• The approach consists in analytically determining the evolution of the properties or quantities of matter transported by the movement (here humid air) through the device (the Earth to Air Energy Exchanger). • The method could be applied to solve many other practical convective transport problems.

In the context of increasing energy demand and limited access to clean cooking and heating fuels in the Republic of Congo, agricultural and forestry residues represent a promising resource for energy production. The aim of this study is to identify, quantify and assess the energy potential of the residues generated across eight departments of the Country. Ten residues were characterized: sugarcane bagasse, peanut shells, corn stalks and cobs, rice husks, cassava stalks and peelings, sawdust, wood chips and wood slabs. Proximate analyses were carried out using a muffle furnace and an oven, while the calorific value was estimated using empirical formulas. Results of proximate analysis showed that moisture content ranged between 8.80 ± 0.14 % and 45.17 ± 1.57 %, ash content from 1.00 ± 0.23 to 15.07 ± 0.15 %, volatile matter content from 67.86 ± 0.02 to 82.14 ± 0.14 % and fixed carbon content from 12.13 ± 0.33 to 19.87 ± 0.37 %. The lower calorific value ranged between 14.98 and 18.04 MJ/kg. Approximately 137 921.16 tonnes of available residues were generated in 2025, representing an estimated energy potential of 1876.78 TJ/year. These residues constitute a significant resource for solid biofuel production and decentralized electricity generation.

In the context of increasing energy demand and limited access to clean cooking and heating fuels in the Republic of Congo, agricultural and forestry residues represent a promising resource for energy production. This study aims to identify, quantify and assess the energy potential of the residues generated across eight departments of the country. Ten residues were characterized: sugarcane bagasse, peanut shells, corn stalks and cobs, rice husks, cassava stalks and peelings, sawdust, wood chips and wood slabs. Proximate analyses were carried out using a muffle furnace and an oven, while the calorific value was estimated using empirical formulas. Results of the proximate analysis showed that moisture content ranged from 8.80 ± 0.14% to 45.17 ± 1.57%, ash content from 1.00 ± 0.23 to 15.07 ± 0.15%, volatile matter content from 67.86 ± 0.02 to 82.14 ± 0.14% and fixed carbon content from 12.13 ± 0.33 to 19.87 ± 0.37%. The lower calorific value ranged between 14.98 and 18.04 MJ/kg. Approximately 137,921.16 tons of the assessed residues were estimated to be generated in 2025, corresponding to a first-order theoretical energy potential of approximately 1876.78 TJ/year. These findings provide useful evidence for public policies aimed at promoting the sustainable valorization of agricultural, agro-industrial, and forestry residues, diversifying the national energy mix and supporting the development of decentralized bioenergy systems in the Republic of Congo.