Life cycle assessment of anaerobic digestion systems

Abstract

PurposeIt is well known that sustainability is the ideal driving path of the entire world and renewable energy is the backbone of the ongoing initiatives. The current topic of argument among the sustainability research community is on the wise selection of processes that will maximize yield and minimize emissions. The purpose of this paper is to outline different parameters and processes that impact the performance of biogas production plants through an extensive literature review. These include: comparison of biogas plant efficiency based on the use of a diverse range of feedstock; comparison of environmental impacts and its reasons during biogas production based on different feedstock and the processes followed in the management of digestate; analysis of the root cause of inefficiencies in the process of biogas production; factors affecting the energy efficiency of biogas plants based on the processes followed; and the best practices and the future research directions based on the existing life cycle assessment (LCA) studies.Design/methodology/approachThe authors adopted a systematic literature review of research articles pertaining to LCA to understand in depth the current research and gaps, and to suggest future research directions.FindingsFindings include the impact of the type of feedstock used on the efficiency of the biogas plants and the level of environmental emissions. Based on the analysis of literature pertaining to LCA, diverse factors causing emissions from biogas plants are enlisted. Similarly, the root causes of inefficiencies of biogas plants were also analyzed, which will further help researchers/professionals resolve such issues. Findings also include the limitations of existing research body and factors affecting the energy efficiency of biogas plants.Research limitations/implicationsThis review is focused on articles published from 2006 to 2019 and is limited to the performance of biogas plants using LCA methodology.Originality/valueLiterature review showed that a majority of articles focused mainly on the efficiency of biogas plants. The novel and the original aspect of this review paper is that the authors, alongside efficiency, have considered other critical parameters such as environmental emission, energy usage, processes followed during anaerobic digestion and the impact of co-digestion of feed as well. The authors also provide solid scientific reasoning to the emission and inefficiencies of the biogas plants, which were rarely analyzed in the past.