THERMO-ENVIRONMENTAL PERFORMANCE EVALUATION OF A RETROFIT INTEGRATED GASIFICATION COMBINED CYCLE (IGCC) POWER PLANT
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Abstract
Nigeria’s energy security is heavily reliant on natural gas, a strategy hampered by supply unpredictability and growing global decarbonisation requirements. To address frequent outages caused by gas supply constraints and CO₂ emissions of 350-400 kg/MWh, a strategic pivot is necessary. This study proposes a transformative approach to addressing these dual challenges by retrofitting the Afam VI Natural Gas Combined Cycle (NGCC) power plant into an innovative Integrated Gasification Combined Cycle (IGCC) system. The study looks into the techno-environmental feasibility of repurposing existing infrastructure to use domestic coal and biomass blends, hence increasing fuel flexibility and lowering the plant’s carbon footprint.
This work applies a rigorous simulation-based technique using EBSILON® Professional. A validated baseline model of the present Afam VI plant, which operates at 49.88% efficiency at base load, was created. This model was later updated to incorporate a gasification unit, air separation unit, syngas clean-up techniques and pre-combustion carbon capture. Necessary modifications were also made to the topping and bottoming cycle of the thermal block for syngas combustion. Thermal analysis was carried out to assess system performance under both design and off-design scenarios. The results shows that the IGCC retrofit model reduces the net plant emission of the natural gas baseline model from about 300kg/MWh to about 50kg/MWh, indicating an 85.7% reduction in CO2 emission with a potential for carbon neutrality using biomass as feedstock. However, this comes off on the back of a trade off with the thermal performance of the plant. The retrofit model was found to have an energy efficiency penalty of about 4% points with respect to the natural gas baseline. This results suggests that retrofit IGCC technology is not only technically feasible, but also strategically important for decarbonising the energy industry. It offers a practical, data-driven strategy for using indigenous energy resources to create a more resilient, sustainable, and secure power system. By presenting a feasible model for deep decarbonisation of existing infrastructure, this effort combines national development aspirations with global climate action, establishing IGCC as a baseline for future flexible and clean power generation.
This work applies a rigorous simulation-based technique using EBSILON® Professional. A validated baseline model of the present Afam VI plant, which operates at 49.88% efficiency at base load, was created. This model was later updated to incorporate a gasification unit, air separation unit, syngas clean-up techniques and pre-combustion carbon capture. Necessary modifications were also made to the topping and bottoming cycle of the thermal block for syngas combustion. Thermal analysis was carried out to assess system performance under both design and off-design scenarios. The results shows that the IGCC retrofit model reduces the net plant emission of the natural gas baseline model from about 300kg/MWh to about 50kg/MWh, indicating an 85.7% reduction in CO2 emission with a potential for carbon neutrality using biomass as feedstock. However, this comes off on the back of a trade off with the thermal performance of the plant. The retrofit model was found to have an energy efficiency penalty of about 4% points with respect to the natural gas baseline. This results suggests that retrofit IGCC technology is not only technically feasible, but also strategically important for decarbonising the energy industry. It offers a practical, data-driven strategy for using indigenous energy resources to create a more resilient, sustainable, and secure power system. By presenting a feasible model for deep decarbonisation of existing infrastructure, this effort combines national development aspirations with global climate action, establishing IGCC as a baseline for future flexible and clean power generation.
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