Marine energy

Major island electrical infrastructure needed to feed power generated by marine energy systems, which includes substations, high voltage transmission and distribution grids, conventional fossil back-up power stations, energy storage systems, are physically located within the defined coastal area. In an island context, especially for non-interconnected islands, there are other more technical arguments for including also land energy infrastructure in the marine energy analysis. There is a difference between marine electricity, and other marine products obtained from other blue economy related activities, such as aquaculture, marine biotechnology or seabed mining. Electricity generation from marine RES systems installed in island surrounding waters, is not a commodity that could be stored, transported over long distances, and sold in overseas markets, but is energy that must be fed to the island electrical grid, and consumed in the island. Marine RES power generation from the supply-side must be balanced at every instant of time with demand-side electricity consumption of the island. This grid balancing in the island context is an important technical challenge for non-interconnected island electrical systems, especially in high RES penetration scenarios. The forms of ocean energy are waves, tides, marine currents, salinity gradient and temperature gradient. Wave and tidal energy are currently the most mature technologies.

The impacts on marine energy are related with:

  • Different population densities
  • Different seasonal variation in tourist activities
  • Different dependence on fishery and aquaculture activities
  • Different past successful stories promoting Green energy (on-land RES), or paradigmatic Circular economy experiences (successfully implementing 3R waste management: Reduce, Reuse, Recycle).
  • Different geographical areas/different countries: One Atlantic island (to choose from Madeira, Gran Canaria or an island in Azores); three Mediterranean islands (to choose from Cyprus, Malta, Crete, Corsica, Majorca, Sardinia or Sicily).


Hazard Biophysical impacts Socio-economic impacts
Increased frequency and intensity of extreme climate events
  • Damage to marine RES energy generation system
  • Damage to associated electrical infrastructure: transmission and distribution grid; energy storage (off-shore and marine energy systems require expensive infrastructure)
  • Increase cost of maintenance, insurance and adaptation actions to increase resilience and reduce vulnerability of energy infrastructures
Temperature rise
  • Increased need for more power generation installed
  • Transmission and substation capacities reduced.
  • Gas-turbine power plant generation efficiency reduction
  • Stressed energy demand by demand rising for electricity
  • Higher energy demand for cooling and water production (sea and brackish water desalination)
Sea level rise
  • Increased risk for electrical substations and other electrical coastal infrastructures
  • Negative impacts on fuel transportation and storage infrastructure, including pipelines, barges, and storage tanks
  • Increased costs for design and implementation  of measures/policies to reduce the vulnerability of energy infrastructure to flooding
Lack of rain and increased evapotranspiration
  • Increased needs to install reverse osmosis seawater desalination plants
  • Increased costs of sea-water reverse osmosis desalination for covering water needs
Concentration of CO2
  • Increase corrosion damage due to increase in atmospheric CO2, and carbon induced corrosion, is a major cause of reinforcement corrosion in concrete infrastructures
  • Increased costs of operations due to electricity consumption for air-conditioning
  • Increase in ocean acidity can increase corrosion of marine exposed infrastructures
Interannual variability of temperature
  • Variable electricity demand. Complication in Demand Side Management needed to maximize RES integration in the small island electrical systems.
  • Higher variations in energy demand due to larger temperature variability will require more flexible energy systems (more expensive)
  • Increase in the energy intensity, due to increase in air conditioning
  • Increase in peak power demand



Marine Renewable Energy Sources (RES) have doubled in the last decade and represent approximately 1% of the more than 2 million MW RES installed worldwide capacity (IRENA, 2017). They have the potential to become an important source in the energy mix of coastal regions, and some projections indicate that given the expected rapid growth.

Off-shore wind is the most promising of the technologies, but several energy options are trying to develop and become also cost-competitive alternatives over time, capable of contributing to the exploitation of the energy potentials of our seas and oceans. Besides wind, there is huge clean and renewable energy resources potential in the ocean waves and underwater currents; in the water temperature gradients of tropical regions (Ocean Thermal Energy Conversion – OTEC); in the salinity gradients (still R&D early stage); and in tides (tidal stream technology).

Offshore wind is the fastest growing activity of the blue economy. Wind is steadier at sea than on land, so the average capacity factor is higher and the disturbance to cherished landscapes smaller. As of January 2017, 12,631 MW of capacity was connected to the grid. The EU is a global leader with about 90 % of the newly finished projects in the world. It is estimated that 80% of the EU’s wind resource are in waters too deep for traditional fixed turbines. Floating turbines could extend the deployment to deeper waters such as those off the Iberian Atlantic coast or the Mediterranean (IRENA, 2017).

