A MCDA-Based Assessment of Biomethane Generation and Use in Sardinia

The selection of a local and sustainable use of biogas, and biogas feedstocks, towards the upgrading process to biomethane, is a key aspect towards more consistent energy planning within the frame of the EU Green Deal and Sustainable Development Goals. In this paper, four biomethane production and utilization pathways were assessed in the view of economic, environmental, technological, and social dimensions compared to a reference scenario in which direct biogas use in a cogeneration unit is assumed. The technologies analyzed included membrane systems, amine scrubbing, water scrubbing, and biological methanation, regarding the Sardinian context. The impact assessment was carried out using the TOPSIS method. As an output, thirteen consistent indicators reflecting the holistic aspect of sustainability were designed and proposed based on an in-depth literature review and the authors' technological knowledge. The results show that the reference scenario was the preferable one. In terms of environmental and social considerations, biological methanation emerged as the most environmentally and socially responsible alternative. From the economic perspective, all the upgrading options depicted similar results. The technological-oriented weighting showed that the two most widespread upgrading options highlighted the optimal results.