9Process simulation of a single-step synthesis of DME based on CO 2 -enhanced gasification of 10 rice straw was conducted using Aspen Plus TM . The process consists of gasification unit, heat 11 recovery unit, gas purification unit, single-step DME synthesis, and DME separation unit. In the 12 simulation, highly pure DME was produced by the control of CO 2 concentration in syngas to a 13 very low level prior to synthesis. A gasification system efficiency of 36.7% and CO 2 emission of 14 1.31 kg/kg of DME were achieved. Bio-DME production based on CO 2 -enhanced gasification of 15 biomass was found to be more cost-effective as it required 19.6% less biomass than that of DME 16 production based on conventional biomass gasification. The performance and environmental 17 benefits of the proposed process could be further improved by the utilization of unreacted gases 18 and the handling of CO 2 generated via incorporating poly-generation concept or carbon storage, 19 which could also potentially improve process economics. 20