All fixed oil platforms in the Brazilian Northeast are near their design lives presenting low productivity. This scenario will lead to a decision-making process about decommissioning. An alternative use for these platforms could be an interesting option to reduce decommissioning costs and social impact. The Brazilian Northeast is already known for its great wind power potential. In this way, this region shows an interesting possibility of reuse fixed oil platforms under decommissioning process to generate wind power. Moreover, many of these fixed platforms are near the coast, installed in shallow waters, close to a major metropolis with significant energy demand, which could potentially reduce the cost of energy transmission. On the wind power operator side, the use of these structures as wind turbine foundation would also reduce the corresponding construction and installation costs. Thus, decommissioning associated with wind turbine installation could be an attractive opportunity for both operators: wind and oil. The objective of this work is to evaluate the technical feasibility of the reuse of these jacket structures for this new proposal, based on economic information already available. On a first step, the work will involve developing a case study in a Brazilian scenario, based on a qualitative analysis of existing wind farm data in Brazil and worldwide. The second step will be to gather global market tendencies, which will be used to define the offshore turbine requirements and data to be used in the following step. Next, the structural capacity of a representative number of jackets will be evaluated considering the wind turbine characteristics defined in the previous steps. A general evaluation will be performed in order to verify the application of the results obtained to all platforms in the field, which will determine the wind farm configuration. Finally, the Levelised Cost of Electricity (LCOE) will be calculated and compared with worldwide values in order to determine the economic viability of the business. This work intends to verify if it is possible to use existing Brazilian offshore oil fields, composed by fixed platforms, as offshore wind farms. For this purpose, a basic methodology to evaluate the structural capability of these structures will be established, which could be applied in other brown fields around the world in the same life situation. Nowadays there are hundreds of ageing platforms/oil fields to be included into decommissioning processes that could be considered as potential Power Wind Farms. The present study could be used as a first approach to permit start a decision-making process, with the adequate region adjustments.
It is useful to complement model tests of a floating wind turbine with simulations mimicking the scaled-down turbine. Standard engineering tools have some short-comings to model a rotor at the very low Reynolds that Froude scaled wind and rotor’s rotation speed impose. The flow around an airfoil at the scale of a wave basin brings new distinct challenges than at full scale. The capacity of standard engineering tools for the design of wind turbines to capture this complexity may be questioned. Therefore, work-around solutions need to be proposed. This paper looks at a common solution that consists of optimizing the load coefficients of the rotor to reproduce the measured rotor loads. 3 variants of optimizations are applied to a semisubmersible floating wind turbine at scale 1/50th, the DeepCwind semisubmersible platform. The effects of the differences between these 3 methods on the motions of the floater in waves and wind are analyzed. In the absence of a controller for the rotor, no significant differences related to the induced aerodynamic damping was noticed, but an offset in the motion related to a thrust deficit was observed.
Scaling effects caused by applying Froude-scaling to both wind and waves during model-testing of floating offshore wind turbines (FOWTs) results in poor model-scale aerodynamic performance of geometrically scaled turbines. This led to the “performance-scaled” MARIN Stock Wind Turbine (MSWT) which showed to be successful in obtaining the correct thrust loads at model-scale conditions. Additionally it was found that conventional blade-element-momentum-theory-based (BEMT) modelling tools are not suitable for model-scale conditions. Recent research in which these problems have been addressed are presented in this paper. First a 3D CFD study was performed in which the behaviour of the flow over the commonly studied NREL 5MW baseline turbine and the MSWT geometries was performed. Both model and full-scale conditions were studied for a fixed non-moving platform and rotor-only turbine. It was found that scaling effects are indeed significant and a highly three-dimensional and additionally separated flow was observed. Based on these findings two methods were proposed to expand the applicability of BEMT-based tools to off-design and modelscale conditions. First, instead of using commonly used 2D XFOIL data, 2D CFD RANS data was used. The use of purely 2D data from 2D CFD RANS computations did however not result in the desired improvements when compared to XFOIL-based results. The second proposed method is based on the use of 2D airfoil data obtained by post-processing of 3D flow data coming from 3D CFD computations. This new approach was shown to be successful and can therefore be extremely useful for future model-scale FOWT testing campaigns to do preliminary performance predictions. All BEMT-based and CFD results presented in this paper were compared to model-scale experimental data of the NREL 5MW turbine and the MSWT over the full range of TSR.
Urban sound propagation is influenced by multiple reflections on horizontal and vertical surfaces, either specular or diffusive in nature, diffraction around edges and meteorology, causing refraction and scattering of sound waves. This paper initiates multiple benchmark cases for urban sound propagation, with the purpose of comparing the suitability of computational methodologies. The benchmark cases are two-dimensional cross-sections of typical urban geometries, involving all of the effects mentioned above. The sound source is either geometrically screened or is in the line of sight from the receiver's position. When meteorological conditions are included, results obtained from computational fluid dynamics simulations are used. All details of the benchmark cases are concisely described, and results from two numerical methods for outdoor sound propagation are included. Both methods solve the linearized Euler equations (LEE). The first method is the Fourier pseudospectral time-domain method (Fourier-PSTD) implemented in the open source software openPSTD v2.0. The second method is the finite difference time domain method FDTD. A detailed comparison of the results obtained from the two methods is presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.