scholarly journals Comparison of Second-Order Loads on a Semisubmersible Floating Wind Turbine

2014 ◽  
Author(s):  
Sébastien Gueydon ◽  
Tiago Duarte ◽  
Jason Jonkman
Keyword(s):  
International Energy Agency ◽  
Oil And Gas Industry ◽  
Second Order ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Massachusetts Institute Of Technology ◽  
Commercial Development ◽  
Energy Agency ◽  
Slow Drift ◽  
Floating Platforms

As offshore wind projects move to deeper waters, floating platforms become the most feasible solution for supporting the turbines. The oil and gas industry has gained experience with floating platforms that can be applied to offshore wind projects. This paper focuses on the analysis of second-order wave loading on semisubmersible platforms. Semisubmersibles, which are being chosen for different floating offshore wind concepts, are particularly prone to slow-drift motions. The slack catenary moorings usually result in large natural periods for surge and sway motions (more than 100 s), which are in the range of the second-order difference-frequency excitation force. Modeling these complex structures requires coupled design codes. Codes have been developed that include turbine aerodynamics, hydrodynamic forces on the platform, restoring forces from the mooring lines, flexibility of the turbine, and the influence of the turbine control system. In this paper two different codes are employed: FAST, which was developed by the National Renewable Energy Laboratory, and aNySIM, which was developed by the Maritime Research Institute Netherlands. The hydrodynamic loads are based on potential-flow theory, up to the second order. Hydrodynamic coefficients for wave excitation, radiation, and hydrostatic forces are obtained with two different panel codes, WAMIT (developed by the Massachusetts Institute of Technology) and DIFFRAC (developed by MARIN). The semisubmersible platform, developed for the International Energy Agency Wind Task 30 Offshore Code Comparison Collaboration Continuation project is used as a reference platform. Irregular waves are used to compare the behavior of this platform under slow-drift excitation loads. The results from this paper highlight the effects of these loads on semisubmersible-type platforms, which represent a promising solution for the commercial development of the offshore deepwater wind resource.

scholarly journals Response of the IEA Wind 15 MW – WindCrete and Activefloat floating wind turbines to wind and second-order waves

2021 ◽  
Author(s):  
Mohammad Youssef Mahfouz ◽  
Climent Molins ◽  
Pau Trubat ◽  
Sergio Hernández ◽  
Fernando Vigara ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Reference Model ◽  
Numerical Models ◽  
International Energy Agency ◽  
Second Order ◽  
Offshore Wind ◽  
Wave Forces ◽  
Energy Agency ◽  
Floating Offshore Wind Turbines ◽  
Floating Platforms

Abstract. The EU Horizon 2020 project COREWIND has developed two floating platforms for the new International Energy Agency (IEA) Wind 15 MW reference model. One design – WindCrete – is a spar floater, and the other – Activefloat – is a semi-submersible floater. In this work the design of the floaters is introduced with their aero-hydro-servo-elastic numerical models, and the responses of both floaters in both static and dynamic simulations are verified against the operational and survival design limits. The static displacements and natural frequencies are simulated and discussed. Additionally, the effects of the mean wave drift forces, and difference second order wave forces on the systems' responses are presented. The increase in the turbine's power capacity to 15MW in IEA Wind model, leads to an increase in inertial forces and aerodynamic thrust force when compared to similar floating platforms coupled to the Danish Technical University (DTU) 10MW reference model. The goal of this work is to investigate the floaters responses at different load cases. The results in this paper suggest that at mild wave loads the motion responses of the 15MW Floating Offshore Wind Turbines (FOWT) are dominated by low frequency forces. Therefore, motions are dominated by the wind forces, and second order wave forces rather than the first order wave forces. After verifying and understanding the models' responses, the two 15MW FOWT reference numerical models are publicly available to be used in the research and development of floating wind energy.

scholarly journals Response of the International Energy Agency (IEA) Wind 15 MW WindCrete and Activefloat floating wind turbines to wind and second-order waves

