Gwynt y Mor Offshore Wind Farm

Gwynt y Môr generates 576 MW using Siemens 3.6 MW turbines, supplying enough energy to power approximately 400,000 homes annually.

Project name: Gwynt y Môr 576 MW Offshore Wind Farm Installation
Location: 13 km off the North Wales coast, United Kingdom
Year: 2012-2013
Application: Monopile foundations

The main challenge was reducing the overall installation period of the foundations by maximizing the time for grouted connections between monopiles and transition pieces. Equally critical was designing a foundation strong enough to support the tower and turbine while enduring dynamic loads over its 25-year lifespan.

Harsh offshore conditions—wind, waves, and low temperatures—impact installation windows and grouting operations. Given the high cost of specialized vessels, optimizing their use is essential. Effective cost control remains a top priority for clients throughout the project.

RWE prioritized a grouting material capable of low-temperature application to align with their installation vessel’s enhanced wave height capability. SikaGrout®-9500, operable at 0°C, was the clear choice.

FoundOcean, Sika’s certified grouting contractor (CGC), has been grouting transition pieces aboard RWE’s vessel throughout winter, handling ambient temperatures as low as 2°C. The rapid strength development and low-temperature suitability of SikaGrout®-9500 accelerated foundation installations, maximizing vessel efficiency. 

Customer Benefits

• SikaGrout®-9500 enabled grouting in harsh offshore conditions, optimizing vessel use.
• Improved cost control and reduced expenses for vessel operations.
• Fast foundation construction ensured timely wind turbine installation.
• Turbines began producing electricity by August 2013, just 6–7 months after grouting, ensuring a quick return on investment.

 
Quick Facts

• Amount of material used: 6,100 tons
• Number of turbines: 160 × Siemens 3.6 MW
• Windfarm total capacity: 576 MW
• Homes equivalent: 400,000
• Turbine tip height: up to 150 m above mean sea level
• Area of wind farm: 79 km²
• Foundation type: Monopile / Transition piece
• Size of monopile: Steel tube between 50 and 70 m long, approx. 5 m diameter, weighing between 500 and 700 tons each
• Size of transition piece: Steel tube 22 m long, approx. 5 m diameter, weighing 200 tons each, fitted with 4 levels of platforms and ladders
• Typical water depth: 12 - 28 m