Estimation of Energy Potential by Anaerobic Digestion of Agricultural Residues in Agro-ecological Zone 5 in Benin

Aims: Evaluate the available dry matter deposit of crop residues and assimilated as well as its methanogenic and energetic potential in the agro-ecological zone 5, in Benin.

Place and Duration of Study: Rural Engineering Laboratory, National University of Agriculture, Benin, between October 2021 and October 2022.

Methodology: This evaluation was done through a prospective approach based on the Solagro-Indigo method. The potential yield was evaluated using national agricultural statistics and the residue-to-product ratios available in the literature. An exploratory survey was conducted to evaluate the availability of residues in the study area. The methanogenic and energetic potential was determined from the specific bio-methane potentials of each type of residues from previous studies.

Results: This study shows that 71% of the total dry matter produced is not valorized. This important deposit represents more than 248 million cubic meters of methane and is equivalent to approximately 210 kilo tons of oil equivalent and more than 100% of the total wood energy needs in the region. Additional studies on the optimal conditions for digestion of the main residues identified could promote initiatives for their valorization.

Conclusion: The assessment of agricultural residues potential in the ZAE5 revealed a huge deposit of organic matter that is underpriced and largely abandoned with considerable energy potential. Data are available for each commune and could be used for municipalities development strategies. However, an in-depth study of the optimal methanization conditions and more accurate and precise spatial analyses should be carried out for implementation for energy valorization initiatives.