A seasonal inventory of household fuel consumption and associated emissions using digital methods in Eastern Rwanda

Around 2.3 billion people globally rely on biomass for cooking, contributing to severe health, environmental, and climate challenges, with household air pollution responsible for over 4 million deaths each year. This widespread dependence underscores the urgent need for accurate measurement of biomass consumption and associated emissions. The primary objective of this study is to enhance the understanding of household biomass energy use by quantifying the contributions of woody biomass and crop residues, examining seasonal consumption patterns, and estimating the resultant CO₂e emissions. The study's novelty lies in its application of a digital, sensor-based system to continuously and accurately monitor biomass consumption across 420 households in Eastern Rwanda, conducted over three agricultural seasons. This approach generates high-resolution, region-specific data on the utilization of firewood, crop residues, and charcoal, while directly linking consumption patterns to CO₂e emissions. The findings indicate that firewood accounts for 86% of the total biomass used for cooking, followed by crop residues at 13% and charcoal at 0.8%. The estimated daily household consumption amounts to 3.1 kg of firewood, 0.47 kg of crop residues, and 0.03 kg of charcoal. The relatively high amount of crop residue suggests a chronic shortage of firewood, despite the intensive tree-planting campaigns. Firewood consumption remained stable during season A (short rainy) and season B (rainy), with a slight decrease in season C (dry). Crop residues decreased steadily from Season A to B, and further to C. The estimated annual CO_2e emission from biomass combustion is 1.32 tons per household and 0.48 tons per capita. Digital methods provide precise, time-resolved data on fuel types and consumption, offering valuable insights for energy planning and carbon financing. Future research should integrate PM₂.₅ emissions to better assess health impacts and determine the sustainable balance between using crop residues as fuel and returning them to the soil.