Our oceans can produce energy of two types: thermal energy from the heat of the sun and mechanical energy from the tides and waves. The oceans hold an immense amount of energy and are also close to very many large population centers. Ocean and marine energy has the potential to provide a substantial amount of new, renewable energy to our world.
Energy from the oceans
There are currently five distinct technologies for extracting energy from the oceans:
Wave energy
Wave energy converters derive energy from the movement of waves and can be located flexibly – on the shoreline, the nearshore or offshore at depths of over 100m – to harness the available energy most efficiently.
Stream/current turbines
Stream/current turbines harness the flow of the ocean currents to produce electricity. Current turbines can be fixed directly to and mounted on the seabed, or tethered/moored to the seabed and buoyant, floating on surface or in mid water.
Read more about stream/current turbines
Tidal range
Tidal range uses the difference in sea level between high and low tides to create power. Tidal range technology uses the same principles as conventional hydropower, and requires a barrier to impound a large body of water, driving turbines generating electricity.
Ocean Thermal Energy Conversion (OTEC)
Ocean Thermal Energy Conversion (OTEC) exploits the temperature difference between deep cold ocean water and warm surface waters to produce electricity via heat exchangers.
Salinity gradient power generation
Salinity gradient power generation utilizes the difference in salt content between freshwater and saltwater, found in areas such as deltas or fjords.
Read more about salinity gradient power generation
Challenges and solutions in marine environments
What are the challenges and how can they be overcome?
Energy potential from the oceans
The potential exists to develop up to 80,000 terawatt-hours electricity per year (TWh/y), generated by changes in ocean temperatures, salt content, movements of tides, currents and waves swells*.
In Europe alone, the ocean energy industry plans to deploy 100GW of production capacity by 2050, meeting 10% of electricity demand. Enough to meet the daily electricity needs of 76 million households and create 400,000 skilled jobs all along the supply chain.**
Sources:* "Ocean—potential". International Energy Agency (IEA). Archived from the original on 2015-05-22. Retrieved 2016-08-8.** www.oceanenergy-europe.eu
Global potential
| Form | Annual generation |
| Tidal energy | >300 TWh |
| Marine current energy | >800 TWh |
| Osmotic power - salinity gradient | 2,000 TWh |
| Ocean thermal energy - thermal gradient | 10,000 TWh |
| Wave energy | 8,000 - 80,000 TWh |
Source: IES-OES, Annual report 2007
