CETO is a wave-energy technology that converts kinetic energy from ocean swell into electrical power and (in CETO 5) directly desalinates freshwater through reverse osmosis. The technology was developed and tested onshore and offshore in Fremantle, Western Australia. In early 2015 a CETO 5 production installation was commissioned and connected to the grid. As of January 2016 all the electricity generated is being purchased to contribute towards the power requirements of HMAS Stirling naval base at Garden Island, Western Australia. Some of the energy will also be used directly to desalinate water.^[1]

CETO is designed to be a simple and robust wave technology. As of January 2016 CETO is claimed to be the only ocean-tested wave-energy technology globally that can be both fully submerged and generating power/desalinated water at the same time. The CETO technology has been independently verified by Energies Nouvelles (EDF EN) and the French naval contractor DCNS.^[2]

The name is inspired by the Greek ocean goddess, Ceto. As of January 2016, the system distinguishes itself from other wave-energy devices in being fully submerged. Submerged buoys are moved by the ocean swell and driving pumps that pressurise seawater delivered ashore by a subsea pipeline. Once onshore, the high-pressure seawater is used to drive hydro-electric turbines, generating electricity. The high-pressure seawater can also be used to supply a reverse osmosis desalination plant, producing freshwater. Some historic conventional seawater desalination plants are large emitters of greenhouse gases; this is due to the amount of energy required to drive the grid-connected pumps that deliver the high-pressure seawater to reverse osmosis membranes for the removal of the salt.^{[failed verification][3]}

As of January 2016, CETO 6 is in development, and differs from CETO 5 in having a larger buoy, with the electrical generation onboard and the power being transferred to shore by an electrical cable. The buoy is designed for deeper water and further offshore than CETO 5.^[4]

On completion of Stage 1 of the Perth Wave Energy Project, Carnegie enlisted Frazer-Nash Consultancy Ltd to verify the CETO 3 unit's measured and modelled capacity. During the CETO 3 in-ocean trial, Frazer–Nash verified the peak measured capacity to be 78 kW and delivered a sustained pressure of 77 bar (1,120 psi), above what is required for seawater reverse osmosis desalination.

Stage 1, already completed, involved the manufacture, deployment and testing of a single commercial-scale autonomous CETO unit off Garden Island. For this stage, the CETO unit was not connected to shore but was stand-alone and autonomous, providing telemetric data back to shore for confirmation and independent verification of the unit's performance.

Stage 2 involved the design, construction, deployment and operational performance evaluation of a grid-connected commercial-scale wave-energy demonstration project, also at Garden Island. The facility consisted of multiple submerged CETO units in an array, subsea pipeline(s) to shore, hydraulic conditioning equipment, and an onshore power generation facility.

In early 2015 a multi-megawatt system was connected to the grid, with all the electricity being bought to power HMAS Stirling naval base. Two fully submerged buoys, which are anchored to the seabed, transmit the energy from the ocean swell through hydraulic pressure onshore to drive a generator for electricity, and also to produce fresh water. As of 2015, a third buoy is planned for installation.^[5][6]

The Réunion Island project is a joint venture between Carnegie and EDF Energies Nouvelles. The project will initially consist of the deployment of a single, autonomous commercial scale unit (stage 1) which will be followed by a 2MW plant (stage 2) and a further expansion of the project to a nominal 15MW installed capacity (stage 3). As of April 2011 stage 1 has been awarded $5M of French government funding.^[7]

A cable between a buoy and the seabed anchored hydraulic pump snapped in a CETO 4 prototype installation in January 2014. The buoy was swept away during Cyclone Bejisa, which also led to a fatality and widespread damage on Réunion Island. The design was an earlier iteration than the Perth CETO 5 installation and lacked the quick-release mechanism that was included in CETO 5.^[8]

Carnegie has signed a formal funding and collaboration agreement^[when?] with the Irish Government's Sustainable Energy Association (SEAI) for a €150,000 project to evaluate potential CETO wave sites in Ireland and develop a site-specific conceptual design. The project is 50% funded by the SEAI and 50% by Carnegie and forms the first phase of detailed design for a potential 5 MW commercial demonstration project in Irish waters. The project was underway in 2011 and is being managed through Carnegie's Irish subsidiary, CETO Wave Energy Ireland Limited.^[2]

In December 2021, CETO Wave Energy Ireland Ltd. was announced as one of the companies selected to develop their technology in the EuropeWave programme with the ACHIEVE project.^[9] This project was successful in completing Stages 1 and 2, and in September 2023, was selected as one of three technologies to progress to Stage 3.^[10]

Stage 3 of EuropeWave will result in a CETO device being tested for a year at the Biscay Marine Energy Platform (BiMEP) in the Basque Country. Carnegie Clean Energy secured a berth, originally reserved by Wave Energy Scotland, in April 2024.^[11] Also in April 2024, they passed the EuropeWave authorisation to proceed milestone, enabling them to award the first contracts for fabrication of the device.^[12] The Stage 3 contract was worth €3.75m.^[13]

In September 2023, as part of the Renamrinas Demos Program the Spanish government awarded €1.2m funding to Carnegie's Spanish subsidiary, Carnegie Technologies Spain. This will allow them to enhance and extend the deployment of the device.^[13]

• Western Australian Government – $12.5M grant for the Perth Wave Energy Project at Garden Island.
• Australian Department of Defence & Defence Support Group – MoU for Collaboration on a CETO power and water project and offtake.
• EDF EN – Northern Hemisphere CETO Power licensee and JV development partner.
• French Government – $5M grant for Carnegie/EDF EN Stage 1 Réunion Island power project.
• DCNS – Northern Hemisphere EPCM partner.
• Sustainable Energy Authority of Ireland – Collaboration agreement & concept funding for a 5 MW Irish CETO power project.
• British Columbia Government – Grant of $2M for a Canadian CETO project.
• Australian National Centre of Excellence in Desalination – Desalination research project with funding granted.^[2]

• Wave energy is a renewable, high-availability source of power.
• About 60% of the human population lives within 60 kilometres of a coastline, minimising transmission issues.^{[citation needed]}
• Since water is about 800 times denser than air, the energy density of waves exceeds that of wind and solar, increasing the amount of energy available for harvesting.
• Waves are predictable in advance, making it easier to predict mismatches between supply and demand.
• CETO does not stand for Cylindrical Energy Transfer Oscillating unit – a popular misconception. The name refers to Ceto, a Greek sea goddess.
• CETO sits underwater, moored to the sea floor, with minimal visual impact above the water. In practice, buoys have been fitted with warning lights on a mast above water.
• CETO units operate in deep water, away from breaking waves, meaning there is minimal impact on popular surfing sites.
• CETO units are designed to operate in harmony with the waves. This means, that apart from anchor points, there is no need for massive steel and concrete support structures to be built.
• CETO units act like artificial reefs because of the way they attract marine life.^{[citation needed]}

• Water desalination
• Wave farm
• Baseload
• World energy resources and consumption

• Carnegie Wave Energy Limited
• World of Energy
• RISE Archived 26 January 2008 at the Wayback Machine
• Carbon Trust