2BE Umbrella Project 2013

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2-B Energy is developing a dedicated offshore wind turbine with a comparatively lower Cost of Energy (CoE) based on: a full jacket support structure concept with integrated design of support structure and foundation; suitable for large distance from the coast with helicopter access; sophisticated control system to reduce dynamic and extreme loads; and optimized for high availability by efficient service, maintenance & repair. The turbine is categorized as a 6MW, 2 blade horizontal axis wind turbine. The turbine is referred to as 2B6.

This FLOW umbrella project has focused on the realization of the 2B6 in an offshore demonstration project. A collection of separate, research and development, work packages has been combined in an umbrella project to take a further step towards offshore demonstration. The intent of this umbrella project was to carry on a research of this specific topic and explore their influence on offshore wind turbine costs.
The onshore demonstration design has been finalised and is installed in Eemshaven as part of 2-B Energy’s onshore demonstrator project. The onshore demonstrator project reveals the feasibility of the offshore wind turbine concept of 2-B Energy. The figure below shows a photograph of the 2B6-Gamma turbine at Eemshaven, Netherlands dated December 2015. On 18th of December 2015 a major milestone was achieved by the first production of electricity during the commissioning phase of the wind turbine.

Main objective
The main objective of this project is to reduce Cost of Energy by a combination of separate research and development projects. A collection of separate, confidential, independent R&D work packages has been combined in an umbrella project to take a further step towards offshore demonstration of the 2-B Energy wind turbine concept.

The following work packages were investigated:

The 2-B Energy Power Block integrates the transformer substation concept into the support structure. Within this work packages its impact on the design of the offshore full jacket structure was analysed.
A conical Transition piece FEM calculation is performed to identify its advantages in comparison to a cylindrical transition piece.
The access strategy of 2-B Energy, using helicopter platform, was discussed with Civil Aviation Authority (CAA); Helideck Certification Agency (HCA); CAA Flight Op.
The identification of backlash in the turbine was investigated to increase the fatigue lifetime.
A specific lightning protecting system has been developed and implemented on the demonstrator turbine.
After DNV and GL merged into the new organisation DNVGL, the individual standards of each organisation were combined and released, along with new stipulations based on recent research. For the fatigue analysis of offshore support structures, one of these stipulations was that the weld roots of tubular joints would have to be analysed for fatigue. If it could be shown that the stress concentration factors (SCFs) calculated through Finite Element Analysis for the 2BE tubular joint was lower than the SCFs calculated via the parametric equations of the new DNVGL standard, then less material could be used for the support structure, therefore making it cost effective. A FEM assessment is performed to identify the advantages of the FEA.

Contribution of the project
This project focused both on cost reduction of far offshore wind energy and risk reduction of far offshore wind energy as well as acceleration of the deployment of far offshore wind.

Power Block: 2-B Energy Power Block integrated transformer substation concept, which reduces costs and improves availability of the grid infrastructure.
Concept Conical Transition Piece: A Conical Transition Piece is more advantageous compared to a cylindrical transition piece. It has the potential to reduce the costs of the support structure (jacket) by means of reducing material; removing a bay and reducing production costs. Additionally, also the O&M costs could be reduced due to the additional space available in the transition piece. The conical Transition piece will be applied in the future offshore demonstrator project.
Access strategies: Helicopter access reduces operational cost due to resulting higher availability. Currently with boat access only, turbines cannot be reached due to weather conditions (Waves, high winds, etc.), up to 50% of the time. Acceleration of deployment is achieved by identification of the opportunities to redefine specific regulations for the helicopter platform. This will be demonstrated in the future offshore demonstrator project.
Active Backlash Control: By identification of the impact of the backlash on the turbine and the active backlash control, the fatigue life of the support structure can be optimised resulting in a cost of energy reduction.
Lightning protection system: The implementation of the 2-B Energy specific Lightning protection system in the onshore demonstrator project reduces the O&M costs and risks by maximising the safety and reliability of components through a simple and effective protection system.
Various: By lowering the SCF’s used in the design of the support structure, a cost reduction can be archived as the lower SCF allows the usage of less materials in the fabrication of the support structure.

Using the FLOW Cost Model for evaluating the Cost of Energy reduction, the reduction in CoE, due to the above mentioned items is estimated around 1.24%.

The future work for 2-B Energy involves the offshore demonstration project, situated offshore of Methil, Scotland UK on the UK part of the Continental shelf. This small wind farm is set to start with 2 turbines with an eventual increase to 9 turbines for the demonstration of the Power Block concept. The use of a helideck on the 2B6 wind turbine will be demonstrated as well as the conical transition piece.