The role of biochar as a microbial carrier in enhancing biogas production efficiency in anaerobic digestion systems

The energy transition (ET) refers to the provision of sustainable energy for both present and future human needs. It focuses on quantifying the relationship between policy-driven energy shifts and emission outcomes. At the same time, it seeks to safeguard the environment from the long-term adverse effects of energy consumption. In certain developed countries, where recovery efforts were aligned with climate objectives, energy transition (ET) progressed at an annual growth rate of 2.2–3.6 %. This study analyzes the environmental impacts of renewable energy source (RES) technologies through a comprehensive review, with particular focus on anaerobic digestion (AD), a globally utilized and promising approach for biogas production. Research in this field has increasingly emphasized intensification techniques targeting hydrolysis, acidogenesis, acetogenesis, and methanogenesis to achieve sustainable biogas yields while maintaining stable digester performance. Since microorganisms are capable of thriving in diverse environmental conditions, including cold regions or under sanitation-related constraints, their role in anaerobic digestion (AD) highlights significant industrial potential. Furthermore, within the AD process, biochar-microbe interaction enhance biogas production (73 %) comparing to mono-digestion, establishing it as one of the most accessible and sustainable renewable energy sources. Moreover, the application of AD technology not only improves biogas quality but also mitigates environmental impacts by reducing the proportion of CO₂ (10–20 %) and 95 % H₂S major constituents of raw biogas. This review aims to highlight the biochar-microbes interaction in enhancing the efficiency of the AD process for biogas production, with a particular focus on their mutual interactions, the challenges influencing AD performance, and the broader economic and environmental significance of biogas production.