Scaling up sustainable carbon fibre production

This project successfully optimised and scaled a novel, sustainable route to produce high-lignin carbon fibres using carbon nanotube reinforced precursors. Using Royce pilot facilities, the work demonstrated extended fibre spinning and provides a foundation for further industrial scale-up of low cost, lower carbon fibre technologies from abundant biomass resources.

Background and context

Carbon fibre composites enable lightweight, energy-efficient technologies across transport, renewable energy, and construction applications. They help reduce fuel consumption, extend electric vehicle range, and improve wind turbine efficiency. However, conventional carbon fibres are made from predominantly petrochemical precursors such as poly(acrylonitrile) (PAN); conventional processes also use energy-intensive processing and hazardous chemicals, which contribute to high product costs compared to materials such as steel, aluminium and glass fibre.

Demand for carbon fibre is increasing rapidly, driven by decarbonisation targets and advanced manufacturing, but is limited by the high cost. Lignin is the second most abundant biopolymer on Earth, present in wood, and an underutilised by-product of cellulose production across the world: 65 million tonnes are extracted each year, making it a readily available renewable raw material.

Under the right conditions, lignin forms long filaments using melt or solvent assisted fibre spinning. Lignin’s renewable origin, potential low cost (as it is a by-product) and comparatively high carbon yield (>35%) show promise for it being a feasible sustainable and cost-effective precursor for carbon fibre production. If successfully demonstrated as an alternative for fossil-based carbon fibre or glass fibre, it is anticipated that it will also contribute to reducing the life cycle footprint of carbon fibre composites further.

A key challenge of turning lignin into attractive carbon fibres lies in identifying suitable fibre spinning approaches. Lignin’s relatively short chains make it difficult to process it into precursor fibres without substantial amounts of spinning additives, while the complex and variable chemical structure is a challenge for obtaining well-ordered, aligned carbon structures that are needed for higher performance grades.

This project addressed these barriers by developing a novel, scalable lignin-based carbon fibre spinning process that delivers a high lignin content, high carbon yield, and enhanced ordering. These outcomes align with Royce’s goals of advancing sustainable materials and UK leadership in low carbon technologies.

Project Details and Results

This project aimed to scale up a new route to lignin-based carbon fibre precursors, building on a patented approach developed at Imperial College London. Central to the innovation is the use of small amounts of carbon nanotubes (CNTs) in the lignin based spinning formulations, with the nanotubes both supporting fibre formation and enhancing the resulting carbon fibres.

The project produced reproducible, scalable wet-spinning dopes with high (95%) lignin content, significantly greater lignin content than existing literature systems, using commercially relevant lignin feedstocks and automated processing. Continuous fibre spinning was achieved at laboratory scale.

The work then progressed to pilot scale trials using the Henry Royce Institute’s Fibre Technologies Platform, validating the process under more realistic conditions and enabling systematic exploration of spinning parameters, fibre handling, and process stability.

Finally, the precursor fibres were thermally converted into carbon fibres, achieving expected proof of concept level mechanical performance and excellent carbon yields. Overall, the project established technical feasibility and generated key knowledge to guide further scale-up and optimisation efforts. The data gathered from these experiments are feeding into a Technoeconomic and Life Cycle Assessment.

Impact & Next Steps

With further optimisation of the mechanical properties, lignin carbon fibres represent a major opportunity to reduce the environmental impact and cost of advanced composites. By replacing fossil derived precursors with renewable biomass, lignin-based precursor technology could significantly lower the carbon footprint of carbon fibre production, while also improving resource efficiency through the valorisation of industrial byproducts.

For industry, lower cost carbon fibres could unlock new markets, particularly in automotive and construction sectors, where current material costs limit adoption. Wider use of lightweight composites can contribute to reduced energy consumption in transport, improved performance of renewable energy systems such as wind turbines, and longer lasting infrastructure due to the excellent durability and corrosion resistance of carbon fibre materials.

From an environmental perspective, the process has the potential to reduce greenhouse gas emissions both during production and throughout the lifecycle of the materials. The use of lignin, which is currently underutilised, also supports a more circular and sustainable materials economy.

Looking ahead, further optimisation of the material properties of lignin derived carbon fibres to exceed the stiffest glass fibres (tensile modulus >80 GPa) or achieve tensile properties for automotive applications (1.72 GPa tensile strength and 172 GPa tensile modulus) and scale up to high fibre count tows (3,000 to 48,000 fibres) would enable this technology to compete directly with existing carbon or glass fibre production routes. The project therefore lays the foundation for a new generation of sustainable structural materials with significant societal and economic benefits for the UK and beyond.

Project collaborators

This project exemplifies the strength of collaborative research in advanced materials, bringing together expertise from academia, national infrastructure, and industry. Imperial College London led the project, contributing specialist expertise in materials chemistry, lignin processing, and nanocarbon technologies. The Imperial team developed the core spinning formulations, laboratory-scale processing, and material characterisation.

The University of Manchester, through the Henry Royce Institute, provided access to advanced fibre spinning infrastructure and technical support. Royce application scientists enabled the execution of pilot scale trials and contributed valuable fibre processing expertise, helping the project move beyond laboratory demonstrations toward industrially relevant conditions.

The industry partner, Syensqo, added a vital commercial perspective on real-world requirements for carbon fibre production, including scalability, performance targets, and manufacturability. Their involvement helped ensure the work remained aligned with industrial needs and future deployment pathways, while strengthening the case for continued investment and development.

The collaboration enabled rapid iteration between materials development and process testing, with feedback from pilot trials informing ongoing optimisation. It also facilitated knowledge exchange across chemistry, engineering, and industrial practice. This integrated approach accelerated progress, improved the quality of outcomes, and helped ensure the project delivered both scientific and practical value.

How Royce support contributed

Support from the Henry Royce Institute enabled the project to move beyond laboratory-scale development and test the lignin/CNT spinning process under more industrially relevant conditions. Royce provided access to specialist fibre spinning infrastructure, including pilot-scale equipment capable of continuous processing and multifilament configurations.

This facility allowed the team to explore key scale-up factors such as extrusion rate, coagulation conditions, fibre handling, and process stability, while drawing on Royce technical expertise to adapt laboratory protocols for pilot-scale trials. This support helped de-risk the technology, accelerate learning, and provide confidence for further scale-up and industrial development.