted S-LCA (4.53 vs 4.07 for System B and 3.47 for System A), reflecting stronger community benefits, inclusion and job creation. Prime-mover choice was the single biggest driver of environmental and economic outcomes across all systems. The study also identified key trade-offs, including between technological complexity and social inclusivity, and between environmental optimisation and financial viability. The findings underscore the necessity of designing multi-functional, socially integrated WtE systems to ensure sustainability in developing country contexts. Contributions to Sustainable Development Goals (SDGs), particularly SDGs 7, 11, 12, and 13, were demonstrated. This research advances methodological approaches for integrated LCSA in developing regions and offers practical policy and design recommendations for scaling sustainable waste-to-energy solutions in Nigeria and similar socio-economic contexts.

Publication Type:	Thesis (Doctoral)
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences T Technology > TD Environmental technology. Sanitary engineering T Technology > TK Electrical engineering. Electronics Nuclear engineering
Departments:	School of Science & Technology > Department of Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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