Lignin valorization for carbon neutrality: From green materials to carbon capture and utilization

Lignin, the second most abundant biopolymer after cellulose, is still largely combusted as low-value fuel, yet it offers significant potential as a versatile carbon resource for low-emission materials and processes that reduce carbon footprints in high-emitting industries. This review critically analyzes how lignin valorization can contribute to carbon neutrality across power generation, transportation, construction materials, and carbon capture and utilization (CCU). We synthesize recent advances in lignin-based adsorbents and catalysts, polymer composites, biofuels, and electroactive materials relevant to these sectors. The study introduces a technological readiness levels (TRLs)-based framework to assess the maturity of lignin applications, revealing disparities across sectors from early-stage developments in energy storage and biofuels to commercial-ready solutions such as activated carbon. We further discuss key bottlenecks including lignin’s structural heterogeneity, high extraction costs, and varying TRLs which impede large-scale implementation. Finally, this review emphasizes the need for cross-disciplinary strategies, standardized processing methods, pilot-scale demonstrations, and life-cycle assessments, highlighting that comprehensive assessments are crucial for integrating lignin into a circular bioeconomy and for maximizing its contribution to global carbon neutrality efforts.