BURKE, S.D. - In the first step of what could be a decades-long project, a preliminary permit in Gregory County has been filed with the Federal Energy Regulatory Commission to study building a hydropower project along the Missouri River.

The project is currently in the midst of a 60-day comment period. If approved, it would allow the applicants from the Western Minnesota Municipal Power Agency three years to study the site for a potential hydropower generation plant.

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The WMMPA, a municipal corporation based in Ortonville, Minn., has filed the permit. It finances the construction and acquisition of generation and transmission facilities for members of Missouri River Energy Services, based in Sioux Falls, which provides energy to a number of municipalities in South Dakota, North Dakota, Minnesota and Iowa.

An application filed in April says a detailed feasibility study will be conducted to finalize the technical features of the project and confirm the project's economic viability. The project is also intended to evaluate the best arrangements for configuring the equipment.

Missouri River Energy Services Manager of Generation Resources Brent Moeller said the permit is to allow more research to be done and to reserve the site for that work. The site would be in south-central South Dakota.

The proposed project calls for an open-loop pump storage project, with an upper reservoir, which will cover 1,350 acres and be constructed by a 62-foot-high earthen levee. An open-loop project is one that is connected to a naturally flowing water feature, which in this case is Lake Francis Case and the Missouri River, the lower reservoir in this case. An underground powerhouse would be located more than 600 feet below the river level, Moeller said.

During low demand periods, water would be pumped up the side of the river bluffs - about 700 feet - to the levee reservoir. During high demand periods, the water would flow back down to the pumps and turbines and would be generated into electricity.

The power plant could be tied into the region's wind farms, which would allow the water to be pumped uphill during low demand times, while the water flowing downhill through the turbine would create electricity during high-demand periods, or when wind production is lower. Moeller made the comparison to how a battery functions.

"For this to get any wheels to go anywhere, we would have to get the energy out of the region and to people," Moeller said. "Right now, it's just a concept at this stage. There will have to be a substation at some place where all this will come together and currently, the area doesn't have the transmission buildout to support it."

The 60-day period is scheduled to close on Aug. 7. Comments can be filed through the FERC website at www.ferc.gov and using docket number P-14876.

The idea of building a hydro-power plant in Gregory County is not a new one. A feasibility study in 2004 looked at a possible plant as being a peaking unit and using fossil-fired generation sources.

A 2013 report from Schulte Associates looked at a bulk storage and wind combination plant as an alternative to coal-fired generation. The report made the case that a 2,400-megawatt capacity plant (1,200 with pumped storage and 1,200 of outlet transmission) is feasible for South Dakota. That was written by Bob Schulte, a Huron native and former general manager of the South Dakota region for Northern States Power Company, now known as Xcel Energy.

Schulte had noted that the U.S. Army Corps of Engineers has identified the Gregory County site has the best potential pumped hydro-storage site on the Missouri River.

The Gregory County site is also located along the proposed Power from the Prairie line, Moeller said, a proposed 4,000-megawatt transmission line which would run from southeast Wyoming potentially into Iowa, with the potential to connect to thousands of megawatts of renewable energy in Nebraska and South Dakota.

The effort is one part of a number of proposed projects that could make South Dakota a hub for energy creation and transmission. South Dakota's power generation could connect with western and eastern markets in the U.S.

Some of that could also be involved with the Southwest Power Pool, which is the electric power market for much of the Great Plains.

Moeller noted that there's currently $3 million available from the U.S. Department of Energy to study the long-term benefits of two pumped storage hydropower projects.

"We're in the process of filling out an application for being one of those opportunities. The government recognizes there's a lot of value in the pump storage," Moeller said. "It's very hard to get one off the ground ... but the Department of Energy has put some dollars out there to be evaluated. We feel Gregory County would be a very good fit for them."

The estimated cost for the studies related to the project is between $500,000 and $750,000. If the project were to happen, Moeller said, it would likely be on a 15- to 20-year timeline, with four-to-five years involved in getting the proper licenses, about five years of design and about five years of construction. It would also involve numerous power and utility companies in the region to help fund the project.

"You're looking at least 10 to 15 years and that's only if people really decide to get this done," he said.