Multi-Criteria Decision Analysis-Supported Evaluation of Biowaste Anaerobic Digestion Options in Slovakia

Anaerobic digestion is an effective and green alternative to treat various types of organic waste and to convert part of the feedstock into biogas that can be further treated to yield biomethane. Slovakia´s biomethane production potential represents up to 10 % of Slovakia´s natural gas consumption and is largely unexploited to date. Batch or continuous-type reactors may be employed, in which organic substrates are transformed into biogas and digestate. Depending on feedstock properties, two technological approaches can be considered, differing in feedstock solids content: wet (below 15%) and dry (above 20%). The biogas produced consists (on a dry basis) largely of methane (~55% vol.), followed by carbon dioxide (~40% vol.), with nitrogen, oxygen, and hydrogen sulphide representing typical minor components and impurities. The aim of this paper is to develop a model of each available technology (continuous, dry batch, wet batch), as well as that of a biogas treatment unit, andto evaluate the energetic, economic, and environmental potential of building a new anaerobic digestion plant in Slovakia, supplied by organic waste collected with a radius of 30 km. Feedstock composition and availability, energy integration, and product usability are evaluated. Multi-criteria decision analysis (MCDA) is applied to the considered plant configurations to identify the most viable and sustainable solution for anaerobic digestion plant application in Slovakia.