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ABSTRACT
Energy is a vital determinant of the modern life. Every economy needs access to regular and stable energy supply to support its growth. Depleting global fossil fuel reserves and the negative impact of their utilization on global climate coupled with increasing global energy demand have led to increased research in energy generation from renewable resources, such as biomass. This projects biomass gasification as a potential renewable energy technology for future energy generation. Hence, this study intends to develop a pilot biomass gasification system to convert wood residues in Nigeria into synthesis gas from which renewable energy can be generated. To achieve this aim, a preliminary study was carried out to characterize wood wastes in Benin metropolis. Thereafter, a downdraft gasification system was developed and fabricated using locally available materials. The performance of the gasification system was tested for synthesis gas production using wood wastes as feedstock. An equilibrium model was later developed using Aspen Plus to investigate the effects of varying operating parameters on performance of the downdraft gasifier. The developed model was validated with experimental results reported in literature and from the present study. The economics of coupling the downdraft gasification system to a household generator for electricity generation was also evaluated using the levelized cost of electricity (LCOE) method. The obtained LCOE was compared with grid electricity tariff in Nigeria and, the cost of electricity generation using the generator fuelled with gasoline over the same specified period. The results obtained revealed a wood waste generation rate of about 8,200 tonnes per year from sampled sawmills and plank markets. The performance test on the developed wood-fired downdraft gasification revealed that wood wastes consumption rate was about 3.313kg/h, yielding syngas that burns with a stable blue flame for about 43 minutes. Average syngas yield was 2.02kg per kg of wood waste consumed. The averaged molar syngas composition obtained was 28.15% CO, 16.64% H2, 6.19% CO2, 2.54% CH4 and 46.02% N2, while the average syngas LHV was 6.353MJ/Nm3 . The economic evaluation gave an LCOE of vii approximately N15.76/kWhel (electrical energy). This generation cost was much lower than that (N82.81/kWhel) of generator fuelled with gasoline and electricity tariffs for some cities fixed by Nigerian government in 2020. These results indicates that the post‐filter syngas produced has good quality in terms of the evaluated parameters, and that it is suitable to fuel household generators as well as presents a cheaper alternative than gasoline for electricity generation in Nigeria in the absence of grid electricity. Hence, development of such power projects should be encouraged in Nigeria to ease the present electricity crisis, especially in the rural areas, as well as manage wood wastes effectively in the country.
