Wave and tidal power has the potential to contribute significantly to the overall energy mix, but its development is significantly lagging other renewables such as wind and solar. This is largely because of the challenges of harnessing this power in what is a constantly harsh environment. [Engerati-Time to Put Wave Energy Back on the Power Map]
But Australian wave energy developer Carnegie Wave Energy is demonstrating that it can be done, with its Perth wave energy project now exporting power into Western Australia’s grid. Power from the array is being supplied to the Australian Department of Defence for use by HMAS Stirling, Australia’s largest naval base, on Garden Island, located just off the Western Australian coast.
“This is the first array of wave power generators to be connected to an electricity grid in Australian and worldwide,” said Ivor Frischknecht, CEO of the Australian Renewable Energy Agency (ARENA), which is providing Au$13.1 million (US$10 million) funding support for the project.
Carnegie’s CETO technology has been under development for approximately 10 years and has had some Au$100 million (US$78 million) invested in its commercialization over this period.
The CETO system consists of buoys that are fully submerged that drive seabed pump units to deliver high pressure fluid onshore via a subsea pipe to standard hydroelectric turbines. In this way they are both protected from the vagaries of the weather and invisible from the shore.
The current CETO 5 version is a 240kW unit. Three of these units are operating in an array at the Garden Island site. At the end of January the first CETO 5 unit had been operating for over 1,700 hours, and had experienced a range of sea states, including waves up to 3.8m in height.
“The Perth Wave Energy Project is the culmination of many years’ work by the Carnegie team,” commented CEO, Dr Michael Ottaviano. “I’d like to thank all our staff, both past and present, along with our shareholders, the Western Australian and Federal Governments, the Department of Defence and the many other important project stakeholders”.
The high-pressure water produced by the CETO system can also be used to supply a reverse osmosis desalination plant, and the project is set to be integrated into Carnegie’s newly commissioned desalination plant on Garden Island – thereby becoming the first wave power station to produce both power and freshwater.
CETO 6 in development
Work is currently underway on the next generation, CETO 6, with a targeted capacity of 1MW. For this unit, the diameter of the buoyant actuator, which has the most significant influence on power output, has been increased to approximately 20m – almost double the 11m diameter of the CETO 5 units.
CETO 6 will also incorporate the power generation offshore and subsea rather than solely onshore as with the current CETO 5 generation. Locating the power generation within the buoy removes the need to attach pumps, accumulators and other hydraulic components to the seabed, removing the requirement for offshore heavy lift vessel capacity. This also reduces offshore installation and maintenance time and cost, and will allow installation in deeper, more distant to shore wave resources.
A 3MW CETO 6 demonstration is planned, with construction starting in 2016. Thereafter the first commercial CETO project, a 25MW array comprising 25 1MW units, is slated for 2018.
The ARENA funding for the development has been matched with grant funding from Government of Western Australia’s Low Emissions Energy Development (LEED) Program. The CETO desalination plant is 50% funded through a Au$1.27 million (US$1 million) AusIndustry grant from the Clean Technology Innovation Program.
Wave resources an abundant source of energy
Wave resources offer an abundant and consistent source of clean energy. For example, according to Carnegie, the CETO 6 Garden Island site records waves above 1m for 93% of the time and Albany, exposed to the Southern Ocean in the southwest of Western Australia, for 100% of the time. The CSIRO has also estimated that wave energy is at least three times more predictable than wind.