Case Study: Pathways from Forest to Energy in a Circular Economy at Lafões

The present case study deals with new pathways in demand for forest residues disposal in the Lafões region (Portugal), since this biomass is presently regarded as a residue and eliminated through open air burning. Different biomass-to-energy conversion systems have a high sustainability value and, thus, the energy potential of the biomass supplied by the forest of Lafões was assessed, using GIS-based methods and assumptions from the literature. The Lafões region produces large amounts of chicken manure from which energy can be recovered through anaerobic digestion. The energy potential held by the effluent of the several classes of the poultry industry of Lafões was assessed, using IPCC 2006 guidelines to estimate their biomass and methane production potential. Furthermore, integrated solutions were pursued. The present challenge is to explore complementarities between effluents for anaerobic digestion to achieve improved energy and waste management system performances. The complementarity between the residues from maritime pine forest management and from broiler production was assessed through bench-scale anaerobic co-digestion assays, leading to increased methane production when compared to those achieved with single substrate anaerobic digestion. This result highlights the interest of further research concerning complementarities between other effluents in the Lafões region.

A UAV-Based Thermal-Imaging Approach for the Monitoring of Urban Landfills

The monitoring of waste disposal sites is important in order to minimize leakages of biogas, produced by anaerobic digestion and potentially explosive and detrimental to the environment. In this research, thermal imaging from unmanned aerial vehicles (UAVs) has been proposed as a diagnostic tool to monitor urban landfills. Since the anaerobic decomposition produces heat along with biogas, thermal anomalies recorded over the soil are likely to be associated with local biogas escaping from the landfill terrain and leaving a local thermal print. A simple and novel approach, based only on the processing of thermal maps gathered by the remote sensing surveys, has been proposed for the estimation of the fugitive methane emissions from landfills. Two case studies, concerning two Italian landfills, have been presented. For one of them (Mount Scarpino, Genoa), significant thermal anomalies were identified during several UAV flights and the relevant thermal images processed to obtain a rough estimation of the associated methane leakages. For the second landfill (Scala Erre, Sassari), the thermal map did not reveal any anomaly attributable to local biogas emission. Despite some limitations outlined in the paper, the present approach is proposed as an innovative method to identify significant biogas leakages from an urban landfill and to provide a preliminary evaluation of the methane production potential.