2021 ◽  
Vol 6 (3) ◽  
pp. 867-883
Author(s):  
Mohammad Youssef Mahfouz ◽  
Climent Molins ◽  
Pau Trubat ◽  
Sergio Hernández ◽  
Fernando Vigara ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Numerical Models ◽  
International Energy Agency ◽  
Second Order ◽  
Offshore Wind ◽  
Wave Forces ◽  
Energy Agency ◽  
Frequency Wave ◽  
Floating Offshore Wind Turbines ◽  
Floating Platforms

Abstract. The EU Horizon 2020 project COREWIND (COst REduction and increase performance of floating WIND technology) has developed two floating platforms for the new International Energy Agency (IEA) Wind 15 MW reference wind turbine. One design – “WindCrete” – is a spar floater, and the other – “Activefloat” – is a semi-submersible floater; both designs are made of concrete. In this work the design of the floaters is introduced with their aero–hydro–servo-elastic numerical models, and the responses of both floaters in both static and dynamic simulations are investigated. The static displacements and natural frequencies are simulated and discussed. Additionally, the effects of the mean wave drift forces and second-order difference-frequency wave forces on the systems' responses are presented. The increase in the turbine's power capacity to 15 MW in IEA Wind model leads to an increase in inertial forces and aerodynamic thrust force when compared to similar floating platforms coupled to the Technical University of Denmark (DTU) 10 MW reference model. The goal of this work is to investigate the floaters' responses for different load cases. The results in this paper suggest that at mild wave loads the motion responses of the 15 MW floating offshore wind turbines (FOWTs) are dominated by low-frequency forces. Therefore, motions are dominated by the wind forces and second-order wave forces rather than the first-order wave forces. After assessing and understanding the models' responses, the two 15 MW FOWT numerical reference models are publicly available to be used in the research and development of floating wind energy.

scholarly journals Numerical Analysis of a Catenary Mooring System Attached by Clump Masses for Improving the Wave-Resistance Ability of a Spar Buoy-Type Floating Offshore Wind Turbine

2019 ◽  
Vol 9 (6) ◽  
pp. 1075 ◽  
Author(s):  
Zhenqing Liu ◽  
Yuangang Tu ◽  
Wei Wang ◽  
Guowei Qian
Keyword(s):  
Wind Turbine ◽  
International Energy Agency ◽  
Wave Resistance ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Induced Response ◽  
Mooring Lines ◽  
Energy Agency

The International Energy Agency (IEA), under the auspices of their Offshore Code Comparison Collaboration (OC3) initiative, has completed high-level design OC-3 Hywind system. In this system the wind turbine is supported by a spar buoy platform, showing good wave-resistance performance. However, there are still large values in the motion of surge degree of freedom (DOF). Addition of clump masses on the mooring lines is an effective way of reducing the surge motion. However, the optimization of the locations where the clump masses are added is still not clear. In this study, therefore, an in-house developed code is verified by comparing the results of the original OC3 model with those by FAST. The improvement of the performance of this modified platform as a function of the location of the clump masses has been examined under three regular waves and three irregular waves. In the findings of these examination, it was apparent that attaching clump masses with only one-tenth of the mass of the total mooring-line effectively reduces the wave-induced response. Moreover, there is an obvious improvement as the depth of the location where the clump masses mounted is increased.

Computation of Slowly Varying Second-Order Hydrodynamic Forces on Floating Structures in Irregular Waves

1989 ◽  
Vol 111 (3) ◽  
pp. 223-232 ◽  
Author(s):  
T. Matsui
Keyword(s):  
Velocity Potential ◽  
Near Field ◽  
Fluid Pressure ◽  
Hydrodynamic Forces ◽  
Second Order ◽  
Irregular Waves ◽  
Floating Structures ◽  
Slow Drift ◽  
Submerged Body ◽  
Element Technique

An exact second-order formulation is presented for computing the slowly varying second-order hydrodynamic forces on floating structures in irregular waves. The near-field approach based on direct integration of the fluid pressure on the submerged body surface is employed in conjunction with numerical first-order solutions by means of the hybrid finite element technique. Green’s second identity is exploited to evaluate the second-order forces due to the second-order velocity potential. Numerical results are presented for the slow drift excitation forces on an articulated column and a semi-submersible platform. It is shown that the contribution from the second-order velocity potential is more significant to the roll moment than to the sway and heave forces on the semi-submersible.

