The art of balancing wind turbines

Seaqualize has developed an active heave compensation system that prevents even the heaviest components on a vessel to move. The Seaqualize Delta compensates for the vertical movements with minimal effort. This means that even in bad weather, heavy and vulnerable parts can be safely placed. This saves contractors millions and makes expensive new jackups unnecessary. An interview with Gjalt Lindeboom.

What is the problem you solve?

“When installing wind turbines, loads of 600 tons and up are lifted and placed, usually with jackups, some parts already from floating ships. Jackups are slow, contractors spend hours with positioning, fixing legs and picking them up again. Now wind farms are being built in deeper water and hub heights are increasing, existing jackups are no longer sufficient. Motion control is the key enabler for installation from a floating ship. Heavy actuators can compensate for movements of weights up to 400 ton. However, this requires megawatts of power with the risk of going completely wrong. Our Balanced Heave Compensation (BHC) system addresses these problems.”

What is the core of your innovation?

“We have designed a compensation system that balances a heavy load with hydro-pneumatic springs. The idea of spring balancing dates back to the 19th century. It was based on linear steel springs. A well-known desk lamp, for example, is based on that principle: you can adjust the lamp in any direction and height without falling on the table. Another example is a Steadicam harness, perfectly balancing a camera into ‘weightlessness’. But a steel spring is not suitable for variable weights and heavier loads. You need hydro-pneumatic springs for this. Unfortunately, these springs don’t show the desired linear behaviour. After years of development, we now have realised a properly controllable and adjustable spring balancing system suitable for offshore operations. Together with Ampelmann, we first developed a compensation system for a 4-ton walkway. We are now working on an in hook BHC for installing wind turbines: The Delta.”

What is so pioneering about your solution?

“Our passive spring system dampens around 95% of the vertical movement, so with a very low active effort the load can be controlled. This is a leap forward from existing AHC’s, maxing out at around 75% passive compensation. Only 100 kW of power is needed for holding 600 ton still. As a result, we can scale up virtually unlimited. The first Delta will balance a weight of 300 to 600 ton, the weight of next generation transition pieces and nacelles. "

What are the benefits?

“The Delta is lighter, more flexible, cheaper and much more energy efficient than current technologies. No heavy actuation system needs to be installed onboard, the whole system fits in the crane hook. This is unprecedented for such loads. You do not have to adjust the existing crane in any way. The system is also safer because only a very small actuator is on board, which can never impose unexpected movements on the load. Moreover, the Delta only costs a fraction of a new jackup. And the fact that you don't have to supply megawatts of power saves a lot of diesel and installed power capacity taking up space. "

What does your innovation deliver?

“Most Dutch contractors have jackups and/or floating ships. For them, saving energy is a nice side effect, but they are mainly concerned with saving time and cost benefits. For example, placing 70 transition pieces with jackups takes around 60-75 days, with a ship this can be done 15-20% faster. In addition, the Delta enables contractors to operate in the fall and winter: they do not have to wait for weeks or months until the weather conditions are good enough. According to our calculations, this results in a 20-30% workability increase, certainly in the North Sea. In all, that has the potential to save millions of euros. Installing turbines at once will be a huge step forward for the offshore wind industry."

How far are you now?

“The Balanced Heave Compensation system for the walkway has now been certified by DNVGL. Together with Ampelmann we develop walkways and cranes up to 50 ton. We are now assembling the first system, which will be tested offshore after the summertime. For the Delta, we performed simulations with Heerema Marine Contractors and we tested prototypes of 50 kilos and 2 ton. We are now in the process of sourcing the required funding for a 600 ton demonstrator.”

What are the challenges?

“We face many technical challenges to implement a full-scale Delta 600 in practice. For example: at that scale it is impractical to test subsystems onshore or offshore, so we need to test the whole thing at once offshore. We also have to come up with smart tricks for the problem that the sensor mechanism - the Motion Reference Unit - is applied differently than normally. Several installation parties are interested in testing the Delta. However, their largest ships are almost always occupied. In turn, the contractors have to convince the park owners. "

What are the next steps?

“After the summer we will start with the 600 ton demonstrator. At the end of 2020 we want to test it offshore, provided that we finalize our funding in time. Scaling up this big is quite a step. We dare to do that because all subsystems have already been fully tested on a smaller scale. Thereafter, we will scale up the Delta to 2000-2400 tons, suitable for installing complete wind turbines of the next generation at once. This will take at least another three to five years, in time for the current roadmap up to 2030."

What is the added value of Offshore Wind Innovators and TKI Wind op Zee?

“We received a subsidy from the Top Sector Energy for the project with Ampelmann and the simulations with Heerema Marine Contractors. We hope to receive a subsidy for the Delta 600 demonstrator again. Martin Weissmann from Offshore Wind Innovators knows the market. He comes up with tips with whom we should talk. He has a large network, knowledge of existing techniques and financial arrangements and acts as a sounding board. And a service like the Innovation Award helps to raise awareness. Let’s see if we can win it this year…”

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