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Pumped-storage hydro idea hopes to marry Wyoming’s big wind with an old technology at a reservoir northeast of Rawlins


by Allen Best

The Seminoe Pumped Storage project would create what would essentially be a giant battery in southern Wyoming joined at the hips—or at least substations—with massive amounts of new wind generation being built for export to Arizona, California, and other southwestern states.

Cost of this Wyoming pumped-storage project would be in the range of $2.3 billion to $2.5 billion, according to rPlus Hydro, the proponent. The project took a small step forward last week with submission of a draft license application to both state and federal agencies.

The same company also contemplates pumped storage hydro in Colorado’s Yampa River Valley. Xcel Energy is considering a pumped-storage project south of Grand Junction.

See: A short rope for Xcel and pumped storage

Pumped-storage hydro constitutes 90% to 95% of existing energy storage in the United States — and, in Colorado, the single largest storage device. The Cabin Creek project — upper and lower reservoirs in the Georgetown area — has two units with a combined 324 megawatts of potential generation to meet peak demands by Xcel Energy customers, such as hot summer afternoons.

The water released to run through the turbines, generating electricity, can then be pumped back uphill when electricity is more plentiful.

A smaller pumped-storage hydro project exists near Leadville at Twin Lakes.

Denver-based Ron Lehr, a former public utility commissioner in Colorado for 8 years and now a board member of New Energy Economics, points to the advantages of pumped-storage as compared to some other, still unproven or expensive technologies. He points to $500 million in federal loan guarantees recently delivered to a hydrogen storage project in Utah.

Pumped-storage hydro has “many fewer moving parts and tech challenges and a long history of successful operation. Making and storing hydrogen at relevant volumes, not so much,” he said in an e-mail reply to questions. “Good to have diversity, helps to manage risks, but need to keep an eye on what’s cost effective at the same time.”

The Wyoming  pumped-storage hydro project would be at Seminoe, a reservoir on the North Platte River 35 miles northeast of Rawlins. A new reservoir would be built 1,000 feet higher in elevation on federal land administered by the Bureau of Land Management.

“Being co-located with the wind energy in Wyoming means that the Seminoe project would basically be the battery of Wyoming wind energy and can really help make more efficient use of transmission being built to deliver wind to markets,” said Matthew Shapiro, chief executive of rPlus Hydro.

The reservoir would require 12,000 acre-feet of water to begin operations, and then an estimated 300 acre-feet annually after that to cover evaporation. Altogether 10,900 acre-feet would be sent through the turbines to generate electricity.


Wyoming has massive amounts of wind, but nowhere is the bluster greater than along Interstate 80. The Chokecherry and Sierra Madre Wind Energy Project has been taking shape in south-central Wyoming since 2016 in the wind-drenched plains south of I-80.

The giant wind farm would deliver up to 3,000 megawatts of electricity. By comparison, the three units of Comanche Generating Station, Colorado’s largest coal complex, can generate up to 1,635 megawatts.

As of April, according to a release by the Power Company of Wyoming, the project had completed more than 135 miles of roads and pads for 178 turbines. It is to ultimately have 900 turbines. Total estimated project costs have been placed at $5 billion.

The company is an affiliate of Denver-based The Anschutz Corporation, which is owned by billionaire Philip Anschutz. Anschutz, who grew up in Kansas, expanded a nest egg into a fortune by exploiting the natural gas deposits in the Overthrust Belt of southwestern Wyoming during the 1970s.


Exporting the wind energy westward

Transmission of this electricity is a story unto itself. Two major power lines, both with a capacity of 500 kilovolts, are planned to export the power from these and other wind projects, one with a terminus at Las Vegas and the second ending in Utah.Power Company of Wyoming

The second transmission line, the 500-kilovolt Gateway South, is planned by a major utility, PacifiCorp. The line is to extend 400 miles from the Aeolus substation near Medicine Bow, Wyo., southeast of Seminoe Reservoir, to a substation in Utah.

The pumped-storage hydro would connect with this line at the substation near Medicine Bow.

PacifiCorp has projected that it will have the line in service by late 2024. It received approval by Utah state regulators in April and Wyoming regulators in early June. The utility plans to retire 33 coal burning units by 2040 as it adds 3,700 megawatts of new wind power.

Both lines are to traverse Colorado’s northwest corner. The TransWest line secured a right-of-way in December from two property owners, Cross Mountain Ranch and the Colorado Cattleman’s Agricultural Land Trust.

The Wyoming developer, rPlus Hydro, a subsidiary of Salt Lake City-based land developer Gardner Company, has several projects in the planning pipeline in Western States. The most advanced is in eastern Nevada, at a site called White Pine. The company is working with the Federal Energy Regulatory Commission on a final licensing application. The company hopes to reach that same status for its Wyoming project in December.

The company’s idea in Colorado is less developed. “It is still in the very early stage of evaluation,” said Shapiro. A preliminary permit has been awarded by the Federal Energy Regulatory Commission, but that, he said, is just a placeholder of an eventual license application.

The next step on Craig-Hayden is geotechnical evaluation of the site south of the Yampa River in the area on the border of Routt and Moffat counties between Hayden and Craig. The site is located on private land and two reservoirs would be necessary, higher and lower.

This contrasts with the Wyoming project, which involves a federal reservoir and adjacent federal land. That federal presence makes the Wyoming project more complicated.


Wyoming wind and Colorado customers?

Can Colorado benefit from this development of wind and possibly pumped-storage hydro in Wyoming?

Jonathan Naughton, director of the Wind Energy Research Center at the University of Wyoming, told Wyofile that the southeastern part of the state has wind capacity factors of more than 50% compared to 35% in other interior states.

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

Naughton also said Wyoming wind tends to be more consistent during winter months and evening hours throughout the year, providing a balance to power demands in other western states.

But existing transmission between Wyoming and Colorado, already limited, tends to be entirely full when the wind is blowing hard in Wyoming.

One idea was to link Wheatland, Wyo., and Brush, Colo. This would foster wind generation north of Cheyenne.

“I think it would have a large impact on Colorado and would complement Colorado’s own renewable resources,” he says.

In a paper he and others produced in 2013, Naughton emphasized the value of diversity of resources, in this case those of Wyoming and Colorado. “It is not just being able to produce lots of electricity, but how you produce a more consistent amount of electricity,” he told Big Pivots.

He sees Colorado utilities joining or developing a new regional transportation organization, or RTO, or independent system operator, or ISO, that would further benefit maximized development of renewable resources.

If Wyoming and Colorado were in the same ISO, that would really change things, in my view. States try to develop their own resources for economic development, but renewables work better when sourced from a large area.

Allen Best
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