Transmission Line Projects

Nogales Interconnection Project

New transmission resource for improved reliability.

Hunt Power, LP is in the preliminary planning stage of building a new 150-megawatt (MW) interconnection that would connect UniSource Energy Services’ electric grid in southern
Arizona with electric facilities in northwestern Mexico. The project is intended to strengthen regional electric reliability for both electric systems and will create economic
benefits by developing access to cross-border markets.

The project is in a preliminary planning stage, which involves seeking input from the public to inform subsequent stages in the routing process. The proponents have not pursued any
land rights, applied for permits or received any approvals for construction.

What are the components of the project?

The project will consist of three components:

  • The new 10-15 acre Gateway Substation on land currently owned by Tucson Electric Power (TEP) where direct current (DC) equipment would be located.
  • A new, approximately 3-mile 138-kV transmission line segment originating at UniSource Energy Services’ (UES’) Valencia Substation in Nogales, Ariz., and extending west and
    south to the new Gateway Substation.
  • A new, approximately 2-mile 230-kV transmission line segment extending south from the new Gateway Substation and across the U.S.-Mexico border to interconnect with a
    transmission line to be constructed by the Comisión Federal de Electricidad (CFE).

Why is the Nogales Interconnection Project needed?

Nogales is at the southern end of the Western Electricity Coordinating Council (WECC) grid and relies on the approximately 55-mile-long Vail to Valencia 138-kV transmission line
for power. The addition of the proposed Gateway Substation and connection to the electrical system in Sonora, Mexico would provide an additional source of energy for customers
in and around Nogales, Arizona in the event of a transmission line outage or other problem involving the WECC system.

What are the project benefits?

The Nogales Interconnection would contribute to reliable electric service in Santa Cruz County as demand continues to grow. The project brings the following benefits:

  • Supports the reliability of the current system.
  • Allows access to additional energy sources and ancillary benefits, such as voltage support.
  • Creates regional economic development opportunities. In addition to temporary construction and supply chain jobs, the project will create a more robust electric grid to
    support business growth in the region.
  • Enables the WECC and CFE grids to support each other in times of emergency.
  • Creates a potential alternative energy resource that would allow UES and CFE to take advantage of diverse energy markets and pass along benefits of reduced costs to

For more information, visit the project website hosted by Hunt Power, call 1-800-240-5718 or email