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In floating wind systems, turbines are built on a steel-and-concrete floating foundation that is tethered to the ocean floor. Compared to fixed wind platforms, floating structures allow operators to generate wind power in deeper waters; the downside is that costs are higher when heavy foundation parts must be shipped at least 30 miles away from a coast. Purdue University engineers are researching ways to make these parts out of 3D-printed concrete, a less expensive material that would also allow parts to float to a site from an onshore plant. This technique reduces cost, improves quality and design flexibility, and eliminates conventional manufacturing limitations. The Purdue researchers are working with RCAM Technologies, a startup founded to develop concrete additive manufacturing for onshore and offshore wind energy technology.
Driven by the evidence of climate change many governments have decided to reduce carbon emissions associated with the production of electricity. Hence, there has been an increase in the use of renewable energy. Additional benefits include moving towards an energy supply which is more sustainable and more distributed. International targets for decarbonisation of the economy have been agreed at COP21 meetings in Paris in 2015. Of the renewable electricity technologies available, offshore wind allows electricity to be generated at scale and at a reasonable price (as can be seen from the second round of UK contract for difference see [
Offshore Wind (OSW) is rapidly maturing sector and is increasingly seen as a major contributor to electricity supply in states with coastal demand centres and good wind resource. While there is a 28-year history and set of experiences that has been learned in the European theatre, the U.S. is only recently beginning to move forward with grid scale projects. The U.S. Department of the Interior's Bureau of Ocean and Energy Management (BOEM) has, to date, leased fifteen Wind Energy Areas (WEAs) to developers along the eastern continental shelf of the U.S which to date have auctioned for a total of over $472 million [
The history of offshore wind power has included some notable hurdles and set-backs. Where these were due to fundamentals of design or analysis, large fleets of offshore assets were affected. Examples include failures of gearboxes, grounted connections and accelerated blade surface erosion. As floating wind is scaled up, to minimise similar exposure to technical risks, formal processes will help to identify the novel features, novel applications and components with the highest risk. Assumptions about suitability of existing onshore or offshore technical solutions must be challenged. Also care must be taken when using demonstration projects comprising single units as the basis for scaling up technologies. Currently, although monitored and scrutinised so as to be proven technically, these have comprised small-scale wind farms, under experimental conditions.
Multi-turbine floating offshore platforms (MUFOPs) are emerging as a viable concept for reducing levelized cost of energy in offshore wind developments. If properly designed, the cost per megawatt of electric power generated can be lower compared to single-turbine platforms. To maximize yield, minimize cost and ensure a safe design, the spacing between rotor-nacelle assemblies (RNAs), must be carefully considered. This spacing (R), is the sum of the platform column spacing (c), and tower horizontal projected length (h). Rotor diameters pose considerable challenges to the arrangement of multiple wind turbines on one platform; challenges pertaining to safe operations, feasibility of construction and transportation. Specific insights are necessary to facilitate the development of viable concepts. The parametric study presented in this paper discusses the optimization of MUFOPs using tower inclination and column spacing.
Representative configurations (adjusting tower inclination and / or column spacing) are developed with a multi-turbine semi-submersible-type platform and analyzed in time domain using coupled analysis. The configurations consist of two 5 WM reference turbines of the National Renewable Energy Laboratory (NREL), U.S.A. A non-dimensional parameter (R/c), is used to characterize the configurations. Wind, wave, and current loads are applied in analysis to assess the behavior of the system holistically. Hydrodynamic, aerodynamic, elasto-dynamic, servo-dynamic and mooring-dynamic effects are captured interactively at each time-step of analysis. An operational turbine condition is simulated in analysis using full-field turbulent wind to capture spatial variations of wind loads acting on each turbine of the system.
Characteristic responses of the nacelle, tower and platform are assessed to determine the optimal combination which avoids both inadequate and excessively conservative designs of multi-wind-turbine platforms. By analyzing the spectral densities of the responses, the potential impact of the observed responses on fatigue design is qualified. Optimal configurations from the scenarios considered, allow minimal or no wake interactions, tolerable towerbase loads and acceptable accelerations and motions of the nacelle and platform. Results indicate that optimal solutions exist at R/c ratios greater than 1.0.
