Biogas production plants; existing classifications and proposed categories

Production of biogas from anaerobic digestion has the potential to be part of the transition to a renewable based energy system. However, diverse classifications may obstruct knowledge sharing within and between countries, thus potentially hindering development of biogas solutions, as part of an environmentally sustainable renewable based energy system. The aim of this study is to present an approach to categorize biogas production plants and to investigate and compare some country-specific classifications of biogas production plants. The study shows that there are differences between the country specific classifications studied, both in the terminology and in the underlying descriptions when the terminology is the same. It is also shown that the biogas plants studied do not fit into all of the in-depth country specific European classifications studied. A Framework for Categorization that includes seven categories is proposed. When the biogas plants studied are inserted into the framework, similarities between different plants are shown. These similarities are not found when using the existing European biogas plant classifications. It has also been shown that only three of the proposed categories are included in any of the four in-depth European classifications studied. The Framework, developed in this study, shows the complexity of common categories for biogas production plants, and it is an attempt towards finding a common classification for biogas plants. (C) 2017 Elsevier Ltd. All rights reserved.