Riding the changing tide of Australia’s energy future

OCEAN waves have a vast potential to generate energy. The most established wave energy conversion (WEC) technology developer in Australia, Oceanlinx, has installed more than 750 kilowatts of prototype wave energy converters across the country, resulting in more than 40,000 hours of operating experience and 5000 hours of electricity generation.
Oceanlinx’s renewable energy technology provides versatility: it can be deployed in shallow or deep waters, as well as with oil and gas platforms; it can be used to provide desalinated water;
and it offers coastal protection and is safe for marine life.
The company’s core patented technology, based on the established science of wave energy, comprises a small number of simple elements: an oscillating water column (OWC), a turbine and a generator and control system.
The technology
OWCs are simple constructions that act in the same manner as a piston and cylinder: as a wave rises within the OWC, it replicates the action of a piston, driving a column of air ahead of it and
past a turbine. As the wave recedes the opposite effect is experienced – air is sucked back into the OWC and past the turbine.
Oceanlinx developed two variants of the OWC concept: the greenWAVE for shallow water and the blueWAVE for deeper water.
The greenWAVE shallow water units are mounted on seabeds in about 10m of water and can be made from any material, although they are generally constructed from concrete.
Following construction, each greenWAVE is sealed to create a buoyant structure. The structure is floated to its deployment site, where the buoyant seal is removed and the greenWAVE is sunk
to its resting position. The distance of the unit from shore will depend on the area’s seabed slope and how rapidly the nominal 10m depth is achieved.
In addition to the structure below the waterline, the greenWAVE extends several metres above sea level.
The electrical output of a greenWAVE unit is dependent on the local wave climate: in a very good climate, a single 20m-wide greenWAVE device would be rated at 1 megawatt or more. The
units can be used for the production of electricity or to desalinate seawater, or for both purposes.
The blueWAVE deep water units each comprise a cluster of six floating OWCs joined together by a space-frame, anchored to the seabed in between 40m and 80m of water. While the structure
can technically be made from any material, it is generally fabricated from steel.
The method of anchoring the floating structure to the bottom of the ocean is dependent on the geotechnical nature of the seabed where the unit is deployed: gravity, drag or suction anchors are
typical candidates for the task.
Each blueWAVE is floated to its deployment site to be secured to an anchoring system. The distance from shore will depend on the slope of the seabed and how rapidly the nominal 40m to 80m water depth is achieved.
Besides the portion of the blueWAVE that lies below the waterline, each of the units’ six OWCs extend several metres above sea level.
The blueWAVE technology differs from greenWAVE in several key areas: besides being a floating structure in deeper water, its six OWC chambers make it bigger than the greenWAVE. It
is also typically constructed from steel, as opposed to the greenWAVE’s concrete construction.
The electrical output of a blueWAVE unit is dependent on the local wave climate. In a good climate, a single blueWAVE device would be rated at 2.5MW or more. As with the greenWAVE, the blueWAVE units can be used to produce electricity, to desalinate seawater, or for both tasks simultaneously.
When compared to other OWC technologies on the market, Oceanlinx’s units offer major improvements in terms of system design, turbine use, and construction technique. Both the greenWAVE and the blueWAVE use the same fundamental OWC principles, the same generator and control systems, and the same highly-specialised airWAVE turbine. Most turbines are
designed to function with gas or liquid flowing constantly in a single direction, however the oscillating nature of wave energy rendered turbines designed for single-direction movement and
constant flow ineffective. There were many attempts made to design turbines that could overcome this limitation, but success was limited and the turbines generally offered very low efficiency.
Oceanlinx’s patented airWAVE turbine design successfully overcomes the limitations experienced by other turbines. A design evolution, the airWAVE incorporates fewer moving parts and a conversion efficiency that is higher than other comparable turbines.
In Oceanlinx’s OWC designs, the turbine sits well above the ocean, coupled to a power generator, with no moving parts in the water, improving the overall wave-to-wire efficiency of both the
greenWAVE and blueWAVE products.
Developing the future
Oceanlinx’s greenWAVE and blueWAVE technologies were the culmination of more than a decade of research and development and, today, Oceanlinx is the only wave energy technology
company in the world to have had three different demonstrations of its technology installed in the ‘real’ ocean – each representing a logical sequence in the design evolution of the technology.
The first demonstration was MK1: a 500t OWC chamber that sat on the seabed under its own weight at Port Kembla, about 100km south of Sydney.
The second was MK2, a floating unit that was also installed at Port Kembla; and in March 2010 Oceanlinx installed the pre-commercial MK3 unit, a cluster of eight floating OWCs, at Port Kembla.
“The operational data supplied by these three demonstration units…has allowed Oceanlinx to refine the design, to the point where fully commercial products have now been developed and
are ready for implementation in new projects,” Oceanlinx reported.
“While there has been some cross-fertilisation of the technology, the greenWAVE product is essentially the logical evolution of MK1, while the blueWAVE product is the logical extension of MK2 and MK3.”
According to Oceanlinx, the airWAVE turbine also underwent a design evolution following its first use in the MK1 unit.
“The turbine used in Mk1, named the Denniss-Auld turbine, has been the subject of ongoing development, resulting in the latest commercial version, the airWAVE turbine,” it reported.
“The result of the Oceanlinx design evolution has been a rapid decrease in the cost of electricity produced from ocean waves.”
Environmental benefits
Oceanlinx undertook an initial lifecycle assessment of its WEC devices to calculate their potential emission outputs across a 25-year operating life, based on the work and knowledge it gained from the greenWAVE and blueWAVE design process.
“Considering all processes involved in the construction, installation, operation and decommissioning phases…it is estimated that an Oceanlinx greenWAVE or blueWAVE WEC device will have life cycle carbon emissions as low as 24 grams of CO2e [carbon dioxide equivalent] per kilowatt hour, which may vary depending on specific construction requirements and project capacity factor,” the company reported.
“This is approximately 33 times less emissions than those derived from a black coal-fired power station. If black coal is the fuel replaced or avoided for power generation purposes, an Oceanlinx WEC unit will be able to save up to 4400 tonnes of CO2 equivalent per year.
“Where installed, ocean waves will be a local energy source that can make a contribution to the security of energy supply. In many places it will reduce the dependence on fuel imports and, in turn, reduce fuel cycle emissions, particularly those related to fuel transportation.”
Oceanlinx cited energy usage in raw materials extraction and fabrication processes as the main contributors to its WEC units’ emissions, as well as lesser contributions from diesel fuel consumption in vessels used to transport the structures and equipment to site.
“It is also projected that emissions from Oceanlinx devices will reduce in the future with improvements in the structure, foundation configurations, and efficiency conversion factors,” the company reported.
“In addition, the Oceanlinx technology does not have any moving parts underwater…minimising the risk of any impact on the marine environment. “The WEC units will be deployed at distances that are far enough offshore to have minimal visual impact and noise emission issues.”
In early July, Oceanlinx announced that it had been awarded $3.97 million from the Federal Government’s Emerging Renewables Program to put toward development of its $7.24 million
Oceanlinx 1MW Commercial Wave Energy Demonstrator project.
“This will enable Oceanlinx to fully demonstrate [its greenWAVE technology] on a commercial scale in South Australia,” the company reported.
“The project is anticipated to take 12 months, with grid connection in late 2013.”
The company reported that the project cost included one year of operations following connection to the grid.

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