BIG STOEN CITY, S.D. (Bart Pfankuch / South Dakota News Watch) – This small city in northeastern South Dakota already serves as a major hub for energy – it is home to a coal-fired power plant, a Poet Biofuels ethanol plant and a major electrical substation that is critical to the region’s power grid.
A planned multistate, multibillion-dollar expansion of the region’s transmission system would make Big Stone City an even bigger spoke for the Upper Midwest’s energy economy.
If a proposed 765-kilovolt transmission line through town is built in the next few years as planned, it would easily become the highest-capacity power line in the state. It also would set the stage for new natural gas, wind and solar electricity generation in South Dakota.
“The key piece here is that transmission infrastructure supports all development,” said Matt Prorok, an electricity policy analyst for the nonprofit Great Plains Institute, based in Minneapolis. “It’s essentially creating access to buying or selling whatever you need when you want to.”
That means new jobs and greater need for trained workers, and not just in the state’s growing renewable energy economy. More capacity to move electricity through the state will also create opportunities for a wide range of new industrial, commercial and residential growth in the coming decades.
Furthermore, the high-capacity line also would strengthen and stabilize the region’s electric grid during weather disasters, generate numerous new jobs in the energy and construction industries and ultimately lower costs for ratepayers, according to Midcontinent Independent System Operator, or MISO, the regional grid operator behind the project.
South Dakota is expected to see several new transmission line projects in the coming years. The major one through Big Stone City is part of wide-ranging plans by two major power grid operators to expand electric capacity through dozens of Great Plains and Midwestern states over the next 10 to 20 years with a price tag of nearly $30 billion.
The new transmission line projects will pave the way for growth not only in energy production but also for a variety of commercial, industrial and residential developments, Prorok said.
Prorok said that while planning, forecasting, siting and funding transmission lines is a complex, multi-year process, the benefits can be simplified by comparing the expanded lines to roads in farm country. As new roads are built or existing roads are expanded, it opens the door for more commerce on a wide variety of fronts.
For instance, higher-capacity transmission lines could prepare the way for new power plants and wind farms as well as for industrial plants, residential complexes or new technologies like data centers to be built in South Dakota or neighboring states, he said.
Beyond that, the new transmission lines will protect utility customers by allowing for energy to flow during natural disasters and should ultimately save ratepayers money, Prorok said.
“Customers will pay less overall, because when transmission projects get approved, they are required to demonstrate a net benefit over time,” he said.
South Dakota is part of two separate regional transmission organizations that manage the electrical grid in multiple states.
MISO manages energy flow in 15 states, including the northeast portion of South Dakota and in Manitoba, Canada. The Southwest Power Pool, or SPP, oversees energy flow in 14 states, including most of South Dakota.
MISO has plans for 488 individual projects to be done over the next 10 years at a cost of $22 billion.
In South Dakota, the MISO expansion calls for construction of a 345-kilovolt line from Alexandria, Minnesota, to Big Stone City and development of a new 765-kilovolt line from Big Stone City to White and to the city of Trimont in southwestern Minnesota.
SPP has approved plans for 89 transmission projects to include 2,333 miles of new lines and about 500 miles of rebuilt lines at an overall cost of $7.7 billion.
The SPP projects in South Dakota would include a new 50-mile, 115-kilovolt line from Carpenter to Lake Preston, reconstruction of an existing power line in Watertown and the construction of a new 345-kilovolt line for 440 miles from Belfield, North Dakota, to New Underwood in western South Dakota and then south to Laramie, Wyoming.
The new transmission lines in and out of South Dakota should open the door to future development of energy in the state, especially in regard to sustainable sources such as wind and solar.
South Dakota has been a national leader in rapid expansion of wind energy production over the past decade and has a welcoming environment for greater solar production as well.
As of 2024, South Dakota had 3,600 megawatts of wind energy in production, according to Public Utilities Commission records. About 60% of the wind production has come online since 2020, a five-year period in which the state added about 2,100 megawatts of production by almost 700 new turbines.
However, applications for new wind production facilities have slowed dramatically, largely due to a lack of transmission line capacity in the state and Great Plains region.
“We’re pretty much stalled right now,” PUC Commissioner Chris Nelson told News Watch.
