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Conference programme 

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Poster session

Lead Session Chair:
Stephan Barth, Managing Director, ForWind - Center for Wind Energy Research, Germany
James Carroll University of Strathclyde, United Kingdom
James Carroll (1) F P Alasdair McDonald (1) David McMillan (1)
(1) University of Strathclyde, Glasgow, United Kingdom

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Presenter's biography

Biographies are supplied directly by presenters at OFFSHORE 2015 and are published here unedited

Mr. Carroll has been working in the Wind Industry for 5 years. He is currently a PhD student at the University of Strathclyde in Scotland. He has completed a Bachelors in Mechanical/Manufacturing Engineering in Ireland and a Masters in Technical Management in Germany. He has held a wind and site position with SoWiTec, a developer in Latin America. He has also worked as a performance engineer with a leading manufacturer in their turbine performance department. His research is focused on improving the CoE through the selection of the most appropriate turbine design and its maintenance and operations strategy.


Quantifying O&M savings and availability improvements from wind turbine design for maintenance techniques


This paper shows the results of an O&M cost and availability analysis when different design for maintenance techniques are considered.

Improved repair times through visual inspection ports and leaned nacelle lay outs, inbuilt lifting mechanisms and redundancy are the design for maintenance techniques examined in this analysis.

An O&M cost and availability baseline were determined using an O&M cost model populated with O&M field data from a number of European Offshore wind farms.

Results from introducing the design for maintenance techniques to the model are seen through the variance in the O&M cost and availability baseline.


The following steps were completed to create this paper:

1. Obtain O&M data for a number of offshore wind farms from industrial partner

2. Use data to populate O&M cost model

3. Determine a baseline O&M cost from populated model

4. Introduce improved repair times to the model and analyse its effect on the baseline O&M cost

5. Introduce in built cranes and lifting equipment to the model and analyse its effect on the baseline O&M cost

6. Introduce generator and convertor redundancy to the model and analyse its effect on the baseline O&M cost

Main body of abstract

The main body of the paper consists of:

- Details and an analysis of the offshore population from which the O&M data was obtained e.g. population size, population age and installation dates etc.

- A description of the O&M model used (1)

- A literature review and overview of possible methods for reducing repair times e.g. “leaning out” processes, easier access to frequently changed components, visual inspection portals etc.

- A literature review and overview of inbuilt lifting equipment.

- A literature review and overview of redundancy in wind turbines, what is currently available, what are the future possibilities etc.

- A results section in which the O&M cost baseline figures are presented and the adjusted figures from using the design for maintenance techniques are also presented

- A discussion section which the results from the previous section are explained and discussed

The novelty in this work comes from both the large population of offshore turbines for which data was obtained and from combining this large data set with an offshore model to determine actual cost savings that could be achieved for design for maintenance techniques.

The “supply chain, logistics and O&M” track for this conference has an “area of special interest” called “How design of wind turbines can help optimise maintenance”. It is felt that the content of this paper is suitable for that track.

(1) I. Dinwoodie, Analysis of offshore wind turbine operation & maintenance using a novel time domain meteo-ocean modeling approach


Using empirical O&M data combined with an O&M cost model this paper has shown that O&M costs can be reduced by up to 15% through the introduction of design for maintenance techniques.

The analysis has shown that out of the design for maintenance techniques analysed, the introduction of inbuilt cranes and lifting equipment has the greatest reduction on O&M costs, this is mainly due to the reduction in the use of expensive jack up vessels. The reduction in repair times also shows large reductions in O&M costs due to improved accessibility as shorter repair windows are required.

Learning objectives
Following the reading of this paper, the reader will get an overview of the potential O&M savings and availability improvements from design for maintenance techniques, specifically the reader will know how much O&M costs:

- are reduced through the leaning out of repair time by 20%

- are reduced through the use of an in built lifting mechanisms

- would decrease and availability increase through generator and convertor redundancy