Reconversion to Biomethane of an Agricultural Biomass Plant: The case of "La Falchetta"

This thesis explores the production of biogas from agricultural biomass and the strategic conversion of existing biogas plants to biomethane facilities, within the broader context of the energy transition and circular economy. It provides a comprehensive overview of the Italian agricultural biogas sector, with an emphasis on policy frameworks, regulatory incentives, and the role of the public authority Gestore dei Servizi Energetici (GSE). The core of the work focuses on the case study of the "La Falchetta" plant, originally designed for electricity generation through anaerobic digestion and currently undergoing reconversion to produce biomethane suitable for injection into the distribution gas grid. The thesis details the technological, biochemical, and microbiological aspects of the anaerobic digestion process, as well as the characteristics of input biomass and process parameters. It also examines the main upgrading technologies for biogas, with a focus on the membrane separation system adopted at "La Falchetta". A thorough technical, environmental, and economic analysis of the reconversion project is presented, highlighting key performance indicators such as energy efficiency, capital and operational expenditures, and CO₂ emissions reduction. Finally, future development opportunities are discussed, including the integration of biochar into the digestion process and carbon dioxide valorisation strategies. The results confirm the feasibility and sustainability of converting agricultural biogas plants to biomethane production, positioning this transition as a key enabler of climate targets and rural economic resilience.