SunZia Transmission seeks approval of 500-kV project in New Mexico

SunZia Transmission LLC, in an application received by the New Mexico Public Regulation Commission on March 12, said that it seeks an order that approves the location of two 500-kV transmission lines and related facilities in certain areas of Lincoln, Socorro, Sierra, Luna, Grant, Torrance, and Hidalgo counties.

The application also seeks that the order determines that a total right of way (ROW) width of about 400 feet – i.e., 200 feet for each transmission line – which may require a width of up to 1,000 feet in a few locations, is necessary for the construction, operation, and maintenance of the project.

Under the application, SunZia added, SunZia proposes to build and operate the two 500-kV alternating current (AC) lines, as well as the associated facilities, in areas of New Mexico and Arizona. The lines would extend about 520 miles, including 320 miles in New Mexico and 200 miles in Arizona, SunZia said, noting that in New Mexico, the lines would cross about 134 miles of federal land, 96 miles of New Mexico State Land Office lands, and 90 miles of private lands.

The lines would originate at a new substation in Lincoln County, N.M., (SunZia East substation), and terminate at the existing Pinal Central substation in Pinal County, Ariz., the company said. The lines would be located in portions of Torrance, Socorro, Sierra, Luna, Grant, and Hidalgo counties in New Mexico, as well as Cochise, Greenlee, Graham, Pima, and Pinal counties in Arizona. SunZia added that the new substation facilities would be built in Luna and Hidalgo counties.

Based on SunZia’s engineering analysis and depending on terrain, three to four transmission structures per mile would be required for each of the two lines. SunZia also said that typical tangent structures would have a height of 140 feet and may extend up to 160 feet in height in some locations to accommodate terrain conditions, longer spans, or other conditions.

The lines would have a total transfer capacity of 3,000 MW, which would include a substantial amount of energy generated by renewable resources, particularly high capacity factor wind energy resources in Lincoln, Torrance, and Guadalupe counties.

SunZia added that it also has the option of either initially building or later converting one of the 500-kV AC transmission lines to direct current (DC) operation. Implementing a DC electrical configuration would likely increase the project’s total power transfer capacity from 3,000 MW to about 4,500 MW, SunZia said, noting that it would decide whether to utilize a DC electrical configuration based on the level of market demand for additional transmission capacity and service.

The total estimated capital cost of the SunZia project configured as two 500-kV AC transmission lines and related facilities in Arizona and New Mexico would be about $2bn, SunZia said, noting that the estimated capital cost for the New Mexico portion of the project would be about $1.2bn.

SunZia also noted that it expects to begin construction of the first 500-kV AC transmission line and related facilities this year, and to place the facility in commercial operation during 4Q20.

SunZia said that the project would facilitate significant development of renewable energy resources in New Mexico, and, in so doing, would relieve existing transmission congestion in the region; accommodate the development and transmission of renewable energy resources; provide power to meet electricity demand in Western states; as well as provide needed jobs and associated state and local revenues within the project areas in New Mexico.

SunZia noted that in September 2008, it filed an application for an ROW for the project facilities with the U.S. Bureau of Land Management (BLM), adding that an environmental impact statement (EIS) was prepared in support of the ROW application in accordance with the National Environmental Policy Act (NEPA) and BLM requirements. The BLM in January 2015 issued its record of decision (ROD), in which it approved the selected alternative route for all lands traversed by the project and authorized the granting of an ROW over federal lands in New Mexico and Arizona for the project.

SunZia further noted that in September 2015, it filed an application for a certificate of environmental compatibility (CEC) with the Arizona Power Plant and Transmission Line Siting Committee. The committee approved the project in February 2016, and that concluded determination of the project’s location in Arizona.

SunZia added that it will not seek to condemn public utility property in New Mexico, and that it does not propose to own, develop, operate, or build any generation plant as a part of the project. SunZia noted that it is negotiating with developers of potential renewable energy generation projects in New Mexico, and has selected Pattern Energy as its anchor customer for transmission service.

SunZia said that it and Pattern have entered into an agreement under which Pattern would interconnect about 1,500 MW of wind generation to the SunZia project, utilizing all of the transmission capacity available on the project’s first 500-kV transmission line.

FERC last September issued an order approving the process through which SunZia selected Pattern as its anchor tenant and authorizing SunZia to charge Pattern a negotiated rate for transmission service, SunZia said.

As noted in the filing, SunZia is an independent transmission project company that is owned by multiple parties – Salt River Agricultural and Improvement District Project is a minority owner, while ECP SunZia LLC and Southwestern Power Group II, LLC – which are wholly owned subsidiaries of MMR Group – are the majority owners.

About Corina Rivera-Linares 3286 Articles
Corina Rivera-Linares was TransmissionHub’s chief editor until August 2021, as well as part of the team that established TransmissionHub in 2011. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial from 2005 to 2011. She has also covered such topics as health, politics, and education for weekly newspapers and national magazines.