This invention relates to a sulfur tolerant, dynamic, compact, lightweight fuel process and system that is capable of converting sulfur bearing carbonaceous fuels to hydrogen rich gases suitable for fuel cells or chemical processing applications. The process and system is based on the AHR and WGS reactions, followed by cleanup of byproduct sulfur-containing gases and carbon oxides that would otherwise poison the fuel cell electrocatalyst. Advantageously, this is accomplished via an ASMS and a methanator or an AWMR. The process and system preferably uses a special sulfur tolerant catalysts and hardware designs that enable the conversion in an energy efficient manner while maintaining desirable performance characteristics such as rapid start-stop and fast response to load change capabilities.