scholarly journals New perspectives in offshore wind energy

Author(s):  
Giuseppe Failla ◽  
Felice Arena

The design of offshore wind turbines is one of the most fascinating challenges in renewable energy. Meeting the objective of increasing power production with reduced installation and maintenance costs requires a multi-disciplinary approach, bringing together expertise in different fields of engineering. The purpose of this theme issue is to offer a broad perspective on some crucial aspects of offshore wind turbines design, discussing the state of the art and presenting recent theoretical and experimental studies.

2021 ◽  
Vol 11 (2) ◽  
pp. 574
Author(s):  
Rundong Yan ◽  
Sarah Dunnett

In order to improve the operation and maintenance (O&M) of offshore wind turbines, a new Petri net (PN)-based offshore wind turbine maintenance model is developed in this paper to simulate the O&M activities in an offshore wind farm. With the aid of the PN model developed, three new potential wind turbine maintenance strategies are studied. They are (1) carrying out periodic maintenance of the wind turbine components at different frequencies according to their specific reliability features; (2) conducting a full inspection of the entire wind turbine system following a major repair; and (3) equipping the wind turbine with a condition monitoring system (CMS) that has powerful fault detection capability. From the research results, it is found that periodic maintenance is essential, but in order to ensure that the turbine is operated economically, this maintenance needs to be carried out at an optimal frequency. Conducting a full inspection of the entire wind turbine system following a major repair enables efficient utilisation of the maintenance resources. If periodic maintenance is performed infrequently, this measure leads to less unexpected shutdowns, lower downtime, and lower maintenance costs. It has been shown that to install the wind turbine with a CMS is helpful to relieve the burden of periodic maintenance. Moreover, the higher the quality of the CMS, the more the downtime and maintenance costs can be reduced. However, the cost of the CMS needs to be considered, as a high cost may make the operation of the offshore wind turbine uneconomical.


Author(s):  
Ricardo Faerron Guzmán ◽  
Kolja Müller ◽  
Luca Vita ◽  
Po Wen Cheng

Aligned with work performed in deliverable D7.7 of the H2020 project LIFES50+, this study supports the definition of the numerical setup in the design of floating offshore wind turbines. The results of extensive simulation studies are presented, which focus particularly on determining the requirements for the load simulations in the design process. The analysis focusses on the cases of: (1) fatigue during power production and (2) ultimate loads during power production and severe sea state. For the fatigue load case, sensitivity study is performed in order to determine relevant load conditions and the expected impact of a variation in the environmental loading. Additionally, focus is put on the requirements regarding the run-in time, number of seeds and the simulation length for both fatigue and ultimate limit state (FLS, ULS) analysis. Another topic addressed is the benefit of using an increased number of seeds rather than extending the simulation time of single seeds, when a given total simulation time is required as described in the guidelines. The run-in time may be shortened when using predetermined steady states as initial conditions. Requirements for the steady state simulations are also determined and presented.


2020 ◽  
Author(s):  
Auraluck Pichitkul ◽  
Lakshmi N. Sankar

Abstract Wind engineering technology has been continuously investigated and developed over the past several decades in response to steadily growing demand for renewable energy resources, in order to meet the increased demand for power production, fixed and floating platforms with different mooring configurations have been fielded, accommodating large-scale offshore wind turbines in deep water areas. In this study, the aerodynamic loads on such systems are modeled using a computational structural dynamics solver called OpenFAST developed by National Renewable Energy Laboratory, coupled to an in-house computational fluid dynamics solver called GT-Hybrid. Coupling of the structural/aerodynamic motion time history with the CFD analysis is done using an open File I/O process. At this writing, only a one-way coupling has been attempted, feeding the blade motion and structural deformations from OpenFAST into the fluid dynamics analysis. The sectional aerodynamic loads for a large scale 5 MW offshore wind turbine are presented, and compared against the baseline OpenFAST simulations with classical blade element-momentum theory. Encouraging agreement has been observed.


Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2650 ◽  
Author(s):  
Lubing Xie ◽  
Xiaoming Rui ◽  
Shuai Li ◽  
Xin Hu

Owing to the late development of offshore wind power in China, operational data and maintenance experience are relatively scarce. Due to the harsh environmental conditions, a reliability analysis based on limited sample fault data has been regarded as an effective way to investigate maintenance optimization for offshore wind farms. The chief aim of the present work is to develop an effective strategy to reduce the maintenance costs of offshore wind turbines in consideration of their accessibility. The three-parameter Weibull distribution method was applied to failure rate estimation based on limited data. Moreover, considering the impacts of weather conditions on the marine maintenance activities, the Markov method and dynamic time window were used to depict the weather conditions. The opportunistic maintenance strategy was introduced to cut down on the maintenance costs through optimization of the preventive maintenance age and opportunistic maintenance age. The simulation analysis we have performed showed that the maintenance costs of the opportunistic maintenance strategy were 10% lower than those of the preventive maintenance strategy, verifying the effectiveness of the proposed maintenance strategy.


2022 ◽  
Vol 8 ◽  
pp. 1207-1228
Author(s):  
Alexandra Ciuriuc ◽  
José Ignacio Rapha ◽  
Raúl Guanche ◽  
José Luis Domínguez-García

Author(s):  
Marit Reiso ◽  
Geir Moe

Offshore wind turbines are becoming more common due to the scarcity of suitable land sites. By going offshore, maintenance costs become one of the driving expenses. Hence more reliable components should be implemented on offshore wind turbines. The down-wind rotor configuration does not require as powerful yaw drive as the upwind rotor configuration to align with the wind direction. Thus the yaw system can be simpler with fewer components that can fail and require maintenance. This paper presents numeric simulation studies of how the tower shadow impacts the blades when they pass through the wake behind the tower. The work concentrates on bottom-fixed offshore wind turbines designed for the specifications of the NREL offshore 5-MW baseline wind turbine. The blade response has been compared for a full truss tower and a conventional tubular tower to show how the different tower shadows influence the blades. The blades on the more transparent truss tower experience less root flapwise moment fluctuations due to the weaker tower shadow. The simulations were performed by means of GH Bladed, version 3.82.


Author(s):  
Edgar Ubaldo Pena Sanchez ◽  
Severin David Ryberg ◽  
Heidi Ursula Heinrichs ◽  
Detlef Stolten ◽  
Martin Robinius

Due to the increasing global importance of decarbonizing human activities, especially the production of electricity, the optimal deployment of renewable energy technologies will play a crucial role in future energy systems. To accomplish this, particular attention must be accorded to the geospatial and temporal distribution of variable renewable energy sources (VRES) such as wind and solar radiation in order to match electricity supply and demand. This study presents a techno-economical assessment of four energy technologies in the hypothetical context of Mexico in 2050, namely: onshore and offshore wind turbines, and open-field and rooftop photovoltaics. A land eligibility analysis incorporating physical, environmental, and socio-political eligibility constraints and individual turbine and photovoltaic park simulations, drawing on 39 years of climate data, is performed for individual sites across the country in an effort to determine the installable potential and the associated levelized costs of electricity. The results reveal that up to 54 PWh of renewable electricity can be produced as a cost of less than 70 EUR/MWh. Around 91% (49 PWh) of this would originate from 23 TW of open-field photovoltaic parks that could occupy up to 578,000 km2 of eligible land across the country. The remaining 9% (4.8 PWh) could be produced by 1.9 TW of onshore wind installations allocated to approximately 68,500 km2 of eligible land that is almost fully adjacent to three mountainous zones. The combination of rooftop photovoltaic and offshore wind turbines account for a very small share of less than 0.03% of the overall techno-economical potential.


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