Offshore wind energy generation has huge potential

2019 ◽  
Keyword(s):  
Wind Energy ◽  
International Energy Agency ◽  
Offshore Wind ◽  
Offshore Wind Energy ◽  
Chinese Firms ◽  
Energy Agency ◽  
Content Type ◽  
Wind Energy Generation ◽  
Cost Reductions ◽  
Order Books

Subject Offshore wind costs and potential. Significance The International Energy Agency (IEA) released a report on October 25 estimating that offshore wind capacity will rise 15-fold over the next two decades. Costs have been falling ahead of expectations and further cost reductions will help the sector to build more momentum. Impacts North European turbine producers and wind project developers see huge export potential, but Chinese firms will provide stiff competition. Offshore construction vessels will support rising offshore wind deployment and help to bolster currently weak shipyard order books. Governments and regulators will create supportive policies for offshore wind, but this will occur gradually and differently across regions.

World Oil Industry: Forecasts of Development up to 2035

2013 ◽  
pp. 54-61
Author(s):  
N. Baykov
Keyword(s):  
Oil And Gas ◽  
International Energy Agency ◽  
Oil Industry ◽  
Oil And Gas Industry ◽  
Primary Energy ◽  
Department Of Energy ◽  
Energy Resources ◽  
Energy Agency ◽  
Gas Industry ◽  
Probable State

The fresh forecasts on the probable state of world oil and gas industry up to 2035 have appeared in late 2011. The article deals with the main points and conclusions of the available forecasts of the International Energy Agency and the U.S. Department of Energy, especially concerning supposed indicators of output and consumption of primary energy resources, primarily crude oil, in the whole world and with breakdown by regions.

scholarly journals Development and Verification of an Aero-Hydro-Servo-Elastic Coupled Model of Dynamics for FOWT, Based on the MoWiT Library

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1974
Author(s):  
Mareike Leimeister ◽  
Athanasios Kolios ◽  
Maurizio Collu
Keyword(s):  
Wind Turbine ◽  
International Energy Agency ◽  
Coupled Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
System Behavior ◽  
Energy Agency ◽  
Realistic Representation ◽  
Non Linear System ◽  
Fully Coupled

The complexity of floating offshore wind turbine (FOWT) systems, with their coupled motions, aero-hydro-servo-elastic dynamics, as well as non-linear system behavior and components, makes modeling and simulation indispensable. To ensure the correct implementation of the multi-physics, the engineering models and codes have to be verified and, subsequently, validated for proving the realistic representation of the real system behavior. Within the IEA (International Energy Agency) Wind Task 23 Subtask 2 offshore code-to-code comparisons have been performed. Based on these studies, using the OC3 phase IV spar-buoy FOWT system, the Modelica for Wind Turbines (MoWiT) library, developed at Fraunhofer IWES, is verified. MoWiT is capable of fully-coupled aero-hydro-servo-elastic simulations of wind turbine systems, onshore, offshore bottom-fixed, or even offshore floating. The hierarchical programing and multibody approach in the object-oriented and equation-based modeling language Modelica have the advantage (over some other simulation tools) of component-based modeling and, hence, easily modifying the implemented system model. The code-to-code comparisons with the results from the OC3 studies show, apart from expected differences due to required assumptions in consequence of missing data and incomplete information, good agreement and, consequently, substantiate the capability of MoWiT for fully-coupled aero-hydro-servo-elastic simulations of FOWT systems.

