Chinese project could be first for eel-like floating foundation

Maridea BV’s Moray Base foundation, first unveiled by OWJ in 2022, was designed with mass production and cost-effectiveness in mind, and has been selected by Fujian YongFu Power Engineering Co for a project offshore China.

A contract signed by Maridea and the Chinese company on 18 April 2023 will see Maridea optimise the design and mooring system for its Moray Base foundation for conditions offshore China. The foundation will be optimised to withstand the effects of typhoons.

Maridea managing director Jeroen Lusthof told OWJ, “We are confident the present efforts will result in a full-scale demonstrator. The project will involve the development of a 16-MW floating offshore wind turbine.”

As highlighted by OWJ in 2022, model tests suggest the Moray Base has excellent motion characteristics and is capable of supporting a 15-MW turbine in harsh environments. Maridea said the patent-pending design has low capex and opex costs compared with other solutions and would require minimal maintenance.

The large diameter, thick-walled tubes that form the basis of the Moray Base are designed to deal easily with turbine loads during bad weather and with thrust from a turbine. The long radius segmented elbows have superior strength and fatigue behaviour compared with the joints of semi-submersible or jacket-type units. Maridea said this makes the structure less prone to fatigue and will reduce the need for inspection and repair work. The location of the turbine on the corner of the structure allows for access with crane vessels if a turbine needs maintenance or repair.

Named after the moray eel because of its shape, the Moray Base is fabricated from steel tubes and would not require additional structures such as braces. Maridea said the absence of structures such as braces allows for the adoption of proven, highly efficient monopile production techniques.

A 15-MW turbine can be supported using a 12-m diameter steel tube, a diameter that is suitable for production using existing manufacturing technology. The company believes a 15-MW turbine on Moray Base foundation would be much less expensive than the same turbine on a spar, semi-submersible or tension-leg platform.