The invention relates to a heat storage and recovery system and process comprising at least one cylindrical external wall (51), at least one first volume (30), at least one second volume (31) and at least two fluid injection/withdrawal means. The first (30) and second (31) volumes are separated by at least one heat storage means (20) comprising at least one bed of heat storage particles. Furthermore, the storage means (20) and the first (30) and second (31) volumes extend substantially over the entire axial length of the cylindrical external wall (51). The longitudinal axis of the said cylindrical external wall (51) is horizontal.
The invention also relates to a system and to a process for the storage and recovery of energy by compressed gas comprising such a heat storage means.