Assessing the Importance of the Slow Drift Motion of Floating Wind Turbine Platforms

2014 ◽  
Author(s):  
Richard C. Lupton ◽  
Robin S. Langley
Keyword(s):  
Wind Turbines ◽  
Diffraction Theory ◽  
Second Order ◽  
Offshore Wind ◽  
Offshore Platforms ◽  
Floating Structures ◽  
Drift Motion ◽  
Offshore Wind Turbines ◽  
Slow Drift ◽  
Slow Drift Motion

As offshore wind turbines are installed in deeper water, interest is growing in floating wind turbines because, among other reasons, they may become cheaper than fixed-bottom turbines at greater depths. When analysing floating wind turbines, linear diffraction theory is commonly used to model the hydrodynamic loads on the platform. While it well known that slow drift motion due to second-order loads can be important for other floating offshore platforms, it has not yet been established how important such effects are for floating wind turbines. In this paper we aim to give a general result by developing approximate closed-form expressions to estimate the second-order slow drift motion of platforms of different sizes. The values are bench-marked against a typical calculation of the slow-drift response of a platform. The results show that floating wind turbines, which tend to have smaller dimensions than other floating structures, may be expected to show smaller slow-drift motions.

scholarly journals Bichromatic Wave Selection for Validation of the Difference-Frequency Transfer Function for the OC6 Validation Campaign

2019 ◽  
Author(s):  
Nathan Tom ◽  
Amy Robertson ◽  
Jason Jonkman ◽  
Fabian Wendt ◽  
Manuela Böhm
Keyword(s):  
Nonlinear Wave ◽  
International Energy Agency ◽  
Low Frequency ◽  
Wave Interaction ◽  
Offshore Structures ◽  
Difference Frequency ◽  
Offshore Wind ◽  
Energy Agency ◽  
Validation Data ◽  
Irregular Wave

Abstract The focus of the Offshore Code Comparison Collaboration, Continuation, with Correlation and unCertainity (OC6) project, which operates under the International Energy Agency Wind Task 30, is to refine the accuracy of engineering tools used to design offshore wind turbines. In support of this work, a new validation campaign is being developed that seeks to better understand the nonlinear wave loading that excites floating wind systems at their low-frequency, rigid-body modes in surge and pitch. The validation data will be employed in a three-way validation between simplified engineering tools and higher-fidelity tools, such as computational fluid dynamics (CFD). Irregular wave spectrums, which are traditionally used to examine the nonlinear wave interaction with offshore structures, are too computationally expensive to be simulated in CFD tools, and so we will employ bichromatic wave cases instead. This paper reviews the process used to choose the bichromatic wave pairs to be applied in the campaign to validate the second-order difference-frequency quadratic and potential loads at the surge and pitch natural frequencies of a floating semisubmersible.

Petroleum production and development across Australia 2017

2018 ◽  
Vol 58 (2) ◽  
pp. 469
Author(s):  
Graeme Bethune ◽  
Susan Bethune
Keyword(s):  
Oil And Gas ◽  
International Energy Agency ◽  
Oil And Gas Industry ◽  
Gas Production ◽  
Petroleum Exploration ◽  
The West ◽  
Energy Agency ◽  
Gas Industry ◽  
Oil And Gas Production ◽  
Short Supply

This Petroleum Exploration Society of Australia review looks in detail at the trends and highlights for oil and gas production and development both onshore and offshore Australia during 2017. Gas production soared while oil production plummeted yet again. Liquefied natural gas (LNG) did well; 2017 was a great year for LNG and 2018 should be even better. There are stark contrasts between domestic gas on the west and east coasts. On the west coast, prices are affordable and supply relatively plentiful. On the east, prices are high and gas is in short supply. This paper canvasses these trends and makes conclusions about the condition of the oil and gas industry in Australia. This paper relies primarily on production and reserves data compiled by EnergyQuest. In its latest review of Australian energy policy, the International Energy Agency comments yet again on the weaknesses of Australian oil and gas statistics. This paper also makes some observations on these weaknesses.

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