NOVELTY - A fuel cell system (S1) comprises fuel module comprising fuel tank, fuel module identification unit, fuel filter unit, and energy conversion module. The fuel tank comprises stored raw fuel. The fuel filter unit converts raw fuel to refined fuel. The fuel module identification unit comprises fuel module data. The energy conversion module comprises control module and fuel cell. The control module accesses fuel module data from fuel module identification unit. The fuel cell stack utilizes refined fuel to generate electrical energy. The fuel module is detachable from energy conversion module.    USE - Fuel cell system.    ADVANTAGE - The control module will control fuel valve to maintain a shut position and not accept fuel from fuel module, thus preventing use of unauthorized or counterfeit fuel that degrade operational performance.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) controlling the system (S1) which comprises accessing fuel module data of data storage unit; and selecting operating mode of the system (S1) based on fuel module data, where fuel cell comprises control system (50) and fuel module (44); and    (2) providing a fuel to a fuel cell which comprises providing a commercial fuel; providing a fuel module comprising the commercial fuel; coupling fuel module to energy conversion module; routing fuel module information between fuel module identifier unit and energy conversion module; determining whether fuel module passes authentication based on information provided between fuel module identifier member and energy conversion module; allowing fuel transfer between fuel module and energy conversion module when fuel module passes authentication; and disallowing fuel transfer between fuel module and energy conversion module when energy conversion module fails authentication.    DESCRIPTION OF DRAWING(S) - The drawing is a flow chart diagram depicting a method for providing fuel to a fuel cell system.    Fuel module (44)    Control system (50)    Stack (60)    Recuperator (68)