In August 2003, “Pirates of the Caribbean: The Curse of the Black Pearl” was plundering movie theaters while radio listeners were in love with Beyoncé’s “Crazy in Love.”

That was also when UniSource Energy Services was formed, after the parent company of Tucson Electric Power (TEP) completed the acquisition of gas and electric facilities in Arizona from Citizens Communications Company.

Since then, UniSource has added more than 42,000 natural gas customers and more than 25,000 electric customers to support growing communities throughout the state. Here are some ways UniSource has grown and worked to improve service for customers over the last two decades.

By the Numbers 2003 2023
Gas Customers
Electric Customers
Natural Gas Service
Miles of main lines
2,627 3,169
Electric Service
Miles of transmission lines
56 circuit miles (115 kilovolts) 60 circuit miles (upgraded 138 kilovolts)
Miles of 69-kilovolt transmission lines 229 576
Distribution Substation Capacity in megawatts (MW) 539 MW 1,354 MW
Transmission Substation Capacity 550 MW 885 MW

A More Reliable Electric Grid

UniSource has made significant investments in the local energy grids that serve our electric customers. We’ve added 10 new substations and rebuilt or replaced six others, bringing the total to 45 serving customers in Santa Cruz and Mohave Counties.

UniSource has added 62 miles of new transmission lines, which are critical for importing energy from generating resources to serve electric customers. This includes upgrading transmission lines to 138 kilovolts (kV) from 115 kV for more reliable service.

Electric system operators have greater oversight of our local energy grids thanks to computer systems that allow real-time monitoring and operation of transmission and distribution equipment. When combined with calls from customers affected by power outages, these systems allow UniSource to more quickly assess outage causes and restore electric service.

New Electric Generation

We’ve added about 250 megawatts (MW) of new natural gas-fired generating resources, including:

  • A combined-cycle unit at the Gila River Generating Station in Gila Bend that’s shared with sister company TEP. UniSource controls 140 MW of the unit’s output.
  • The Black Mountain Generating Station in Mohave County, which includes two 45 MW turbines.
  • A new 21 MW turbine at our Valencia substation in Nogales.

UniSource also has incorporated more than 100 MW of wind and solar energy into the energy grid since 2003, when the company had virtually none. These resources generate enough energy to serve the annual electric needs of more than 31,000 homes. The company owns and operates the 7 MW Rio Rico Solar Array in Santa Cruz County and the 5 MW Jacobson Solar Facility in Mohave County. We also support more than 7,800 residential and commercial customers who installed their own rooftop solar systems.

Safer, More Reliable Gas Service

UniSource has reconstructed several of the ‘city gates’ that connect our local gas distribution systems to regional transmission pipelines. These critical facilities are used to reduce natural gas pressure before delivery to customers. They’re also where UniSource performs an important safety measure by adding a chemical that gives natural gas a distinctive smell often compared to rotten eggs.

We’ve also made other improvements to our natural gas system, including installation of digital pressure monitoring equipment that provides our operators with nearly real-time performance data. UniSource also relocated a key high-pressure natural gas line in Santa Cruz County to allow for safer operations.

A Dedicated Workforce

Our employees are loyal. In 2022, just 11 percent of U.S. workers had been with their current employer for at least 20 years. At UniSource, it’s about double that number. Approximately 22 percent of the company’s gas and electric employees have been serving Arizona since the company was founded. Some have gained invaluable experience through longer tenures with the company, including a metering technician in Lake Havasu City with 33 years and a gas service technician in Flagstaff with 44 years.

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