Energy innovation plays a crucial role in the reduction of carbon emissions. In order to design climate and energy policies that promote the development, deployment and diffusion of new energy technologies, policy makers not only require a theoretical understanding of the energy innovation system, but also empirical evidence of the effects that policy actions have had. This paper focuses on public energy R&D, a traditional and controversial option among the various climate technology policies, and empirically analyses its relationship with carbon emissions per GDP (i.e. carbon intensity) and its two components: energy intensity and the carbon factor. Evidence of the causality links that have prevailed in 13 advanced economies over [...]