GIS-based model for determining the optimal potential of co-digestion mixtures in the Spanish Iberian Peninsula

Abstract

Agricultural and livestock biogas exploitation trough co-digestion power plants is still poorly deployed in Europe -e.g., in Spain, this Renewable Energy Source (RES) represents only the 0.17% of installed RES capacity- although most authors agree and even EU Directive 2009/28/EU stipulates that biogas and this type of energy can contribute to a reduction of at least 35% of greenhouse gas emissions. Furthermore, biogas can be used to upgrade gas pipelines, which results of great interest. Nevertheless, it has been observed that the biogas production its underrated in many EU member states, especially in Spain, and it still has a very low penetration rate in the energy mix. Most currently installed co-digestion power plants in our country show low installed capacity values (the 66% of installed co-digestion power plants have a rated power less than 500 kW) and are restricted to local resources. In this paper, through a Geographical Information System (GIS) approach, 8 different co-digestion mixtures have been evaluated and the most profitable ones have been optimized for the Spanish Iberian Peninsula to set their real biogas generation potential according to the geographical distribution of the resources. Moreover, for each different mixture, optimal clusterization have been proposed, according to maximum potential generation and minimum transport cost ratios. This analysis results fundamental for the optimal deployment of co-digestion power plants in Spain and the adequate allocation of RES. Results show that the most feasible co-digestion mixtures available in the Spanish Iberian Peninsula are based on slurry, glycerine and agricultural residuals, and 4 mixtures show a great energetic potential, estimated in more than 277 MW of electrical power capacity in co-digestion power plants economically feasible. The Spanish Iberian Peninsula potential is estimated in the range from 175 MW to 550 MW.