Energy from seas and oceans

by Gianmaria Sannino and Adriana Carillo, ENEA

DOI 10.12910/EAI2017-030

Marine energy can represent an important source of renewable energy in the near future. In Italy, activities performed in this sector are growing rapidly both in terms of assessment of the resource and of development of new devices

The growing interest in the Blue Energy sector represents an opportunity for sustainable growth of maritime economies, sustainable development of marine areas, and sustainable use of marine resources. The EU’s Renewable energy directive has established a target of 20% of energy production from renewable energy by 2020. Seas and oceans have the potential to become an important source of clean and renewable energy contributing to reach such a target, the contribution of ocean energy to the EU power demand has been estimated to be around 10% by 2050.

Five different marine resources have been identified as liable for ocean energy exploitation:

• tidal current extracts kinetic energy from tidal flow;
• tidal range captures the potential energy created by the difference in sea level between high and low tides;
• wave converts kinetic energy transmitted by the wind to the upper surface of the ocean;
• ocean Thermal Energy Conversion exploits the temperature difference between deep and surface ocean layers;
• salinity gradients exploits the chemical potential due to salinity gradients in water bodies.

These resources are not uniformly distributed on the globe; moreover the degree of maturity of the technology necessary to their exploitation is different. In the Mediterranean Sea, the two most interesting ocean sources are represented by tidal currents confined in the Strait of Gibraltar and Messina and by waves. …