Figure 11 Wind turbine, courtesy of GE Vernova.
Function
The turbine converts kinetic energy from the wind into three-phase AC electrical energy.
What it costs*
The cost for a 15 MW wind turbine is about £18.2 million. This includes components as well as assembly and wind turbine supplier aspects of installation and commissioning, plus warranty provision. Installation and commissioning costs relate mainly to logistics and staff costs at its head office, the construction port, on the installation vessel and on the turbine relating to mechanical and electrical completion, testing and pre-handover checks and trouble shooting. These costs typically exceed £1 million per turbine.
Who supplies them
Suppliers include CSSC Haizhuang, Doosan, Dongfang Electric Corporation, Envision, GE Vernova, Goldwind, MingYang, Shanghai Electric, Siemens Gamesa Renewable Energy (SGRE), Vestas and Unison.
Key facts
Most designs have upwind, pitch controlled, variable speed rotors with three blades. Compared to onshore wind turbines, turbines are much larger and there is an increased focus on reliability and maintainability and a decreased impact of noise, visual and transport constraints.Â
Wind turbine suppliers are systems integrators, buying bespoke or standard components from a wide range of suppliers. Blades are typically manufactured in-house, along with a few other components in some cases, depending on the industrial strength and breadth of the supplier.Â
There are fewer offshore turbine suppliers than onshore. The high investment costs, large project sizes but relatively low overall sales volumes make it difficult for new suppliers to enter the market.
Typically, after a new turbine platform is developed, turbine variants are offered with higher rating and/or larger diameter rotor. These variants become possible once the loads and factors of safety are better understood through early operation of first turbines in a new platform. This extends sales lifetime of a given platform while minimising development costs.
Wind turbine suppliers prefer to operate a small number of nacelle assembly facilities and blade manufacturing facilities, to gain economies of scale, reduce quality risks and avoid adding complication and cost to their supply chains. The choice of site depends on the size of the local market, the locations of key suppliers, skills availability, and support for local job creation. The typical design life of an offshore turbine is 25 years. A trend for longer design life is due to the maturing of the industry, as asset owners now expect to operate wind farms for at least this long without the technology becoming obsolete or unsupported by suppliers. The design driver for many components is fatigue loading when generating. Extreme loads due to storms, abnormal events and faults during operation can also be critical. Typically, an offshore turbine will be turning for up to 90% of the time.
Turbines are type certificated by third party authorities. This confirms that the wind turbine type is designed, documented and key features of performance verified in conformity with specific standards and other technical requirements. This certification also covers the suppliers of the key components.
Health and safety requirements are focused on safety by design where the need for people to be put in hazardous environments is minimised or avoided at the design stage.