This research examines whether study of the controversial evolution of energy systems and emerging energy technologies can contribute to the debates in energy policy and STS, especially those concerning the ongoing search for solutions to energy and environmental problems through the promotion of low-carbon technologies. The focus of this study is on the emergence and growth of a technological project in the renewable energy sector, Wave Hub in Cornwall, UK. The analysis, informed by actor-network theory, helps to explore the emergence of Wave Hub as a complex socio-technical system and a macro-actor. The case study reveals that the project is associated with various controversies and problematic temporalities. The construction of credibility and viability of the technological project is explored, including the 'public face’ of the project, various meanings attributed to Wave Hub and its symbolic capital. The discourse around Wave Hub is critically reviewed, as regards stakeholder assumptions about the technological feasibility of the project. Consideration is also given to the political dimensions of credibility, including the promissory role of policy discourse. An actor-network theory approach helps questioning the idea of policy as ‘macro context’; the utility of an analytical approach to policy as an actant is thus investigated. I ask to what extent, and in what sense, policy can be understood as an element of an actor-network, not merely a context. Furthermore, this helps to build a critical discussion around the evolution of the actor-network with policy as its active element and critically assess to what extent this approach might help to understand the destiny of a technological project. The politics of expertise in the case of Wave Hub is shown to play a critical role for the ‘credibility-economy’ of the project. Exploring how the expertise is understood and performed in the case of Wave Hub, I consider the question of the self-representation of experts and how the expert knowledge and the expert status are constituted. Studying the contestation of expertise and its categorisation helps to analyse various forms of collaboration formed around Wave Hub, but also antagonism which was revealed between different groups of experts