Marine energy uses the movement of water to generate electricity from tides, waves or ocean currents. Australia's long, surf-swept coastline is a massive potential source of marine energy.
Waves are created by wind passing over the surface of the ocean. Wave power plants can harvest the energy in the up and down motion of waves and convert it into electricity.
Wave energy is strongest where there are trade winds and ocean swells. In Australia, our wave energy resources are greatest along the southern coastline.
Tides cause movements in ocean waters and constrained topology near coastlines can accelerate these movements. Tidal energy generates electricity using the regular local flows of the tidal cycle.
The Kimberley and Pilbara coasts of northern Western Australia see the largest tides in Australia. Other potential sources of tide power are the Torres Strait off the coast of Darwin, Broad Sound in Queensland and Bass Strait in Tasmania.
Ocean thermal energy
Ocean thermal uses temperature variations in the ocean to generate electricity.
As sea water becomes colder with depth, the temperature difference between water near the surface and water at a depth of 1000 m can be up to 20°C in tropical regions. Ocean thermal can extract energy from these regions using a heat exchange process.
The ocean's energy can be harnessed using a variety of technologies and methods. Generally, floating buoys, platforms or submerged devices are placed in the water and use hydraulic systems coupled with an electrical generator.
The Australian Wave Energy Atlas, an initiative of CSIRO, delivered a searchable, free and publicly available online web atlas of Australia's national wave energy resource and marine management uses in 2018. It also provided best practice guidelines on physical impact assessments for wave energy developments in Australia's marine domain.
Similarly, Tidal Energy in Australia, a joint research project of CSIRO, the Australian Maritime College at the University of Tasmania, the University of Queensland and industry partners will develop a hydrodynamic tidal model to map the scale and distribution of the nation's tidal energy resources to the nearest 500 m.
In other marine developments, Sydney company Wave Swell Energy has created a prototype to harness the power of waves, effectively acting as an artificial blowhole. The company will build a $7 million large-scale unit on the seabed near the coast of King Island that will feed into Hydro Tasmania's grid, and at peak times will provide up to half the island's power.