There are three main ways to exploit energy from the ocean: from the tides, from waves and from the ocean’s natural temperature variance as depth increases.

Tidal energy is a global, large resource that can be exploited through tidal barrages, which take advantage of the ebb-and-flow of the tides to release water through turbines, and exploitation of tidal currents, where there are many technologies still in development. Ranging from small-scale turbine units on the sea floor to large-scale turbines on vertical towers or suspended from boats, tidal current exploitation technology is still very much in the infant stage of development.

Wave energy is a renewable resource, created as winds pass over open bodies of water, transferring their energy to form waves. Wave energy has many important advantages over other energy sources, including the increase it gains in power over winter, when electricity demand peaks; low environmental costs; and the ability of satellites to predict waves two days in advance.

Ocean Thermal Energy Conversion (OTEC) uses the temperature difference between the warm tropical surface water and the cooler, deep water in the ocean to generate energy. Although still being developed, OTEC technology promises a renewable, constant source of energy that may even serve to reduce levels of heat and carbon dioxide from the ocean’s surface layer, currently increasing due to global warming and emissions. OTEC plants can be land-based, ‘floating’ (offshore fixed plants), or ‘grazing’ plants that are allowed to drift through the areas of the ocean with high temperature differences, storing the energy they produce as liquid hydrogen.

Note

The Marine section of this area of the website collates information on Wave energy, Tidal energy and Ocean Thermal Energy Conversion technologies. For further details please refer to the WER 2013 report marine chapter.