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Tidal, wave and other ocean energy

Ocean contains a vast renewable energy potential, which could support sustainable long-term development and can be a crucial component in the world’s emerging blue economy. Ocean energy technologies are utilizing different resources. They can provide both reliable and stable electricity, as well as support other components of the blue economy, such as aquaculture and desalination

The four main technologies developed are: 

  • Wave energy: Utilizes the movement of waves to generate electricity. Depending on the design, they can take advantage of wave motion, the height difference or they can use trapped air to drive turbines. Multiple designs have been suggested, from ocean deployed, large capacity devices to smaller capacity devices deployed in larger numbers in coastal sites, such as ports.  

  • Tidal energy: Two main technologies have been developed to produce electricity. Tidal range that harvests power from the water level differences between high and low tide and tidal stream that utilizes the kinetic energy of the tidal current. Tidal range applications are not currently being pursuit at large due to their limited deployment location, costs and environmental impacts. Tidal stream devices can be both placed on the seabed or on the sea surface.    

  • Salinity gradient energy: Based on the difference of salt concentration between the freshwater of a river and the saltwater of the sea where the river empties.  

  • Ocean thermal energy conversion: Utilizes the difference of temperature between the sea surface and the seawater in depths 800-1000m. These devices require a temperature difference between the sea surface and the deep sea of at least 20-25o C, making them viable only in tropical regions. 

 

The ocean energy sector has significant potential to contribute to the energy mix and therefore to the decarbonisation of the EU, having a theoretical potential in Europe of about 2800TWh for wave and 50TWh for tidal energy annually (Magagna D, 2020). The highest potential exists along the Atlantic coast followed by the Baltic and the Mediterranean. 

MATURITY: Look at sub-types of solutions.  

Ocean energy technologies are still under development with few designs currently being available in the market. In the last 5 years the ocean energy sector has developed rapidly and in the coming 2-3 years, multiple commercial designs are planned to be deployed commercially.    

 

Tidal energy has the most mature technologies, with tidal range projects having being commercialized in the past. However, due to site limitations, cost and environmental impacts, currently only a few projects globally are being considered. Some tidal stream designs have also reached maturity. Currently horizontal axis designs (HS1000) are being commercially deployed, while more designs (O2, Dragon class) are currently being demonstrated at a full scale.  

 

Various wave energy technologies are in a demonstrator phase and pre-commercial stage, however the technology hasn’t converged into specific designs. Focus is currently at improving components of different devices (SEA-TITAN), validating their efficiency (IMPACT, VALID) and reducing the costs (OPERA). 

 

Salinity gradient and ocean thermal energy conversion technologies are still in an initial development phase with only a handful of projects being deployed globally as demonstrators. 

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