Recycling consists of processing waste to alter its physicality so that it can be transformed into a new, usable material. Possible processing methods include shredding, melting, and composting, among others. Which process is used depends on the material being recycled.
How easily something can be processed determines whether it will end up in a landfill or return to use. Composite materials increasingly used in aircraft manufacturing are notoriously hard to process and, therefore, often considered impossible to recycle. See “What’s Up with Composite Materials?” at end of article.
Nevertheless, the number of composite materials used in aircraft airframes has steadily increased with new aircraft iterations. For example, according to The Aeronautical Journal, “composites in primary and secondary structural parts of the Boeing 787 account for approximately 50% of the total airframe weight, as opposed to approximately 10% for the older generation Boeing 777.”
The reason for this increase is that composite materials provide comparable strength with much less weight than aluminum, meaning the aircraft will require less fuel to travel from point A to point B. Aeroclass.org notes that “the 777 has a fuel consumption of 9 miles per gallon, while the 787 has a fuel efficiency of 11 miles per gallon.” (The 787 is also more aerodynamically designed than the 777, but at least part of those savings is due to the reduction in overall airframe weight. Also, a two-mile difference may not seem significant off-hand, but consider the gallons saved during a 3,000+ mile trans- or intercontinental flight.) All this is great for the environment—during the aircraft’s operational life.
Like so many superheroes, composite materials eventually become the villains. Once the aircraft reaches its end-of-life, the former mitigators of environmental impact become major offenders, releasing toxic chemicals during disposal, and filling up landfills. Fortunately, associations like the Aircraft Fleet Recycling Association (AFRA) are working on potential solutions to this problem.
AFRA is “the leading global organization for developing and promoting the safe and sustainable management of circularity of components and aircraft in the aviation sector.” Circularity in this context refers to the circular economy, a concept that has gained traction in recent decades. In a circular economy, economic systems focus on limiting waste by reducing, repairing, reusing, and recycling resources. In 2020, the European Union adopted “A new Circular Economy Action Plan for a Cleaner and More Competitive Europe” and, in 2022, the European Union Aviation Safety Agency (EASA) published the European Aviation Environmental Report (here’s the executive summary) discussing the aviation industry’s progress.
According to Interim-Executive Director Walter Sam O'Connor, AFRA has a charter to “further the ongoing development of composite material recycling.” AFRA took possession of two 787 wings in March and will take possession of the remaining fuselage sections later this spring.
In partnership with the National Manufacturing Institute of Scotland, AFRA’s Research and Development Committee will leverage these 787 assets to “define methods for recycling, reusing, or repurposing” composite materials efficiently and safely. Should the landfill be unavoidable, the team hopes to identify innovative disposal methods with as minimal environmental impact as possible.
Mr. O’Connor also noted that while “AFRA’s efforts are of great value to the industry” such efforts should not be limited to the aircraft’s end-of-life. Sustainability must be at the forefront during the design and development stage. “If you want to understand how to disassemble and recycle a product, you have to understand what’s going into it at the beginning,” he shared.
What's up with Composite Materials?
Composite materials are things – in this case, aircraft parts – made up of multiple layers of other things that are bonded together, i.e., carbon fibers and resins. To be recycled these layers must be taken apart, which is difficult and time-consuming particularly because resins are often made with thermosetting plastics. When exposed to heat thermosetting plastics do not melt, they harden which is exactly what we do not want when we’re trying to melt something down to recycle it!
Another difficulty with composite materials is that they can contain hazardous materials that may pose environmental and health risks. For example, epoxy resins used in some coatings to improve properties like adhesion and resistance (ScienceDirect.com) release toxic fumes when exposed to heat.
(Thank you to Harvey Dent as portrayed by Aaron Eckhart in Warner Bros. Picture's The Dark Knight for the iconic line that inspired this title.)