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 Minerva. Senua's name appears on votive plaques bearing Minerva's image, while Brigantia also shares many traits associated with Minerva. The identification of multiple Celtic gods with the same Roman god is not unusual (both Mars and Mercury were paired with a multiplicity of Celtic names). On the other hand, Celtic goddesses tended to resist syncretism; Sulis Minerva is one of the few attested pairings of a Celtic goddess with her Roman counterpart. Dedications to “Minerva” are common in both Great Britain and continental Europe, normally without any Celtic epithet or interpretation. (Cf. Belisama for one exception.) Based on her name's