Algid Mills

The name for the system of water wheels located up the stone stairs at the base of Otiluke's Linn, that collect the icy waters for for processing into the freezing spheres of condensed cold energy, used for powering many things within the city of Erudition and the surrounding areas, including the system of suspended trams.
As small bowls of frigid water are filled by the slowly turning wheel, workers must collect and carry these minute quantities to larger storage basins, making sure to keep the water moving to prevent it from freezing. Once collected in a sufficient volume, the water is pressurized into a frozen sphere, which once melted releases its energy as heat. If the water is allowed to freeze, it cannot be thawed to then be concentrated and refrozen. A sufficient amount of water is needed to condense into a size that contains a usable amount of energy. While workers are dawned in special protective garb, cold related injuries, as well as heat related from unwanted discharge of both small and large quantities, are very common.
An integral part of the city's function and economy, the factory area and its personnel are stringently guarded. That does not stop others from trying to collect the waters on their own, but lacking the correct tools and training, often leads to none or disastrous results.