NOVELTY - The device (100) has a fuel cell to produce electric energy by oxidation of hydrogen. A hydrogen storage reservoir (120) stores low pressure hydrogen in the form of hydride, and extends along a large axis (121). A casing (130) extends along a longitudinal direction (110), and comprises a support unit to maintain the casing in a stable position while the longitudinal direction of the casing is in a vertical plane or a horizontal plane. Maintaining units maintain the reservoir integrated with the casing, so that the axis is horizontal irrespective of the stable position of the casing.    USE - Autonomous electric energy producing device for use during electrical interventions in rough ground e.g. sites of natural disaster.    ADVANTAGE - The design of the fuel cell and the hydrogen reservoir supports the horizontal position of the large axis by the effect of gravity, so that the hydrogen reservoir is placed in a optimal stable position favorable to the prevention of the compressing of the hydride powder, and the improved orientation of the axis of the hydride reservoir is obtained without articulation or complex suspension device inside the casing, thus prolonging lifespan and performance level of the hydride reservoir and realizing robustness and reliability of the device. The support unit maintains the casing in the stable position while the longitudinal direction of the casing is along the vertical plane to allow the device to be transported easily by rolling the casing and along the horizontal plane to enable the device to be rectified in vertical stable position in on-site. The configuration of the casing allows optimal distribution of energy on the field site while ensuring safety of the operator on inclined grounds.    DESCRIPTION OF DRAWING(S) - The drawing shows an exploded front perspective view of a device in vertical position.    Autonomous electric energy producing device (100)    Longitudinal direction (110)    Hydrogen storage reservoir (120)    Large axis (121)    Casing (130)