May 11, 2023
By Joe Schulz

Wisconsin utility will explore converting abandoned mines into hydroelectric generators
'The pump storage system is in effect working like a large battery,' says Dairyland Power Cooperative official

This is a hydroelectric pumped storage power plant on Dniester river in Moldova. A Wisconsin utility, Swedish company and Michigan college hope to bring a similar concept to abandoned mines in the upper Midwest. Global Water Partnership - a water secure world (CC BY-NC-SA 2.0)

A Wisconsin utility has a new plan to convert abandoned mines in the upper Midwest into hydroelectric energy sites.

Last week, La Crosse-based Dairyland Power Cooperative announced a partnership with Sweden-based Mine Storage International and Michigan Technological University. Together, the three entities are exploring options to install pumped storage hydropower in closed mines. It's a way of storing energy using two water reservoirs at different heights. To generate power, the water is released from the upper reservoir to the lower one, passing through a turbine that generates electricity.

"The pump storage system is in effect working like a large battery to store energy at economic times when it's not needed, and have it there to discharge and produce power when it is needed," said John Carr, who is leading the project for Dairyland.

This is a conceptual drawing that illustrates how pumped storage hydropower works. It pumps water is from a lower reservoir to the upper one when energy is not needed. At times of high demand, the water is released from the upper reservoir to the lower one, passing through a turbine that generates electricity. Photo courtesy of Dairyland Power Cooperative

Carr said the combined effort to repurpose former industrial sites will support the utility's carbon reduction goals, its grid reliability and renewable energy production.

He said the utility is looking at potential sites in Wisconsin, as well as other Midwestern states. Carr said Dairyland is using a large database of abandoned underground mines and narrowing it down to suitable candidates.

Wisconsin has been home to mining for more than 2,000 years, according to the state Department of Natural Resources. In fact, mining copper, lead, iron and zinc helped shape the history of some regions in the state, and played a major role in Wisconsin's development.

"It's safe to say that Wisconsin would be in that mix of locations that we're considering, but we're even looking broader than that here in our initial start," Carr said. "Ideally, we would find suitable sites that are close to home. But we're starting very broad, and we think that's necessary to make sure that we're finding the right site."

Dairyland has been exploring storage alternatives for the last several years, and reached out to Mine Storage last year in response to supply chain issues affecting battery storage, Carr said. Shortly after, the utility connected with Michigan Tech, which has conducted "a lot of research" into pumped storage hydropower, he said.

"This technology will be highly dependent on finding the right site, and making sure that there's community engagement and support behind it," Carr said. "We believe we have two very strong partners to assist us in that effort."

Raine Vasanoja, chief commercial officer at Mine Storage International, said the company was founded about three years ago, but its key leaders have decades of experience in the energy sector.

He said Mine Storage has developed a portfolio of projects in several countries, and its first plants in Sweden are expected to begin construction in the next 12 months or so.

"They're in the mid-Swedish area and in southern Sweden, where most of the people live. It's a little bit like Milwaukee and Madison in Wisconsin," Vasanoja said. "That's where we have the transmission challenges with the electrical grid, so it's perfect from our point of view, and from a system point of view as well."

He said the partnership with Dairyland provides Mine Storage with its opportunity to enter the American market.

"We realize that the U.S. market is actually moving right now," Vasanoja said. "It's a big market with different state laws and different regulations, so we basically chopped it into different parts. And for now we're focusing on the upper midwest."

Both Carr and Vasanoja said the using old mines for pump hydro storage creates an opportunity to revitalize an abandoned industrial site in a way that's environmentally friendly and creates an economic value for former mining communities.

Converting mines to pump storage hydropower facilities will generate jobs during the construction phase of a project, as well as ongoing operation and maintenance jobs as a site comes online, Carr said.

"It's full circle," he said. "Rather than rely on a technology that may require more mining of rare earth materials, metals, that type of thing, you're using a mine that's already run the course of its useful life and putting it back into productive power generation."

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