Continuous solar-driven gasification of oil palm agricultural bio waste for high-quality syngas production.

Empty fruit bunch (EFB) from oil palm is a solid agricultural bio-waste obtained from the edible oil process. Continuous solar-driven gasification of EFB offers a bright carbon-neutral avenue to convert both EFB bio-waste and renewable solar energy into sustainable and clean syngas. High-temperature concentrated solar heat is used to provide the reaction enthalpy, and therefore biomass waste feedstock is entirely dedicated to produce hydrogen and carbon monoxide (syngas). Solar energy is stored as a high-quality syngas and can be easily transported as a convertible and dispatchable chemical form. In this study, the performance of continuous steam gasification of EFB, fully powered by concentrated solar heat, was experimentally investigated in a solar gasification reactor. Experiments were carried out with continuous EFB biomass injection to evaluate the influence of temperature (1100-1300 °C) and biomass feeding rate (0.5-1.8 g/min). As a result, syngas yields and reactor performance were substantially enhanced by rising the EFB feeding rate and gasification temperature. An optimal EFB biomass feeding rate enabling maximum gasification performance was found to be 1.4 g/min at 1300 °C and 1.0 g/min at 1200 °C. Carbon conversion approaching 97%, energy upgrade factor of 1.38, and solar-to-fuel energy conversion efficiency up to 20% were demonstrated. Finally, the maximum syngas yield was found to be 81.1 mmol/g at 1300 °C (with H and CO as the main constituents), closely approaching the maximum theoretical expected value reached at thermodynamic equilibrium (85.2 mmol/g). Combining concentrated solar energy and biomass waste gasification was shown to be a promising and sustainable pathway toward waste valorization into carbon-neutral solar fuels.