An assessment of a range of tower inclinations and column spacing for optimal design of multi-wind-turbine platforms is a study that has not been documented in literature, and deserves attention considering current industry trends for floating offshore wind turbines. This paper offers significant insights on the characteristics of optimal tower and column arrangements for such platforms and provides reliable benchmarks for future designs.
Over the last few years, the oil and gas industry has been challenged by prolonged volatile hydrocarbon prices and market instability. As a direct consequence of these challenging conditions, the industry has experienced a shift of focus to the development and application of more advanced and efficient technologies.
One of the most revolutionary subsea technological developments implemented in the latest years has been the subsea compression system installed at the Åsgard field, located offshore Norway. It has successfully been in continuous operation since September 2015. This has proven the feasibility of installing a compressor on the seabed, and at the same time verified a large number of power and control system technologies required for the control and operation of the subsea compressor. This includes large subsea transformers, power cables and terminations and high voltage wet-mate connectors, all of which are essential technologies for subsea substations for offshore wind application.
Today, the rapidly expanding offshore wind power industry could benefit from utilizing some of these high voltage power techonlogies recently qualified for subsea oil and gas processing applications. Many of the subsea power technological developments, skills and expertise gained in the oil and gas industry can be adapted for offshore wind application.
This paper presents the concept of a subsea high voltage substation applied to floating offshore wind parks. Both the system characteristics and the individual power technology features that are required to make the substation compact, efficient and reliable are emphasized. In addition, the differences and benefits of a subsea substation versus a floating substation will be highlighted.
In 2017 the authors conducted an experimental hydro-aero-dynamic (station-keeping) campaign in MARIN's Offshore Basin aimed at validating its floating offshore wind turbine simulation tools. Since wind turbine dynamics cannot be readily downscaled in presence of Froude-scaled hydrodynamics, a bespoke coupling approach was developed. This was based on real-time load actuation using a winch system jointly with simulation software running on a data feed from the basin acquisition system. The result was a softwarein-the-loop experimental setup allowing to introduce controlled aerodynamic loading in the tests based on both the model's live response and simulated turbine physics. The software involved in this campaign, specifically developed for this task, is a customised version of NREL FAST, a standard open-source wind turbine simulator. Software-in-the-loop strategy emerges as a viable option to introduce multi-physical coupling in floating wind turbine tests in a controlled way.
Floating offshore wind turbine technology, much of it developed domestically, is rapidly advancing and is in the early implementation phase, while floating substation technology is still at an early development stage. This study presents novel floating wind power substation platform designs for deepwater wind farm applications. Two types of floating substations configurations are considered to compare technical and cost performance: a semi-type "X-WindStation" and a TLP-type "TX-WindStation". The floating substation platforms are considered for a 200 MW wind farm located in 100 m (328 ft) water depth off the Northeast coast of the United States. The floating substation supports a two-deck electrical power facility that provides sufficient electrical power equipment layout area and includes temporary quarters. Both floating substation platforms are evaluated for global performance and mooring systems (catenary for semi-type and tendon for TLP-type) with the site design metocean conditions for the extreme and survival storm seas. The results are assessed in accordance with industry standards ABS and API, and offshore engineering practices. Capital expenditure (CAPEX) of both substation platforms for a 200 MW farm is estimated by including the electrical substation, platform hull, mooring lines, anchors, integration, installation and commissioning costs. Installed CAPEX costs of the platforms show that the semi-type substation platform cost is lower than the TLP-type cost for the case where each tendon has a dedicated anchor, whereas the cost for the TLPtype with two tendons sharing an anchor is highly comparable to, if not less than, the semi-type platform.
In 2017 the authors conducted an experimental hydro-aero-dynamic (station-keeping) campaign in MARIN's Offshore Basin aimed at validating its floating offshore wind turbine simulation tools. Since wind turbine dynamics cannot be readily downscaled in presence of Froude-scaled hydrodynamics, a bespoke coupling approach was developed. This was based on real-time load actuation using a winch system jointly with simulation software running on a data feed from the basin acquisition system. The result was a software-in-the-loop experimental setup allowing to introduce controlled aerodynamic loading in the tests based on both the model's live response and simulated turbine physics. The software involved in this campaign, specifically developed for this task, is a customised version of NREL FAST, a standard open-source wind turbine simulator. Software-in-the-loop strategy emerges as a viable option to introduce multi-physical coupling in floating wind turbine tests in a controlled way.
