Preprints
https://doi.org/10.5194/wes-2021-121
https://doi.org/10.5194/wes-2021-121

  25 Oct 2021

25 Oct 2021

Review status: this preprint is currently under review for the journal WES.

Analysing the effectiveness of different offshore maintenance base options for floating wind farms

Nadezda Avanessova1, Anthony Gray2, Iraklis Lazakis3, R. Camilla Thomson4, and Giovanni Rinaldi5 Nadezda Avanessova et al.
  • 1Industrial CDT in Offshore Renewable Energy (IDCORE), University of Strathclyde, Glasgow, G1 1XQ, UK
  • 2Offshore Renewable Energy Catapult, Glasgow, G1 1RD, UK
  • 3Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, Glasgow, G1 1XQ, UK
  • 4School of Engineering, Institute for Energy Systems, The University of Edinburgh, Faraday Building, The King’s Buildings, Edinburgh, EH9 3DW, UK
  • 5Renewable Energy group at the University of Exeter, Penryn Campus, Treliever Road, TR109FE, Penryn, Cornwall, UK

Abstract. With the growth of the floating wind industry, new Operation & Maintenance (O&M) research has emerged evaluating tow-to-port strategies (Offshore Wind Innovation Hub, 2020) but limited work has been done on analysing other logistical strategies for offshore floating wind farms. In particular, what logistical solutions are the best for farms located far offshore, that cannot be reached by crew transfer vessels (CTVs)? Previous studies have looked at the use of Surface Effect Ships (SES) and CTVs during the Operation and Maintenance (O&M) of fixed wind farms but only some of them included Service Operation Vessels (SOV). This study analyses two strategies that could be used for floating wind farms located far from shore using ORE Catapult’s in-house O&M simulation tool. One strategy comprises of having a SOV performing most of the maintenance on the wind farm and the other strategy uses an Offshore Maintenance Base (OMB) instead which would be located next to the offshore substation and would accommodate three CTVs. This paper provides an overview of the tool and the inputs used to run it, including failure rates of floating wind turbine subsea components and their replacement costs. In total six types of simulations were run with two strategies, two different weather limits for CTVs and two weather datasets ERA5 and ERA20C. The results of this study show that the Operational Expenditure (OPEX) costs for the strategy with an OMB are 5–8 % (depending on the inputs) lower that with SOV but if Capital Expenditure (CAPEX) costs are included in the analysis and the Net Present Value (NPV) is taken into account then the fixed costs associated with building the offshore maintenance base have a significant impact on selecting a preferred strategy. It was found that for the case study presented in this paper the OMB would have to share the foundation with a substation in order to be cost competitive with the SOV strategy.

Nadezda Avanessova et al.

Status: open (until 06 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on wes-2021-121', Iver Bakken Sperstad, 23 Nov 2021 reply
  • RC2: 'Comment on wes-2021-121', Anonymous Referee #2, 25 Nov 2021 reply

Nadezda Avanessova et al.

Nadezda Avanessova et al.

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Short summary
This study analyses two logistical strategies (a service operation vessel and an offshore maintenance base) that could be used for floating wind farms that cannot be reached by crew transfer vessels. The results of this work showed that having one service operation vessel is a preferable strategy if costs and energy availability are taken into consideration. This work also shows how the selection of weather data and wave limits of vessels affects the results.