Progress in lignocellulosic biomass valorization for biofuels and value-added chemical production in the EU: A focus on biochemical conversion processes

Abstract

In light of the growing environmental challenges associated with rapid industrialization, climate change, and escalating global energy demand, the transition to sustainable and renewable energy sources has become increasingly urgent. The European Union (EU) Renewable Energy Directive targets 42.5% renewable energy by 2030, compared with about 25.2% in 2024, highlighting the urgent need to expand sustainable energy tech nologies. The valorization of lignocellulosic biomass for the production of bioenergy and value-added chemicals is particularly critical for advancing sustainable waste management practices and enabling a low-carbon circular bioeconomy. In the EU, biomass supply is dominated by agriculture (70%) and forestry (27%). Lignocellulosic biomass availability increased from approximately 492 million tons of dry matter in 2015 to 513 million tons in 2020 and is projected to reach nearly 551 million tons by 2030. This study provides a comprehensive overview of advanced biochemical conversion pathways for lignocellulosic biomass, with a specific focus on anaerobic digestion, dark fermentation, and syngas fermentation. These processes are examined in terms of their under lying mechanisms, operational conditions and product yields alongside the unique challenges and opportunities associated with each technology. The emphasis on biochemical routes is motivated by the fact that our previous work extensively covered thermochemical conversion processes, and this review aims to provide a complementary perspective. To set the foundation for future research in biochemical and integrated lignocellulosic biomass valorization, this study also synthesizes prior research efforts, identifies key knowledge gaps, and highlights emerging prospects for sustainable bioprocess development.