Function
All installation and commissioning of balance of plant and turbines, 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 [I.7] or straight to site. Activities are complete by the wind farm construction works completion date, where assets are handed over to operational teams.
What it costs*
About £1 billion for a 1 GW wind farm. This includes the installation of the balance of plant and turbines, with related offshore logistics. It also includes developer’s insurance, construction project management and spent contingency (not itemised in sections below).
Who supplies them
Installation: Suppliers listed in relevant sections below.
Full engineer, procure, construct and install (EPCI) services: Boskalis, DEME Group (A2Sea, GeoSea and Tideway), Jan de Nul, MPI Offshore, Subsea 7 (Seaway Heavy Lifting, Seaway Offshore Cables) and Van Oord Offshore Wind.
Key facts
Today, the typical process for installation is to install the wind farm in the following sequence, with overlaps where possible:
- Onshore substation and onshore export cables
- Foundations
- Offshore substations
- Array cables
- Offshore export cables, and
- Turbines.
The installation period for a 1 GW wind farm is typically between two and 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.
Wave height is the most widely used metric to assess the limitation of offshore activities. In reality, this needs to be combined with wave periodicity, direction, persistence (the length and frequency of suitable weather windows), wind speed and direction and tidal flow to define the fraction of workable and non-workable days for different activities.
Sites with deeper water and farther from shore are typically associated with more adverse weather conditions and higher weather downtime.
The opportunity for innovation to reduce costs is substantial and increasing the operating range of offshore operations is key as this increases vessel utilisation and shortens project installation time. Improvements in forecasting models, vessel capabilities, and installation techniques can help optimise scheduling and reduce delays. 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. A concern is that some innovations in installation aimed at reducing costs tend to push the boundaries of what can be achieved in adverse conditions. Addressing health and safety considerations needs to remain a focus.
Installation services are supplied on a day rate or lump sum basis, principally for the vessels and the crew and equipment onboard. Additional costs are fuel and harbour dues.
Developers vary in strategy 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 may award a single EPCI but this has been less favoured in the UK, particularly by experienced developers that can manage the interface risks between packages.