Circular Carbon for Sodium-Ion Battery Production

Background and context

Microalgae are increasingly used in industrial CO₂ capture systems across sectors such as brewing and wastewater treatment. While these systems provide a sustainable route to reducing emissions in operation, they generate significant volumes of residual biomass once the algae reach the end of their useful cycle. In most cases, this biomass is disposed of or used in lower value applications such as fertiliser, representing a missed opportunity for higher value utilisation.

At the same time, the demand for sodium-ion batteries as an alternative to lithium-ion systems is growing rapidly, particularly for grid scale storage applications. Whilst demonstrating improved sustainability over lithium-ion, a critical component of sodium-ion batteries is hard carbon, traditionally derived from coal or geographically limited biomass sources such as coconut shells. Developing alternative, sustainable, and regionally adaptable carbon sources is therefore key to the transition to renewable energy.

About the Project

This project to tackle both challenges through reframing “waste” biomass as a strategic resource for energy systems.

Led by the University of Swansea, in collaboration with Batri Ltd, Bluestone Brewery, and Royce facilities at the University of Liverpool, the project set to establish the technical feasibility and scalable potential of converting microalgae to the production of hard carbon for sodium-ion battery anodes.

In bringing together expertise and industrial application across materials science, algal biotechnology and battery manufacturing, the consortium demonstrates a translational model in which early‑stage materials discovery is embedded within industrial validation and techno‑economic assessment from the outset.

Project Details and Results

With the objective of establishing the technical and early-stage economic feasibility of the proposed value chain, the project was structured into three integrated work packages.

The first focused on establishing appropriate biomass selection and preparation. Utilising microalgae biomass supplied from Bluestone Brewery’s industrial CO₂ capture operations, two strains were characterised for compositional suitability. The data collected enabled standardised drying and preparation protocols to be developed to improve batch reproducibility and inform selection for subsequent optimisation.

The second work package addressed carbon synthesis and optimisation to achieve industrial performance benchmarks. Multiple carbonisation routes were investigated to convert the screened microalgae biomass into hard carbon including direct pyrolysis and hydrothermal carbonisation followed by pyrolysis. The portfolio of candidate hard carbon materials were structurally characterised, including small‑angle and wide‑angle X‑ray scattering conducted at the Henry Royce facilities at the University of Liverpool. This enabled correlations to be drawn between nanoscale structure and electrochemical performance, benchmarked against commercial hard carbon materials. Through iterative optimisation of processing parameters, a comparative synthesis report was produced linking precursor properties to the required carbon microstructure and processing conditions.

The third work package focused on electrochemical validation and techno-economic feasibility. The best performing samples demonstrated capacity and cycling stability within feasibility study expectations. Conducting a techno-economic assessment sought to investigate scalability, precursor cost sensitivity, and processing energy demand for potential value‑chain integration. Residual biomass remaining after extraction of higher-value compounds could achieve a more economically viable pathway to scaled circularity.

Overall, the project successfully demonstrated that microalgae‑derived carbon can achieve electrochemical performance comparable to established biomass‑derived hard carbons for sodium-ion battery anodes. Defining reproducible processing pathways, key structural parameters governing battery behaviour, and identifying an economically viable value chain, the project has been critical to advancing from academic investigation towards market.

Impact & Next Steps

Valorising waste biomass has the potential to reduce landfill and low‑value disposal routes, whilst displacing the traditional fossil‑derived carbon in battery manufacturing. Doing so through locally-derived carbon precursors is of national imperative to reducing exposure to critical material risks, strengthening supply chain security.

For industry, the project opens a new value stream for sectors already investing in microalgae‑based CO₂ capture. The project has illustrated that it can be utilised as a feedstock for high-value energy systems. This creates opportunities for cross‑sector collaboration between carbon capture, bioprocessing, and battery manufacturing industries. Working specifically with Batri and Bluestone Brewery, as two Welsh organisations, has further demonstrated how local industrial ecosystems can be linked to form circular value chains that deliver both economic and technological benefits.

The feasibility data generated through this project position the team to pursue scale‑up funding, deeper techno‑economic modelling, and pilot‑level validation. The broader vision is to create a scalable platform technology that can be adapted to diverse microalgae sources globally, supporting sustainable battery supply chains and accelerating the transition to low‑carbon energy systems.