 Water from reservoirs in the Snowdonia Mountains would provide the hydro-electricity needed to run the mill.In 1907 aluminium reduction ("aluminium smelting") began in the factory utilising electricity from the distant Cwm Dyli power station, and in 1916 a rolling mill was added.In 1924 a hydro-electric plant was built next to the aluminium works to assist in the running of the mill.