A method, apparatus, and system for a solar-driven bio-refinery that may include a entrained-flow biomass feed system that is feedstock flexible via particle size control of the biomass. Some embodiments include a chemical reactor that receives concentrated solar thermal energy from an array of heliostats. The entrained-flow biomass feed system can use an entrainment carrier gas and supplies a variety of biomass sources fed as particles into the solar-driven chemical reactor. Biomass sources in a raw state or partially torrified state may be used, as long as parameters such as particle size of the biomass are controlled. Additionally, concentrated solar thermal energy can drive gasification of the particles. An on-site fuel synthesis reactor may receive the hydrogen and carbon monoxide products from the gasification reaction use the hydrogen and carbon monoxide products in a hydrocarbon fuel synthesis process to create a liquid hydrocarbon fuel.