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
Battle of Aquae Sextiae Battle of Aquae Sextiae The Battle of Aquae Sextiae (Aix-en-Provence) took place in 102 BC. After a string of Roman defeats (see Battle of Arausio), the Romans under Gaius Marius finally defeated the Teutones and Ambrones. The Teutones and the Ambrones were virtually wiped out, with the Romans claiming to have killed 90,000 and captured 20,000, including large numbers of women and children who were later sold into slavery. Some of the surviving captives are reported to have been among the rebelling gladiators in the Third Servile War. Marius took up a strong position on a carefully selected hill and