Could bio-based carbon fibre help the bike industry clean up?

The subject of sustainability and the end-of-life of materials has been in sharp focus lately as companies get to grips with the dirty legacy some products can leave. Sean Meager explores a new “bio” carbon fibre innovation to see if it has legs for cycling…

The benefits of a carbon fibre chassis on bikes have been known in cycling for many years. In 1989, Greg LeMond debuted the Look TVT at the Tour de France, a bike 1kg lighter than that of his competitors. He won by eight seconds, a difference that could easily be attributed to his bike’s weight. Since then, ‘carbon bikes’ have steadily increased in prevalence to become the norm.

Recently, the demand for carbon fibre composites, in general, has increased dramatically. Companies such as BMW have used carbon fibre in electric vehicles, Boeing in its Dreamliner planes and Vestas’ in wind turbines. The TU Dresden university campus will even become the first building reinforced by carbon fibres instead of steel.

The benefits are clear. Carbon fibres are incredibly thin, light and yet they are five times stronger than steel and twice as  stiff. Meaning more fuel-efficient vehicles (be they bikes, cars or planes). However, the process of producing petroleum-based carbon fibre is resource heavy. Production is estimated to be about 14 times more energy-intensive than conventional steel production. The high cost of carbon fibre is partly due to this complex and energy-intensive production process. Global output is just 150,000 tonnes per year, to 1.86 billion metric tonnes of steel.

Other downsides to the material are that it is difficult to recycle and dispose of, although ways of reusing it are now being developed and the conventional process also produces toxins.

As more companies commit to improving their green credentials, the unsustainability of carbon-based bikes will likely come under scrutiny more and more. The release of Trek’s first Sustainability Report highlights the differences between producing a high-end carbon race bike, versus a mass market aluminium bike. Therefore, for bicycle makers to become carbon neutral, it is likely alternative means of production will be required.

Dr Erik Frank, the Head of Carbon Fiber Development at the German Institutes of Textile and Fiber Research in Denkendorf, believes the future of carbon fibre production could be in “bio-based carbon fibres.” Bio-based fibres are those that come from plants or other non-fossil fuel feedstocks. Frank is exploring ways of turning lignin, a support substance found in most plants, and which is a by-product of the paper industry, into carbon fibres.

The process has the potential to significantly reduce emissions in carbon fibre production. A sensitivity analysis conducted in the International Journal of Life Cycle Assessment concluded that there could be a 20% reduction in energy use in the conversion of lignin to carbon fibre and that, since lignin is a waste product of paper production, there would be no energy use needed. Overall, a 30% reduction in life cycle energy use could be obtained.

To produce carbon fibre from lignin Frank is “[using] chemical methods to purify it and get it into a good shape. Then we can spin this into fibres, which we’re trying to do directly in water rather than having to use toxic solvents. And the fibres that you get can be directly turned into carbon fibres. This means we’ve taken the carbon from the air via the plants, rather than adding carbon from fossil sources like petroleum or coal into the atmosphere”

However, the process isn’t quite there yet, producing carbon fibre “on the medium to lower-end” compared to petroleum- based fibres, he added. “I should say the bio-based carbon fibres won’t replace the [petroleum]-based ones. It will just be a second market running alongside.”

As the prevalence of electric vehicles and a need for manufacturers to increase the efficiency of their vehicles increases, the demand for sustainable, high-performance materials means that bio-based carbon fibres could soon become more affordable as research and development increases around the world.

Research has also taken place into considering the viability bio-based glass fibre in producing a Look compatible road cycling clipless pedal. The pedal tested was found to be “mechanically viable and [have] a significantly lower environmental impact than full synthetic composites”. It is likely that more will take place.

Alongside all of these comes innovations with Flax fibre. Hummingbird has brought to market a 6.9kg folding bike with a frame made from a woven linseed (pictured).

Flax is, many believe, a viable carbon alternative and as such is already in use in the motorsport industry, to name just one. The key draw? It’s lighter than most carbon structures, offers excellent vibration reduction and best of all for a business world now tasked with generating sustainability reports, it’s biodegradable too.

Carbon Fibre as waste

Carbon fibre is also incredibly difficult to reuse or recycle. A report produced by the environmental charity Green Alliance in February 2017 identified carbon fibre as one of several novel materials that could create waste problems in the future unless swift action is taken to make it ready for recycling and reuse.

The key problem is that carbon fibre cannot simply be melted down and reformed like aluminium. Carbon fibre composites get their strength from long, precisely aligned carbon fibres, fixed within a glue-like polymer that is cured at high temperatures and pressures. Once cured, most of these tough polymers will not melt and have to be burned off or chemically dissolved to reclaim the valuable fibres.

Companies like Gen 2 Carbon are working on ways to increase the recyclability of carbon fibre in industries such as automotive, commercial aerospace, rail, electronics and renewables.

“There are already quite a few recycled carbon fibres and they’re even being used in products. Of course, they become worse with every cycle and at some point, they will have to be disposed of. Burning isn’t an option because it’s really hard to burn. A lot of the time it is stored in old mines.”