scholarly journals Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1995
Author(s):  
Alexandre Mathern ◽  
Christoph von der Haar ◽  
Steffen Marx
Keyword(s):  
Wind Turbines ◽  
Wind Farms ◽  
Steel Structures ◽  
Production Costs ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Future Trends ◽  
Support Structures ◽  
Offshore Wind Farms ◽  
New Developments

Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.

Seismic Design for Offshore Wind Farms – Lessons Learnt From the ACE Joint Industry Project

2021 ◽  
Author(s):  
Marcus Klose ◽  
Junkan Wang ◽  
Albert Ku
Keyword(s):  
Seismic Design ◽  
Wind Turbines ◽  
Wind Farms ◽  
The United States ◽  
Offshore Wind ◽  
Seismic Load ◽  
Support Structures ◽  
Offshore Wind Farms ◽  
Asian Pacific Region ◽  
The Impact

Abstract In the past, most of the offshore wind farms have been installed in European countries. In contrast to offshore wind projects in European waters, it became clear that the impact from earthquakes is expected to be one of the major design drivers for the wind turbines and their support structures in other areas of the world. This topic is of high importance in offshore markets in the Asian Pacific region like China, Taiwan, Japan, Korea as well as parts of the United States. So far, seismic design for wind turbines is not described in large details in existing wind energy standards while local as well as international offshore oil & gas standards do not consider the specifics of modern wind turbines. In 2019, DNV GL started a Joint Industry Project (JIP) called “ACE -Alleviating Cyclone and Earthquake challenges for wind farms”. Based on the project results, a Recommended Practice (RP) for seismic design of wind turbines and their support structures will be developed. It will supplement existing standards like DNVGL-ST-0126, DNVGL-ST-0437 and the IEC 61400 series. This paper addresses the area of seismic load calculation and the details of combining earthquake impact with other environmental loads. Different options of analysis, particularly time-domain simulations with integrated models or submodelling techniques using superelements will be presented. Seismic ground motions using a uniform profile or depth-varying input profile are discussed. Finally, the seismic load design return period is addressed.

An Assessment of Structural Design Guidelines for Offshore Wind Turbines

2007 ◽  
Author(s):  
Rakesh K. Saigal ◽  
Dan Dolan ◽  
Armen Der Kiureghian ◽  
Tim Camp ◽  
Charles E. Smith
Keyword(s):  
Renewable Energy ◽  
Wind Turbine ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Guidance Document ◽  
Support Structures ◽  
Design Standards ◽  
Offshore Wind Farms ◽  
Design Requirements

This paper addresses the need for U.S. standards to establish design requirements for offshore wind turbine support structures. There are wind power resources in U.S. waters that can be developed to generate substantial amounts of clean, renewable energy. While a number of offshore wind farms have been proposed for U.S. waters none have been built. The U.S. Minerals Management Service and the National Renewable Energy Laboratory have recently commissioned a study to compare and benchmark the International Electrotechnical Commission (IEC) design standards with the American Petroleum Institute (API) recommended practices. Offshore wind farms that are operating in Europe have been designed using standards developed specifically for offshore wind, such as those developed by Germanischer Lloyd (GL) and Det Norske Veritas (DNV). The IEC has recently drafted design requirements specifically for offshore wind farms that provides a comprehensive definition of load conditions and references other standards, where needed, to provide a complete guidance document. The intent of this paper is to examine the range of applicability of the various design standards and to assess how these standards apply to the design of U.S. offshore wind turbine (OWT) support structures.

Optimization of O&M for Offshore Wind Farms Modelling for WMTC Conferences

2015 ◽  
Author(s):  
Thomas Nivet ◽  
Ema Muk-Pavic
Keyword(s):  
Wind Farm ◽  
Wind Farms ◽  
Cost Effective ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Farms ◽  
Climate Conditions ◽  
Operation Analysis ◽  
Cost Effective Approach ◽  
Failure Evaluation

Offshore wind energy is one of the most upcoming sources of energy, and it is already partially replacing the fossil fuelled power production. However, offshore wind turbine technology is also associated with harsher weather environment. Indeed, it experiences more challenging wind and wave conditions, which in turn limits the vessels capabilities to access the wind farms. Additionally, with the constant rise of power utilization, improvements in the Operation Maintenance (O&M) planning are crucial for the development of large isolated offshore wind farms. Improvements in the planning of the O&M for offshore wind farms could lead to considerable reduction in costs. For this reason, the interest of this research paper is the investigation of the most cost effective approach to offshore turbine maintenance strategies. This objective is achieved by implementing a simulation approach that includes a climate conditions analysis, an operation analysis, a failure evaluation and a simulation of the repairs. This paper points out how different O&M strategies can influence the sustainability of a wind farm.

