Joint Distribution of Environmental Condition at Five European Offshore Sites for Design of Combined Wind and Wave Energy Devices

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Lin Li ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Renewable Energy ◽  
Wave Energy ◽  
Environmental Data ◽  
Offshore Wind ◽  
Response Analysis ◽  
Energy Devices ◽  
Joint Distributions ◽  
Wave Parameters ◽  
Extreme Response

The design of wind turbines requires information about joint data for wind and wave conditions. Moreover, combining offshore wind and wave energy facilities is a potential way to reduce the cost of offshore wind farms. To design combined offshore renewable energy concepts, it is important to choose sites where both wind and wave energy resources are substantial. This paper deals with joint environmental data for five European offshore sites which serve as basis for the analysis and comparison of combined renewable energy concepts developed in the EU FP7 project—MARINA Platform. The five sites cover both shallow and deep water, with three sites facing the Atlantic Ocean and two sites in the North Sea. The long-term joint distributions of wind and wave parameters are presented for these sites. Simultaneous hourly mean wind and wave hindcast data from 2001 to 2010 are used as a database. The joint distributions are modeled by fitting analytical distributions to the hindcast data. The long-term joint distributions can be used to estimate the wind and wave power output from each combined concept and to estimate the fatigue lifetime of the structure. The marginal distributions of wind and wave parameters are also provided. Based on the joint distributions, contour surfaces are established for combined wind and wave parameters for which the probability of exceedance corresponds to a return period of 50 years. The design points on the 50-year contour surfaces are suggested for extreme response analysis of combined concepts.

scholarly journals Joint Environmental Data at Five European Offshore Sites for Design of Combined Wind and Wave Energy Devices

2013 ◽  
Author(s):  
Lin Li ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Renewable Energy ◽  
Deep Water ◽  
Wave Energy ◽  
Environmental Data ◽  
Energy Resources ◽  
Offshore Wind ◽  
Wave Power ◽  
Joint Distributions ◽  
Wave Parameters

The costs for an offshore wind farm, especially with bottom fixed foundations increase significantly with increasing water depth. If costs can be reduced to a competitive level, the potential for wind farms in deep water is huge. One way of reducing costs might be to combine offshore wind with wave energy facilities at sites where these resources are concentrated. In order to design combined renewable energy concepts, it is important to choose sites where both wind and wave energy resources are substantial. Such facilities might be designed in ultimate limit states based on load effects corresponding to 50-year wind and wave conditions. This requires a long-term joint probabilistic model for the wind and wave parameters at potential sites. In this paper, five European offshore sites are selected for analysis and comparison of combined renewable energy concepts developed in the EU FP7 project – MARINA Platform. The five sites cover both shallow water (<100m) and deep water (> 200m), with three sites facing the Atlantic Ocean and the other two sites in the North Sea. The selection of the sites is carried out by considering average wind and wave energy resources, as well as extreme environmental conditions which indicate the cost of the system. Long-term joint distributions of mean wind speed at 10-meter height (Uw), significant wave height (Hs) and spectral peak period (Tp) are presented for selected sites. Simultaneous hourly wind and wave hindcast data from 2001–2010 are used as a database, which are obtained from the National and Kapodistrian University of Athens. The joint distributions are estimated by fitting analytical distributions to the hindcast data following a procedure suggested by Johannessen et al. (2001). The long-term joint distributions can be used to estimate the wind and wave power output from each combined concept, and to estimate the fatigue lifetime of the structure. For estimation of the wind and wave power separately, the marginal distributions of wind and wave are also provided. Based on the joint distributions, contour surfaces are established for combined wind and wave parameters for which the probability of exceedance corresponds to a return period of 50 years. The design points on the 50-year contour surfaces are suggested for extreme response analysis of combined concepts. The analytical long-term distributions established could also be applied for design analysis of other offshore structures with similar environmental considerations of these sites.

