Enhancing circular bioeconomy in Europe: Sustainable valorization of residual grassland biomass for emerging bio-based value chains

The growing interest in value-added materials from lignocellulosic biomass residues highlights their potential for environmental and economic benefits. However, a comprehensive understanding of the socio-technical implications of transitioning to a circular bioeconomy remains underexplored. This paper addresses this gap by introducing a conceptual framework delineating the niche innovation mechanisms that foster emerging circular grass-based value chains within this context. The analysis builds on an exploratory case study framework, expert interviews and workshops identify obstacles coinciding with different valorizing approaches: cascading, substitution, and complementary. The results indicate that the cascading approach struggles with biomass quality, efficiency, and industrial integration. The substitution approach underscores the need for streamlined processes and niche marketing, while the complementary approach requires technology adaptation and capacity-building programs. In light of these challenges, this study emphasizes three strategic niche management processes critical for the transition. First, active engagement of local farmers and landowners in waste stream valorization is proposed to unlock synergies and drive innovation in emerging value chains. Second, learning activities should prioritize continuous monitoring of novel grass-based products and promote open communication with end-users to enhance marketability. Third, given the institutional uncertainty and ambiguity, aligning expectations becomes crucial. This implies the necessity of coordinating interests among actors such as combining top-down and bottom-up policy measures. These are effective mechanisms for accelerating the transition to circular bioeconomy.