Ocean energy

Ocean power accounts for the smallest portion of renewable electricity globally, and the majority of projects remain at the demonstration phase. However, with large, well-distributed resources, ocean energy has the potential to scale up over the long term.

Five different ocean energy technologies are under development:

• Tidal power: the potential energy associated with tides can be harnessed by building a barrage or other forms of construction across an estuary.
• Tidal (marine) currents: the kinetic energy associated with tidal (marine) currents can be harnessed using modular systems.
• Wave power: the kinetic and potential energy associated with ocean waves can be harnessed by a range of technologies under development.
• Temperature gradients: the temperature gradient between the sea surface and deep water can be harnessed using different ocean thermal energy conversion (OTEC) processes.
• Salinity gradients: at the mouth of rivers, where freshwater mixes with saltwater, energy associated with the salinity gradient can be harnessed using the pressure-retarded reverse osmosis process and associated conversion technologies.

Tidal projects produce variable, but highly predictable, energy flows. Generation from wave power is variable, depending on the state of the sea.

None of these technologies is widely deployed as yet. The engineering challenges associated with efficiently intercepting energy from wave or tidal power are significant, particularly given the need to survive and operate in difficult conditions. Other issues that need to be considered include impacts on marine life, the marine environment and other marine users such as shipping, fishing industry, etc.

Tidal barrages are most advanced as they use conventional technology. However,  only two large-scale systems are in operation worldwide; the 240 MW La Rance barrage in France has been generating power since 1966, while the 254 MW Sihwa barrage (South Korea) came into operation in  2011. Other smaller projects have been commissioned in China, Canada and Russia.

For other ocean technologies, design concepts are still being researched but the leading ones have now reached the point where megawatt scale installations are being demonstrated. The largest demonstration project is the 6 MW MeyGen tidal array in Scotland.

Technology Collaboration Programmes (TCPs)

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Ocean Energy Systems TCP

The aims of the IEA TCP on Ocean Energy are to accelerate the viability, uptake and acceptance of ocean energy systems in an environmentally acceptable way. This includes unbiased, quality analysis of technologies to generate electricity from ocean movements (waves, swells, tides, currents), temperature differences or salt concentrations; as well as technologies related to desalination. There are currently 21 Contracting Parties, including China, Mexico, Nigeria, South Africa and Monaco.

Learn more about the Ocean Energy Systems TCP >

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