Commercial cellulosic ethanol plants require mature and year-round biomass feedstock supply. Decentralizing pretreatment operation from central ethanol plant into local regional biomass collection depots provides an important solution to reach this goal. In this study, we introduced a newly established pretreatment technology, dry acid pretreatment, into the decentralized pretreatment operation by its advantages on zero wastewater generation and high volumetric density. Collection radius of crop residues feedstock is extended to nearly 100 km by decentralizing dry acid pretreatment, and biorefinery scale for cellulosic ethanol production is increased to the scale of modern petroleum refining factories in the densified agricultural regions in China and USA with the minimum ethanol selling price of below $2/gal. The technology overcomes the barrier of cellulosic ethanol cost increase with increasing biomass collection range, and provides a methodology for optimal supply method of large biorefinery plants in agricultural countries.