Understanding inter-system interactions and their impacts

[Introduction] Changes in technologies, processes, behaviour and relationships are an essential part of transitions of socio-technical systems. They are induced by 'impulses' within and outside the system. There is a large body of literature discussing interactions within socio-technical systems, between niches and regimes and possibly landscapes (e.g. Geels 2007) or between elements of a system oriented towards specific purposes (Borrás and Edler 2015). However, interactions occur not only within a certain system, but between systems and in different forms and intensities of exchange between the components of two or several systems. Some examples of system interactions are the food-water-energy nexus, smart energy as a field resulting from electricity and ICT, functional foods as a nexus between food and pharmaceuticals, or interlinkages between electricity, transport and heat-ing (Hiteva and Watson 2019; Hoolohan et al. 2019, Papachristos et al. 2013, Rosenbloom 2019). The interactions between systems may have significant impacts on related transformations, e.g. by accelerating changing processes, but these interactions could also have hampering and conflicting effects. Hence, multiple relationships and dynamics have to be taken into account in transitions research. In this context, Rosenbloom states that 'interactions taking place between socio-technical systems merit further attention in sustainability transitions research' (Rosenbloom 2018, p. 229). We also think there is still a need to further explore where and how these interactions take place, what characteristics and features of interactions between socio-technical systems exists and what the implications for the systems and their transitions are. Thus, the objective of this paper is to elaborate a typology for analysing interactions between socio-technical systems and identifying their impacts on innovations and transition of systems. We review how interactions between two or more socio-technical systems are discussed in the transition literature, set up a systematic framework to identify interactions between systems and try to understand how interactions impact socio-technical systems and their transitions. We use the energy transition, in particular, the interaction between the heating and electricity system as an example to illustrate the arguments.