Tidal energy has the technical potential to form part of a low carbon electricity sector, however, its ‘social potential’ is less clear, as few empirical studies of public beliefs and responses have been conducted to date. This research addressed this gap by investigating a tidal energy convertor in Northern Ireland, said to be the first grid-connected device of its kind in the world. Data was collected from 313 residents of two nearby villages using mixed methods, guided by a conceptual framework that avoided ‘NIMBY’ assumptions and instead drew on place theory. Findings indicated strong support for the project, arising from beliefs that the project enhanced local distinctiveness by ‘putting the area on the map worldwide’; appeared visually familiar and helped tackle climate change. These positive beliefs outweighed concerns about outcome and process aspects, which were preponderant in one of the two villages. The project was interpreted to have few positive local economic outcomes, to potentially threaten local livelihoods and local ecology. Moreover, residents expressed cynicism about consultation procedures, and reported low levels of behavioural engagement. Implications of the findings for the literature on public acceptance of renewable energy, and for the emerging marine energy sector specifically, are discussed.