Our Offshore Wind Accelerator programme is taking the best new designs for offshore wind turbine foundations from design through research and development to deployment.
In 2009, we ran a global competition to identify innovative, cost-effective, and robust foundation designs that could be used for the challenging conditions that will be encountered in Round 3: water depths of 30-60m, complex soils, and harsher metocean conditions. Our competition attracted more than 100 entries from all over the World, from leading civil engineers and naval architects to marine experts in the oil and gas industry. Seven foundation concepts were short-listed in Stage 1, all of which have the potential to deliver a step-change in cost reduction.
For Stage 2, the OWA has taken forward four of these concepts into a detailed design phase which will consider fabrication, installation and transportation. These concepts are highlighted below.
Universal Foundations: suction bucket monopile
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Structure
- Less steel, simple welds
- Suitable for 30-60m
Installation
- Fewer offshore operations and smaller vessels and equipment
- Simpler installation as foundation towed to site
- No piling
- Less scour protection required
Decommissioning
- Easier to retrieve for decommissioning
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Keystone: innovative jacket
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Structure
- Twisted jacket uses less steel vs conventional jackets
- Elegant engineered transition piece
- Uses innovative composite materials
- Proven in Hurricane Katrina
- Suitable for 30-60m
Installation
- Faster installation time
- Fewer installation manoeuvres
- No driving template required
- Improved utilisation of deck space increases transportation efficiency
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Gifford/BMT/Freyssinet: gravity structure
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Structure
- Slipforming stem – reduces production time
- Mass fabrication process developed
- Concrete prices less variable than steel
- Suitable for 30-45m
Installation
- Cheaper, bespoke unmanned vessel transports structure to wind farm
- Entire foundation / turbine structure may be transported
Decommissioning
- Structure easy to de-ballast and remove
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SPT Offshore & Wood Group: tribucket
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Structure
- Self-installing tribucket
- Entire foundation / turbine structure assembled in port
- Suitable for 30-60m
Installation
- Entire foundation / turbine structure transported to wind farm
- Standard marine equipment
- No piling or drilling
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It is intended that these concepts will be demonstrated at full-scale by the OWA Partners. They have the potential to reduce the total cost of foundations in a wind farm by as much as 30%. This demonstration phase could include as much as £20m of OWA investment.