Renewable marine energies: a capital to be made fruitful. Sea water is blowing hot and cold. Towards a robust wave energy system. The salinity gradient to conquer the world. A dyke which produces electricity

Various renewable marine energies are emerging. The most mature technology is the fixed-foundation offshore wind energy. Such projects are foreseen or under construction along the French coasts, as well as floating wind energy projects (call for projects are foreseen). But perspectives of development of other types of renewable marine energies are overviewed: wave energy (a lack of reliability is still to solved), tidal energy (pilot installations are already existing), and also the exploitation of the different of temperatures between deep and surface waters. A second article discusses the emergence of electricity generation from sea thermal energy: even the business model is still to be found, some applications are already running. The Wavegem project is then presented: test of a wave energy prototype which uses an internal sea water circulation to recover wave energy, a robust solution which can be associated with solar energy, but with a productivity which still needs to be improved. Another article addresses the exploitation of osmotic energy with the development of much more efficient membrane by Sweech Energy. Finally, the project of construction of a positive-energy coastal dyke in 2024 is presented: it comprises a wave energy system which damps the force produced by the impact of waves to transform it into electric power