2. Underground thermal storage

2.1 Types of storage classified by temperature level

Storage facilities are often classified according to their temperature level. A distinction is made between :

• hot storage (75 to 180°C), associated with power generation systems, industrial waste or incineration plants;

• lukewarm storage (25 to 75°C) combined with solar energy or certain waste heat ;

• cold storage (below 25°C), often using ambient air. This can be used for heating, generally in conjunction with a heat pump, or for storing cold in winter for cooling in summer.

Generally speaking, in the case of underground thermal storage, the higher the temperature, the greater the risk...