Wave power

Waves are generated primarily by wind passing over the sea's surface and also by tidal forces, temperature variations, and other factors.

Other forces can create currents, including breaking waves, wind, the Coriolis effect, cabbeling, and temperature and salinity differences.

As of 2023, wave power is not widely employed for commercial applications, after a long series of trial projects.

Among these was the concept of extracting power from the angular motion at the joints of an articulated raft, which Masuda proposed in the 1950s.

Substantial wave-energy development programmes were launched by governments in several countries, in particular in the UK, Norway and Sweden.

In small-scale tests, the Duck's curved cam-like body can stop 90% of wave motion and can convert 90% of that to electricity, giving 81% efficiency.

[16] The £10 million Saltire prize challenge was to be awarded to the first to be able to generate 100 GWh from wave power over a continuous two-year period by 2017 (about 5.7 MW average).

A 2017 study by Strathclyde University and Imperial College focused on the failure to develop "market ready" wave energy devices – despite a UK government investment of over £200 million over 15 years.

[18] Public bodies have continued and in many countries stepped up the research and development funding for wave energy during the 2010s.

Like most fluid motion, the interaction between ocean waves and energy converters is a high-order nonlinear phenomenon.

In major storms, the largest offshore sea states have significant wave height of about 15 meters and energy period of about 15 seconds.

A given wind speed has a matching practical limit over which time or distance do not increase wave size.

Wave energy converters (WECs) are generally categorized by the method, by location and by the power take-off system.

[39] One point absorber design tested at commercial scale by CorPower features a negative spring that improves performance and protects the buoy in very large waves.

Under normal operating conditions, the buoy bobs up and down at double the wave amplitude by adjusting the phase of its movements.

The firm claimed a 300% increase (600 kW) in power generation compared to a buoy without phase adjustments in tests completed in 2024.

[43] Significant noise is produced as air flows through the turbines, potentially affecting nearby birds and marine organisms.

[44] Overtopping devices are long structures that use wave velocity to fill a reservoir to a greater water level than the surrounding ocean.

Submerged pressure differential based converters[45] use flexible (typically reinforced rubber) membranes to extract wave energy.

Submerged pressure differential converters typically use flexible membranes as the working surface between the water and the power take-off.

This means that by optimizing depth, protection from extreme loads and access to wave energy can be balanced.

Floating in-air converters potentially offer increased reliability because the device is located above the water, which also eases inspection and maintenance.

[46] The converter includes a buoy that is moored to the bottom and situated below the surface, out of sight of people and away from storm waves.

[48] Locations with the most potential for wave power include the western seaboard of Europe, the northern coast of the UK, and the Pacific coastlines of North and South America, Southern Africa, Australia, and New Zealand.

[31][52] Socio-economic challenges include the displacement of commercial and recreational fishermen, and may present navigation hazards.

In 2019, for example, Seabased Industries AB in Sweden was liquidated due to "extensive challenges in recent years, both practical and financial".

[56] These limitations stem from the complex and dynamic nature of ocean waves, which require robust and efficient technology to capture the energy.

[57] Additionally, optimizing the performance and efficiency of wave energy converters, such as oscillating water column (OWC) devices, point absorbers, and overtopping devices, requires overcoming engineering complexities related to the dynamic and variable nature of waves.

The devices interact hydrodynamically and electrically, according to the number of machines, spacing and layout, wave climate, coastal and benthic geometry, and control strategies.

[62] Additional research finds that wave farms located near lagoons can potentially provide effective coastal protection during maritime spatial planning.