It is well known that the success of the entire renewable power generation industry is highly dependent on the levelised cost of energy (LCoE). In 2015, the Offshore Renewable Energy (ORE) Catapult presented an assessment result,
Fig. 1.2, showing an LCoE reduction for offshore wind, from £136/MWh for the 2010–2011 completion projects to £131/MWh for the 2012–2014 completion projects. The LCoE was projected to be £121/MWh for 2012–2014 final investment decision projects
[3].
Efficiencies, including design efficiency, system efficiency and operational efficiency, together with system availability that is dependent on the subsystem reliability, are the key elements in the offshore wind energy cost battle and are the main focus of this book. Amongst other parameters, the annual availability and OPEX (operation and maintenance expenditure) of the power plants would be
one of the easiest measurable performance indicators that will influence energy cost. The offshore wind industry, in addition to its high capital expenditure (CAPAX), also suffers from higher OPEX as compared to its onshore counterpart. Lifetime OPEX of offshore wind is close to 90% of its CAPAX. Unlike the large mechanical drive-train components, such as gearboxes and bearings, the design philosophy adopted by the power electronics system industry, that is, power converters, power conditioners, etc., to overcome the fragile nature and maintain high system availability, is usually to modularise the system with easily swappable subsystems. This concept has proven to be effective in many of the onshore projects as on-site repairs can be performed without the need for major system replacement. However, when it comes to offshore, due to the extremely costly offshore logistics and highly weather-dependent vessel scheduling, any intermittent failures of power electronic systems that require manual reset or component replacement would have a significant impact, possibly as great an impact as failures of mechanical components, to the plant O&M in terms of OPEX.
In recent years, there have been a number of UK- and European-funded research projects looking into system robustness improvement, health condition monitoring and lifetime prognosis methodologies, to improve overall wind turbine availability. Deployment further offshore in deeper waters would potentially further increase the OPEX. How condition monitoring techniques can help on these issues is addressed in
Chapter 18 ‘Condition monitoring of offshore wind turbines’, in
Part IV of the book, which includes three other chapters to discuss other aspects about the installation and operation of offshore wind farms:
These are complemented by three chapters in
Part I of the book which addresses the resource and siting criteria for offshore wind: