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
Aquae Flaviae details of that founding remain obscure. Ptolemy suggests that it was founded in Turodi territory, a theory that has been strengthened by the existence of epigraphic evidence documenting the presence of Turodi. Aquae Flaviae Aquae Flaviae (or "Aquæ Flaviæ") is the ancient Roman city and former bishopric (now a Latin Catholic titular see) of Chaves, a municipality in the Portuguese district of Vila Real. The northwest peninsular region is an area of hot springs and Roman settlements linked to the exploitation of valuable natural resources. Aquae Flaviae was the principal "municipium civitas" in the northwest (from epigraphic findings) implanted in