Feasibility of cow-dung groundnut-shell composite as a decentralized renewable fuel for clean cooking

Conventional biomass fuels (e.g., untreated firewood and raw cow dung cakes) continue to be the predominant household energy source in rural areas, but this can lead to serious indoor air pollution and associated health consequences. This study presents a cost effective, scalable, and environmentally friendly energy source derived from a mixture of locally available cow dung and groundnut shell powder. Fuel cakes are made in the form of a disc so that they could be used in current rural cookstoves, making them user-friendly and requiring minimal change in cooking habits. Four different composition ratios C1 (100% cow dung), C2 (75% cow dung + 25% groundnut shell), C3 (50% cow dung + 50% groundnut shell), and C4 (25% cow dung + 75% groundnut shell) are experimented. The C4 ratio results in a 29.6% higher calorific value (19,700 ± 370 kJ kg^- 1) compared to pure cow dung with significant emission reduction up to 43% of particulate matter ≤ 2.5 μm in diameter, 29% of carbon dioxide, and 53% formaldehyde. The present study contributes directly to Sustainable Development Goal (SDG) 7 (affordable and clean energy) and SDG 13 (climate action), providing a realistic solution to reduce pollution, improve indoor air quality, and promote energy equity in disadvantaged populations.