The Western Area Power Administration’s (WAPA) Desert Southwest Region and Hunt Power subsidiary Southline Transmission, L.L.C., signed a participation agreement on Jan. 31, committing both parties to developing the Southline Transmission Project, WAPA and Hunt Power said on Feb. 5.
Southline Transmission, L.L.C., is the sponsor of the transmission project, according to the statement.
The project combines upgrades to WAPA’s existing electrical infrastructure and construction of new transmission lines to provide about 1,000 MW of transmission capacity along a 360-mile path between southern New Mexico and Arizona, the statement noted.
- The New Build Section, which would involve the construction of about 240 miles of new 345-kV, double-circuit electric transmission lines in New Mexico and Arizona, and would provide capacity of up to 1,000 MW. The New Build is defined by end points of the existing Afton substation, south of Las Cruces, N.M., and the existing Apache substation, south of Willcox, Ariz. The section includes an approximately 30-mile segment between Hwy 9 and I-10 – which would facilitate potential access to the renewable resource areas of southern New Mexico – and a five-mile loop between the existing Afton substation and the existing Luna-Diablo 345-kV transmission line
- The Upgrade Section, which would convert about 120 miles of existing single-circuit, 115-kV transmission lines, currently owned by WAPA, to double-circuit, 230-kV lines between the existing Apache substation and the existing Saguaro substation northwest of Tucson, Ariz. That would provide up to 1,000 MW of transmission capacity between those substations. A new line segment, about two miles in length, will be required to interconnect with the existing Tucson Electric Power Vail substation, located just north of the existing WAPA line
The project will interconnect with up to 14 existing substation locations and may include development of a new substation in Luna County, N.M., the document noted.
The project is needed to improve reliability, the document said, noting that there is limited existing electrical transmission capacity in the region. The project is also needed to relieve congestion, according to the document, which also noted that since existing transmission capacity is fully used, additional transmission capacity in the region is needed to relieve congestion and help local utilities access the most cost-efficient energy sources.
In addition, the project is needed to sustain growth, the document said, adding that the Desert Southwest area is expected to experience substantial long-term growth, creating increased demand for power and therefore a greater need for transmission capacity to provide that power.
The project is needed to facilitate renewable energy, the document said, adding that a major challenge facing renewable energy development is insufficient transmission access.
Current cost estimates for the project are about $800m, and are subject to change based on the final project design, regulatory approvals, and routing, according to the document, which is dated August 2017. Southline Transmission, L.L.C., will bear the costs of developing and building the project, and once the project is brought in service, Southline Transmission, L.L.C., will recover those costs from the line’s users, according to the document.
The Feb. 5 statement noted that the line will cross federal lands managed by the Bureau of Land Management and other agencies, as well as state and private lands.
Under the participation agreement, the organizations agreed to a commercial framework that allocates transmission rights on each segment of the project, the statement added. When the line is energized, WAPA’s share of transmission capacity will be incorporated under WAPA’s Parker-Davis Project, according to the statement.
Several associated key agreements will be negotiated over the coming months, including construction, operations and maintenance, as well as ownership and lease agreements, the statement noted.
"Public and private organizations each bring unique strengths toward infrastructure development and modernization,” Mark Gabriel, WAPA administrator and CEO, said in the statement. “Our successful partnership with Southline Transmission, L.L.C., allows us to use these strengths to develop new critical energy infrastructure that will support affordable and reliable electricity for our customers for decades to come."
Hunter Hunt, president of Hunt Power, said in the statement: "We are thrilled to advance our long-running successful relationship with WAPA with this important milestone for the Southline Transmission Project. We look forward to working with WAPA and all our stakeholders to deliver this much needed project in a manner that maximizes benefits while minimizing impacts."
Project activities completed to date are:
- Completing an environmental impact statement and final federal approvals in April 2016
- Obtaining state siting approvals from Arizona in February 2017
- Obtaining state siting approval from New Mexico in August 2017
- Soliciting transmission capacity requests on Southline’s share of the future line through a FERC-approved open solicitation process
The statement also noted that construction is anticipated to begin in late 2018, with transmission operations phased into service starting in 2020.