Design and Testing of a Portable Biogas Digester for Household Energy Production in Rural Ekiti State

Household dependence on firewood and charcoal for cooking energy in rural South West Nigeria contributes to deforestation, indoor air pollution, and disproportionate time burdens on women engaged in fuel collection. This study presents the design, fabrication, and performance testing of a portable fixed-dome biogas digester sized for single-household use in rural Ekiti State, using cattle dung as the primary feedstock. The digester, with an effective volume of 2 cubic metres, was constructed from reinforced ferrocement and designed for burial installation in residential compound spaces. Feedstock loading rates, slurry mixing ratios, and hydraulic retention time were determined based on available literature and adjusted for ambient temperature conditions in the Ekiti highland zone. Biogas production was monitored daily over an 8-week observation period, and gas yield, methane content, and combustion performance on a standard domestic burner were evaluated. The digester produced an average of 0.8 cubic metres of biogas per day during steady-state operation, sufficient to support two hours of daily cooking for a household of five. Gas quality analysis confirmed methane content of approximately 62 percent, enabling clean and stable combustion. Total construction cost was 47,000 naira, with estimated payback period of under two years through fuel savings. Keywords: biogas digester, fixed-dome design, household energy, rural communities, Ekiti State.