What is Wave Energy?
Wave energy (also called tidal energy) is a recently developed concept which uses the force of waves to generate electricity. Unlike hydro-power, wave energy uses the ocean current and does not require a dam or fast moving river.
How Does Wave Energy Work?
There are a number of current wave capture technologies which are broadly categorised below:
Point Absorber Buoy
These are buoy-like devices which float on or near the water surface and are attached to the seabed by cables. As the waves roll in, the buoy will rise and fall, driving a hydraulic pump to generate electricity. There is a similar device called the Surface Attenuator, which is essentially a row of connected buoys. The rolling waves cause the attenuator to flex, driving the hydraulic pump and generating electricity.
Oscillating Water Column
This device uses an air chamber and turbine to generate electricity. It sits below the ocean surface, and as the waves swell, the pressure will compress the air through the turbine, generating electricity.
An overtopping device is a water reservoir that sits at ocean level. As waves crash into it, the reservoir will fill, suspending water at an elevated level. Once it is adequately filled, the water is released through a series a turbines which generate electricity as it spins.
Wave Energy in Australia
Australia is one of the few countries that have significantly invested in wave energy. There are currently two wave technology companies, Carnegie – operating off the coast of Fremantle and Garden Island in WA – and Oceanlinx, which is based in NSW.
Carnegie generates electricity using Point absorber buoys and retails it through WesternPower. OceanLinx develops and sells oscillating water column generators, targeted for those in remote, coastal regions. There is no suggestion on the Oceanlinx website the company produces or sells its own electricity.
Wave technology accounts for a very, very small amount of electricity generation in Australia. It is a developing technology, though the future of wave energy is unclear given other alternatives such as solar, hydro and wind power.