UNS Energy is a vertically integrated utility services holding company, headquartered in Tucson, Arizona, consisting primarily of three wholly owned subsidiaries: Tucson Electric Power, UNS Electric and UNS Gas. It is engaged through its subsidiaries in the regulated electric generation and energy delivery business, primarily in the State of Arizona, serving approximately 538,000 electricity customers and 165,000 natural gas customers. In 2021, the companies met a peak natural gas demand of 108 TJ and a peak electricity demand of 3,164 MW.