Opportunities for technology development. The implications of accessing further from shore and deeper water sites, and the opportunities to increase cost effectiveness are different for each key component of the offshore wind farm, and are explored in turn. Wind turbines Offshore wind turbines are, to date, largely marinised versions of the largest onshore wind designs that are designed to be suitable for high capacity factors. The engineering and quality control challenge required to operate in the marine environment is considerable. Some of the early turbines, such as the V90 turbines from Vestas, have experienced multiple failures, particularly in gearboxes. Vestas temporarily ceased further sales of the V90 to the offshore wind market and prioritised increasing the quality and reliability of the turbine39.
A year later they have now reportedly addressed these issues and have resumed sales of the improved V90. Failures contributed to the poor availability at Kentish Flats, as well as at Scroby Sands, which were as low as 63-65% compared to the expected availability, achieved at North Hoyle, of 90-95% (Chart 4e). Poor availability at some wind farm sites has been the main driver of lower than expected load factors, reducing the amount of electricity generated and therefore the offshore wind farms’ revenues (Chart 4f). If further from shore sites are necessary, improvements
in reliability will be even more critical given the long travel distances and greater potential for weather to
disrupt maintenance operations. Given the time to design, develop and build investor confidence in radical new technology, offshore wind turbines are likely to remain fundamentally based on the three-blade, upwind design until 2020 (see the side box: ‘the three-bladed turbine is here to stay for now’). ‘Radical new designs are not feasible by 2020 and are unlikely to deliver as much as is sometimes believed’ Interview with turbine manufacturer, 2008 Nevertheless, there are significant incremental improvements possible both to increase reliability further and to drive cost reduction.