A modular block for storing thermal energy having a bottom wall and lateral walls defining a chamber. The lateral walls are made from a mouldable material. First thermal management elements are disposed in the chamber, which has at least one communication passage to the outside environment to allow a refrigerating fluid or a heat-transfer fluid a in heat exchange relationship with the first thermal management elements to pass into and out of the chamber. The modular block has second thermal management elements arranged laterally around the lateral walls or included in the mouldable material of the lateral walls for the thermal management of the chamber. The first thermal management elements are separated from the second thermal management elements by a part of the mouldable material of the lateral walls.