"The future of offshore wind technologies"

Morten Pilgaard Rasmussen, Offshore CTO, gives his perpective

Denmark / 4 March 2021

Climate change is the biggest challenge facing our generation, and action is urgently needed – we only have a few years left before it will be too late to reach the targets agreed in the Paris Agreement, which aims for a maximum temperature increase of 1.5°. The urgency only makes our efforts to develop and produce wind turbines even more important. Today, while offshore wind is competitive in comparison to all other energy sources, we are, as a leading offshore wind manufacturer, working together with customers and suppliers, as part of the solution to the climate crisis.

Offshore CTO

Morten Pilgaard Rasmussen

Offshore wind almost offers endless opportunities, and new markets emerge nearly daily as more and more countries and regions define their ambitions and policies on marine energy. The EU has a target of having 300 GW of offshore wind installed by 2050 – by mid-2020, “only” 23 GW was installed. Additionally, the fact that many countries are strongly focused on green energy to promote an economic recovery from COVID-19, means that there are near to no restrictions.

But what does the future of offshore wind look like? How big of a role can offshore wind play in concrete terms? And what technologies must be in place for such ambitious targets to be achieved?
Climate change is the biggest challenge facing our generation
Development of offshore wind turbines
It is technically possible to develop increasingly large wind turbines. The difficult part is to make all aspects go hand in hand: R&D, cost, production facilities and logistics. Although we have one of the lightest nacelles in the industry, which weighs less than 500 tons because of the simple Direct Drive train, it is still a large machine that needs to be produced, transported and installed. Everything must be pre-prepared when handling such a large machine, and thus there are high demands on the entire supply chain in terms of being ready in time for the projects to be executed at sea.
We constantly focus on developing our offshore wind turbines; both to improve them, but also to meet new market requirements in relation to technical solutions. One example of this is our 14 MW direct drive turbine with a 222-diameter rotor. It is a further development of our existing platform, but with some technological adjustments such as a change from a 33 to a 66-kV electricity system – implemented because it was necessary in relation to technical requirements in some markets, and also to minimize voltage loss.

It is also a challenge to design the large blades, which must be able to withstand 25 years of operation in a tough offshore environment. At 11 m/s, approximately 520 tons of air will pass through the area of the rotor of 222 meters every second. In fact, on the 14 MW 108-meter blade, we have quadrupled the bending torque of the 75-meter blade, measured in newton meters, so that it is strong enough to counteract the necessary rotational force. To put it into perspective: if an arm is about one meter long and you spin a bottle with one liter of water in your hand, then the force pulling the shoulder is about 10 newton meters. For a 100-meter-long blade on a relevant sized turbine with a tip speed of about 100 meters/s, the force is about 70 million newton meters! So, a 108-meter blade, must be able to withstand huge power out at sea - where there are more windy days and 30% higher wind speeds than we have on land.
Finding new ways: Wind to hydrogen (Power-2-X)
In the battle to secure orders – and the climate fight – further development of a platform and making the turbines larger is only one piece of the puzzle. We also want to move into other areas and help drive the green transition in a broader sense. One of the ways to achieve this is to get green energy to extend beyond the electricity sector and into heavy transport and industry. At Siemens Gamesa we have taken the first step in developing green hydrogen production with a hydrogen test site located here in Denmark, connected directly to a wind turbine near Brande. On this site, we can test how the turbine and electrolysis run in island mode (without connection to an electricity system) thanks to our innovative control technology. Here, we will test the technology to produce hydrogen directly from wind and, among other things, explore how to make cost-effective hydrogen production on a large scale.
In January this year, we also announced a large-scale collaboration with Siemens Energy, in which we are investing almost 900 million kroner in developing a fully integrated offshore wind-to-hydrogen system. Here, each turbine is a production unit for hydrogen, which is produced by connecting the wind turbine and electrolysis directly on the turbine platform, so that the conversion to hydrogen is placed as close as possible to the green energy source. In this way, we can reduce losses in the system, and because it is a solution that is independent of grid connection, an offshore wind-to-hydrogen solution, the mechanisms can be installed where there is the most wind. A modular solution like this has an enormous potential for industrialization and can bring green hydrogen down in price, making it a competitive alternative to the fossil fuels currently used in heavy transport and industry. Our goal is to have the first prototype in the water by 2026.
Floating wind turbines - a part of the future
Another area that we see as the future of offshore wind is floating turbines. We foresee a big growth in several new markets, and although we have some experience with turbines on floating foundations, it will still require some fine-tuning when we develop these new giant wind turbines. There need not be an immediate technical difference from a wind turbine on a solid foundation, but new software needs to be developed so that the wind turbine and the foundation work with each other to optimize the amount of steel used for the turbine's foundation and anchorage.
Morten Pilgaard Rasmussen, CTO Offshore SGRE

There may be different ways of making a floating foundation. Some concepts use the filling/emptying of ballast tanks to counteract inclination and dampen movements from, for example, wave loads – the wind turbine controller should be aware of this, just as the foundation controller should know when the wind turbine experiences wind loads. In other concepts, no active damping measures are expected.

Before we see large-scale deployment of floating foundations, however, there are a number of challenges that need to be addressed. The whole industrialization of the production of foundations must be raised to the same level as wind turbine production when the big projects get under way. We work with various solutions that we believe can help the whole industry in the right direction. In addition, the industrialization of cable solutions and anchorage solutions must also follow suit.

Production capacity for the production of large quantities of foundations is also a major factor. The way you produce jackets today requires both time and space. Several floating foundation designs are similar to jackets, and if you can optimize jacket production you can also optimize the floating foundation production. Today, the best jacket manufacturers can produce between 40 and 50 jacket foundations a year, and that does not extend to the large market we are looking into. We want to help them to produce 3-4 times as many foundations a year.

Innovations in floating offshore wind and hydrogen will also have synergies in the long run. When heavy shipping and aircraft need hydrogen as a component of their green fuels, we will need to use sites far out at sea with strong winds and large water depths. Under these conditions, grid connection is difficult, and this obstacle can be addressed by the use of hydrogen wind turbines that function in island mode.

There is a lot to do if we are to solve the climate crisis. Wind power - specifically offshore wind - can play a major role. Continuous innovation will be key to our success in converting the world to green energy.


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