World economic growth is strictly linked to the global energy availability. Main energy sources currently are not renewable and also are limited, while nuclear fusion is still being tested and time needed for its industrialization can not be estimated yet. Economy, therefore, will require a rising production of renewable energies. Potential of traditional renewable energies suchas wind and water is not going to be increased in the future in order to satisfy the rising worldrequest for energy, therefore the development of other energy sources, especially renewable ones, is necessary to satisfy the demand for world energy. The osmotic energy capacity of oceans andseas has been estimated at 2.6 TW, similar to thepotential of ocean thermal energy.