For five years, Norwegian research groups and industry players have been collaborating on new tools for designing offshore wind farms. The results will enable researchers to calculate wind and wave stresses, analyse optimal wind utilisation, and study solutions for an interconnected electricity grid.

The project received funding under the Research Council of Norway’s Large-scale Programme on Clean Energy for the Future (RENERGI).

According to John Olave Tande, comprehensive planning of the offshore grid is critical to the future development of offshore wind power. He is pictured here at the SINTEF Energy Research laboratory for conducting planning simulations. (Photo: Stein Morch) Interaction between turbine and foundation

Until now no tools have been available for calculating how wind turbines and their foundations react as a unit to the forces of wind and waves. New solutions have been developed through this project, explains project manager John Olav Tande of SINTEF Energy Research.

“These are an important means for achieving optimal design of offshore power plants. There is no doubt that better results are obtained when the calculations take into account the interaction between turbine and foundation. Our solutions help to make sure the turbine and foundation are properly dimensioned and constructed for their actual operating conditions. Other objectives are to ensure durability and minimise expenses.”

Optimal use of winds

Another aim of the project was to study how the wind farm as a whole – not simply each individual turbine – could best utilise wind resources.

The project has shown how overall power generation can be increased through coordinated regulation of a wind farm’s many turbines. For instance, by partially reducing the output of the first (upwind) turbine, the downwind turbines receive more wind – so that on the whole the wind farm produces more electricity. The project’s researchers used wind tunnel trials as well as mathematical calculations to study these complex interactions.

The project has shown how overall power generation can be increased through coordinated regulation of a wind farm’s many turbines. (Photo: Shutterstock) Integrated offshore grid

The project’s third main focus was on analysing how to connect wind power to the grid.

“There are so many more factors to deal with than simply the nearest point on land,” says Dr Tande. “As offshore wind power expands more and more, it becomes all the more important to approach the challenge from a macro-perspective, analysing the entire spectrum of conditions to find what yields the optimal results overall. We have come a long way in developing a grid planning model for connecting electricity generated offshore.”

Planning the offshore power grid must take into account the location not only of the wind farms but also of the suitable connection points on land and cable connections between land sites, as well as integration into the total power system.

Wind power for running offshore petroleum installations

Offshore power plants can provide a critical source of electricity for oil and gas installations.

Norwegian offshore installations currently consume 20–25 TWh per year, virtually all of which is produced by natural gas-fired turbines located at the installations.

“If instead we could feed that consumption with clean, renewable energy such as wind power,” explains Dr Tande, “it would be an effective measure for reducing CO2 emissions substantially. At a price of roughly NOK 1 per kilowatt produced by offshore gas turbines, and with natural gas prices expected to rise, offshore wind power is not far from being competitive in price.”