Value of site-specific information for the design of offshore wind farms

2019 ◽  
Author(s):  
Jorge Mendoza Espinosa ◽  
Jochen Köhler
Keyword(s):  
Safety Margin ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Specific Information ◽  
Offshore Wind Farms ◽  
Site Specific ◽  
A Value ◽  
Probabilistic Characterization ◽  
Clear Guideline

<p>Monopiles are the most common offshore wind turbine support structures. They are to be designed so that resonance with the rotor-passing excitation is avoided. However, the estimation of the eigenfrequencies is strongly influenced by the soil-structure interaction, whose characterization with prior information is associated with large uncertainties. No clear guideline is given regarding the safety margin to be left between the structure first natural frequency and the excitation regions. In this paper, the expected consequences of leaving a certain margin are studied and quantified. The decisions regarding the investment in site-specific characterization are coupled into the decision scenario by means of a value of information analysis. The results provide insight on the efficient allocation of resources at the design point in time and the sensitivity of the decisions regarding the probabilistic characterization of the design scenario.</p>

Fatigue Life Analysis of Offshore Wind Turbine Support Structures in an Offshore Wind Farm

2018 ◽  
Author(s):  
Bryan Nelson ◽  
Yann Quéméner
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farm ◽  
The Body ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Analysis Tool ◽  
Support Structures ◽  
Offshore Wind Farm ◽  
Actuator Disk

This study evaluated, by time-domain simulations, the fatigue lives of several jacket support structures for 4 MW wind turbines distributed throughout an offshore wind farm off Taiwan’s west coast. An in-house RANS-based wind farm analysis tool, WiFa3D, has been developed to determine the effects of the wind turbine wake behaviour on the flow fields through wind farm clusters. To reduce computational cost, WiFa3D employs actuator disk models to simulate the body forces imposed on the flow field by the target wind turbines, where the actuator disk is defined by the swept region of the rotor in space, and a body force distribution representing the aerodynamic characteristics of the rotor is assigned within this virtual disk. Simulations were performed for a range of environmental conditions, which were then combined with preliminary site survey metocean data to produce a long-term statistical environment. The short-term environmental loads on the wind turbine rotors were calculated by an unsteady blade element momentum (BEM) model of the target 4 MW wind turbines. The fatigue assessment of the jacket support structure was then conducted by applying the Rainflow Counting scheme on the hot spot stresses variations, as read-out from Finite Element results, and by employing appropriate SN curves. The fatigue lives of several wind turbine support structures taken at various locations in the wind farm showed significant variations with the preliminary design condition that assumed a single wind turbine without wake disturbance from other units.

scholarly journals Stability Analysis of the Floating Offshore Wind Turbine Support Structure of Cell Spar Type during its Installation

2019 ◽  
Vol 26 (4) ◽  
pp. 109-116
Author(s):  
Paweł Dymarski ◽  
Czesław Dymarski ◽  
Ewelina Ciba
Keyword(s):  
Stability Analysis ◽  
Wind Farms ◽  
Offshore Wind ◽  
Design And Technology ◽  
Offshore Wind Turbine ◽  
Ocean Engineering ◽  
Support Structure ◽  
Offshore Wind Farms ◽  
University Of Technology ◽  
The Stability

Abstract The article presents the results of selected works related to the wider subject of the research conducted at the Faculty of Ocean Engineering and Ship Technology of the Gdansk University of Technology, which concerns design and technology of construction, towing, and settlement on the seabed, or anchoring, of supporting structures for offshore wind farms. As a result of this research, several designs of this type of objects were developed, including two stationary types: gravitational and Jack-up, which are placed on the seabed, and two floating types: TLP and SPAR, anchored with tendons and anchors in the form of nailed or suction piles. Below presented is the stability analysis of the new floating CELL SPAR type support structure for offshore wind turbines during its installation in waters with a depth of over 65 m.

scholarly journals Numerical Study of a Proposed Semi-Submersible Floating Platform with Different Numbers of Offset Columns Based on the DeepCwind Prototype for Improving the Wave-Resistance Ability

2019 ◽  
Vol 9 (6) ◽  
pp. 1255
Author(s):  
Zhenqing Liu ◽  
Yicheng Fan ◽  
Wei Wang ◽  
Guowei Qian
Keyword(s):  
Wind Turbines ◽  
Numerical Study ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Offshore Wind Turbines ◽  
Irregular Wave ◽  
Decay Test ◽  
Floating Offshore Wind Turbines

DeepCwind semi-submersible floating offshore wind turbines have been widely examined, and in some countries this type of floating offshore wind turbine has been adopted in the construction of floating wind farms. However, the DeepCwind semi-submersible floating offshore wind turbines still experience large surge motion that limits their operational time. Therefore, in this study, a semi-submersible floating platform with different numbers of offset columns, but with the same total weight, based on the DeepCwind prototype is proposed. From the free-decay test, it was found that the number of the floating columns will affect the natural frequency of the platform. Furthermore, the regular wave test in the time domain and the irregular wave test in the frequency domain show that increasing the number of the floating columns will reduce the surge motion greatly, while the effects in the heave and pitch motions are not obvious.

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