Carbon capture through solar-driven CO2 gasification of oil palm empty fruit bunch to produce syngas and biochar

Oil palm empty fruit bunch (OPEFB) is an abundant organic waste in Malaysia that is often disposed of through field burning. A previous study has shown that solar-driven steam gasification of OPEFB can produce hydrogen-rich syngas with an energy upgrade factor of 1.2 and a carbon conversion efficiency of 95.1 %. Beyond its potential as a biofuel, OPEFB can also act as a carbon sink, capturing photosynthetically stored carbon. This study explores the potential of amplifying OPEFB's negative carbon emissions through solar-driven gasification, using CO 2 as the gasifying agent. In this work, a Central Composite Design (CCD) approach was employed to assess the influence of temperature (1100–1300 °C) and CO 2 /OPEFB molar ratio (1.6–3.0) on H 2 /CO molar ratio and energy upgrade factor, with a constant OPEFB flow rate of 1.8 g/min. The results demonstrated that at an energy upgrade factor of 1.4, 94.9 % of the total carbon was converted into syngas with a H 2 /CO molar ratio of 0.3. The maximum observed net carbon capture yield of 0.4 g C/g OPEFB was achieved at 1300 °C and a CO 2 /OPEFB molar ratio of 3.0. The remaining carbon (94.4–95.7 wt %) was converted into biochar with low heavy metal content, which has potential as a soil enhancer. • Solar-driven CO 2 gasification of OPEFB captures carbon into syngas and biochar. • Net carbon capture reached 0.4 g C /g OPEFB , with 94.9 % carbon conversion efficiency. • H 2 /CO molar ratio achieved 0.3, equating to a high CO content of 58.5 mmol/g OPEFB . • Energy upgrade factor of syngas reached 1.4, showing efficient storage of energy. • Biochar with high carbon and low-heavy metals is ideal for soil enhancement.