SunZia Southwest Transmission Project

The SunZia Southwest Transmission Project is two 514-mile single circuit 500-kV transmission lines located adjacent to one another. One of the lines would be constructed and operated as an AC line, and SunZia may construct and operate one of the proposed transmission lines as either AC or DC. The project originates at the new SunZia East substation in New Mexico and heads west, with significant portions running parallel to I-25 and the Rio Grande River. The route follows a pipeline corridor north of I-10 in New Mexico and continues into Arizona, where it alternately uses existing pipeline and utility corridors where available before terminating at the Pinal Central substation in Pinal County near Coolidge, Arizona. The project is being sponsored by a consortium of five companies: Southwestern Power Group II/MMR Group, Shell WindEnergy inc., and Tucson Electric Power, the three accounting for 86%; and Salt River Project (13%), and Tri-State Generation and Transmission Association (1%). It will promote the development of wind, solar and geothermal energy and increase reliability of the existing high voltage transmission systems in New Mexico and southern Arizona.  The project is one of seven selected by the Rapid Response Pilot Program.

Project Sponsor Line Miles Voltage (kV) From State To State Year in Service
SunZia Transmission LLC 520 500 NM AZ 2020
Estimated Costs ($M) Voltage Type Project Status Project Group Origin Point Destination Point
2000 Planned SunZia East Pinal Switchyard
Interstate Build Start NERC ISO/RTO Country Project Partners
WECC US Tri-State Generation and Transmission, Salt River Project, Shell WindEnergy, Southwestern Power Group II/MMR Group, and Tucson Electric Power