Wind Turbine and Wind Blade Fundamentals

Wind turbines function by turning kinetic energy from the rotation of the wind blades into electricity. A typical wind turbine consists of many components, the most important being the wind blades, gear box, electric generator and tower. When the wind blows, the combination of the lift and drag of the air pressure on the wind blades rotate the wind blades and rotor, which drives the gear box and generator to create electricity.

Wind turbine mechanical overview

  1. Rotor Blade
  2. Pitch drive
  3. Nacelle
  4. Brake
  5. Low-speed shaft
  6. Gear box
  7. High-speed shaft
  8. Generator
  9. Heat exchanger
  10. Controller
  11. Anemometer
  12. Wind vane
  13. Yaw drive
  14. Tower

Source: American Wind Energy Association.

Wind turbines are often grouped together in wind farms. The connection or access of wind turbines to a power grid is of the utmost importance when locating wind turbines. Electricity from each wind turbine travels down a cable inside its tower to a collection point in the wind farm and is transmitted to a substation for voltage step-up and delivery into the electric utility transmission network, or grid. Electricity generation is most commonly measured in kWh. According to the Energy Information Administration the average U.S. household uses over 10,800 kWh of electricity each year. According to NREL, a 1.5 MW wind turbine can generate over 3 million kWh of wind energy annually, representing about as much electricity as 275-300 U.S. households use in one year.

The configuration of a wind turbine, including its wind blade design, is intended to optimize electricity generation and minimize down time in specific wind conditions, or “wind classes.” Key characteristics of wind blades include:

  • Wind blade length and air foil shape, which contribute to the efficiency of the wind blade in turning kinetic energy from the rotation of the wind blades into electricity;
  • Strength and weight, which contribute to efficiency and impact of the wind blade on the rest of the turbine; and
  • Structural integrity, which affects the long-term reliability of the wind blade.

Wind blade length is expected to increase globally as wind turbine OEMs develop increased rotor diameters and wind blades as a primary driver for market differentiation and cost competitiveness. While the global mainstream wind blade length has been 40-45 meters, according to MAKE, by 2020 wind blades greater than 50 meters in length are expected to become the global norm. The trend toward larger wind blades indicates the potential phase out of smaller wind blades, as larger blades have the greatest impact on energy efficiency and LCOE reduction across all global regions.

The development of larger wind turbines and recent improvements in wind blade design, materials and manufacturing technology have significantly increased the power generating capacity of wind turbines. Today, wind blades are typically composed of advanced, high-strength, lightweight and durable composite materials. In addition, longer wind blades, which allow for a larger area of wind to be swept by the wind blades, coupled with taller towers, results in greater energy capture and reduces the overall cost of wind energy. The evolution of the wind turbine has resulted in improved energy output, including in areas of low wind speed. The capacity factor of a wind turbine—which measures actual energy output as a percentage of potential capacity—has increased considerably under more recent designs for the same wind speed. These improvements in wind blade design have made wind energy a highly cost-competitive source of electricity.

A growing trend is the emergence of wind turbines designed specifically for regions with lower wind speeds. These regions have not traditionally been regarded as cost-effective locations for wind generation. However, during the past three years, all of the top ten wind turbine suppliers in the world have introduced wind turbines with longer wind blade lengths and taller towers designed to capture more energy at the lower end of the wind speed scale. Most single wind turbine platforms can now support multiple wind blade lengths, and today’s wind turbines can efficiently generate electricity when the wind speed is anywhere between 7 and 56 mph, speeds that are in abundance around the globe. We believe that installation of wind turbines in regions with lower wind speeds is encouraged due to proximity to energy demand centers, thereby reducing the amount of transmission infrastructure required. We expect this trend of expansion to regions not traditionally classified as high wind resource regions to continue.

As the location of wind turbine installations diversify to areas with varying wind classes, emphasis in the wind blade production process has shifted towards demonstrating the flexibility to supply a broader range of wind blade models designed for varying wind conditions. The trend towards multiple wind blade models requires advanced composite and production expertise, sophisticated process technologies and modular megawatt-size precision molding and assembly systems. Given this required level of sophistication, wind blades now represent approximately 15% of the cost of a wind turbine, the second largest cost component, as depicted below. We believe that OEMs that keep pace with these technological advancements while controlling costs will enjoy a significant competitive advantage. Wind blades and pitch systems remain the most important elements to reduce LCOE, driven by ongoing improvement in aerodynamic efficiency, load controls and cost reduction.

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