Saitec’s floating wind turbine off the coast of Bilbao was knocked over when it was hit by 10 metre-high waves around dawn and low tide, in storms that exceeded weather forecasts for Hurricane ‘Epsilon’, the floating foundation manufacturer has confirmed.
The waves from the storm also knocked down the cement sign of ‘Santander city’ in El Sardinero, water flooded into entered restaurants with some further damage along the peninsula of La Magdalena, El Diario Montanes reported.
The floating foundation manufacturer Saitec Offshore Technologies secured the test site for the first deployment of its full-scale Sath (“swinging around twin hull”) platform in June.
The 30kW turbine was installed at the Biscay Marine Energy Platform research centre off Santander Coast on Abra del Sardinero in August.
Saitec said it had completed its wave tests before the waves hit and had been planning to take the prototype back to land before winter.
But workers were prevented from recovering the vessel because of a series of storms including Alex and Odette.
With waves around 10 metres high near the platform, the waves were the equivalent of 60 metres high according to the wind turbine scale of 1:6.
A meteorological buoy registered waves as high as 11.06 metres in the area on 29 October before an orange warning (important risk) was issued by the State Meteorological Agency (AEMET) due to adverse coastal phenomena.
The wind turbine was submerged before it was later recovered, when divers assessed the damage and it was taken to port for repairs.
David Carrascosa, technical director of Saitec, told the local media that a reduced size wind turbine was installed Abra de El Sardinero, where waves are usually three metres high, or 18.6 metres to scale.
The waves that hit the structure left it leaning more than 35 degrees.
Speaking to local press, Carrascosa said: “…we are really proud of the resistance of the prototype, which has withstood the storm Alex with waves of seven metres, which is as if they were 43.2 metres on a real scale.
“It worked as we expected, but a wave of 10 metres was not expected – that would make it lose stability.”
Saitec is planning larger wind turbines to scale, with Carrascosa adding that “..we already know what the maximum resistance is”.
He said: “The evaluation of the results obtained has shown the excellent behaviour in all the design scenarios found in the oceans of the world and even more than double them, being an exaggerated breaking wave for the size of the reduced model.”
Saitec’s Sath platform has two cylindrical and horizontal hulls with conical edges braced by a concrete frame.
The company said the vessel can align itself around a single point of mooring, which can match the direction of waves and wind.
Saitec was analysing the platform’s behaviour under operational and extreme conditions to collect real-life data by building, operating and maintaining the turbine.
The manufacturer also plans to commission a 2MW turbine on its Sath platform off the Basque Coast (Biscay), Spain before the end of 2020.
The pilot 2MW DemoSATH project will last three and a half years – 18 months for planning and construction, followed by two years of operations at a site 3.2km off the coast, in water depths of about 85 metres.