Waves of power rolling in

The push to become less dependent on fossil fuels and to lower carbon emissions has world leaders calling for new and innovative renewable energy technology. In previous posts, here and here, we have explored the potential for tidal power – but there are other options. One option has a much larger potential for generating power from the world’s ocean.

Wave Power.

With 70% of the Earth’s surface covered by oceans, society does not need to look far to find alternative energy sources. Each wave rolling towards to shore can be harnessed to generate electricity.

As early as the 1890’s there have been attempts to harness wave energy but it wasn’t until Yoshio Masuda developed a navigation buoy powered by wave energy that this renewable power source took on new meaning. Masuda is considered the father of modern wave energy and the bouys he developed have been commercialized in Japan since 1965.

Ocean Energy Systems (OES) is an intergovernmental collaboration between 23 countries operating under a framework established by the International Energy Agency in Paris. OES estimates that the global potential for wave energy is 29,000TWH/year. With 44% of the earth’s population living within 150km or 100miles from the coast, wave and tidal energy combined has the potential to meet roughly 10-15% of the current global electricity consumption.

 

OES depiction of global ocean energy resources

OES depiction of global ocean energy resources

Waves are produced by wind. Energy is transferred from the wind to the ocean through friction between the air and water molecules. As these waves move across the ocean, it allows them to develop large amounts of “power”. The resource of waves is generally described as power per unit length (along the crest of the wave).

Wave energy converters (WECs) are designed to capture the energy from the rising and falling water level. These devices operate in the ocean and are therefore subject to extreme ocean conditions such as storm surges, damage by corrosion, or barnacles and other biofouling growing on the machinery.The European Marine Energy Centre (EMEC) in Orkney, Scotland, have identified eight main types of wave energy converters.

Below we’ve described three of the more common options;

Attenuator technology consists of a floating device which operates in parallel to the wave direction – it rides the waves. The device captures energy from the motion of the devices two arms moving as the wave passes them.

Point Absorber technology consists of a floating structure that absorbs energy from all directions through its movements at or near the watersurface. It converts the motion of the buoyant top structure of the device into electrical power.

Oscillating Wave Surge Converter technology extracts energy from wave surges. An arm sways as a pendulum mounted on a pivoted joint in response to the movement of the waves

The remaining four types are; an oscillating water column device, overtopping/terminator device, submerged pressure differential device and a rotating mass device. For more information about each of these please visit the EMEC site here.

The extraction of energy is highly dependent on the movement and stability of the WEC structure and mooring these devices can provide unique challenges. To help mitigate these risks, and understand the effects of current, wave, and dynamic platform motion, wave energy companies are running dynamic simulations of their devices and moorings.

The structures need to be held in place, but to capture the energy from the waves the mooring systems need to be flexible. On top of this, similarly to other structures moored in the ocean they must also endure extreme wave conditions and loading.Numerical modelling or dynamic analysis of a system provides a quick and accurate analysis of the structure’s response and loading in various environmental conditions, including those for normal operating and also extreme survival. Dynamic Systems Analysis (DSA) created ProteusDS and this can be used to assess the structure and how it will behave in these conditions.

DSA works with companies in North America and Europe on the design, development, and installation analysis of WEC devices. DSA is also a founding member of the West Coast Wave Initiative (WCWI) based out of the University of Victoria.

Over the past three years the WCWI has been working to provide the significant gap in data needed of physical measurements and numerical model results describing the West Coast Vancouver Island (WCVI) wave energy resource. For the WEC developer partners, the project will produce the first data set describing the performance of WECs off of Vancouver Island and how these performances need be accommodated on-shore with energy storage technologies.

Members of the WCWI design a buoy mooring system with ProteusDS

The following video is a ProteusDS simulation of a wave energy converter(WEC) designed by Resolute Marine Energy.

To learn more about DSA’s involvement with WCWI or our work with wave energy companies please email Contact Us.