A method of producing power using a fuel cell power system, the method comprising: providing an open cathode PEM fuel cell stack (103, 503) comprising a plurality of fuel cells (111, 511), each cell (111, 511) having an anode side and a cathode side that enables operation of the cathode side at substantially ambient pressure; feeding water from a water storage (106, 206, 506) to a rotary bed reactor to generate hydrogen by the hydrolysis of a fuel in the reactor; and, routing hydrogen to the anode side of the fuel cell stack (103, 503) at a hydrogen flow rate sufficient for producing power; wherein the rotary bed reactor comprises: an outer stationary housing having a water inlet in fluid communication with a water storage (106, 206, 506); a cylindrical insert rotatably disposed within the outer housing and having a plurality of feed openings in fluid communication with the water inlet of the stationary housing; a plurality of slits disposed in the walls of the cylindrical insert; and an outlet for removing hydrogen; and, the fuel provided inside the cylindrical insert in the form of particles, wherein the fuel generates the hydrogen and solid by product by hydrolysis reaction with water from the water storage (106, 206, 506); the hydrogen generated is removed from the outlet and routed to the anode side of the fuel cell stack (103, 503); and the rotating movement of the cylindrical insert urges preferential removal of a fraction of the reaction solid byproduct through the slits. providing an open cathode PEM fuel cell stack (103, 503) comprising a plurality of fuel cells (111, 511), each cell (111, 511) having an anode side and a cathode side that enables operation of the cathode side at substantially ambient pressure; feeding water from a water storage (106, 206, 506) to a rotary bed reactor to generate hydrogen by the hydrolysis of a fuel in the reactor; and, routing hydrogen to the anode side of the fuel cell stack (103, 503) at a hydrogen flow rate sufficient for producing power; wherein the rotary bed reactor comprises: an outer stationary housing having a water inlet in fluid communication with a water storage (106, 206, 506); a cylindrical insert rotatably disposed within the outer housing and having a plurality of feed openings in fluid communication with the water inlet of the stationary housing; a plurality of slits disposed in the walls of the cylindrical insert; and an outlet for removing hydrogen; and, an outer stationary housing having a water inlet in fluid communication with a water storage (106, 206, 506); a cylindrical insert rotatably disposed within the outer housing and having a plurality of feed openings in fluid communication with the water inlet of the stationary housing; a plurality of slits disposed in the walls of the cylindrical insert; and an outlet for removing hydrogen; and, the fuel provided inside the cylindrical insert in the form of particles, wherein the fuel generates the hydrogen and solid by product by hydrolysis reaction with water from the water storage (106, 206, 506); the hydrogen generated is removed from the outlet and routed to the anode side of the fuel cell stack (103, 503); and the rotating movement of the cylindrical insert urges preferential removal of a fraction of the reaction solid byproduct through the slits.