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 Albae in Byzacena Aquae Albae in Byzacena Aquae Albae in Byzacena (also typographed Aquæ Albæ in Byzacena) was an Ancient city and bishopric in Roman Africa and remains a Latin Catholic titular see. Its present location is Ain-Beida, in modern Tunisia (which has namesakes, notably in Algeria and Morocco). Aquae Albae was important enough in the Roman province of Byzacena to become one of the many suffragans of its capital Hadrumetum's Metropolitan Archbishop, but was to fade. The diocese was nominally restored in 1933 as a Latin Catholic titular bishopric. It has had the following incumbents, all of the lowest (episcopal) rank :