Energy system scenarios and modelling exercises may under-represent the learning potential of emerging technologies such as marine energy. The research described here was devised to represent this potential, and thereby explore the possible role of marine energy in future energy systems. The paper describes a scenario for the accelerated development of marine energy technology, and the incorporation of this scenario into wider scenarios of UK energy system decarbonisation from now to 2050. The scenarios suggest that the accelerated development of marine energy could contribute significantly to the decarbonisation of energy supply in the UK, especially over the medium to long term. However, this is predicated on sustained innovation, learning and cost reduction over time. Encouragingly, a number of recently established policy support programmes are now beginning to stimulate the development of marine energy in Scotland, the UK and beyond. As the paper discusses, building on these initiatives, and ‘realising’ the accelerated development of marine energy, present a number of challenges, and will increasingly require international efforts. However, the potential rewards are very substantial.