Life cycle assessment of waste management: comparison of biogas emissions using drone quantification methods and other data sources

Achieving a circular economy system requires the adoption of environmental management tools capable of improving the performance of products, processes and systems for an efficient use of resources. In recent years, the life cycle approach, so-called Life Cycle Thinking, has extended from the product to the production site and to organizations as a whole. The aim is to take into account all the activities of the supply chain, from the extraction of raw materials to the final management of waste, using the Life Cycle Assessment (LCA) tool. Particularly in the waste sector, numerous studies demonstrate that, in order to quantify the environmental impacts of waste disposal technologies and identify improvement options to mitigate them, LCA plays a fundamental role. Multiple studies have highlighted that among the most critical phases of the LCA of a waste management system is the landfill phase, whose greatest impacts derive from fugitive emissions of biogas and the treatment of leachate. However, especially some environmental declarations, made by landfills under EMAS, show that sometimes the fugitive emission of methane does not represent a significant problem. The issue that arises, therefore, concerns the quantification of such emissions, if associated with emission models or measurements carried out on site. This study shows the results of an LCA study applied to a landfill of non-hazardous waste. The study takes into account the principle "from gate to grave" and includes the following phases of the life cycle of the process: extraction and processing of inert material, functional to the waste treatment and disposal activity, and their transport to the plant; weighing of incoming waste; management of the landfill; energy recovery of landfill biogas; post-management of the landfill; ordinary maintenance of plants and vehicles; transport and disposal/recovery of waste deriving from the aforementioned phases of the life cycle. In particular, a sensitivity of the results depending on the quantification method of the biogas emitted by the landfill is considered. Therefore, a comparison is made between the different scenarios that can occur depending on the type of data source used. For the inventory of methane emitted, we start from the integration of the measurement of emissions made with land boxes. We then proceed to the comparison with the data obtained through a quantification model of fugitive methane emissions using data from measurements made by sensors mounted on drones and from data obtained directly from the literature, as suggested by the Product Categories Rules of the waste treatment sector. The results show that, depending on the quantification methodology of biogas emitted as diffuse emissions, different emission scenarios can be obtained in which the main hot spot varies from the emission of leachate to the fugitive emission of biogas.