Wind Blade Recycling

The importance of wind turbine propeller recycling of obsolete or retired wind turbine blades

With a growing focus on reducing CO2 emissions from fossil fuel power plants, the importance of generating electricity from clean renewable energy sources such as wind power is becoming increasingly important. In recent years, wind power has accounted for a significant share of the world's total electricity generation.  Wind power capacity is set to grow significantly in the coming years as governments ramp up renewable energy generation to meet growing energy demand. However, the generation of retired wind turbine blades will also increase significantly as damaged/aging wind turbine blades are retired and replaced with newer, more efficient, and larger blades.  Wind turbine blades have a service life of 20-25 years and will be retired at the end of the year. The increasing number of discarded wind turbine blades can cause significant environmental problems. Therefore, there is an urgent need to dispose of these waste wind turbine blades in a sustainable way.  While other components of wind turbines, such as gearboxes, generators, foundations, and towers, can be easily recycled, these huge blades are extremely difficult to recover due to the complex and heterogeneous nature of the blades.  Specifically, blades made of thermoset fiber-reinforced polymer composites are designed to be durable and able to withstand more than 20 years of extreme weather, making their recycling extremely difficult and almost impractical.

Conventional Waste Wind Turbine Blade Disposal Methods and Their Disadvantages

Decommissioned/damaged wind turbine blades are usually disposed of in landfills. However, there are the following major drawbacks to this approach:

wind blade landfill High landfill costs:

Composite materials (e.g. wind turbine blades) are subject to high taxes and fees.

Takes up valuable landfill space:

Large, discarded wind turbine blades can take up a lot of valuable landfill space. In addition to landfills, other waste wind blade disposal methods such as mechanical recycling, chemical treatment, and incineration have several drawbacks:

Mechanical recycling:

Although mechanical recycling is possible, the market value of the recycled material is often low.

Chemical treatment:

Chemical treatments that use chemicals and heat to separate polymer composite matrices from fibers can jeopardize the health and safety of workers.

Incineration:

Incineration can produce energy, but it produces air pollutants and loses recyclable materials. Limitations of incineration Although the incineration of retired wind turbine blades in a cogeneration power plant (which can generate electricity and heat), the incineration process produces harmful flue gas emissions due to the inorganic content of the composite materials used to make these blades. As a result, these methods not only fail to sustainably dispose of waste wind turbine blades, but also run counter to the sustainable development goals of wind energy.

Pyrolysis of Waste Wind Turbine Blades Pyrolysis is a method suitable for treating complex heterogeneous

waste like waste wind turbine blades, which can be converted into useful materials/high-value products and energy. The pyrolysis process takes place in an inert atmosphere, and the polymer matrix in the blade is cracked by thermal decomposition at 300-500 degrees Celsius, avoiding the occurrence of combustion.  In this process, the organic part of the composite material is degraded into lower molecular weight components that can be recycled and reused under certain circumstances. Through the pyrolysis cycle of wasted/retired wind turbine blades, fibers, filler pellets, liquid fuels, and organic components can be recovered.  Studies have shown that pyrolysis can successfully recover high-yield glass fibers from discarded wind turbine blades. Pyrolysis requires less energy than other recycling technologies used to decompose glass fiber composite polymer matrices. In addition, pyrolysis does not require additional pretreatment, such as complex shredding and disassembly operations.  The processing temperature required for pyrolysis of wind turbine blades can be reduced by using specific catalysts. Extremely high pyrolysis temperatures will thermally accelerate the diffusion of defects on the surface of the fibers, thereby greatly reducing the tensile strength of the recycled fibers and limiting their secondary use. Different pyrolysis furnaces such as fluidized bed reactors, screw pyrolysis furnaces, rotary kilns, and fixed bed reactors can all be used in the pyrolysis process.

In summary, pyrolysis has become one of the most promising methods for the sustainable treatment of waste wind turbine blades,

as it can effectively recover high-value products (such as glass fibers) and generate gaseous and liquid products that can be used as a heat source for the pyrolysis process, thereby reducing landfill space waste, lowering harmful emissions, and requiring significantly less energy compared to other end-of-life treatment methods.