Nevertheless, as the installed marine RES power expands, and as investment cost reductions are achieved, the concern will be shifting towards guaranteeing the safety and reliability of operation of sea power-generation devices and the complementary electrical infrastructure, under severe storms and other negative climate change impacts.


Renewable energy sources (RES), also called renewables, are energy sources that replenish (or renew) themselves naturally. Typical examples are solar energy, wind and biomass (EC, 2016).

Renewable energy sources include the following:

  • Hydropower: the electricity generated from the potential and kinetic energy of water in hydroelectric plants (the electricity generated in pumped storage plants is not included);
  • Tide, wave, ocean energy: mechanical energy derived from tidal movement, wave motion or ocean current and exploited for electricity generation;
  • Geothermal energy: the energy available as heat from within the earth’s crust, usually in the form of hot water or steam;
  • Wind energy: the kinetic energy of wind converted into electricity in wind turbines;
  • Solar energy: solar thermal energy (radiation exploited for solar heat) and solar photo-voltaic for electricity production.

Wave and tidal energy are currently the most mature ocean energy technologies.

Tidal current energy is created by local regular diurnal (24-hour) or semi-diurnal (12+ hour) flows of ocean water caused by the tidal cycle. Kinetic energy can be harnessed, usually nearshore and particularly where there are constrictions, such as straits, islands and passes.

Wave energy is created as kinetic energy from the wind and transmitted to the upper surface of the ocean. At present there are several different wave energy technologies designs, and some are at the cutting edge of engineering design.

Ocean thermal energy conversion (OTEC) uses the temperature difference between surface and deep water in a heat cycle to produce electricity. Although tropical areas are most favourable for the exploitation of this source of energy, the potential resources are enormous.

Osmotic power generation exploits the energy available from differences in the salt concentration between seawater and fresh water and is especially suited to countries with abundant fresh water resources flowing into the sea. There are two practical methods for this – reversed electro-dialysis (RED) and pressure retarded osmosis (PRO).

Ocean energy is largely derived from the power of currents, tides and waves and to a lesser extent also from thermal and saline gradients in some locations. The resources are plentiful and the regular nature of their power delivery complements more variable renewable sources such as wind and sun. Estimates suggest that ocean energy could meet 10% of the EU’s electricity demand by 2050.

Power generated by the marine RES systems will have to be fed to the island grids. Developing the full potential of marine RES will require heavy investment in electrical infrastructures for connecting off-shore wind farms and other marine RES devices to the island electrical systems. The energy transition to a more sustainable low carbon energy system, especially in those islands with a big resident population and high tourist activity, will require developing their specific and more viable marine RES. Also, the application of proper Demand Side Management/Demand Response will contribute to peak shaving of the island electrical demand curve, which combined with energy storage infrastructure, will allow for managing the variability and intermittence of non-dispatchable marine RES generation.

Soclimpact assumptions

Conditions for a future development of marine RES in islands are comparatively better than those exhibited by mainland territories. As technology progresses (floating wind energy platforms, tidal sensitivity devices, etc.) islands will take advantage of their diverse conditions alongside their coastlines areas to produce energy.

Secondly, a big part of the energy production, transport and distribution infrastructures are strongly linked to coastal areas. Electric grid goes near to the shoreline, being exposed to marine and coastal climate shocks. Additionally, conventional electric power plants area mostly built at the shoreline precisely to take advantage of the sea proximity as a source for refrigeration and as a sink for wastewaters. Finally, although there are distributed renewable-based electric plants relatively far from the sea line, those are sensitive to extreme climate events, affecting the costs of the blue economy activities of the European islands.

Thirdly, energy is a crucial input for the economic production of islands, while energy shocks, including those linked to climate hazards, will have a great influence, via costs, on the blue economy sectors and hence on the whole islander economies. Additionally, on the demand side, energy uses and/or production features are considered attributes of the tourism products and experiences offered by these destinations, and critical factors to underline them as climate/environmentally friendly. Thus, the energy sector interacts with blue economy activities in islands not only in an intensive way but also from both supply and demand sides.

The strong relation between the energy sector and the blue economy in the islands, and the unlimited borders that blue sectors have in the context of insular economies fully justify the selection of the whole energy sector under the Soclimpact analysis, regardless of the limitations that could arise from the availability and aggregation of data and the functional relations between the marine-based energies and the whole energy systems.