Descriptive Text of Value Chain Step
The box-like nacelle module is considered the heart of a wind turbine. It sits on top of the tower and is connected to the rotor. The nacelle is usually made of fiberglass and houses the drivetrain. The drivetrain is responsible for converting the low speed incoming rotation to high speed rotation that the generator needs to begin producing electricity. The drivetrain is typically composed of the rotor shaft, gearbox and generator. In addition, the nacelle also contains a yaw drive system and a control system. The yaw drive ensures the rotor is always facing into the wind, and the control system adjusts the pitch angle of the blades under different wind speeds to prevent structural damage to the wind turbine.
Nacelles are produced in assembly facilities. There are four components of nacelle production: (1) nacelle structural assembly, (2) drivetrain assembly, (3) nacelle electrical assembly, and (4) yaw assembly. According to the cost report by National Renewable Energy Laboratory (NREL), the nacelle module accounted for approximately 36% of the total cost of an on-shore wind power project in 2015.
Nacelle components are either produced in-house or by outside suppliers to the specifications of the nacelle original equipment manufacturer (OEM), and then the components are assembled at the nacelle plant. Many foreign OEMs are localizing nacelle production in the United States to take advantage of the growing market and reduce transportation costs and logistical challenges.
GE Renewable Energy, Siemens, Vestas, and Phoenix are the four major wind turbine nacelle assembly manufacturers with production facilities located in the United States. As of 2016, these major nacelle assembly facilities are capable of producing approximately 11,700 MW of turbine nacelles annually.
The drivetrain components that go into the nacelle module are included in “Speed Changer, Industrial High-Speed Drive, and Gear Manufacturing” (NAICS 333612). and “Mechanical Power Transmission Equipment Manufacturing” (NAICS 333613). The overall nacelle assembly is part of “Turbine and Turbine Generator Set Units Manufacturing” (NAICS 333611). As reported in the 2012 Economic Census, there are 183 establishments, 36,955 employees covered under the “Turbine and Turbine Generator Set Units Manufacturing” industry with a value of shipments of 16.9 billion dollars. However, even at their most disaggregated level (six-digit code), each NAICS code covers a range of components, products, and services beyond those specific to nacelle component manufacturing and nacelle assembly.
Figure DI.1 Capital Expenditures for the Reference Onshore Wind Plant Project
Source: Recreated from Figure 5 in Mone et al. (2017) 2015 Cost of Wind Energy Review, National Renewable Energy Laboratory Technical Report NREL/TP-6A20-66861.