Long-term extreme response analysis for semi-submersible platform mooring systems

2020 ◽  
pp. 147509022097651
Author(s):  
Yuliang Zhao ◽  
Sheng Dong
Keyword(s):  
Environmental Data ◽  
Distribution Model ◽  
Response Analysis ◽  
Accurate Assessment ◽  
Response Distribution ◽  
Short Term ◽  
Floating Structure ◽  
Extreme Response ◽  
Term Analysis

The accurate assessment of long-term extreme responses of floating-structure mooring system designs is important because of small failure probabilities caused by long-term and complex ocean conditions. The most accurate assessment would involve considering all conceivable sea states in which each sea state is regarded as a stochastic process and performing nonlinear time-domain numerical simulations of mooring systems to estimate the extreme response from a long-term analysis. This procedure would be computationally intensive because of the numerous short-term sea states involved. Here, a more feasible approach to evaluate the long-term extreme response is presented through immediate integration combined with Monte Carlo simulations. A parameter fitting procedure of the short-term extreme response distribution under irregular wave conditions is employed to solve the long-term response integration. Case studies were conducted on a semi-submersible platform using environmental data measurements of the Gulf of Mexico and a joint distribution model of the environmental parameters was considered. This approach was observed to be effective and the results were compared with those of traditional methodologies (univariate extreme value design and environmental contour methods). The differences were reflected using a reliability analysis of mooring lines, which indicated that the design standards must be stricter when using long-term analysis.

scholarly journals Extended Environmental Contour Methods for Long-Term Extreme Response Analysis of Offshore Wind Turbines1

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Xiaolu Chen ◽  
Zhiyu Jiang ◽  
Qinyuan Li ◽  
Ye Li ◽  
Nianxin Ren
Keyword(s):  
Turbulence Intensity ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Contour Method ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Modified Method ◽  
Extreme Response ◽  
Wind Turbulence

Abstract Environmental contour method is an efficient method for predicting the long-term extreme response of offshore structures. The traditional environmental contour is obtained using the joint distribution of mean wind speed, significant wave height, and spectral peak period. To improve the accuracy of traditional environmental contour method, a modified method was proposed considering the non-monotonic aerodynamic behavior of offshore wind turbines. Still, the modified method assumes constant wind turbulence intensity. In this paper, we extend the existing environmental contour methods by considering the wind turbulence intensity as a stochastic variable. The 50-year extreme responses of a monopile-based offshore wind turbine are compared using the extended environmental contour methods and the full long-term method. It is found that both the environmental contour method and the modified environmental contour method, with the wind turbulence intensity included as an individual variable, give more accurate predictions compared with those without. Using the full long-term method as a benchmark, this extended approach could reduce the nonconservatism of the environmental contour method and conservatism of the modified environmental contour method. This approach is effective under wind-dominated or combined wind-wave loading conditions, but may not be as important for wave-dominated conditions.

On the Long-Term Reliability Analysis of a Point Absorber Wave Energy Converter

2017 ◽  
Author(s):  
Jarred Canning ◽  
Phong Nguyen ◽  
Lance Manuel ◽  
Ryan G. Coe
Keyword(s):  
Wave Energy ◽  
Reference Model ◽  
Wave Energy Converter ◽  
Environmental Data ◽  
Energy Converter ◽  
Short Term ◽  
Point Absorber ◽  
Extreme Response ◽  
Term Response

Of interest in this study is the long-term response and performance of a two-body wave point absorber (“Reference Model 3”), which serves as a wave energy converter (WEC). In a previous study, the short-term uncertainty in this device’s response was studied for an extreme sea state. We now focus on the assessment of the long-term response of the device where we consider all possible sea states at a site of interest. We demonstrate how simulation tools may be used to evaluate the long-term response and consider key performance parameters of the WEC device, which are the heave and surge forces on the power take-off system and the power take-off extension. We employ environmental data at a designated deployment site in Northern California. Metocean information is generated using approximately 15 years of data from this site (National Data Buoy Center site no. 46022). For various sea states, a selected significant wave height and peak period are chosen to describe representative conditions. Then, using a public-domain simulation tool (Wave Energy Converter Simulator or WEC-Sim), we generate various short-term time-domain response measure for these sea states. Distribution fits to extreme response statistics are generated, for each bin that represents a cluster of sea states, using the open-source toolbox, WDRT (WEC Design Response Toolbox). Long-term distributions for each response variable of interest are estimated by weighting short-term distributions by the likelihood of the sea states; from these distributions, the 50-year response can be derived. The 50-year response is also estimated using an approximate but more efficient inverse reliability approach. Comparisons are made between the two approaches.

