Marine renewable energy has the potential to solve both the energy-security and coastal-protection problems affecting coastal societies. In this article, the potential benefits arising from the combination of marine renewable energy technologies with infrastructural needs for coastal protection and other local needs are analysed. Classifications of technologies are developed to inform future coastal planning. Explanations of the resources and technologies are presented in layperson’s term. The threat of coastal inundation under climate-change scenarios is a major global issue. The investment in new infrastructure demanded by cities, ports and communities at risk of inundation could very substantially reduce the levelised cost of electricity from renewable sources, provided the infrastructure is designed with the dual purpose of power generation and coastal protection. Correspondingly, the sale of electricity from such infrastructure could defray the long-term cost of installing coastal protection. Furthermore, many marine renewable energy technologies provide a platform on which other forms of renewable energy generation could be mounted. It is noted that the complex geophysical and engineering issues arising from this opportunity must be assessed considering socio-economic factors.