The examples CAES (Compressed Air Energy Storage), Magnetic, Pumped Hydro, Oil/Gas, CO2 -plus (storing and producing energy with supercritical CO2) all showed that caverns in rock are used and that the operations are frequently characterized by cycling pressure and temperatures and that the surrounding rock should be impermeable.

Construction of rock cavern s has to be done in sections for several reasons: The stability of the opening requires small cross-sections, and the construction process has to be in stages. The interaction of excavation and placing support is therefor quite intricate.

The complex construction and operating processes need to be represented in models. Models that can do so exist ranging from 3-d Finite Element models to Discrete Fracture Network models.

Particularly important is the fact that construction and operation are affected by uncertainties, which in turn affect risk. The concept of decision making under uncertainties allows one to assess the uncertainties and thus risk, and they also show how the uncertainties can be reduced. The Decision Aids for Tunneling” (DAT) allow one to assess uncertainties affecting cavern construction. Virtual exploration not only allows one to reduce uncertainties but to determine if exploration to do so is worthwhile. All this is implemented in a case involving gas storage caverns.