Achieving zero CO₂ emissions from integrated biomass gasification with CO₂ capture and utilization (IGCCU)

Biomass energy plays a crucial role in mitigating carbon emissions. However, the existing gasification technology faces challenges such as releasing undesirable CO₂ in the produced syngas. Here we propose a new concept for achieving zero CO₂ emissions by integrating gasification with CO₂ capture and utilization (IGCCU) for the first time. During lignin gasification, valuable syngas (H₂/CO) can be produced, and CO₂ in the gaseous products can be simultaneously captured by CaO. After completing the lignin gasification process, the captured CO₂ can be effectively converted to CO by switching the carrier gas from N₂ to H₂. The results show that the entire process achieves zero CO₂ emissions with carbonation and hydrogenation process at 400 °C and 550 °C, respectively. This approach allows a significant reduction in CO₂ yield from 0.95 mmol g⁻¹_CaO g⁻¹_lignin (benchmark experiment) to nearly 0, using CaO as an adsorbent and catalyst. The disappeared CO₂ was converted into 0.95 mmol g⁻¹_CaO g⁻¹_lignin of CO, by introducing H₂ to the sorbent regeneration stage. Furthermore, excellent cyclic stability has been achieved with zero CO₂ emissions after five cycles and consistent 100% CO₂ conversion during the CO₂ utilization stage.