TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Device: (b1) Comprises at least a fluid-wetted surface region and a fluid-free solid region and (c1) comprises at least a catalyst-coated surface region and a catalyst-free solid region in such a fashion that a relative motion between (b1) and the (c1) acts to vary contact area between the fluid-wetted surface region and the catalyst-coated surface region for adjusting a hydrolysis reaction rate or hydrogen production rate proportional to a need for the hydrogen. (b1) Comprises several fluid-wetted surface regions and fluid-free solid regions positioned in an alternate sequence and (c1) comprises several catalyst-coated surface regions and catalyst-free solid regions positioned in an alternate sequence in such a fashion that a relative motion between (b1) and (c1) acts to vary the contact area between the fluid-wetted surface regions and catalyst-coated surface regions for adjusting hydrogen production rate proportional to a need for the hydrogen. The apparatus further comprises an actuator to control relative motion between (b1) and (c1). The wicking material comprises a network of interconnected pores to accommodate the fuel fluid. The pores have a pore diameter gradient for creating a capillary pressure gradient. The wicking material comprises tapered pores or channels in the tank and a capillary pressure gradient created by the tapered pores or channels. The wicking material comprises an absorbent material. The fuel cell is mounted on the fuel tank. The power source further comprises an actuator driven by the fuel cell to activate a relative motion between the first disc and the second disc to adjust a hydrogen production rate. The relative motion is responsive to a power demand of the fuel cell. The power source further comprises a control circuit in control relation to the actuator. The relative motion is sliding and/or rotational motion. The apparatus further comprises a moveable wall connected to or integral with (b1). The moveable wall, (b1), and walls of the fuel tank, in combination, form a hydrogen gas chamber to accommodate the generated hydrogen with a gas pressure (P1) exerting a force (F1) on a first surface of the moveable wall, where the chamber is in fluid communication with a conduit and a valve means. The moveable wall is equipped with counteracting force unit exerting a force (F2) on a second surface of the moveable wall opposite to the first surface; and a force differential of (F1-F2) drives the relative motion between the first disc and the second disc to vary the contact area between a fluid-wetted surface and the catalyst-coated surface to regulate hydrogen production rate. The counteracting force unit comprises a spring and/or a compressed air chamber. The valve unit is adjustable and is adjusted to vary the force (F1). The counteracting force unit comprises a spring connected to a spring force-adjusting unit to adjust the force (F2).    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The catalyst is platinum and/or ruthenium. The fuel fluid comprises a solution of hydride (preferably sodiumborohydride (NaBH4), lithiumborohydride, potassiumborohydride (KBH4), aluminumborohydride, iron-titanium hydride, palladiumhydride or NaBH4 and water), solution of NaBH4, sodiumhydroxide and water or a solution of KBH4, potassium hydroxide and water. The hydride solution produces hydrogen on contact with the catalyst.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The fluid comprises a hydrocarbon or organic fluid (preferably ammonia, liquid methane, methanol, ethanol and/or hydrazine).