The U.S. Department of Energy (DOE) works with wind technology suppliers to promote advanced manufacturing capabilities. The goals are to increase reliability while lowering production costs, and to promote an industry that can meet all demands domestically while competing in the global market. The Wind Energy Technologies Office supports industry partnerships and targeted R&D investments that integrate new designs, materials, and processes into manufacturing facilities, thus making wind turbines a more affordable domestic energy source for communities around the country.
Manufacturing Is the First Step in Affordable Wind
The U.S. wind market has grown substantially over the years into an increasingly complex supply chain. There are more than 500 U.S. manufacturing facilities specializing in wind components such as blades, towers, and generators, as well as turbine assembly across the country. In fact, modern wind turbines are increasingly cost effective, reliable, and have scaled up in size to multi-megawatt power ratings. Improved turbine performance has supported a robust domestic wind industry, with U.S. wind turbine technology exports growing from $16 million in 2007 to over $100 million per year. Additionally, since 1999, the average turbine generating capacity has increased by 180% to 2 MW.
Advancements in composite materials, automation, and more efficient manufacturing processes have helped domestic manufacturers dramatically increase productivity throughout the past decade. The wind supply chain that has developed in the United States in recent years has increased the domestic content of wind turbines installed in the United States, with over 80% of nacelle assembly and tower manufacturing occurring in the United States for turbines installed here.
As the size and complexity of wind turbines grow, so do the manufacturing process requirements and component transportation costs which, in turn, increase the need for local manufacturers who can overcome technical and logistical challenges. Currently, the average utility-scale wind turbine contains roughly 8,000 parts, including blades up to 75 meters (250 feet) in length and towers over 80 meters (262 feet) high, roughly the height of the Statue of Liberty. New towers are being made even taller to capture stronger winds at higher elevations.
Potential capacity maps show land areas in the United States that may be suitable (with an average capacity factor of 35% or greater) for wind energy development using new 110 meter turbines and planned 140 meter turbines. Advanced manufacturing and assembly techniques must be developed in order for wind energy to expand to land areas with untapped wind resource potential.
The Manufacturing Process
Due to the size and complexity of turbine blades, each blade must be crafted to the highest quality standards in order to ensure reliability. This fabrication process can be very costly and labor intensive, but a partnership between DOE, Sandia National Laboratories, TPI Composites, and Iowa State University helped establish advanced techniques that reduce the time it takes to produce a single blade by approximately 37% (from 38 to 24 hours). DOE is also investigating 3D printing of blade molds, which could save time and money during the blade development process. Turbine blades must be able to maintain their strength and aerodynamic structure during virtually non-stop operations over twenty years.
The tower-top components inside the nacelle that convert the force of the wind-driven rotor blades into electricity are called the drivetrain. Advanced designs and related manufacturing techniques developed in conjunction with DOE's Next-Generation Drivetrain projects are expected to produce more efficient, reliable, and affordable drivetrains. These advancements include new single-stage gearboxes, permanent magnet generators, high efficiency power electronics, and superconducting generators. New and innovative approaches to drivetrain manufacturing will continue to be necessary as turbine components continue to increase in size and energy capacity in response to market demand.
As the demand for renewable energy increases and wind turbines are "scaled-up" to ever larger sizes, American manufacturers must find ways to overcome infrastructure and logistics constraints to lower the cost of wind energy. These constraints include highway underpass heights limiting the size of wind towers, availability of cranes able to lift and install nacelles, and the trucking fleet's difficulty in transporting longer wind blades. A study released by the Energy Department, Enabling Wind Power Nationwide, concluded that the technological innovations enabling development of very large wind turbines have significant potential to reduce the cost of wind energy. However, transportation and logistics challenges are limiting the size and height of towers and turbines that can be deployed throughout the country. Addressing these challenges head-on, in January 2014, DOE announced $2 million for two organizations that will advance technologies that avoid these logistical barriers.