A Multi-Country Assessment of the Biohydrogen-Derived Urea Potential Across West Africa from Cereal Crop Residues.

Abstract

The importation of urea fertilizer into West Africa has shown an increase over the years due population growth, which puts a threat to food security. The importation urea fertilizer is disrupted by volatile global markets which put pressure on national economies, and on fertilizer to smallholder farmers. The region possesses vast agricultural residue resources that are underutilized, despite their potential as feedstock for bio-urea production. There is a critical gap in the integration of agricultural residue-to-hydrogen and subsequently fertilizer across West Africa. The study aims to investigate the viability of substituting the urea demand in West Africa with sustainable, locally viable resources to create a circular economy to improve agricultural production. To achieve this, the urea production potential was estimated through the conversion of residues of high-yielding cereals into biohydrogen through the process of biomass gasification, followed by ammonia and urea synthesis using a stoichiometric model. The outcome was geospatially represented using Quantum Geographic Information System (QGIS) software version 3.30.0. System and conversion efficiencies benchmarks, idealized biomass gasification and water-gas shift, the Haber-Bosch process, and urea synthesis via the Haber- Meiser reaction were utilized. An economic analysis capturing surplus and gap matrix with a novel Tiered Benchmark Scoring System aligned with Economic Community of West African States (ECOWAS) self-sufficiency goals was used to assess the urea coverage across the nations. Results show a sharp difference across the 16 West African states for both technical biomass availability and biohydrogen potentials. Nigeria shows a lead with 36.61Mt/year in technical potential. Similar recordings of technical biohydrogen output were observed: Nigeria yields up to 14.8 Kt/year, with Niger, Mali, and Burkina Faso showing substantial technical potential. The corresponding ammonia yields indicate Nigeria could produce 303.8 Kt/year, while Niger reaches 192.5 Kt/year. Urea synthesis estimates place Nigeria at 466 Kt/year, far ahead of other countries like Ghana (75.9 Kt/year) and Mali (235.4 Kt/year). An economic gap analysis highlights countries exceeding national fertilizer needs, such as Niger, Burkina Faso, and Guinea, where substitution percentages reach over 2,000%. Conversely, Côte d'Ivoire and Nigeria face sizable gaps, covering only 54% and 76% of national urea demand, respectively. The results obtained from the Tier Benchmark Scoring Analyses reveal that some countries, like Niger, far exceed their fertilizer needs and could become exporters and regional hubs, while others face supply shortfalls. These findings emphasize the importance of tailored infrastructure, residue mobilization strategies, and scalable technologies, ranging from modular biorefineries to decentralized urea systems. By bridging agricultural waste with green fertilizer synthesis, this study offers a roadmap for a circular economy for agricultural residue and agricultural resilience in West Africa.