This study presents an experimental evaluation of the bioenergy potential of Enterolobium cyclocarpum (“orejero”) fruit peel residue, an underutilized agroforestry by-product in tropical America. Although the species is widely used for shade and fodder in livestock systems, its fruit peel has not yet been characterized for energy recovery purposes. Fruit samples were collected in rural areas of Tesalia (Huila, Colombia), and the peel fraction was analyzed in certified laboratories. The moisture content of the peel was determined as 11 wt%, and the lower heating value was measured as 0.015 TJ/t following ASTM E711-06. Elemental analysis according to ASTM D5373-16 yielded (dry basis): 37.2 wt% C, 4.09 wt% H, 0.45 wt% N and 0.13 wt% S. Based on Colombian cultivation and production data, the theoretical energy potential was estimated as 3.6 TJ/year per hectare. The technical energy potential reached 0.18 and 0.21 TJ/year per hectare for combustion and gasification, respectively. CO₂-equivalent emissions were also estimated for both conversion routes, revealing a trade-off between the higher energy yield and higher specific emissions associated with gasification. Overall, the results show that E. cyclocarpum fruit peel residue has a calorific value comparable to widely used agri-food residues in Colombia (e.g., sugarcane bagasse and oil palm fiber), but with a substantially higher per-hectare energy potential due to its large residue fraction. Its high availability, favorable fuel properties, and compatibility with decentralized combustion and gasification technologies support its use as a promising feedstock for bioenergy generation in rural or off-grid areas, in line with circular economy and sustainable energy transition strategies.

The organic fraction of municipal solid waste (OFMSW) represents between 40% and 50% of the solid waste of a megacity and despite its great potential for use, continues to generate environmental problems, which highlights the need to continue the search for sustainable and efficient solutions [1]. Current research processes have been geared towards anaerobic digestion (AD) as a promising technology to treat this waste. To this end, this study focuses on examining variables and mathematical models to precisely implement AD processes in a megacity, while exploring its technical and economic feasibility to address the increased amounts of these wastes, in order to optimize current technological developments. In megacities such as Bogotá, the case study area for this research paper, addressing the environmental, social and public health impacts generated by OFMSW is of the utmost importance. Anaerobic digestion is projected as an innovative and sustainable alternative, which not only contributes to treating waste, but also as a source of renewable energy, in addition to generating valuable by-products for agriculture. However, successfully applying AD in a megacity requires an in-depth analysis of the processes involved and the examination of multiple variables for its integration into models that become essential decision-making tools.The following are among the technical variables of analysis for these processes and their subsequent modeling: OFMSW composition, temperature, carbon-to-nitrogen ratio, pH, volatile fatty acids and the presence of inhibitors as critical factors that impact AD performance. Given this scenario, having an adaptive approach that ensures predictive and consistent results over time is indispensable. In addition to these variables, aspects associated with economic, environmental, and social viability should be included, such as population size and projections, climate variability and seasonality, costs associated with the comprehensive service, correct separation at the source, policies and governance models, and land use plans established within the development plans of the cities[2]. Thus, the results obtained from this research study will provide a comprehensive understanding of the factors, processes and variables that influence the efficiency of AD of OFMSW in a megacity. These findings will not only contribute to the design of more efficient systems, but also support decision-making processes, as well as the formulation of waste management strategies, policies and practices at the city level.[1] L. M. Ulloa-Murillo, L. M. Villegas, A. R. Rodríguez-Ortiz, M. Duque-Acevedo, and F. J. Cortés-García, "Management of the Organic Fraction of Municipal Solid Waste in the Context of a Sustainable and Circular Model: Analysis of Trends in Latin America and the Caribbean," Int J Environ Res Public Health, vol. 19, no. 10, 2022, doi: 10.3390/ijerph19106041.[2] L. Mu, L. Zhang, K. Zhu, J. Ma, and A. Li, "Semi-continuous anaerobic digestion of extruded OFMSW: Process performance and energetics evaluation," Bioresour Technol, vol. 247, pp. 103-115, 2018, doi: 10.1016/j.biortech.2017.09.085.

The global interest in utilizing waste from agro–industrial processes through the implementation of clean technologies is rapidly increasing. This study evaluates the technical, economic, and environmental feasibility of valorizing regional agro–industrial residues in Santander, Colombia, specifically coffee mucilage, cocoa mucilage, and pig manure, using integrated biorefinery scenarios. Modernizing these processes is essential given a theoretical energy potential of 75,000 TJ/year, which could generate up to 20,833 GWh/year. Three biorefinery scenarios were designed and simulated using Aspen Plus^® to produce bio-hydrogen, methane, and methanol. The total plant capacity was established at 31.7 t/day, distributed according to regional biomass availability: 4.62 t/day of cocoa mucilage, 1.83 t/day of coffee mucilage, and 25.25 t/day of pig manure. The technical results for Scenario 1 indicated a reformed H₂ production of 0.15 t/day with an associated preheating energy requirement of 193,365 kJ/h. Environmental impact assessment using the ReCiPe 2015 Midpoint methodology identified Scenario 3 as having the lowest direct CO₂ mass flow (9.28 t/day) due to carbon consumption during methanol synthesis. However, Scenario 1 reported a CO₂ equivalent (CO₂e) of 194.37 t/day, reflecting indirect emissions from thermal and energy requirements. Economic analysis, validated through engineering cost references, demonstrated that while Scenario 3 offers a diverse product portfolio, it is currently not cost-effective as the production costs exceed the total expected income. Consequently, Scenario 2 is identified as the most balanced alternative for the Santander context, offering a sustainable compromise between technical efficiency, environmental mitigation, and economic viability.