ABSTRACT
Biogas is an energy vector that can either be upgraded in a high-energy content gaseous fuel (i.e., biomethane) or directly used for generating usable energy (i.e., heat and power). This energy source has been produced at a large scale in different developing and developed countries at different scales, most of them being implemented as a stand-alone process. Nevertheless, this process requires financial support to reach valuable economic performance. Thus, biorefineries as complex systems where biomass is upgraded into a series of value-added compounds and energy vectors seems to be a feasible option for implementing biogas production. This chapter outlines the four main aspects: a) fundamentals of the anaerobic digestion process and biogas production; b) an overview of the biogas potential from several feedstocks; c) simulation approach to estimate the maximum biogas yield reported in the open literature; and d) the technical and economic performance of a biorefinery involving the biogas production as a product or source of energy to supply a share of the process energy requirements. Additionally, the influence of the processing scale on the biorefinery economic performance was assessed. This chapter reveals the high potential of non-lignocellulosic biomass to produce high volumes of biogas. Simulation approaches based on the complete chemical characterization appear as the best routes to estimate the theoretical biogas potential of any feedstock. Finally, the findings of this study indicate that the implementation of biogas production in biorefineries as an energy source is feasible from a technical and economic perspective. Nevertheless, improvements to reduce the capital investment of the process should be implemented to reduce both the capital and operational expenditures of the biorefinery.
