Sociotechnical imaginaries (SIs) have emerged as a popular and generative concept within Science and Technology Studies (STS). This article draws out the affective component of SIs, combining a review of relevant literatures with an empirical case study of an anti-fracking imaginary in Ireland to suggest how we might theorize an affective technopolitics of SIs. The literature review identifies three key aspects of SIs that would benefit from a more coherent conceptualization of affect: the utopian, productive, and collectivizing dimensions of imaginaries. Emotions such as desire and fear appear prominently in the SI literature, but in ways that require development. Using empirical examples from my research, I outline what this developed understanding of emotions in imaginaries might look like. I examine the role that emotions played in the development and settlement of an anti-fracking imaginary in Ireland, highlighting how the intensive, multimodal, and dynamic nature of affect underpinned the productive, collective, and utopian dimensions of the SI. I conclude with some remarks about how this developed theory of emotion positions STS researchers to address issues of humanity, representation, and the building of better worlds.