Geothermal heating a total capacity of 15 GW extracted 88 PJ of heat energy for space heating. Global ground-source heat pump capacity is growing by 10% annually. Hot springs have been used for bathing at least since Paleolithic times. The oldest known spa is a stone pool on China's Mount Li built in the Qin dynasty in the 3rd century BC, at the same site where the Huaqing Chi palace was later built. Geothermal energy supplied channeled district heating for baths and houses in Pompeii around 0 AD. In the first century AD, Romans conquered Aquae Sulis in England and used the
Sulis the similarly local pre-Hellenic deities in the local epithets that they assigned, associated with the cult of their Olympian pantheon at certain places (Zeus Molossos only at Dodona, for example). The Romans tended to lose sight of these specific locations, except in a few Etruscan cult inheritances and ideas like the "genius loci", the guardian spirit of a place. The gilt bronze cult statue of Sulis Minerva "appears to have been deliberately damaged" sometime in later Antiquity, perhaps by barbarian raiders, Christian zealots, or some other forces. About 130 curse tablets, mostly addressed to Sulis, have been found in the