Explaining the drivers of technological innovation systems: The case of biogas technologies in mature markets

Biogas as an energy carrier can play an important role in low carbon energy transitions. However, in some countries, biogas technologies are just starting to be used, while in others a more mature stage has been reached. Such heterogeneous development raises a basic question: what are the driving forces behind biogas technologies? In order to address this question, we conduct a systematic literature review on seven mature biogas markets: Austria, France, Germany, Italy, Sweden, the Czech Republic and the United Kingdom. As a result, we synthesize our findings under a typology of what we call system drivers - i.e. drivers of technological innovation systems e and conceptually explain their potential links to system functions. Based on the findings from 42 systematically selected publications and some grey literature, we categorize the system drivers under four interrelated groups (1) proaction to challenges, (2) policy support, (3) cooperation and (4) capability of technology. We argue that the notion of 'system drivers' sheds some light on why socio-technical transitions are ahead in particular sectors in certain countries. In doing so, we extend the previous literature on the functions of technological innovation systems, which previously has offered limited explanations on the causal mechanisms behind sociotechnical transitions. In addition, we offer some suggestions for policymakers and practitioners who seek to initiate or expand the diffusion of biogas technologies. (C) 2020 The Authors. Published by Elsevier Ltd.