Artificial structures such as wave and tidal energy devices provide surfaces and structures that are naturally colonised by marine flora and fauna. Properties of the building material, surface texture and structural complexity of the infrastructure will determine the suitability as a habitat for marine organisms. While it may be desirable to inhibit fouling of some parts of the energy devices, the colonisation of other features may not compromise their overall functionality. Here we explore opportunities to not just tolerate the colonisation of marine infrastructure, but to design and manipulate features that would deliberately attract and host marine organisms. Serendipitous colonisation would be transformed into deliberately creating artificial reefs on the seafloor as well as floating reefs. This paper focuses on conceptual options for coastal, close-to-shore infrastructure, and it introduces two case studies: a proposed tidal lagoon that exploits tidal range energy and a wave energy converter. Positive reef-effects of these devices could include the enhancement of biodiversity of invertebrates and fish, habitat restoration or the production of commercial species.