Storage system and generation of electrical energy in an aquatic or underwater environment, comprising: - a plurality of submerged weights, - a generator lift capable of cooperating with each of the weights and arranged, in generation mode, to allow said weights to descend to the bottom zone and, in drive mode, to raise them back up towards the surface, - an underwater PAG platform capable of supporting below the surface the upper portion of the generator lift; said platform comprising floating elements and anchoring cables which allow it to be stabilised at a given depth, - a reversible motor, cooperating with the generator lift and allowing, in generation mode, the production of electrical energy due to the action of the weights as they descend, and, in drive mode, actuation of the generator lift to raise the weights back up; the system characterised in that is comprises: - an underwater platform for attaching and detaching PAP weights anchored on the sea bottom and comprising a plurality of floats with a variable volume of gas permitting the floating capacity of the said platform to be adjusted permanently, the said platform being configured so as to enable the said weights to be detached to the generator lift before the said weights are detached from the PAP platform during the electricity production phase and vice versa during the storage phase, and it that, - underwater platform PAG supports the generator lift when is loaded or unloaded with weights. - a plurality of submerged weights, - a generator lift capable of cooperating with each of the weights and arranged, in generation mode, to allow said weights to descend to the bottom zone and, in drive mode, to raise them back up towards the surface, - an underwater PAG platform capable of supporting below the surface the upper portion of the generator lift; said platform comprising floating elements and anchoring cables which allow it to be stabilised at a given depth, - a reversible motor, cooperating with the generator lift and allowing, in generation mode, the production of electrical energy due to the action of the weights as they descend, and, in drive mode, actuation of the generator lift to raise the weights back up; the system characterised in that is comprises: - an underwater platform for attaching and detaching PAP weights anchored on the sea bottom and comprising a plurality of floats with a variable volume of gas permitting the floating capacity of the said platform to be adjusted permanently, the said platform being configured so as to enable the said weights to be detached to the generator lift before the said weights are detached from the PAP platform during the electricity production phase and vice versa during the storage phase, and it that, - underwater platform PAG supports the generator lift when is loaded or unloaded with weights. - an underwater platform for attaching and detaching PAP weights anchored on the sea bottom and comprising a plurality of floats with a variable volume of gas permitting the floating capacity of the said platform to be adjusted permanently, the said platform being configured so as to enable the said weights to be detached to the generator lift before the said weights are detached from the PAP platform during the electricity production phase and vice versa during the storage phase, and it that, - underwater platform PAG supports the generator lift when is loaded or unloaded with weights.