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SELF-BOUYANT PRECAST CONCRETE FOUNDATION FOR THE CRANELESS INSTALLATION OF COMPLETE OFFSHORE WIND TURBINES: FULL SCALE OFFSHORE PROTOTYPE

Periodic Reporting for period 2 - ELISA (SELF-BOUYANT PRECAST CONCRETE FOUNDATION FOR THE CRANELESS INSTALLATION OF COMPLETE OFFSHORE WIND TURBINES: FULL SCALE OFFSHORE PROTOTYPE)

Reporting period: 2016-06-01 to 2017-05-31

The offshore wind market is a young and rapidly growing market facing technological challenges, as it is set to move into deeper waters further offshore while being able to reduce the costs in order to reach a competitive LCOE (levelised cost of energy).
ELISA project responds to these with a technology is based on the use of a self-transporting GBS and a self-lifting precast concrete tower, suitable for depths in the 20-55m range. The main advantage of this technology is that it does not require the very large, scarce and expensive auxiliary means for transport or erection that are needed for alternative solutions, originating significant savings and increasing the scalability of the solution.
The project has built the first bottom fixed offshore wind turbine in Spain and southern Europe, and the first one in the world ever to be installed with no need for heavy-lift offshore vessels or cranes, in a ground breaking step which paves the way towards new capabilities for low cost deep offshore wind.
WP1 Project management:
During WP1, numerous meetings have taken place within ESTEYCO’s team as well as within the subcontractings, to control the achievement of the project’s schedule and deadlines (technical coordination); and to perform the financial and administrative tasks.
WP2 Design of the prototype foundation: This package covers the entire design of the foundation, following the requirements of the turbine manufacturer and the certification company.
WP3 Design of the auxiliary construction and installation means: WP3 describes and defines the special and/or new equipment and tools required during all the process of manufacturing and installation.
The results have been described in D3.1 which describes the construction project of the main auxiliary means, the project background, the design process and shows the drawings to be followed for the construction.
WP4 Construction of the prototype foundation: It covers the manufacturing of the prototype, starting in the excavation of the dry dock, construction of the base (bottom slab, wall, bulkheads, inner tube and top slab), casting of concrete pieces, assembly on top of the base and setup of the ballasting system.
During the first year of ELISA project, all the earth works were done (excavation, pumping system, compactation and foundations), H&S and quality plans were defined, and the first stage of prototype construction on dry-dock was finished two months ahead of schedule.
During the second year, the base was moved to the second position, in which it was finished (top slab assembly). Afterwards, the concrete pieces were transported to the harbor and assembled on top of it.
WP5 Installation of the prototype foundation.
The AFS is one of the main technologies to be demonstrated in this project and has required a substantial proportion of the total budget. Its objective is to provide stability to the structure during the ballasting process. This way, there is a reduction in the required material in the concrete structure. It was constructed in the Astican yard, in Las Palmas Port and then transported to Arinaga.
Esteyco has performed several test in the harbor, demonstrating the great naval behavior of the floating structure and the safety of the ballasting system, which has all its elements duplicated, in case of failure.
WP6 Monitoring, data post-processing and certification.
During the first year, the definition of the instrumentation and monitoring systems for the prototype foundation have taken place, choosing the sensors to be installed in the prototype foundation.
During the second year of the project, all the instruments of the prototype were supplied and installed. The data was obtained and analyzed, obtaining valuable knowledge on each element. This knowledge serves either to check that the engineering work has been accurate or to refine the hypothesis set in the beginning of the process.
In last place, during the first and second year of the project, the certification of the project has taken place, observing the complete achievement of the technical objectives of the monitoring and post processing of ESTEYCO’s solution.
WP7 Project dissemination paving the way to exploitation.
The specific objectives of this WP are the communication to target audience to establish agreements with strategic stakeholders for exploitation; dissemination in order to increase awareness on the new product and its functionalities compared to the best available technology (BAT) in order to highlight the significant advantages brought by ESTEYCO.
The new solution by ESTEYCO provides savings of approximately 30% in the installation costs, reducing the upfront investment for a wind farm. Moreover, it reduces considerably the maintenance costs, since concrete is much more durable than steel, and is a scalable solution, for turbines of any size and for depth range from 35 to 55 m.
Project beyond state of the art:
The new concept is based in a gravity based foundation configured to act as a buoyant platform during the transportation and installation processes. This concept integrates a self-installing telescopic tower altogether with the complete wind turbine.
ESTEYCO’s technology has been completed and qualified through test and demonstration in real environment, proving that ELISA will provide these improvements:
• Full independence of heavy-lift installation means
• Less work offshore, more work onshore
• Profit from the robustness, economy and durability of concrete
• Great economy
• Focus on a strong, competitive and less stressed supply chain
• Pre-casting for high industrialization and production capacity.
• Durability for extended service life of the infrastructure and improved asset integrity
Expected potential impact
This solution has avoided the dependence on any large auxiliary offshore crane or vessel, and allowing for industrialized on-shore focused construction and better risk control and mitigation.
The technology has contributed to the industrialization capacity and cost competitiveness of an industry which is key to provide EU with the capacity to generate large amounts of locally sourced renewable energy, which improves EU energy security and contributes to the gradual solving of global climate and energy challenges.
• Reducing life-cycle environmental impact
In last place, the demonstration of the prototype has also proved a direct impact in all the phases of the life-cycle considered:
1. The use of concrete as an economic proven material for robust and reliable marine constructions.
2. Greater durability and fatigue lifetime offer the opportunity for lifetime extensions and turbine repowering strategies for increased service life.
• Strengthening the European industrial technology base, thereby creating growth and jobs in Europe
A major part of the substructure shall use precast concrete, allowing for high production rates, as well as high industrialization and quality levels through prefabrication.
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