| Summary: | To strike a better balance between gas quality and production cost of biomass-based syngas, a process for high-safety and cost-effective syngas production is designed and studied, which takes advantage of biomass O<sub>2</sub>-enriched air gasification with 40–70% O<sub>2</sub> purity and methanation synthesis. Based on the simulation data, the process is evaluated from techno-economic aspects, including syngas composition, higher heat value (<i>HHV</i>), upper and lower explosive limits (<i>UEL</i> and <i>LEL</i>), toxicity, unit production cost (<i>UPC</i>) and levelized cost of energy (<i>LCOE</i>). Five kinds of biomass are studied as feedstock. The effects of O<sub>2</sub> purity, methanation pressure, feedstock cost, and plant scale are determined, respectively. The results show that O<sub>2</sub> purity is an important parameter for technical performance, while methanation pressure is a minor parameter except for exergy efficiency. With respect to cost indicators, feedstock cost, and plant scale are crucial variables; by contrast, O<sub>2</sub> purity plays a relatively minor role. This process can generate non-toxic syngas containing 33.2–34.9 vol.% CH<sub>4</sub>. The <i>UEL</i> and <i>LEL</i> are about 34% and 12%, and the average explosive range is about 22%. The <i>HHVs</i> of syngas generated from five kinds of feedstock sit between 13.67–14.33 MJ/m<sup>3</sup>, and the exergy efficiency achieves 68.68%. The <i>UPC</i> varies between 0.05 $/Nm<sup>3</sup> and 0.27 $/Nm<sup>3</sup>, and the <i>LCOE</i> varies between 3.78 $/GJ and 18.28 $/GJ. When the plant scale is rational, the process shows strong competitiveness in either <i>UPC</i> or <i>LCOE</i>. The techno-economic results demonstrate that the studied process offers an alternative and sustainable pathway to supply gaseous fuel for low-income areas.
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