Posted on April 20, 2023
Inevitably, the boom in wind energy means a boom in blade recycling. Replacements are common as new designs emerge. Some blades fail, while others reach the end of their intended lifespan. At present, blade failure occurs at a rate of about 0.54% per year, or approximately 3,800 blades.
During a time of massive wind turbine deployment, it is only natural to focus on new installations. However, the lifespan of wind turbines is not infinite – they’re more like 20 to 25 years.
Blade issues are a fact of life on wind farms. They fail for a variety of reasons, including:
Splitting along fibers
Damage from foreign objects
Gel coat cracks
Rapid Growth of Wind Power
Wind power is the largest renewable energy source in the United States. The U.S. Wind Turbine Database lists more than more than 70,800 turbines as of early 2022. The first wind turbine dates to about 40 years ago. There are now 1500 active wind power projects in 44 states, Puerto Rico, and Guam. Since 1980, the cost of wind power has decreased from $0.55/kWh to $0.032/kWh.
Recycling an Inevitable Outcome
Rapid growth in decommissioned wind turbines is inevitable. By 2050, the weight of decommissioned blades worldwide may be 2 million tons per year. They contain a variety of recyclable materials. Fiberglass is a prime example. Turbine blades also contain calcium oxide, a component of alite, the material in Portland cement that helps it to set. They also contain organic materials like balsa wood and certain kinds of resins.
Recycling a wind turbine blade is a multi-step process:
Split into sections suitable for truck transport
Sections fed into powerful shredders - pieces the size of a deflated football
Further processing for specific applications
Burden on landfills
According to the National Renewable Energy Laboratory (NREL), most wind turbine blades end up in landfills. Motivated turbine owners seek to keep their decommissioned blades out of landfills. In Europe, wind industry insiders have called for a Europe-wide ban on sending blades to landfills beginning in 2025.
Fortunately, it is possible to recycle approximately 85% of a turbine blade. This includes the steel, copper wire, and electronics in the tower and the nacelle. It also includes the fiberglass in blades made with glass fiber-reinforced polymer (GFRP).
The ultimate goal is to shred or otherwise break down the blades before transport. Mechanical grinding reduces blade fragments in stages. Onsite processing reduces transportation costs. High-voltage pulse fragmentation uses high pressure shockwaves to break down blade materials. It delivers longer, cleaner fibers suitable for concrete, but it consumes considerable energy.
Microwave pyrolysis separates glass or carbon fibers from the polymer matrix. The fibers are usable, and liquid or gaseous polymer becomes a fuel. Fluidized bed gasification is good at handling mixed and/or contaminated GFRP. It is possible to use solvents to break polymer bonds, but scalability is a question.
Quantis estimates that recycling a single seven-ton blade eliminates the consumption of:
Five tons of coal
2.7 tons of silica
1.9 tons of limestone
About one ton of other mineral-based material
Advantages in the Concrete Industry
The concrete industry benefits from turbine blade recycling in a variety of ways.
Silica for cement
Silica recovered from wind turbine blades becomes a substitute for some of the sand and clay that goes into cement production. When used as a partial alternative to coal, it can reduce emissions up to 27%, according to GE.
Fibers strengthen concrete
At present GFRP wind turbine blades are the most common. Recycled fibers from these blades can strengthen concrete.
Reduce use of fossil fuels in firing kilns
It is possible to process shredded blades into pebble-sized pieces suitable for use as kiln fuel. This can reduce the use of fossil fuels, reducing emissions in the process.
It is also possible to cut the blades up and use the pieces as concrete reinforcement. This alternative reduces emissions otherwise generated in more complex blade recycling. In fact, this rebar alternative reduces emissions by an estimated 90%.
Blade Recycling: Challenges
Two major obstacles to cost-effective blade recycling remain. One is the size of the blades and the other is the distance from wind farms to recycling facilities. Wind farms are often located atop distant ridges or other out-of-the-way places. Transporting blade sections hundreds of miles becomes a new source of emissions. However, electric and/or hydrogen-powered semis may eventually impact this equation.
Companies are already tackling the challenge of blade recycling. Regen Fiber is an Iowa-based startup, while Veolia is a global waste recycling firm.
Regen Fiber in Iowa
Regen Fiber is an Iowa-based startup using blade fibers to strengthen concrete. At full production, its plant will recycle 30,000 tons of shredded blade material every year. Applications include pavement, slabs-on-grade, and precast products. Regen Fiber will also use the material for the manufacturing of composites and for soil stabilization. Regen recycles blades without heat, chemicals, or burning.
Veolia in Missouri
Veolia has entered into an agreement with GE to shred blades from U.S. wind turbines. It intends to use recovered fiberglass in cement production. In fact, its Louisiana, MO, recycling plant ships about 60 to 80 tons of pulverized blade material to cement manufacturers per day. Roughly 75% of the blade material replaces the raw silica currently used to make cement. The rest replaces some of the coal used to fire the kilns.
Veolia claims 90% blade recycling by weight. About 65% becomes raw material for cement production. Another 28% becomes an alternative to coal in firing the kilns. Veolia says its recycling method reduces CO2 emissions by 27% compared to traditional Portland cement production.
More Eco-friendly Blades
Early on, designers engineered turbine blades for optimum performance. Now, researchers are also looking at new blade materials that are easier to recycle. For example, NREL’s thermoplastic resin research offers a promising alternative. The thermoplastic and epoxy blades had similar stiffness.
The thermoplastic blades exhibit 5-7 times the structural damping of common epoxy/fiberglass blades. This may help to extend the wind turbine lifespans, another source of reduced emissions.
In the future, the cement industry may also benefit from the recycling of other fiberglass-rich items. Boat hulls, airplane wings, and automotive bumper covers are some examples.
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