The developer of a unique platform for floating offshore wind turbines has signed an agreement with sustainable energy supporter InnoEnergy that will help it continue the development of its platform.
X1 Wind said the next stage of development involves the construction and validation of its technology using a scaled-up prototype at the ECN hydrodynamic and ocean engineering tank through the EU MaRINET2 programme.
Partnering with InnoEnergy, X1 Wind will receive financial support and gain access to a network of connections in the energy sector, mentoring and in-kind services to accelerate the development of the platform, in which the entire structure passively weathervanes, following the prevailing wind direction. Thrust from the turbine mounted on it transmitted directly to a mini-TLP type mooring system, with loads being shared equally by all tethers at all times
The Barcelona-based company has designed an integrated system that results in a significant reduction in the overall weight of the foundation and hence a reduction in installation and operating costs.
X1 Wind chief executive and co-founder Carlos Casanovas said, “Despite the recent creation of the company in 2017, our technology is the result of more than 20 years of experience in the offshore renewable energy sector.”
Mr Casanovas started working on the concept in 2012 while studying at Massachusetts Institute of Technology. In 2017, together with Alex Raventos, the company’s other co-founder, he filed a patent and incorporated the company. In addition to being light, the platform they have developed is scalable, easy to install and is not site-limited.
The platform weighs less than 300 tonnes per MW, and is, they said, 4-8 times lighter than most spar and semi-submersible systems under test. It is designed to be installed using non-specialized vessels and a ‘PivotBuoy’ single point mooring (SPM) system also developed by the company.
“We use a single point mooring system and a downwind configuration to allow the platform to weathervane,” they said. “Doing so means that we no longer need a tower or active yaw and active ballast systems, reducing weight and maintenance requirements.
“A downwind configuration also has some benefits compared to upwind systems,” they claimed, “which is particularly important when scaling up to large 10MW and 20MW rotors.”
The PivotBuoy SPM system includes a mini tension leg platform (TLP) allowing for a significant reduction in platform weight compared to spar and semi-submersible systems. The design also makes offshore operations simpler, with the PivotBuoy pre-installed along with the mooring system and electrical connection. After assembly on land the platform is towed into place using a tug with a ‘plug-and-play’ connector.
The innovative floater uses an isostatic-three-legged structural design with a low centre-of-gravity. Unlike a conventional cantilever-tower configuration it is not subject to bending moments at the tower base. The design uses a truss structure not only to reduce weight but to minimize wind turbulence and wave loading on the structure.
The structure is designed in such a way as to allow for modular, scalable construction and a platform for turbines that is not constrained by water depth.
In April 2018, X1 Wind was awarded with Phase 1 funding from the European Commission’s Horizon 2020 SME Instrument programme in order to advance in the development of its disruptive floating wind technology. The project was selected from among more than 2,000 proposals submitted in a call in February 2018.
In January 2018, X1 Wind completed initial tank tests of a 1:64 scale prototype in the wave flume at the Canal d'Investigació i Experimentació Marítima at Universitat Politècnica de Catalunya. During the tests, regular waves with periods from 6 s to 24 s were tested as well as irregular waves including extreme conditions (up to a significant wave height (Hs) of 14 m).
Regular wave tests were used to determine platform RAOs and to adjust and validate simulation models. Irregular wave tests were used to observe platform and TLP behaviour under extreme weather conditions (Hs = 14 m with a maximum wave height of 22 m).