Analyse du cycle de vie de la méthanisation du fumier de poules pondeuses: évaluation de la performance environnementale d'une unité de biogaz en Côte d'Ivoire

Abstract

Poultry manure management constitutes a major environmental issue, owing to its potential contribution to greenhouse gas emissions, nutrient losses, and pollution risks. This study evaluates the environmental performance of anaerobic digestion of laying-hen manure implemented on the Fondation BRIN farm in Bondoukou, Côte d’Ivoire, using the Life Cycle Assessment (LCA) methodology. The system boundary was defined as cradle-to-farm-gate, and the functional unit (FU) was defined as the treatment and recovery of 1 t of raw poultry manure. Environmental impacts were quantified using the ReCiPe 2016 Midpoint (H) method implemented in openLCA, with background processes sourced from the ecoinvent 3.12 database. The multifunctionality arising from biogas and digestate co-production was addressed through system expansion and substitution. Three scenarios were compared : (i) raw anaerobic digestion without effective biogas recovery ; (ii) optimized anaerobic digestion combining energy recovery with agronomic valorization of the digestate ; and (iii) composting. The results indicate that the current configuration is predominantly driven by climate change-related impacts, amounting to 179.459 kg CO2-eq t-1 FU. Raw anaerobic digestion exhibited the highest climate impact, at 226.297 kg CO2-eq t-1 FU, whereas composting reached 24.290 kg CO2-eq t-1 FU. The optimized anaerobic digestion scenario yielded a net favourable score of -111.220 kg CO2-eq t-1 FU, corresponding to a net reduction of 337.517 kg CO2-eq t-1 FU relative to raw anaerobic digestion. The sensitivity analysis confirmed that reducing the fraction of unrecovered biogas constitutes the main lever for improvement. Overall, the environmental performance of poultry manure anaerobic digestion depends primarily on effective biogas recovery, control of methane losses, and agronomically sound digestate management.