Can Carbon Fiber Make Aviation Greener?

Planes account for 1 billion tons of carbon dioxide emitted into the atmosphere every year. Scientists, therefore, are looking for solutions to mitigate their impact on Planet Earth. One such avenue being explored is using advanced composites to build airplanes instead of traditional metals such as aluminum. Advanced composites are ultra-strong, ultra-light materials made by blending tough structural carbon fibers with a hardening plastic glue (polymer resins) - and are also, arguably, the key to making planes more affordable and more sustainable. 

By using advanced composites to build airplanes instead of standard materials, this significantly reduces their weight. As a result, far less fuel is needed to operate these vehicles, meaning carbon emissions plummet. To put it into perspective, on average, it takes about 0.2 kilogram of fuel to transport an extra 1 kilogram of weight over a distance of 1,000 km, plus an additional 0.02 to 0.03 kilogram of fuel per 1,000 kilometer for every extra kilogram added. This is a crucial difference when taking into account the cumulative impact — and major airlines know this. Already, Qatar Airways, Singapore Airlines, and Emirates are implementing advanced composites in their aircraft, and this trend is showing an upwards curve over the years. The Airbus A350, for example, already consists of roughly 70% advanced composites and shows benefits of 25% slower fuel burn and 20 tons of weight saved compared to older, aluminum-heavy bodies.

However, there is a glaring flaw: making carbon fiber is energy-intensive, and recycling it for aircraft is nearly impossible. Current thermal and chemical recycling methods (like pyrolysis) reduce the fiber's strength by 20% to 40%. This means the material is extremely difficult to reuse for flight-grade structures. Combined with the precise trimming needed, this leads to massive waste in the manufacturing process, and skyrocketing carbon footprints through the use of landfills or incinerators. As for other uses of the material, this proves to be troublesome as well: the properties that make them so suitable for airplanes are exactly what make them nearly impossible to recycle. Their strength and the structure of their internal bonds prevent them from being melted down for other purposes, and removing either the carbon fibers or polymer resins from composites often damages them to a far lower quality. 

Beyond the problem of waste, the process of creating these composites comes with issues as well. Most aerospace carbon fiber (an essential component of composites) starts from a precursor such as PAN (polyacrylonitrile), which itself requires energy and chemical processing to produce. Creating virgin carbon fiber also requires baking precursors at temperatures up to 3,000°C in order to stabilize and carbonise them at an industrial scale, a process heavily reliant on fossil fuels and oil-derived chemicals. The key question here on which its sustainability depends is whether decades of fuel savings outweigh the emissions from producing the material, and this differs depending on the exact semantics of how each airline produces and uses them.

While advanced composites promise to make planes more sustainable, they hide a dirty truth: the energy required to manufacture them, combined with the difficulty of recycling them into flight-grade materials, can create a sustainability problem before the plane even flies. Airlines may be trading one carbon problem for another, and unless the industry can balance the emissions from manufacturing and disposal against the fuel and emissions savings achieved during flight, the greenest plane might just be one we never build.

Image sourced via Turkish Airlines. Used for editorial purposes only. No commercial use. All rights belong to their respective owners.