Function
All installation and commissioning of turbines and balance of plant, including land and sea-based activity.
For offshore activities, the process starts by transporting components from the nearest port to manufacture to either the construction port or straight to the site. Activities are complete at the wind farms construction works completion date, where fully commissioned assets are handed over to operational teams.
Who is involved
Full engineering, procurement, construction, and installation (EPCI) services are conducted by specialist suppliers contracted by the developer.
Key facts
The typical process for installation is to install the wind farm in the following sequence, noting there are parallel operations where possible:
- Onshore substation and onshore export cables
- Foundations
- Offshore substations
- Array cables
- Offshore export cables, and
- Turbines
The installation period for a 1GW offshore wind farm is typically three years from the start of onshore works.
Weather downtime is a key cost consideration for any offshore activity with a third of time often lost through waiting on weather. Significant wave height is the most widely used measure of limitation for offshore activity. In practice, this needs to be combined with a number of measurements to determine workability for different activities.
Sites farther from shore are typically associated with more adverse weather conditions and higher weather downtime.
Increases in the size of turbines and foundations have an impact on the weather downtime unless these are accompanied by developments in equipment and processes.
The opportunity for innovation to reduce costs is substantial. Decreasing offshore cycle times and increasing the operating range of offshore operations is key as this increases vessel utilisation and accelerates project delivery.
Already, the season for installation is being extended, even though this increases weather downtime. There can be considerable risk in introducing new processes and technologies to reduce weather downtime and demonstration will be difficult in some cases.
Developers vary the strategy employed, but contracts are usually let for the cable laying (separately for subsea export and array, and onshore), offshore and onshore substation installation, foundation installation and turbine installation. They also award a single EPCI contract to cover all asset installation. This approach is less favoured by experienced developers that can manage the interface risks between packages.
Notable differences for floating
The typical installation process is as follows, noting there are parallel operations where possible:
- Offshore substation installation
- Offshore cable installation
- Onshore export cable installation
- Anchor and mooring pre-installation
- Floating offshore wind turbine assembly, and
- Floating offshore wind turbine installation.
The installation period for a 1 GW floating offshore wind farm is uncertain but is predicted to range typically four-five years from the start of onshore works.
Weather windows of sufficient duration are required for tow-out and hook-up to moorings and array cable. Hook-up operations at site such as cable pull-in require more benign conditions compared to fixed wind farms, however offshore lifts are avoided as final assembly of the turbine with the floating substructure is completed in port.
Addressing health and safety considerations also needs to remain a focus, as new innovations specific to floating offshore wind are introduced.
For floating projects, developers may opt for a single foundation and balance of plant installation contract, because of the multiple potential interface risks and that installation processes need to be engineered around the floating substructure design.
