Let wind turbines conquer the Seven Seas

Wind energy
Peter Hauge Madsen at Energy Supply: In the near future, a huge market for floating wind turbines will open up. Denmark can come to play an important role if we seize the opportunity.

Developmentally, it would represent the third major wind turbine adventure for Denmark. We literally have to sail the wind turbines out into deep water, where their potential for power production is in a completely different league.

The world is crying out for green power that can drive the development towards reducing climate gases while electrifying energy consumption in, for example, the heating and transport sectors. This goal can be realized with floating wind turbines, but to fully exploit the wind potential at sea, further technological development is required.

First, on land

Wind turbines have proven to be the most suitable technology for generating green power. It has happened through two major wind turbine success stories for Denmark. In the 1970s, Denmark was able to take the lead thanks to visionary researchers, environmentally conscious politicians and a budding industry that manufactured the first onshore wind turbines, even though their commercial potential was questionable. However, after many years of research, innovation and development, the technology has been optimized to such an extent that it is now cheaper to produce 1 kilowatt of power from a wind turbine than 1 kilowatt of power from coal-fired power plant.

Next, installed on the seabed

Based on the expertise acquired through establishing wind turbines on land, and with world-class test facilities at DTU, first at Risø and then in Østerild and Høvsøre in northern and western Jutland respectively, companies in Denmark also started to lead the way at developing offshore wind turbines. Fortunately, in the North Sea and the seas around Denmark, the water is so shallow that wind turbine foundations can be constructed on the seabed. Wind turbines now supply almost half of the power consumed in Denmark. Within the foreseeable future, wind turbines will be able to meet our entire need for power. So why do we need to embark on a new wind turbine venture?

"In the near future, a huge market for floating wind turbines will open up. Denmark can (again) play an important role in this market, and proper research efforts can pave the way for another export adventure."
Peter Hauge Madsen

In light of the Danish government’s climate goals and the need for a global transition to green energy, there is a demand for much more renewable energy. In addition, far more power has to be produced than we need today, as society needs to be electrified and large amounts of power are required for Power-to-X. Wind turbines will have to supply power to an unprecedented extent and at even cheaper prices. And the power must not only be produced in Denmark, but globally.

Soon, wind turbines will float

Many countries wanting to generate power from wind turbines face challenges because their waters are too deep. The solution is therefore floating wind farms. The floating foundations are attached to the seabed with cables, enabling the offshore wind turbines to be able to produce energy even in deep water. This is, for example, the case along the US west coast as well as off the coasts of countries such as Japan, Spain, Portugal, and Norway, where the water depths quickly drop to more than 55 metres, which is the limit for offshore wind turbines on conventional foundations.

There are relatively few floating wind turbines in operation, but the potential for floating offshore wind energy is enormous. In 2019, the International Energy Agency (IEA) estimated that the potential for floating offshore wind is in the region of 55,000 TWh, which is more than the total estimated global electricity consumption in 2040 (see IEA Offshore Wind Outlook 2019, p. 51). To utilize just 10 per cent of this potential, a quick mental calculation tells you that it would require approx. 100,000 large offshore wind turbines. This offers huge opportunities for the Danish wind industry.

New production potential and more energy

One of the main advantages of floating foundations is that they can be mass-produced. Unlike wind turbines, which stand on the seabed mounted on foundations out at sea, floating foundations and turbines can be assembled at a harbour and sailed out to their destination. This opens up a whole new world of possibilities for industrializing the process. At the same time, floating wind turbines have the advantage of producing more power than regular offshore wind turbines because they can be placed further out at sea, where the wind conditions are better. This ensures smoother power production, which is an advantage for our energy supply in general and in particular for Power-to-X.

Innovation throughout the value chain

Today, wind turbines on floating foundations are basically the same as those attached to the bottom, but it is not without challenges. The technologies, steering, controls, calculations and, not least, the way in which the ocean’s forces have to be intelligently taken into account are all aspects that require further R&D. Denmark has what it takes, as we are used to looking at turnkey solutions. We are concerned with the entire value chain—from where these floating wind turbines can be placed to how the foundations and turbines can be (re-) designed, and how the energy produced can be transported to shore.

At DTU Wind Energy, researchers are working to solve these challenges. For example, we have developed the computer models which are being used to optimize the function and construction of the wind turbine and the floating foundation. And the global wind atlas, developed at DTU Wind Energy, now makes it possible to easily assess where the potential for both ordinary and floating offshore wind turbines is greatest.

New export adventure

To commercialize floating offshore wind, it is necessary to focus technologically on the production of the large floating foundations, on how the wind turbines within a single wind farm impact one another, as well as how to integrate floating offshore wind turbines with the electricity grid. It is also important to look at how the wind turbines affect each other. The powerful currents created by the wind turbines and their foundations in a wind farm is a key focus area for researchers, and one that will be clarified in the near future. The potential for movement of the turbines as well as the blades (depending on platform and anchoring strategy) is different to that of wind turbines fixed to the seabed. Consequently, a lot of research is still required to ensure that resources are used optimally in a world which is crying out for green power and sustainability.

In the near future, a huge market for floating wind turbines will open up. Denmark can (again) play an important role in this market, and proper research efforts can pave the way for another export adventure.