Long-Term Heat Storage Device and Method for Long-Term Heat Storage of Solar Energy and Other Types of Energy with Changing Availability

The invention relates to a long-term heat storage device for long-term storage of solar energy and other types of energy, in the heat storage material of which a rock bulk material, in particular of volcanic origin, such as diabase, basalt, granite and gneiss, is used. The rock bulk material forms a polydisperse bulk material, in particular as the void volume of the rock bulk material (granulate) having a first particle size or particle size distribution takes up a granulate having a second particle size or particle size distribution. The rock bulk material can be enclosed by a bulk powder fill, in particular an ash fill, in particular with a shell of shaped rocks interposed. The rock bulk material can be enclosed, all around or predominantly, at least laterally, by a shell of shaped rocks which is in particular cylindrical, in particular by a masonry wall.