Estudio de viabilidad para una planta de biogás en la industria agroalimentaria: El caso de La Fageda

Abstract

This study evaluates the technical, environmental, and economic feasibility of implementing a biogas plant within the agro-industrial operations of La Fageda (Girona), a social enterprise that integrates livestock farming, food production, and social care activities. The project is framed within the broader context of energy transition, circular economy, and the need to reduce greenhouse gas emissions associated with conventional organic waste management. Based on a detailed characterization of the available organic waste streams—including cattle manure, whey, fruit residues, and wastewater sludge—a mesophilic continuous stirred-tank digester (CSTR) is proposed, with a treatment capacity of up to 15 tonnes of organic matter per day. The system is expected to produce approximately 363 m³/day of biogas, potentially covering 30–35 % of the facility’s thermal energy demand and partially replacing the current use of propane gas. From an environmental perspective, the system could reduce annual emissions by over 1,668 tonnes of CO₂ equivalent, primarily through methane recovery and fossil fuel substitution. The resulting digestate, with significant agronomic value, would improve soil fertility and close the nutrient loop. The project would also enhance the overall efficiency of the company’s waste management system and ease the load on its wastewater treatment plant. Economically, the project is promising: with a net investment estimated at €485,000, the biogas system could generate annual operational savings of more than €89,000, yielding a payback period of around five years—especially if public funding is secured. The analysis concludes that the project is technically viable, environmentally beneficial, and economically profitable, and could serve as a replicable model for other medium-sized agro-industrial enterprises with circular and social missions