Ocean projects

Generation, storage and power electronics

Marine renewable energies represent a field of great potential for the decarbonisation of the global energy system. The vastness of ocean resources allows the implementation of various energy generation and storage technologies. In general terms, we can divide them into two large groups:

1. Conventional marine renewable energies:
   • Offshore wind energy: Turbines installed at sea, either on fixed or floating structures.
   • Floating solar PV energy: Solar panels floating on sea surfaces.
2. Ocean energies:
   • Wave energy: Capturing the movement of waves to generate electricity.
   • Tidal energy: Harnesses tidal currents by means of submerged turbines.
   • Thermal gradients: Use of the temperature difference between the surface and the ocean floor.
   • Saline gradients: Electricity generation based on the difference in salinity between water bodies.

Each of these technologies presents unique challenges and advantages in terms of efficiency, cost and feasibility on a large scale.

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Offshore Renewable Generation Technologies and Projects

Offshore wind energy

Offshore wind energy has evolved with the development of larger and more efficient turbines. There are two main types:

• Fixed: Installed in shallow waters (less than 60 metres).
• Floating: These allow turbines to be installed in deep water, where winds are stronger and more constant.

Example: Dogger Bank Wind Farm (UK) with a capacity of 3.6 GW will be the largest offshore wind farm in the world.

Floating Solar PV energy

The development of floating solar panels in coastal waters and marine reservoirs complements renewable generation.

Example: Saemangeum Project (South Korea) with 2.1 GW capacity is one of the largest installations of its kind.

Wave Energy

Wave energy harvesting is carried out with buoys and mechanical converters.

Example: Mutriku Project (Spain) – a 296 kW plant that has demonstrated the viability of wave energy.

Tidal energy

It is based on submerged turbines that harness the currents generated by the tides.

Example: La Rance (France) – a 240 MW plant in operation since 1966, remains a reference in this field.

Thermal and Salt Gradients

These technologies, although still in the research phase, can offer continuous and predictable generation. Example: OTEC plant in Hawaii, which uses the temperature difference between shallow and deep water to generate electricity.

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Offshore Energy Storage

Storage is key to the stability of offshore renewable generation. Some of the main solutions include:

1. Offshore batteries: Integrate storage systems in offshore wind farms
   • Example: Hywind Tampen (Norway), with batteries to stabilise its floating turbine grid.
2. Underwater gravity storage: Uses the seabed to store potential energy.
   • Example: StEnSea project (Germany), which uses concrete spheres to store energy by pumping.
3. Conversion to green hydrogen: Offshore hydrogen generation for transport.
   • Example: PosHYdon project (The Netherlands), which combines wind energy with hydrogen production.

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Impact Summary and Key Figures

• Offshore wind power accounts for more than 90% of the installed capacity in offshore energy.
• Installed tidal and wave power capacity is still low, but is estimated to grow by 300% in the next decade.
• Storage projects, especially offshore batteries, can reduce intermittency and improve grid reliability.

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Conclusion

The future of offshore energy generation is promising. The combination of wind, solar and ocean technologies with storage systems will allow greater stability and use of these resources. The transition to cleaner and more sustainable sources still depends on technological development and infrastructure investments

References

1. IRENA (2024). Offshore Wind Energy Global Outlook. https://www.irena.org
2. European Commission (2024). Ocean Energy Strategic Roadmap. https://ec.europa.eu
3. Global Wind Energy Council (2024). Floating Offshore Wind Report. https://gwec.net
4. Fraunhofer Institute (2023). Storage Solutions for Renewable Marine Energy. https://www.fraunhofer.de

Photo of Smithsonite, from which Zinc is extracted, by MyriamB.