Foundations

Designing foundations for offshore wind farms is a complex process that begins with a detailed study of the geotechnical conditions of the seabed. Engineers use advanced computer modeling programs to ensure that the foundations can withstand the forces exerted by wind, waves and ocean currents. The type of foundation is selected according to the conditions of the sea area. The design documentation takes into account the highest level of quality control, building regulations and safety standards. This documentation is then used to obtain the necessary permits. The entire process is closely monitored by a team of experienced engineers, ensuring that the design is in line with the objectives of the farm's construction.

One of the most critical aspects of offshore wind farm design is the foundation that supports the turbine structure and transfers the loads to the soil.

Before designing a subsea foundation, engineers need to conduct a site investigation and a soil characterization to obtain information about the seabed conditions and the geotechnical properties of the soil. The next step in designing a foundation is to perform a load analysis and to define the design criteria. A load analysis involves estimating the magnitude and direction of the forces and moments that act on the foundation due to the wind, waves, currents, and turbine operation. The design criteria involve specifying the acceptable limits of displacement, rotation, stress, strain, and fatigue for the foundation and the soil. The load analysis and the design criteria depend on the type of foundation, the turbine model, the environmental conditions, and the design standards and codes. Based on the site investigation, the soil characterization, the load analysis, and the design criteria, engineers can select and optimize the most suitable foundation type and dimensions for the offshore wind turbine.

Supply of a total of 100 offshore wind turbine foundations consisting of monopiles and transition elements and truss foundations, together with accessories and equipment.

The offshore wind turbine components included in the procurement process are as follows:

• primary steel
• secondary structure and outffitings
• flanges
• corrosion protection systems (paint, cathodic protection)
• cable entry holes
• jackets (pin piles, braces, nodes, transition pieces for jackets)

The production of the Transition Pieces (TPs) includes the supply of a total of up to 100 Transition Pieces (between an offshore wind turbine and monopiles) together with accessories and equipment.

The scope of work for TP production includes: 

• up to 100 units manufacturing
• spare parts for starting on land and at sea
• installation equipment
• LCI documentation with production drawings
• as-built documentation, including making changes to the construction project

TP components included in this procurement process are:

• primary & secondary structures
• davit crane
• seals and cathodic protection
• Low Voltage System
• High Voltage System
• instrumentation & equipment (e.g. Equipment and Temporaries for installation, Markings, Navigation Aids etc.)
• safety equipment

The basic scenario involves the transportation and installation of wind turbines' foundations and foundations with offshore substation platforms (OSS) under a single contract, including the following structures within the package:

• standard monopile with transition piece (TP)
• pin pile jacket for WTG

The selected supplier will have the following activities within its scope:

• transport engineering
• installation and installation aids engineering
• lifting equipment and tools
• piling hammers
• piling noise mitigation equipment
• grouting spread
• vessel grillage and seafastening
• bolting spread and installation gripper frame