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Legislative Council - Fifty-First Parliament, Third Session (51-3)
2009-09-09 Daily Xml
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OCEAN ENERGY

The Hon. J.A. DARLEY (16:32): I rise today to speak about renewable ocean energy. Whilst I have previously had a matter of interest on renewable energy, as Australia is the largest island in the world and the only country to be completely surrounded by water, I believe it is imperative that governments explore ocean energy as a method of power generation. Ocean energy is often seen as complex; however, today I hope to dispel some of the confusion that surrounds this potentially viable source of energy.

Ocean energy consists of two main types: ocean thermal energy conversion and ocean mechanical energy. Ocean thermal energy conversion involves utilising the difference in temperature between the surface water and deep water to produce electricity. There are different methods of conversion, but most involve using the warmer surface temperature to evaporate the water in order to turn a turbine, which activates a generator to produce electricity. Ocean mechanical energy utilises the energy of waves and tides. Whilst this method is reliant upon wave action and tidal movements, predictions of these movements have advanced to a point where forecasts are reasonably accurate.

Ocean mechanical energy can take several forms: those that harness tidal energy and others which utilise wave energy. The ebb and flow of tidal energy can be used to generate electricity by driving turbines connected to generators. Put simply, tidal turbines are similar to wind turbines but are located under water and are driven by tidal movements instead of the wind. Tidal movements can be further utilised by the use of underwater dams, which concentrate water through a channel to enhance these movements. Turbines are placed in the middle of the channel to utilise this concentrated movement.

I have uncovered many different types of wave energy, but they can be broken down into four main categories: channel systems; float systems; oscillating water column systems; and point absorber wave energy. Channel systems, or overtopping devices, direct water into a reservoir to the point where the water overflows. The kinetic energy of the falling water is utilised to generate energy. An example of a float system consists of a segmented tubular device which floats at a 90º angle to the waves. The segmented device bends and flexes with the movement of the waves, and drives a hydraulic pump at the connection point. Another system has been designed to convert the spinning movement of a barrel-like buoy into energy.

Oscillating water column systems channel air pressure caused by waves entering a confined area. As waves enter the space, air is pushed out of a funnel at one end of the structure, which contains a turbine turned by the air pressure. As the waves exit the structure the turbine is turned the other way from the air being sucked back into the space previously occupied by the water. Current absorber wave energy involves buoy-like devices which are anchored to the sea floor so that the buoys sit just below the water surface. The motion of the waves moves the buoys back and forth, which drives a generator situated at the base of the anchoring device.

The possibilities of the ocean seem to be limited only by the creativity of scientists, and trials and plants of different forms of ocean energy are situated all over the world. Australia has been identified as having some of the most viable locations for harnessing ocean energy but, as with other forms of renewable energy, augmentation charges must be subsidised by governments to encourage further development within this area.

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