Several large wind turbines line a green hill in Wyoming
PacifiCorp's Seven Mile Hill wind farm in Carbon County generates 111 megawatts of electrical power. Credit: Dustin Bleizeffer / WyoFile

This article originally appeared at WyoFile.

Having recently cleared key legal and permitting hurdles, developers are slated to begin construction of two major high-voltage transmission lines connecting Wyoming to several states in the West. When completed, the Gateway South and TransWest Express transmission lines will open the door to a major expansion of wind energy development in the Cowboy State, industry officials say.

“The TransWest Express project opens the ability for Wyoming wholesale electricity supplies to reach new markets, like southern California, Arizona and Nevada, that the state is not directly serving today,” Power Company of Wyoming Communications Director Kara Choquette said.

The $3 billion, 732-mile long TransWest Express transmission line will transport electricity from Power Company of Wyoming’s Chokecherry and Sierra Madre Wind Energy Project in south-central Wyoming, as well as other potential new wind energy facilities. Situated in Carbon County, the project’s 900 wind turbines with a total capacity of 3,000 megawatts will be the largest onshore wind energy facility in the United States.

The TransWest Express transmission line will connect wind energy from south-central Wyoming to southwestern states. (TransWest Express LLC)

After years of negotiations, TransWest Express LLC recently secured a right-of-way agreement with a large private landowner in western Colorado. Construction of the TransWest Express transmission line could begin as early as 2023, according to company officials. TransWest Express LLC and Power Company of Wyoming are both subsidiaries of Anschutz Corp. 

Meanwhile, Berkshire Hathaway-owned PacifiCorp received “certificates of public convenience and necessity” from the Wyoming Public Service Commission on May 10 for its Gateway South and a segment of its Gateway West lines. Both are part of PacifiCorp’s larger Energy Gateway transmission expansion project to add more than 2,000 miles of high-voltage power lines connecting Wyoming wind energy to five other western states in PacifiCorp’s service territory.

Construction will begin this summer, according to PacifiCorp. Both Gateway South and Gateway West “Segment D.1” are slated to be operational in late 2024. 

Shift from coal to wind

The added transmission capacity and increased number of “on-ramps” and “off-ramps” that the transmission lines would provide to Wyoming and the Western grid set the stage for a major buildout of wind turbines in the state. When completed, that extra capacity and interconnectivity would also provide PacifiCorp — and possibly others — the ability to retire coal-fired power units in the state by meeting several new state-level power delivery and reliability requirements, according to University of Wyoming energy economist Rob Godby.

PacifiCorp’s Gateway South transmission line is part of the utility’s larger Energy Gateway Transmission project. (PacifiCorp)

“When you have a more flexible system, it’s just less likely that you need coal,” Godby said. “You can rely on a more flexible set of generation alternatives, and that old fossil fuel backbone [coal-fired power] is less relevant.”

Adding interstate transmission capacity — and therefore boosting the ability to move power in and out of Wyoming as needed — is integral to PacifiCorp’s plans to meet the state’s reliability standards, according to PacifiCorp spokesperson David Eskelsen.

“The Gateway South and Segment D.1 transmission projects were modeled in the 2021 [integrated resource plan] as key to system reliability as the energy transition is expected to continue,” Eskelsen told WyoFile.

PacifiCorp says it will retire 14 of its coal-fired power units across several states, including several in Wyoming by 2030, and a total of 19 by 2040. The regulated utility plans to add more than 3,700 MW of new wind power by 2040 throughout its six-state region, including in Wyoming.

Wyoming wind

Wyoming has some of the best wind resources in the continental U.S., according to Jonathan Naughton, professor of mechanical engineering and director of the Wind Energy Research Center at the University of Wyoming. Several regions of the state — mostly in the southeast — have “wind capacity factors” of more than 50%, compared to 35% in other interior states.

Wind bends a flagpole at the historic Virginian Hotel in Medicine Bow in December 2021. (Dustin Bleizeffer/WyoFile)

“It means that the turbines that they put up are running at full capacity more often,” Naughton said.

Wyoming wind also tends to be more consistent during winter months and during evening hours throughout the year, providing a balance to power demands in other western states. When solar power generation drops off in the evenings in California, for example, Wyoming wind can backfill the power supply. The same dynamic applies between eastern Wyoming and the Colorado Front Range.

“There’s some attractive things about combining solar and wind from Wyoming,” Naughton said.  “And if you build out a really robust transmission system, it’s easy to move power around, and it solves a lot of these issues with variability.”

Wyoming’s electrical export

Wyoming exports about three-fifths of the electricity generated in the state, according to the U.S. Energy Information Administration. A supermajority of Wyoming’s total power generation comes from coal-fired power plants.

A truck hauls a wind turbine blade through Medicine Bow in July 2020. (Dustin Bleizeffer/WyoFile)

But the state’s electrical generation profile is rapidly changing.

Coal accounted for 97% of the state’s power generation in 2003, according to EIA. There was a lull in wind energy development in the 2010s, but since 2019 the state has more than doubled its wind energy generation capacity.  Now at more than 3,000 MW, wind accounts for nearly a third of the state’s total electrical generation capacity.

Much more wind power is on the way. Wyoming could see an additional 6,000 MW of new wind power capacity by 2030, according to those close to the industry. Although not every wind power proposal will come to fruition, the inevitability of major interstate transmission projects connecting Wyoming wind resources to western states will help shift the state from a majority coal power exporter to a majority wind power exporter, UW’s Godby said.

“The reality is that [more electrical transmission] creates both the capacity to develop more renewable energy, and in different places,” Godby said.

Meanwhile, PacifiCorp has dialed back electrical generation output from some coal-burning units, including at Jim Bridger, making more room for Wyoming-originating wind energy on existing interstate electrical transmission lines.

WyoFile is an independent nonprofit news organization focused on Wyoming people, places and policy.