Cost of energy modelling and reduction opportunities for offshore wind turbines

Student thesis: Doctoral Thesis

Abstract

The cost of generating electricity from wind turbines, particularly offshore wind turbines is currently too high. To ensure offshore wind energy is truly competitive with traditional fossil fuel and nuclear energy generation, the true cost of offshore wind energy and ways of reducing that cost must be investigated. A number of wind turbine types, differentiated through their drive train configurations, currently exist. Different wind turbine manufacturers have different drive train configurations and some manufacturers have multiple configurations within their own portfolio of turbines. There is no clear evidence as to which wind turbine drive train type is best suited to offshore sites.One way of determining which turbine drive train type is best suited to an offshore wind farm is by investigating which turbine type offers the lowest cost of energy. This thesis provides a detailed analysis of the cost of energy for different offshore wind turbine types and investigates ways in which that cost of energy can be reduced. The highest level research question amongst all of the research questions answered in this work is: “What is the overall cost of energy for different wind turbine types and how can it be reduced?”To answer that research question the author starts off in Chapter 1 by outlining the thesis objective and describing all of the other research questions that must be answered to achieve that objective. The following chapters then provide background and contain novel analyses on the variables that are required to calculate the cost of energy. Chapter two looks at the failure rates of different wind turbine types and includes novel failure rate field analysis of on and offshore wind turbines. Chapter 3 estimates O&M costs and availabilities for 4 different wind turbine types at a number of different hypothetical offshore sites.Chapter 4 estimates the cost of energy of the four different wind turbine types for a number of hypothetical offshore sites. Chapter 5 then investigates ways of reducing the overall cost of energy from offshore wind. Lastly, Chapter 6 concludes the thesis.Results from each chapter are novel and provide some new insight into the variables that contribute towards calculating the cost of energy. The thesis concludes that across all sites examined, the turbine type that offers the lowest cost of energy is the direct drive permanent magnet generator with a fully rated converter. The vessel strategy that offered the lowest cost of energy with this turbine type was the fix on fail strategy across all sites and further cost of energy savings could be made through the use of condition monitoring systems, performance based maintenance contracts or through the reduction in the need for heavy lift vessels through in-built lifting or large component modularity. The results shown in this thesis will be useful for wind farm developers, operators and wind turbine manufacturers. Developers can use the results to assist in the selection of turbine types. Operators can gain an insight into what is driving their O&M costs and manufactures can see which wind turbine drive train type to develop and manufacture to satisfy one of their key customer requirements, a lower cost of energy.
Date of Award7 Oct 2016
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde & EPSRC (Engineering and Physical Sciences Research Council)
SupervisorAlasdair McDonald (Supervisor) & David McMillan (Supervisor)

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