Described herein is a portable storage device that stores a hydrogen fuel source. The storage device includes a bladder that contains the hydrogen fuel source and conforms to the volume of the hydrogen fuel source. A housing provides mechanical protection for the bladder. The storage device also includes a connector that interfaces with a mating connector to permit transfer of the fuel source between the bladder and a device that includes the mating connector. The device may be a portable electronics device such as a laptop computer. Refillable hydrogen fuel source storage devices and systems are also described. Hot swappable fuel storage systems described herein allow a portable hydrogen fuel source storage device to be removed from a fuel processor or electronics device it provides the hydrogen fuel source to, without shutting down the receiving device or without compromising hydrogen fuel source provision.