In 2012, CorPower Ocean AB was established in Stockholm, Sweden. Supported financially by the European EIT InnoEnergy program, the company has been developing a unique device for generating electric power. The CorPower WEC is a buoy that harnesses the energy of ocean waves to produce electricity. The goal is to provide a stable and efficient source of zero-emission electric power. Inspired by the human heart, the device incorporates WaveSpring technology, allowing it to adapt to wave intensity. This means it moves more in calm conditions than in heavy seas.
The system operates by anchoring the buoy to the sea floor and utilizing a pneumatic system that reduces the mass of the oscillating body, thereby increasing its natural frequency. The oscillations are converted into rotational motion through a cascading gearbox (using a design principle similar to that of a planetary gearbox), which in turn drives the electricity generator. The entire development is planned in five phases. The first two phases, which took place from 2012 to 2014, primarily involved testing models at 1:30 and 1:16 scales. Initial tests of the WaveSpring technology were conducted in November 2014 at the Ecole Centrale de Nantes in France, within the Hydrodynamic and Ocean Engineering Tank.
By the third phase, reached in 2018, buoys were tested at a 1:2 scale at the EMEC Scapa Flow sea testing site. The test prototype had a nominal output of 25 kW, a diameter of 4.3 meters, and stood 10 meters high.
Practical Tests in Portugal
From October 2022, the fourth phase commenced, during which the new source of electric power was tested off the coast of Aguçadoura in northern Portugal. In 2022, Maersk Supply Service laid a new 6.2-kilometer-long submarine cable that facilitates communication and energy transmission from a system of four buoys back to shore. The C4 WEC devices were deployed in September 2023, launched at the port of Viana do Castello, and towed to a location 4 kilometers offshore. They were connected to the sea floor using a custom-made anchoring system. After a seven-week commissioning period, they began delivering energy to the electric grid in October 2023.
In this initial testing phase, a peak performance of up to 600 kW was recorded, with potential increases up to 850 kW through upgrades during planned service on land. The C4 WEC buoy, with a nominal output of 300 kW, has a diameter of 9 meters, stands 19 meters high, and weighs approximately 60 tons. In February of this year, the company announced the completion of the first operational cycle, noting that the C4 devices had performed well, demonstrating their ability to respond to changing sea conditions and handle storm waves up to 18.5 meters high. According to the manufacturer, this represents a significant milestone in wave energy production.
The gathered data enabled the calibration of a digital twin—a comprehensive numerical model used for predicting system behavior. The measured data on movement and performance with WaveSpring technology reportedly slightly exceeded the predictions of the digital twin.
The first operational phase concluded with the disconnection and retrieval of all four C4 devices back to CorPower Ocean’s ground base in Viana do Castello for planned maintenance. The buoys are now undergoing inspections, during which they will be adjusted and upgraded based on insights from the first operational cycle. The company plans to install about 25 buoys in clusters, referred to as CorPacks, each capable of generating up to 10 megawatts of electric power, roughly equivalent to the output of a single offshore wind turbine.
