On the survivability of WECs through submergence and passive controllers


  • Elie Al Shami Carnegie Wave energy Ireland
  • Alexandre Pichard Carnegie Clean Energy
  • Mathieu Cocho Carnegie Clean Energy
  • Miguel Santos Herran Carnegie wave energy Ireland
  • Ian Gough CETO Wave energy Ireland




extreme conditions, hydrodynamics, control, survival strategy


The survivability of WECs during extreme seas and heavy storms has proven to be challenging during the deployment of devices as they often fail during extreme storms. The survival mechanism is often inherited with the device design and mode of operation. It is not economically and logistically viable for devices to be taken back onshore in case of storms. Some devices lock their PTOs during heavy storms and others lock all the moving parts all together, in the case of CETO, its design has an advantage where it can be submergepad. CETO is a buoyant actuator WEC composed of a buoy submerged close to the surface. Three tethers connect CETO to the sea-bottom through rotary PTOs, allowing the device to be wound down, submerged, and therefore, less exposed to the extreme loads at the sea surface during large storms. This paper will study the survivability of the device during extreme sea-states and will examine the required depth to bring its response back to operational conditions. This work will also look at the alteration of some passive controllers, such as a conventional spring to minimize the response of the device instead of maximising the power capture. With the PTO objective altered in extreme sea-states to minimize the response instead of capturing power, the possibility of harvesting power during extreme sea-states with the device submerged will be checked. Finally, the survivability strategy of CETO through submergence will be showcased with wave tank experiments conducted at IHC as part of the Europewave program.

Author Biographies

Elie Al Shami, Carnegie Wave energy Ireland

Elie Al Shami is a hydrodynamics enginner working for  Carnegie Wave energy Ireland and is located in Bilbao, Spain. 
Elie graduated with a Doctorate in Mechanical engineering with a speciality in ocean waves energy harvesting in mid-2020 and joined Carnegie right after. Elie has been working on optimising the hydrodynamics of the CETO device with the main objective of reducing the cost of energy. Elie has developed in-depth CETO technology knowledge with extensive numerical and hydrodynamic modelling. 

Alexandre Pichard, Carnegie Clean Energy

Alexandre Pichard holds the position of Chief Technology Officer. Alex graduated with a Doctorate in Physics in 2010 in France and became a Chartered Engineer in 2018. Alex has been working with the engineering team at Carnegie for over 11 years and has an intimate knowledge of the CETO technology and the wave energy industry in general. 

Mathieu Cocho, Carnegie Clean Energy

Mathieu Cocho holds a Masters of Ocean Engineering and has been working as a data analyst and engineer at Carnegie for 7 years. He has successfully delivered the first development steps of the AI-based wave predictor and has been instrumental in developing a range of controllers including the work done to date on the development of the intelligent controllers. 

Miguel Santos Herran, Carnegie wave energy Ireland

Miguel Santos Herran is a Project engineer handling the ACHIEVE Project. Miguel is as an industrial engineer with two MSc’s dedicated to Ocean Energy - one in Renewable Energy and the Energy Market and one in Offshore Renewable Energy. 

He brings great technical expertise with experience in analytical modelling of wave energy converters and the techno-economic assessments of both tidal and wave energy devices. Additionally, Miguel has 7 years of experience in project management, coordinating and collaborating in the design, manufacturing and testing of two novel switched-reluctance direct-drive linear generators, as well as their integration into a full-scale Wave Energy Converter.  



How to Cite

E. Al Shami, A. . Pichard, M. Cocho, M. Santos Herran, and I. Gough, “On the survivability of WECs through submergence and passive controllers”, Proc. EWTEC, vol. 15, Sep. 2023.