Two areas off Norway have so far been opened for developing offshore wind – Utsira North, suited to floating turbines, and Southern North Sea II for both fixed and floating units.
Fixed turbines can currently be installed in waters up to 60 metres deep and account for most offshore wind developments on stream or under construction worldwide so far.
Many different types of support structure are available for fixed turbines. Which of these might be chosen depends on water depth and seabed conditions at the site.
Floaters are the only option today in waters more than 100 metres deep, and various technologies for these are under development.
Their common denominator is that that the floating structure must be able to cope with high waves, currents, and challenging weather.
Water depths on the NCS mean that floating turbines offer the biggest potential for offshore wind there.
Output
The amount of electricity a wind turbine can generate in a year can be calculated from its capacity factor, defined as average output divided by rated peak power.
In other words, it describes the energy actually produced in the course of year as a proportion of total output were the turbine to operate at full capacity throughout.
Modern land-based wind turbines have a capacity factor of around 35 per cent, while the latest offshore units can reach up to 55 per cent.
The government’s 2040 goal of handing out acreage which could yield 30 GW of wind power on the NCS corresponds to 75 per cent of the capacity in the Norwegian power generation system today.
Risk
Offshore wind has features in common with petroleum operations in terms of technological and operational solutions, and for their various stages – design, construction, installation, operation, maintenance and removal.
Several parallels also exist where risk is concerned. But the biggest hazard involved with petroleum – handling large volumes of oil and gas under pressure – is naturally absent for wind power.
The threat of a major accident with the latter is thereby much smaller. Nevertheless, it could also potentially experience major accidents and incidents involving a number of fatalities.