How Does Wave Power Work?





Pelamis wave generator rising out of a wave. Image by P123.

Pelamis wave generator rising out of a wave. Image by P123.

Wave power or wave energy comes from the waves in the ocean. It is important to understand the difference between tidal power and wave power before we continue. Tides are created by the gravity of the moon and to a lesser extent the sun. This causes a bulging of the water on Earth that rotates with the moon thus creating higher and lower water levels at different times. Waves are created by the wind blowing across the surface of the water creating ripples. Of course, stronger winds means larger or stronger waves. There are a few different methods in use to generate electricity from wave energy. One popular version is the Pelamis Machine pictured to the right and below. It floats along the surface of the water anchored down on one end. The rolling motion of the waves generates electricity.

Pelamis Machine Wave Energy Converter

These wave energy generators were the first ever developed and put to use. Multiple pelamis machines combined created “wave farms” for generating offshore electricity. They are designed to be highly resistant to the forces of the open ocean and would be a very resiliant renewable energy source.

How does it work though? The rolling motion of the waves is resisted by hydraulics which pump oil through a hydrolic motor. This motor is what converts the wave motion to electricity by powering electrical generators.

Prototype Pelamis Machine at EMEC in Scotland.

Prototype Pelamis Machine at EMEC in Scotland.

Wave Energy Buoys

While Pelamis Machines have been proven to work there are a few other technologies on the cusp of being put to use. One idea that has gotten a lot of attention is anchoring bouys to the ocean floor and generating electricity by the bobbing up and down. Not only does this generate electricity from moving up and down but also forward and backwards. Look at the image below to see the trajectory that an object floating on the ocean surface takes.

Diagram showing the trajectory of an object floating on a wave. Image by Crowsnest. License: CC BY-SA 3.0.

While energy buoys are a great idea and theoretically work will fine they haven’t been put to commercial use yet. However, in the near future we should begin to see wave energy farms using this technology as well.

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Comments

  1. cosma vasile says:

    Did you know that Romania has a technical solution with the highest efficiency to capture wave power? Patent 108893 entitled Dynamic Engine for Sea Wave Energy Catching. A pioneering invention. It is estimated that “dynamic engine” has the ability to catching wave energy at a rate of over 80% while the other technical solutions known worldwide, are not able to capture wave energy with a higher percentage of about 10-15%.

  2. Henry Walliams says:

    Thank-you.
    Did you know that famous scientist, Alberst Deburkston, invented a wave energy invention called the “Wave En-Collector”. He was only 27 when he thought of this invention in is dream on 17th August 1921.
    This device would be anchored to the sea bed and the cuboid shaped generator would be positioned just underneath the surface of the water.
    As you may know the waves can be felt beneath the water, as well as the surface. The generator uses the push of the wave, underneath the water, and turns it into electricity.
    One weeks worth of this energy could power the whole of the UK for 5 days. this includes all the wi-fi, electronics, TV, Sounds etc…..
    Sadly Alberst’s notes on creating this amazing invention was lost just before he died in 1967.
    These notes were never found and never copied down.
    Scientist’s are still trying to work the equation he used.

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