Weatherproof ocean energy technology prototype hits midpoint

Seven European partners have reached the midway point in the construction of the storm-resistant ocean thermal energy conversion (OTEC) prototype at Hidramar Shipyard in Gran Canaria, Spain.

Fabrication of the OTEC prototype started in March. Upon completion, the cylindrical hull, cold-water riser pipe, and gimbal connection point will be assembled in the Atlantic Ocean for testing. The structure is being developed by PLOTEC, a consortium funded by the EU and composed of seven European companies.

The members of the consortium are Global OTEC (UK), Cleantech Engineering Limited (UK), WavEC Offshore Renewables (Portugal), The Oceanic Platform of the Canary Islands PLOCAN (Spain), Quality Culture (Italy), Agru Kunststofftechnik Gesellschaft m.b.H. (Austria) and University of Plymouth School of Engineering, Computing and Mathematics (UK). 

Recent progress in bringing this technology to life includes finishing the first level of the platform at the shipyard, which involved plasma cutting more than 660 steel plates, ranging from 6 mm to 65 mm. Each plate undergoes preparation for welding, is placed on the keel to ensure proper fit, and then welded securely into place. 

Sam Johnston, Global OTEC’s lead Engineer, describes this project phase as demanding due to the intricate keel structure, which involves welding multiple passes on numerous plates, a process aimed at maintaining structural integrity and reducing the risk of warping caused by welding heat. Furthermore, the mooring pad eyes undergo machining before welding to ensure a strong connection with the keel.

“Once the keel plate is completed, we expect the rate of progress to increase, as many of the more intricate welds will be finished, allowing us to begin assembling the cylindrical shells onto the keel,” said Johnston.

The project aims to support renewable energy adoption in small island developing states (SIDS), which are seen as vulnerable to harsh weather conditions. This involves improving OTEC technology with an offshore platform designed to withstand tropical storms, hurricanes, and cyclones. 

The PLOTEC 1:5  scaled prototype will undergo testing at the Oceanic Platform of the Canary Islands (PLOCAN), about three kilometers offshore. Throughout its operational duration, the platform will endure Atlantic Ocean conditions, facilitating its resilience, materials, and design analysis.

Previous computer simulations and a scaled tank test in London last year have already validated the structure’s intended functionality. The project aims to improve the feasibility of OTEC for tropical islands prone to storms and contribute insights to marine engineering, materials innovation, computational modeling, and the design of offshore floating energy and marine devices.

Horizon Europe and UK Research and Innovation (UKRI) awarded €3.5 million for the project in December 2022.