Integrated LCA analysis of food and energy: the case study of milk and biomethane production

In a world in which food and energy needs go on increasing, the development of methodologies that limit the impact of their production is more important every day. A correct evaluation of the impact is fundamental to obtain an actual reduction in emissions from the systems. This thesis presents an integrated Life Cycle Assessment of dairy and biomethane production chains, with the goal of identifying the most influential choices and factors in their Carbon Footprints and exploring how they interact. After an analysis of the relevant regulations, a scenario-based approach was adopted to assess the effects of different farming choices on emissions from the system. The internal subdivision of emissions has been identified as highly influential on the Carbon Footprint of the Products. Particular attention has been given to the role of allocation techniques, with four analysed frameworks (IDF2015, IDF2022, Economic and FAO) applied and compared. Calculations have been performed using OpenLCA Software with the ecoInvent 3.10 database. The analysis of the different scenarios has shown that productivity, feed charac- teristics, and composition of the herd can be highly influential on the emissions from the dairy cycle, with variations up to over 100% of milk Footprint in the different scenarios. Allocation techniques have proved to be incredibly significant on the impact associated with the various products, with the footprint of milk varying up to 43% inside the same scenario. The allocation effect is limited in the biomethane field, in which there is a detachment from the agronomical practices, with no input emissions from manure following the Renewable Energy Directives. The hypothetical introduction of an input impact associated to manure generated an increase in the final Biomethane Footprint of up to 26% while providing a decrease of Milk Footprint up to 33%. The implementation of anaerobic digestion has shown to reduce emissions from the whole dairy operations by nearly 27% when confronted with the storage on-site and field application of manure. The use of digestate as fertilizer has been found to decrease the emissions of the agronomical system, with a reduction of milk Footprint in the standard scenario between 13% and 18%, depending on the selected allocation method. If considering the Carbon Stock generated with the use of Digestate in the cultivation, the reduction of emissivity by the system increases significantly. The study emphasizes two main conclusions: that agronomic and structural choices in farm management have a fundamental impact on total emissions from the system; and that different allocation methodologies profoundly change the resulting Carbon Footprints of the products. These factors underline how different the emissivity from systems producing the same agronomically originated goods can be, and how the current regulatory frameworks are partially unable to effectively represent the variations. A harmonized and transparent methodology is needed to prevent misleading reductions in product-level emissions and to support more effective strategies for the reduction of emissions in integrated food-energy systems.