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Conference programme 

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Poster session

Lead Session Chair:
Stephan Barth, Managing Director, ForWind - Center for Wind Energy Research, Germany
Martin Jakubowski Seawind Ocean Technology B.V., The Netherlands
Co-authors:
Martin Jakubowski (1) F P Silvestro Caruso (1)
(1) Seawind Ocean Technology B.V., Amsterdam, The Netherlands (2) , ,

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Poster
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Presenter's biography

Biographies are supplied directly by presenters at OFFSHORE 2015 and are published here unedited

Martin Jakubowski works in Renewables since 1990, following a market approach rather than relying on feed-in-tariffs, which are obstacle for technology development. He created the first clean energy distribution companies in Germany, 1995 and UK (Good Energy Plc), 1997. He built onshore wind farms and hydro-power plants in European countries. In 1999 he identified offshore wind as major contributor to a clean energy market. His believes that FITs need to be replaced by a CO2-tax. He installed the first floating wind turbine in 2008 with Blue H and designed a 6.1 MW two bladed turbine on spar buoy in Condor.

Abstract

Self-installing two bladed offshore wind turbine systems to bring down the coe in offshore wind

Introduction

Offshore wind energy needs a radically new approach. Assembling wind turbines in the offshore environment as if they were on land, by placing first the foundation, then the tower, then the nacelle and then the rotor or the blades, is understandable as mind set coming from the onshore experience but leads to unacceptable costs offshore.
Offshore crane or installation vessels kill the economics of offshore wind. Offshore wind turbines systems need to be considered as one system, not a lower part (foundation) and upper part (wind turbine).

Approach

Requirements for economic offshore wind systems are:
- Robustness of the energy conversion part by lowering fatigue on blades and drive train compared to onshore solutions; life time extension to 30+ years;
- Easy and economic maintainability by double access (via sea and via air) directly to the system (no dangerous drop-down boxes) and possibility to repair components on board;
- Assembly of the units at the pier, not at sea, and installation through a simple self-installing process;
- Reduction of weight through two-bladers, less torque, less weight;
- Installation and maintenance operations only with normal tugs and normal supply vessels.


Main body of abstract

Seawind has designed on a blank sheet of paper offshore wind energy systems based on the characteristics water, which is 800 times denser than air, allowing a sinking rather than lifting approach. Starting from this basic Seawind has selected a two-bladed wind conversion technology with teetering hinge, to be integrated in an overall system assembled completely at the pier. For all commercially relevant water depths going from 10 to 500 meters. Handling of two-bladers in harbors is much easier than heavy and star-shaped three-bladers. Two bladers are lighter than three-bladers because of their higher rotation. The introduction of a teetering hinge eliminates bending moments in the drive train, reduces fatigue and ultimate loads and enables the elimination of the pitch control. The teetering hinge overcomes the gyroscopic forces enabling for control by active yawing. This was proofed by the Gamma 60 turbine in the 90s.
Using two-bladers it is possible to install a helideck on the nacelle for larger helicopters if the nacelle is a steel frame. This gives the opportunity to create a very stiff integrated bed-plate-nacelle component on which the drive train can be mounted directly (bed-plate mounted) and creates space for repair onboard.
Two-bladers can be integrated in a self-installing system allowing for complete assembly at the pier, sinking at the side and pile driving or drilling for fixing of the piles in shallow water without the need for crane or installation vessels or in deep water through a simple self-erecting process of a spar-buoy based system.


Conclusion

It is necessary to rethink the approach in the offshore wind energy from the basics. It is insufficient to do things right or doing them better. To bring the CoE in offshore down remains only the third alternative: doing it differently. This will bring the costs down to the onshore level, acceptable for the energy users and in the competition between nations
The way described enables many medium sized companies all over Europe to participate in this process. No money should be thrown after the bad money spent following the traditional approach.
Two bladers can easily go to 10+ MW.



Learning objectives
The entire industry has been influenced by the onshore practice, which is understandable. As main-frame computers had no future any more in the IT industry with PCs coming up, the traditional three-bladed offshore approach installing wind turbines at sea as if they were on land (piece by piece through lifting operations) has no future.