scholarly journals Hydrodynamic Response of a Combined Wind–Wave Marine Energy Structure

2020 ◽  
Vol 8 (4) ◽  
pp. 253 ◽  
Author(s):  
Yapo Wang ◽  
Lixian Zhang ◽  
Constantine Michailides ◽  
Ling Wan ◽  
Wei Shi
Keyword(s):  
Renewable Energy ◽  
Wave Energy ◽  
Offshore Wind ◽  
Hydrodynamic Performance ◽  
Energy Structure ◽  
Marine Energy ◽  
Floating Offshore Wind Turbines ◽  
Central Column ◽  
Combined Structure ◽  
Heave Motion

Due to the energy crisis and greenhouse effect, offshore renewable energy is attracting increasing attention worldwide. Various offshore renewable energy systems, such as floating offshore wind turbines (FOWTs), and wave energy converters (WECs), have been proposed and developed so far. To increase power output and reduce related costs, a combined marine energy structure using FOWT and WEC technologies has been designed, analyzed and presented in the present paper. The energy structure combines a 5-MW braceless semisubmersible FOWT and a heave-type WEC which is installed on the central column of the semisubmersible. Wave power is absorbed by a power take-off (PTO) system through the relative heave motion between the central column of the FOWT and the WEC. A numerical model has been developed and is used to determine rational size and draft of the combined structure. The effects of different PTO system parameters on the hydrodynamic performance and wave energy production of the WEC under typical wave conditions are investigated and a preliminary best value for the PTO’s damping coefficient is obtained. Additionally, the effects of viscous modeling used during the analysis and the hydrodynamic coupling on the response of the combined structure are studied.

Analysis of Environmental Conditions for the Conceptual Design of a 200 MW Floating Offshore Wind Farm in the East Sea, Korea

2019 ◽  
Author(s):  
Hyunkyoung Shin ◽  
Youngjae Yu ◽  
Thanh Dam Pham ◽  
Hyeonjeong Ahn ◽  
Byoungcheon Seo ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Wind Energy ◽  
Environmental Conditions ◽  
Early Stage ◽  
Measurement Data ◽  
Reanalysis Data ◽  
Offshore Wind ◽  
East Sea ◽  
Wind Resource

Abstract Due to global climate change, concern regarding the environment is greater than ever. Also, the energy industry is constantly developing and investing in new and renewable energy to reduce carbon emissions. Korea is planning to increase the proportion of renewable energy generation to 20% by 2030, in accordance with the 3020 renewable energy policy. This will involve 16.5 GW (34%) from wind energy, with a capacity from offshore wind energy of approximately 13 GW. Considering domestic technological wind resource potential (33.2 GW), it seems to be a sufficient target amount. However, in order to start the wind power generation business, the installation area must be analyzed for environmental information, for the evaluation of the wind resource and the early-stage concept design. Because it is difficult to conduct long-term measurements of the entire sea area, the environmental conditions are generally estimated from short-term measurement data and long-term reanalysis data. In this study, the environmental conditions of the East Sea of Korea were selected, and a comparative analysis was performed on the meteorological agency’s oceanic meteorology buoy data, ERA-5 reanalysis data obtained from ECMWF, and NASA’s MERRA-2 data. The extreme sea states of 50 years and 100 years were analyzed by extreme statistical analysis. Finally, environmental conditions required for the basic design of wind turbines were selected following IEC and DNV standards.

Coordinators Overview and Lessons Learned From the Galway Bay Seatrials of the FP7 EU Funded CORES Wave Energy Project

2013 ◽  
Author(s):  
Raymond Alcorn ◽  
Anthony Lewis ◽  
Mark Healy
Keyword(s):  
Renewable Energy ◽  
Wave Energy ◽  
Energy Systems ◽  
Project Manager ◽  
Lessons Learned ◽  
Ocean Energy ◽  
Renewable Energy Systems ◽  
Energy Devices ◽  
Ocean Renewable Energy ◽  
The Coordinator

The paper discusses the lessons learned from the European Funded Framework 7 Research project Components for Ocean Renewable Energy Systems (CORES) which developed and trialed new components and systems for ocean energy devices. The authors are the coordinator and project manager so the paper will give this overview of the project. This will include detail of the work packages, major achievements, significant impacts, summary results and outcomes of the sea trials.

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