The TransWest Express Transmission (TWE) Project is a planned high-voltage interregional electric transmission line in the US that will extend from south-central Wyoming through north-western Colorado and central Utah, to southern Nevada.
The approximately 732-mile-long high-voltage transmission infrastructure is being developed by TransWest Express, a wholly owned affiliate of private holding company The Anschutz Corporation.
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In April 2023, the Bureau of Land Management (BLM), an US Department of the Interior agency, issued the Notice to Proceed (NTP) for the TWE Project.
Construction of the project is planned to commence in 2023, with the first stage expected to be completed in 2027. It is expected to entail an investment of around $3bn.
The TWE Project will transport electricity generated by the Chokecherry and Sierra Madre Wind Energy Project in Wyoming to the Desert Southwest region (California, Nevada, Arizona).
The transmission line will be capable of delivering around 20,000GWh of clean energy annually.
TransWest Express Transmission Project Background
Arizona Public Service Company (APS) initiated the TWE Project in 2005 and undertook multiple routing and planning studies and held several stakeholder meetings.
In 2006, international energy delivery company National Grid and the Wyoming Infrastructure Authority joined APS in the development of the TWE Project.
The three entities and PacifiCorp agreed to jointly study the TWE Project in 2007. The TWE Project ROW application and Preliminary Plan of Development were also submitted to the BLM Wyoming State Office in 2007.
An economic analysis by PA Consulting indicated the economic viability of the TWE Project in 2008.
TransWest Express LLC was formed in July 2008 and it took over the development rights of the TWE Project from APS, National Grid and the Wyoming Infrastructure Authority. It submitted an Amended ROW Application with the BLM in December 2008 and an Amended Preliminary Plan of Development in January 2009.
In January 2010, TransWest submitted an updated Preliminary Right-of-Way application with BLM, amending its 2008 ROW document. An updated Preliminary Plan of Development was also filed.
In 2011, a new federal ‘Rapid Response Team for Transmission’ selected the TWE project as one of five priority transmission projects in the Western US. In the same year, Western Area Power Administration signed an agreement to co-fund the project’s development phase.
The National Renewable Energy Lab released an economic analysis in 2014 that indicated that a direct current transmission line from the California renewable energy market to Wyoming’s renewable energy supplies will be economically beneficial for California utilities and ratepayers.
BLM and Western published their Final Environmental Impact Statement (EIS) in April 2015. The Ute Indian Tribe of the Uintah and Ouray Reservation signed coordination and partnering agreements regarding the construction of the TWE Project in 2016.
Western Area Power Administration and the US Forest Service issued EIS Record of Decision in 2017. BLM issued a federal right-of-way grant for the TWE Project in June 2017.
In April 2018, TransWest sought permission to initiate Phase 1 for the TWE AC and DC Project. The federal and state permitting decisions for the project were secured by April 2019 and all 14 county permitting decisions were complete by January 2020.
TransWest secured nearly all of the rights-of-way for the transmission route by June 2021 and finalised the acquisition of all private land easements in June 2022.
The BLM issued its Notice to Proceed, the final federal authorisation required to begin the construction of the TransWest Express Transmission Project, in April 2023.
TransWest Express project design
The 732-mile long high-voltage transmission infrastructure will include two systems- a 525kV direct current (DC) system with terminals near Sinclair in Wyoming and Delta in Utah; and a 500kV alternating current (AC) system stretching from the Utah terminal to southern Nevada.
The transmission capacity of DC system terminals will be phased over time from 1,500MW to 3,000MW of transmission capacity, while the AC system will have a capacity of 1,500MW.
Typically, the transmission line will have a right-of-way width of 250ft.
The height of the transmission structures can be up to 180ft, depending upon structure type, terrain, and line crossings. The distance between two structures will vary between 900ft and 1,500ft.
The AC and DC structures will look similar, however, the former ones will have three sets of conductor wires instead of two sets.
The substations/ converter stations will be constructed at interconnection points in Wyoming, Utah and Nevada.
HVDC Segment
The project will comprise a 405-mile high-voltage direct current (HVDC) segment with terminals near Sinclair, Wyoming and Delta, Utah.
The 3,000MW, ±500 kV, two-terminal, bi-directional, bi-pole configured, line commutated converter (LCC) HVDC transmission system will stretch from Carbon County, Wyoming to the existing Intermountain Power Project (IPP) 345kV switchyard near Delta, Utah.
The HVDC facilities will be capable of transmitting the full project capacity in bipole configuration in both directions.
HVAC Segment
The project’s HVAC facilities include a 278-mile, 1,500MW, 500kV HVAC, series-compensated transmission system.
The segment will extend from the Utah HVDC Terminal to the Crystal substation located northeast of Las Vegas, Nevada, as well as a 49-mile, 500kV HVAC, 70% series-compensated transmission system extending from the Crystal substation to the Eldorado Substation or other substations in the Eldorado Valley.
Contractors Involved
In December 2022, Siemens Energy secured the contract to supply the high-voltage direct current transmission technology required for the TWE project.
In June 2023, TransWest Express selected Barnard Wilson Joint Venture (JV) as transmission line construction partner. Under the contract, the JV will construct the TransWest Express Transmission Project line and substations.
