Fifteen alternative process designs for the production of synthetic gasoline from coal, biomass, or coal+biomass via gasification, methanol synthesis, and methanol-to-gasoline synthesis are analyzed, including some that produce a substantial electricity co-product and some that employ CO 2 capture, with CO 2 stored in deep saline formations or via injection for enhanced oil recovery. This paper reports process mass/energy balance simulation results and fuel-cycle greenhouse gas (GHG) emissions comparisons. A companion paper addresses economic and strategic issues. Key findings of the performance analysis include: i) for two plants designed with the same liquid fuel output, but with one co-producing electricity, the additional feedstock needed for coproduction is converted to electricity more efficiently than if that feedstock were used in a stand-alone power plant; ii) plants using only coal as feedstock have fuel-cycle GHG emissions greater than the conventional fossil fuels their products would displace, except for a coproduction system with CO 2 capture and storage (CCS) which has about 40% less emissions; iii) plants that co-process 35% to 47%sustainably-provided biomass with coal achieve net zero fuel-cycle GHG emissions; iv) the logistics of biomass supply constrain these latter plants to modest scales (< 10,000 barrels per day gasoline); and v) a biomass-only plant with CCS has highly negative net GHG emissions and a more severe scale constraint (~ 4,000 bpd).