Rocking Power - Generating Electricity Using the Rocking Motion of Waves
The World needs Wave Power
The world is becoming fearful of what effect global warming will have on our children. At present the World is getting less than 10% of its energy from renewable sources.
An efficient wave power generator would make sense because most people on Planet Earth are surrounded by oceans, estuaries and lakes with abundant wave energy. We mostly live near the sea.
It is surprising that so little is being done around the world to make energy out from the ocean that cover 70% of our planet.
The main problem with wave power is that existing wave power devices are inefficient and can only be used in offshore areas. These devices require complex engineering and huge production and maintenance costs. If cheap and efficient wave power devices could be created that could be used in coastal areas, we would greatly limit global warming. Most countries are trying to establish wind or solar energy, but wave power is potentially less expensive.
Most previous wave power designs only use the vertical up and down movement of waves, using a magnet and coil. As shown in the photo the magnets on a shaft moving up and down through a floating coil generates electric current (Faraday Induction ). Utilising the rocking side-to-side movement of a buoy in waves, as well as the vertical motion is potentially much more efficient.
Up and Down Motion Devices
Rocking Motion much more Efficient
As you can see in the image below, the rocking motion has about 4 times the movement (4X) of just up and down movement (X).
Experiments showed that the best rocking buoy design is a long cylindrical buoy, weighted at the base, which will oscillate – rocking several times with each wave, and remains orientated to the waves.
Buoy Motion induced by Waves
Coil and Magnet Power Units
Power Units - The power units consist of magnets in a tube that pass through a coil and generate power. Using two magnets with one fixed and the other levitating on it, by having reversed poles, reduces drag in the tube and makes the movement induced by the rocking much more efficient.
Optimum Buoy Design
Buoy Design - Various prototype buoys were designed to test which would be the best for power generation. The power outputs of the test units compare very well with solar marker buoys. But the rocking buoys would only cost about half as much to make, would have much lower maintenance costs and 24 hour operation. The rocking motion would increase visibility of the maker buoy. The design shown in the image greatly reduced the friction in the tube and the levitated magnet oscillated in and out of the coil with the slightest up and down, or rocking motion. It was estimated that this unit would be 3-5 times more efficient.
For an optimum design, multiple units would be housed inside a hollow buoy as shown. This offers the advantage of a modular design where the units could be manufactured and added in various numbers to smaller and larger buoys for various power outputs.
Cross-section of a buoy with multiple power units
Tethering to Keep the Buoy Parallel with the Waves
The image shows how the buoys would be tethered so that they always maintained orientated parallel to the waves. Multiple buoys would be deployed in multiple buoy farms along the coast near major towns. This would greatly increase the power output of the buoy and reduces cost.
How the buoys would be tethered
A wave power generation system using the rocking motion of a buoy was designed and tested and showed great potential for future development. The system was feasible and could be used in marker buoys.
The system also has the potential for large scale electricity generation.
The rocking buoy design has many advantages over existing magnet and coil buoys:
- There are no moving parts exposed to the sea as everything is inside the sealed buoy.
- It uses the full energy potential of waves with oscillation of the buoy and levitated magnet magnifying the movement produced by the waves.
- Estimates show that these rocking buoys would be cheaper to build than solar navigation buoys, and would require much less maintenance, and would be more visible.
- The rocking buoy is suitable for a wide range of wave sizes and locations and is not affected by tides.
- The simple modular design reduces costs and multiple power units could be added to boost output, and multiple buoys can be used for large scale power generation applications including power generation for coastal communities.
- Further resarch is required to develop the concept into a major coaastal wave power unit.
© 2010 Dr. John Anderson
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