Energy Transfer has announced an increase in the transportation capacity of Transwestern Pipeline’s planned Desert Southwest expansion project to meet additional customer demand. To meet the need for additional capacity identified through a recent open season, the project’s mainline pipeline diameter will be upsized from 42 to 48 in. (106 to 121 cm), which will increase the project’s capacity to up to 2.3 bcf/d (65.1 x 106 m3/d), depending on final compression configuration. There is significant demand growth in the Desert Southwest region, including the potential to retire and or convert coal-fired power plants to natural gas, which could further benefit the project. The ultimate capacity of the Desert Southwest expansion project will be based on market demand.
Energy Transfer LP reached a positive financial investment decision on the project in August 2025. The Desert Southwest pipeline is planned to originate in Winkler County, Texas, and traverse approximately 516 miles (830 km) through New Mexico and Arizona to an end point in Coolidge, Arizona. The underground pipeline will be powered by nine new compressor stations strategically situated along the pipeline route to deliver up to 1.5 bcf/d (42.4 x 106 m3/d) of natural gas to customers.
Additionally, the Desert Southwest expansion will make Transwestern’s Phoenix Lateral bi-directional, adding flexibility to move natural gas in both directions based on operational needs. Bi-directional facilities include the new Gila compressor station in Maricopa County, Arizona; the new Desert Basin compressor station in Pinal County, Arizona; and upgrades at the New River compressor station in Maricopa County, Arizona.
The upsized project is now expected to cost up to approximately US$5.6 billion. As a result, Energy Transfer’s total growth capital expenditures for 2026 are expected to increase by approximately US$200 million.
Energy Transfer expects the project to be in-service by the fourth quarter of 2029.
Energy Transfer owns and operates more than 140,000 miles of pipeline and associated energy infrastructure. Its network spans 44 states with assets in all major US production basins.
