NREL Research Identifies Motivations, Methods for Achieving a Circular Economy for Wind Energy

Feb. 16, 2021

A field of wind turbines
Many wind turbines installed decades ago are reaching the end of their lifetimes, which has prompted NREL researchers to understand what can be done with old turbine parts. NREL file photo

Researchers at the National Renewable Energy Laboratory (NREL) are addressing critical challenges when it comes to achieving a circular economy for wind turbine components.

The motivations for pursuing this research are outlined in a new journal article, “Wind turbine blade material in the United States: Quantities, costs, and end-of-life options.” The paper, written by Aubryn Cooperman, Annika Eberle, and Eric Lantz, appears in the journal Resources, Conservation & Recycling.

Wind turbines have an estimated lifespan of about 20 years (or less if a turbine is repowered prior to reaching the end of its design life). After that, many components like the tower, generator, and turbine’s foundation can be reused or recycled.

Large wind turbine blades, however, are made of sturdy composite materials, which makes recycling them more difficult. Cooperman and her team calculated the projected wind blade waste by 2050 and compared that to remaining landfill capacity by state. Based on the current rate of wind blade material decommissioning, cumulative blade waste may total about 2.2 million tons by 2050, approximately 1% of the total remaining U.S. landfill capacity by volume. However, the impact of wind blade waste will vary by region with some regions utilizing less landfill capacity by volume than the national total and others more—a function of available landfill capacity, local regulations, costs to landfill, proximity to existing wind projects, and a suite of other factors.

“Wind blade waste represents a small portion of remaining landfill capacity, especially relative to total waste produced in the United States,” said Cooperman, an engineering analyst at NREL and lead author of the journal article. “However, waste volume is not the only motivation for adopting alternative materials and sustainable end-of-life processes for wind turbine blades.”

In their research, the study authors explore some of these alternatives, including:

  • Design for circularity, whereby material or design choices could lead to greater recyclability or reuse. For example, novel thermoplastic resins, such as Arkema’s in-situ polymerized Elium resin system, could allow a blade to be melted down and its component parts recycled.
  • Lifetime extension, which involves extending the blade life beyond the typical 20-year lifespan. Although such methods require additional maintenance, such as resurfacing, they have the ability to reduce life-cycle environmental impacts compared to landfilling.
  • Mechanical recycling, which allows the composite material in the blades to be used for new composite products. But the recycled material typically has reduced mechanical properties compared to the original and therefore cannot be used to make new blades.
  • Cement co-processing, which is suitable for glass-reinforced composite blades and has been used in Germany for the past decade. The blades are burned in a kiln and the residual glass fiber incorporated into cement. GE, the largest supplier of turbines in the United States, in December announced it is adopting this process.

Although several process alternatives have been developed to recover material and energy from wind turbine blades, they have not yet reached cost parity with landfilling. More work needs to be done to improve these technologies and develop a more holistic and circular design of wind power plants. NREL scientists and engineers are already working on thermoplastic resin systems, as well as reversible and bio-based thermoset resins, that could allow a blade to be melted down and its component parts recycled. Continued research on recycling technologies for current blades, the design of new blades, and the role of waste management strategies will help push toward a more circular economy for wind blades.

Funding for research into the end-of-life issues involving wind turbine blades comes from the U.S. Department of Energy’s Wind Energy Technologies Office.