The offshore wind industry is facing a challenge investigating sites for future windfarms because of the size, scale and distance from shore
The size and scale of future offshore windfarms and their distance from shore will pose a challenge for conventional survey technology, scientists believe, and new, more efficient ways to obtain accurate high-resolution seabed data will be required.
Royal Academy of Engineering chair in emerging technologies in intelligent and resilient ocean engineering Professor Susan Gourvenec believes a new approach to surveys – and new technology – will be needed to survey the offshore windfarm of the future.
In evidence to a House of Commons Environmental Audit Committee (EAC) inquiry on offshore wind technology earlier this year, Professor Gourvenec called for change. She said new approaches were needed to assess sites for bottom-fixed foundations and moorings and anchors for floating wind turbines.
“Offshore geotechnical testing tools that can be deployed with reduced vessel support are critical to reduce the cost of offshore renewables developments,” she said.
Professor Gourvenec said an economic challenge is arising due to the much greater area required for surveys of offshore windfarms as they grow in size, scale and number.
“A specialist geotechnical vessel could cost in the region of £100,000 (US$122,000) per day and a renewables site investigation will require tens or hundreds of locations to be investigated,” she told the inquiry. Professor Gourvenec contrasted the survey requirements of offshore wind with the requirements for “four locations for the ‘corners’ of a single oil and gas platform or mooring spread.”
She said opportunities for cost reduction of site investigations could include intelligent geotechnical site characterisation tools for remote or autonomous deployment or operation, to upscale capability without upscaling cost; and machine learning techniques to correlate continuous geophysical data with discrete geotechnical data, to optimise development of an engineering ground model of a development area.
“Harnessing the intelligence of sensing, robotics and autonomy, next-generation resiliently engineered systems will enable cheaper, smarter site characterisation, which will accelerate the economic competitiveness necessary to scale up the UK market,” she told the EAC.
Economic challenges will arise, she said, due to the much greater area required for future surveys and the many more structures required for the same energy yield, given the significantly lower power output per renewable energy structure compared to an oil and gas facility.
Offshore Renewable Energy Catapult (ORE Catapult) operational performance engineering manager Tony Fong told the VirtualWind II conference hosted by the ORE Catapult in the UK and Fraunhofer IWES in Germany that he also believes there are challenges for site surveys for foundation design.
He suggested new technology could help increase efficiency and reduce costs and highlighted new technology, including robotics.
Among the challenges that will arise in future North Sea surveys are that they will be further from shore, and significant wave heights far from shore will be greater. Other challenges include higher average wind speeds, increased water depth, variable seabed sediments and increasing competition from assets in other industries.
Still other challenges include increased transit distance, increased depths for survey and monitoring and harsher meteorological conditions, along with a growing need for high bandwidth connectivity for data collected during surveys. Further offshore, floating substructures would be required, which would pose different challenges for survey assets to those already posed by bottom-fixed windfarms.
Fraunhofer IWES senior scientist Dr Stefan Wenau told the conference that seismic imaging could be employed more widely in future. He said it could significantly improve understanding of the geology of the seabed, particularly when applied to potential geohazards affecting turbine locations and foundations. He highlighted the efficacy of multichannel seismic techniques, ranging from conventional 2D to 3D high-resolution seismic spreads that can detect subsurface objects.
Riviera held a series of webinars on offshore wind in June. These are available to view in our webinar library