A second pumped-storage idea in Yampa Valley

This newer proposal would use the subterranean of the Twentymile coal mine for the lower reservoir

by Allen Best

A second proposal for a pumped-storage hydropower project in the Yampa Valley has become public.

A Florida-based company is seeking a preliminary permit from the Federal Energy Regulatory Commission for a project involving the Twentymile Mine. A project in the Craig-Hayden area is also on the FERC processing table but at a more advanced stage.

The 250-megawatt Twentymile Pumped Storage Project would use the existing tunnels, galleries, and other subterranean workings of the coal mine in Twentymile Park as the lower reservoir. The water would be pumped 1,300 vertical feet to a new reservoir on a nearby bluff.

The two reservoirs would be connected by a 16-foot-diameter concrete-lined tunnel.

A 100-foot-high dam would be needed to create the higher 20-acre reservoir.

It would have a capacity of 1,550 acre-feet.

The letter to FERC filed in March 2023 explained that the stored water could operate at full-power generation for up to 6 hours per day.

The application was first reported recently by the Yampa Valley Bugle.

If approved by FERC, the developer can conduct a feasibility study on the project and will have exclusive rights to seek a full permit for the project.

Who is exactly behind this proposal? The Bugle pointed out that the West Palm Beach address matches that of Rye Development. Rye describes itself as “leading a new generation of pumped storage hydropower in the U.S. and helping create a more reliable energy grid.”

One of its projects is Lewis Ridge, which is to get $81 million in federal funds to use a former coal mine in eastern Kentucky. Among the news stories noted on Rye’s website is an AP story from March that explained the Department of Energy is making $475 million available for clean-energy projects on mined-land sites.

Another project, Swan Lake, is near Klamath Falls, in Oregon. Yet another project, Goldendale, would be on the Oregon-Washington border. The company also cites several run-of-the-river projects in Pennsylvania and other eastern states.

Peabody Coal owns and operates Twentymile Mine. It supplies coal to the Hayden Generating Station and possibly to Craig and conceivably to other locations. It’s hard to track the shipment of coal.

Peabody has not clearly laid out its plans. The most recent presentation to investors reported that the mine is producing 1.3 million tons annually and has reserves of 9 million tons.

An older proposal for a pumped-storage hydro project would be on private land east of Craig and in Moffat County.

Work continues on a different project east of Craig in Moffat County. This would be 25 to 30 road miles from Twentymile.

A company called rPlus Hydro has received FERC approval to move forward with its feasibility plans. It has purchased private land, which will lower the permitting bar as compared to a project involving federal land. The company says it hopes to have the pumped-storage hydro project completed by 2033.

rPlus projects that Craig-Hayden Pumped Storage will have 600 to 800 megawatts of generating capacity. Cost has been estimated at $1.5 billion to $2 billion. That pumped-storage project will need 30 to 40 employees.

Matthew Shapiro, the chief executive, tells Big Pivots that the next engineering study is nearing completion. It will provide recommendations about the location of the underground powerhouse, dam types, and other specific features.

A second FERC pre-application document is being prepared. Shapiro said he expects to submit it late this year or early in 2025. This is the next step toward preparation of exhibits for a license application.

A socio-economic impact study is well underway and will likely be completed in October. That study was funded with a $150,000 grant from the Colorado Office of Just Transition. A Broomfield consultant, SWCA, has been retained for the work.

rPlus Hydro has at least 12 projects in various stages of development in Utah, California, and other states, mostly in the West.

Most projects involve construction of new reservoirs, as is the case in Moffat County. In Wyoming, however, rPlus wants to use an existing reservoir, Seminoe. rPlus hopes that FERC will accept the final license application during the next six months. That would kick off the FERC-led environmental review process required by the National Environmental Policy Act, or NEPA. The company hopes to have that project on line in 2032.

Also among rPlus’s projects is Sweetwater, in the northwest corner of New Mexico.

Colorado has several pumped-storage projects. Most prominent is Cabin Creek, Xcel Energy’s project between Georgetown and Guanella Pass.

It began electrical production in 1967. In this closed-loop system, water from the higher reservoir is released through a three-quarter-mile tunnel to the second reservoir 1,192 feet lower in elevation. This can generate a maximum of 324 megawatts to help meet peak demands or to provide power when it’s dark and if the wind suddenly stops. When electricity is more freely available, the water can be returned to the higher reservoir. Very little water is lost, except at elevations of 10,000 and 11,000 feet, a small amount of evaporation.

Colorado has a second pumped-storage project at Twin Lakes with a more modest elevation difference. The units can generate up to 200 megawatts of electricity.

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