Investigation of Optimum Crew Transfer Vessel Fleet for Offshore Wind Farm Maintenance Operations

Abstract

The offshore wind industry, which aims to reduce the operational costs, usually achieved through learning curves and supply chain improvements, has seen drastic cost increase over the last five years. In order to sustain the competitiveness of the offshore wind industry against other renewable energy sources, the cost of offshore wind needs to come down to today's onshore cost. This cost reduction target can be achieved through optimising the offshore related operations which contribute the most to the operating expenditures (OPEX) of the offshore wind farms. In this paper, the investigation of optimum crew transfer vessel fleet, which indicates the influence of fleet size and characteristics of the vessels involved in the operations, is introduced with a focus on power production, total cost of the Operation and Maintenance (O&M) and revenue loss. A time domain Monte-Carlo approach is adopted while taking into consideration the climate parameters, failure characteristics of turbine components, the specification of crew transfer vessels, and the composition of vessel fleet. Through this extensive study, it is concluded the O&M related costs can be reduced significantly while the availability and the productivity of the turbines can be increased by optimising the use of the O&M vessel fleet in terms of fleet size and vessel capabilities.

Sensitivity analysis of offshore wind farm operation and maintenance cost and availability

“…There are a number of wind farm O&M models currently under development incorporating turbine reliability and meteorological conditions both for the onshore [3,4,5] and offshore [6,7,8,9] wind sectors. The majority of models estimate O&M cost, while some consider wind turbine/farm availability.…”

Sensitivity of Risk-Based Maintenance Planning of Offshore Wind Turbine Farms

“…Recent studies show annual failure rates of offshore wind turbines in the range between 6 and 9.5 failures per year: [3]: 9.5 failures/year/turbine; [31]: 8 failures/year/turbine (without major repairs) and [37]: 6 failures/year/turbine. In this study for calibrating the damage model and the software/electrical failure rates an overall annual failure rate of 9 incidents per year is considered.…”

“…These cost assumptions are taken from [13]. An interest rate of 5% is considered in this study, as also considered in other studies performed by [7,13,37]. Table 7.…”

“…High waves have the risk that the technicians suffer from sea sickness. The common limitations (boat: [7,13,37]; helicopter: [7,13,40]) for boat and helicopter operations are the following:…”

Advanced logistics planning for offshore wind farm operation and maintenance activities

“…Regarding vessels for minor maintenance, current transportation methods to offshore wind turbines include mostly the use of small workboats which involves long shuttling journey times resulting in considerable wasted technician time (Dalgic et al, 2015a;Dalgic et al, 2015c). Monohull boats, small catamaran vessels and Small Waterplane Area Twin Hull (SWATH) vessels are generally utilised in minor maintenance operations, which allow operators to keep the costs at acceptable levels.…”