Li, Jiawen (Dalian Maritime University) | Hu, Guanqing (Dalian University of Technology) | Jin, Guoqing (Dalian University of Technology) | Sun, Zhendong (Dalian University of Technology) | Zong, Zhi (Dalian University of Technology) | Jiang, Yichen (Dalian University of Technology)
A novel semi-submersible platform, referred to as HexaSemi, is proposed with a completely new designed heave plate. Compared with the WindFloat-type design, the new heave plate has a single hexagonal shape with a moonpool. From a structural point of view, its integral design can increase the integrity of the structure. In this paper, we mainly study its hydrodynamic performance for an offshore wind turbine. A numerical model is set up to simulate the motion characteristics of the floating wind turbine system, based on WADAM, Star-CCMC, and FAST. The comparative analysis of HexaSemi and WindFloat-type platforms under the storm condition is conducted and discussed. It is found that the integral design can increase the viscous hydrodynamic damping and reduce the heave response and the mooring cable force.
Offshore wind energy is a kind of clean, abundant, and renewable resource, and it has become one of the most promising power generation methods in new energy (Karimirad, 2013). Compared with the land and shallow water, the deep-water areas have the advantages of steadier and stronger wind speed. Therefore, it is an inevitable trend for future wind farms to develop from the fixed type in shallow water to the floating type in deep sea (Gao et al., 2010). The semi-submersible platform is characterized by its small draft combined with hydrostatic stability during installation and substantial waterplane restoring. The structure stability is the foundation of the safe operation of the floating offshore wind turbine. One of the common challenges to the design of floating offshore wind turbine (FOWT) is the ability to predict the dynamic load responses of the coupled wind turbine and platform system, which usually combines a wind loading wave and a stochastic wave (Jonkman, 2010; Tran and Kim, 2015). It is necessary to study the dynamic response of the floating platform under the loading of the marine environment.
Fan, Ting-Yu (Institute of Nuclear Energy Research) | Lin, Chin-Yu (Institute of Nuclear Energy Research) | Huang, Chin-Cheng (Institute of Nuclear Energy Research) | Chu, Tung-Liang (Institute of Nuclear Energy Research)
In this study, time-domain fatigue analyses of multi-planar tubular joints for a jacket-type substructure of offshore wind turbines designed for Taiwan’s local environmental conditions are performed. The potential design load cases could affect the overall calculation procedure. A series of fatigue loads from the IEC 61400-3 standard were calculated to investigate the dominant design load cases and to improve the load calculation efficiency. The stress distributions of tubular joints are computed by finite element analysis to determine the stress concentration factors. The results show that the fatigue damage caused by the power production design scenario accounts for the total cumulative fatigue damage up to 90%. This work, in addition to more efficient load calculation procedure, will be helpful for cost assessment and could accelerate the development of offshore wind farms in Taiwan.
Because of global warming and climate change, using renewable energy has become an inevitable substitute for fossil fuel and coal power. Wind power is one of the most promising renewable energy utilizations, providing an essential contribution to a clean, robust, and diversified energy portfolio. In Taiwan, the government’s reiteration of the target is that 20% of the country’s electricity will come from renewable energy by 2025, with wind power generation accounting for 15% of the renewable energy. In 2017, the first two offshore wind turbines of the 128 MW Formosa 1 Project, each a 4 MW machine, were installed, and the total installed capacity for offshore wind is predicted to reach 5.5 GW by 2025.
Wood has agreed to a deal with Equinor to perform modifications to two platforms in the Norwegian North Sea (Snorre A and Gullfaks A) that are set to receive electric power from floating wind turbines. As part of the 3-year contract, estimated to be worth more than £20 million, Wood will provide the topside modifications necessary for the Snorre A and Gullfaks A platforms to integrate the Hywind floating wind park with existing systems powering the facilities. The scope of work also includes equipment installation on the floating wind turbines and upgrades to the onshore control room in Bergen, Norway, that will remotely operate the wind farm. We are proud to support Equinor on what is a flagship project for the North Sea’s energy transition journey. Wood is fully committed to applying our experience gained from decades of working in the region’s oil and gas industry to reduce the carbon intensity of offshore operations by modifying existing infrastructure,” Dave Stewart, CEO of Wood’s asset solutions business in Europe, Africa, Asia, and Australia, said in a statement.