The technological innovation systems (TIS) approach has become one of the key frameworks for the study of emerging technologies in and beyond the context of sustainability transitions. It focuses on understanding the dynamics of an innovation system associated with a specific technology. The approach is often used to assess the performance of a TIS, to identify shortcomings and to derive policy recommendations for the support of a selected technology (Bergek et al., 2008; Hekkert and Negro, 2009). Since its inception, the framework has seen several conceptual developments, including a clarification of scoping issues, TIS functions as a central tool for performance assessment, a strategic perspective on system building, international and global ties within TIS, and suggestions for the analysis of TIS contexts (Bergek et al., 2015; Binz et al., 2014; Markard et al., 2015). At the same time, however, there are also new conceptual challenges, especially when the TIS is used for sustainability transition studies. One of these challenges is how to study whole system reconfigurations, i.e. to move beyond the focus on specific technologies. Ongoing transitions such as the energy transition currently enter into a new phase of accelerated development, in which multiple emerging and mature technologies interact. Other conceptual challenges include the decline of incumbent technologies, intensified struggles among actors or transition processes transcending sectoral and national boundaries.

--