Southwest Ledger writer Mike Ray has been exploring in detail the controversial proposed Kiamichi River hydro-electric project.
Here is another of his stories.
By Mike W. Ray
Southwest Ledger
The Southeast Oklahoma Power Corporation (SEOPC) has reapplied to the Federal Energy Regulatory Commission (FERC) for permission to build and operate a 1,200-megawatt, closed-loop pumped storage hydroelectric power plant along the Kiamichi River in Pushmataha County.
The projected output of SEOPC’s proposed power plant is more than double the entire maximum production from the hydroelectric power plants on lakes managed by the Tulsa District U.S. Army Corps of Engineers.
The Tulsa District U.S. Army Corps of Engineers operates and maintains eight hydroelectric power plants that contain a total of 22 units that have a generating capacity of 584 megawatts of power.
Seven of the plants are located in eastern Oklahoma: at Lakes Keystone, Tenkiller, Fort Gibson, Eufaula, Broken Bow, plus the Webbers Falls Lock and Dam and the Robert S. Kerr Lock and Dam #15, both on the McClellan-Kerr Arkansas River Navigation System. The eighth hydropower plant is on Lake Texoma, just across the border in Texas.
Power from SEOPC’s proposed facility would be transmitted to an electric substation at Paris, Texas, via a 100-mile-long high-voltage line extending through two Oklahoma counties and two Texas counties.
A pumped storage hydroelectric system produces electricity the same way a dam’s powerhouse does, using generators that are driven by water-propelled turbines.
The difference is that a self-contained, closed-loop system such as that proposed by SEOPC doesn’t depend on a constant flow of water to operate. Instead, it makes electricity by releasing water that flows downhill through the powerhouse generator turbines from a reservoir that’s located at a higher elevation.
After passing through the powerhouse, the water is captured in a lower reservoir, where it is stored until the system operator pumps the water back to the upper reservoir for another release.
The operator sells the power generated by the system into the electric grid for a high price at times when a grid operator needs the energy to keep its power levels constant. Although pumping the water back to the upper reservoir requires electricity, that step occurs at times when the power costs less.
SEOPC’s hydroelectric power plant would be constructed approximately five miles south of Talihina.
According to records filed with FERC, the project would entail construction of an upper reservoir, an upper dam, a headrace runnel, a concrete pumping station, a tailrace tunnel, a lower reservoir, a lower dam, a pair of pump pipes, a regulating reservoir, a water supply channel, an intake structure on the Kiamichi River, and a high-voltage electricity transmission line.
Construction would take three to four years to complete, an SEOPC document states.
The entire project would cost approximately $3.1 billion, SEOPC President Johann Tse said in March. “We have funding to advance the project at this point,” he wrote.
Project components
The upper dam would be built on Long Creek approximately 4.8 miles from its headwaters. The dam would be 886 feet long (the length of almost three football fields) and 282 feet high; it would be a concrete face rockfill detention structure with a 17-foot-high spillway releasing to Long Creek.
The upper reservoir would have a surface area of almost 600 acres – 15/16ths of a square mile in size. The lake would have a storage capacity of 68,269 acre-feet – more than 22 billion gallons of water. [An acre-foot is 325,851 gallons of water, enough to inundate one acre of land to a depth of one foot.] The upper reservoir would have a 98-foot-long by 39-foot-high concrete upper intake/outlet structure.
The headrace tunnel, which would convey water from the upper reservoir to the powerhouse, would be 7,030 feet (1.3 miles) long, 33 feet in diameter (the width of a two-lane highway with 4-foot shoulders), and would be constructed of steel and concrete.
The concrete pumping station would be an underground cavern 550 feet long, 93 feet wide, and 189 feet high (roughly the equivalent of 14 stories), containing four pump/generating units with a total capacity of 1,200 megawatts.
Under normal operations, the power plant would generate electricity during peak energy demand periods for 10 hours per day, producing approximately 4,368,000 megawatt-hours of electricity annually, SEOPC calculated.
The tailrace tunnel would be a concrete tunnel 8,243 feet (a mile and a half) long and 33 feet in diameter. The concrete tunnel would transfer flows between the upper and lower intake structures. A tailrace tunnel is a channel that carries water away from a hydroelectric plant after it has been used to rotate turbine blades.
The lower reservoir would be a lake with a surface area of 887.37 acres (almost 1.4 square miles) and a storage capacity of 48,699 acre-feet of water, 15.8 billion gallons. The reservoir would have a 98-foot-long, 39-foot-high concrete lower intake/outlet structure.
The lower dam would an earthen structure 13,615 feet (two and one-half miles) long and 69 feet high, with a 33-foot-long, 13-foot-high emergency spillway with a channel that would become “a tunnel regulated by a metal gate” releasing flows to the Kiamichi River.
A regulating reservoir would have a surface area of 40 acres and a storage capacity of 1.216 acre-feet (396 million gallons of water).
Two pump pipes 20 inches in diameter and 1,085 feet long, with 110-kilowatt pumps, would move water from the regulating reservoir to the lower reservoir.
The water supply channel would be a 10-foot-long by 10-foot-tall concrete structure containing a pair of 20-inch-diameter, 525-foot-long pipes with 110-kilowatt pumps to move water from the Kiamichi River to the regulating reservoir.
The intake structure would be a concrete structure 40 feet wide and 40 feet long located approximately a foot and a half above the bottom of the Kiamichi River “to allow for constant flow diversions.” The structure would be funnel-shaped and would taper down over its length to the water supply channel.
The 345-kilovolt power transmission line would be 100 miles long. The line would pass through Pushmataha and western McCurtain counties in Oklahoma, and Lamar and Red River counties in Texas, and would connect the SEOPC powerhouse in Pushmataha County to an Electric Reliability Council of Texas (ERCOT) substation at Paris, Texas.
The route would be co-located with existing transmission lines for approximately 23¼ miles; a 150-foot right-of-way (ROW) would be secured for that section of the transmission line. The power line would be constructed along a new path for the remaining 76⅔ miles, and a 1,320-foot ROW would be secured for that section of the line.
Net consumer of energy
Pumped storage projects are net consumers of energy “due to hydraulic and electrical losses incurred during the cycle of pumping from lower to upper reservoirs,” SEOPC acknowledged.
However, the company added, “pumped storage is a dispatchable source of energy that can be deployed quickly during times of peak energy demand, and then take excess energy off the grid by pumping water from the lower reservoir to the upper reservoir during times of low energy demand.”
The “low demand periods” are expected to be “during nights and throughout weekends, while “high demand periods” are expected to be during the daytime hours on weekdays.
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