Timothy Scarlett (left), a Michigan Tech associate professor of archaeology and anthropology, and Roman Sidortsov, an associate professor of energy policy, at the iconic Quincy copper mine in Hancock, Michigan in April 2022.

New funding could spur ‘PUSH’ for hydro energy storage in abandoned mines

Upcoming federal funding aims to boost pumped-storage hydropower, an energy storage technique that builds on the age-old idea of using moving water to generate electricity. Institutional researchers and industry recently have been exploring a different way to use hydropower: in abandoned mines. The idea could breathe new life into Midwestern post-mining communities — if developers can overcome significant policy and regulatory hurdles.

Making a PUSH

The first known examples of pumped-storage hydropower systems date back to Europe in the 1890s, and they were first used in the U.S. in 1930. U.S. Department of Energy data show that 93% of domestic utility-scale energy storage occurs via pumped-storage hydropower, or PSH. The country has 43 PSH plants and the ability to add more to double the current capacity. 

This type of hydroelectric energy storage relies on water moving between reservoirs at different elevations, usually with at least one reservoir at or above ground level. The water generates power when it moves down from one level to the next and passes through a turbine. Open-loop systems connect to a natural body of water, and closed-loop systems are not continuously connected to naturally flowing water. Pumped-storage hydropower systems require some power to pump water back to the higher reservoir.

PSH serves as a giant battery because the water power is stored and then released as needed. For example, the water can flow down to create energy during peak daytime electricity demand and be pumped upward at night when demand is low. The concept shows promise for providing clean power when the sun isn’t shining and the wind isn’t blowing.

New research and development work focuses on adding “u” to the equation and creating a “PUSH” system “underground,” such as in decommissioned mines. In these closed-loop systems, the lower reservoir is entirely underground and the upper reservoir is at or below the ground’s surface. Using existing caverns instead of excavating a new underground water storage space makes the concept less environmentally taxing and less costly. 

Making a mark in the Midwest

The Midwest shows promise for PUSH project implementation considering its access to mines and water sources. In particular, Michigan’s Upper Peninsula houses many abandoned copper and iron ore mines, while Indiana is home to many abandoned coal mines. 

Researchers at Michigan Technological University recently published a report detailing results from their nearly two-year proof-of-concept study on PUSH in the United States, which was funded by the Arthur P. Sloan Foundation. They examined the viability of repurposing the decommissioned Mather B iron ore mine in Negaunee, Michigan, into a pumped underground storage hydro facility as part of a smart grid power system. 

“It was really an intellectual puzzle when we started,” said Timothy Scarlett, associate professor of archaeology and anthropology in the Department of Social Sciences at Michigan Tech. “It was only as we continued thinking about it over the long term … that we came to understand how potentially transformative this is and how realistic the ideas are. It’s quite remarkable.”

The study examined technical, economic, legal, regulatory, water quality, social, and community engagement opportunities and barriers for repurposing decommissioned mines. The analysis indicates no particular chemical pollution or environmental concerns for mines that are properly remediated and upgraded; mines with existing water quality issues could incorporate a water treatment process into the PUSH system.

The researchers determined that the Mather B could be outfitted with technologies that turn it into a profitable long-duration storage facility that provides continuous power to 30,000 people for more than three months. They extrapolated the Mather B results to a national scale and identified about 1,000 locations across the country where grid-scale PUSH could be feasible. 

“The energy grid has been changing over the last five to eight years … and it’s changing the economic dynamics of this,” Scarlett said.

“Energy storage is a critical problem that we know will be a crisis in just a few years. People need to start solving this problem.”

Regulatory and environmental hurdles

Some people believe that technological breakthroughs are the drivers of a successful clean energy transition, said Roman Sidorstov, associate professor of energy policy at Michigan Tech and senior research fellow in energy justice and transitions at the University of Sussex. Instead, he said the answer can lie in a less-siloed view in which technology is just one aspect, along with policy and applications. Such is the case for PUSH projects, Sidorstov said, noting that his group’s study has the potential to transform how people think about energy policy and incorporate energy and environmental justice into project development.

“There’s a bit of non-conventional thinking behind this technological application,” he said.

“The real innovation here is when you combine all the technological applications in a holistic way. … It all comes together as something that accomplishes not just one policy goal, but multiple policy goals.”

Although hydro energy storage research shows encouraging results, industry growth has stagnated. No major PSH projects have been built domestically since the 1990s, and few are located in the Midwest. However, the DOE shows that 67 new PSH projects with a proposed capacity of more than 52 GW were in various stages of evaluation or development at the end of 2019.


A graphic from the U.S. Department of Energy's January 2021 Hydropower Market Report maps PSH project development pipeline by region and development stage.
A graphic from the U.S. Department of Energy’s January 2021 Hydropower Market Report maps PSH project development pipeline by region and development stage.

No PUSH projects exist in the United States, although several have been proposed over the past decade. One was for an abandoned mine and quarry in Elmhurst, Illinois. Municipal employees indicate PUSH isn’t gaining traction at that site because of challenges with land rights and return on investment when teaming up with local utility ComEd.

Bloomington, Indiana-based company Carbon Solutions reportedly is working with researchers at Indiana University-Purdue University Indianapolis to develop plans for converting some of the state’s dozens of abandoned coal mines into PUSH facilities.  (Neither entity responded to Centered’s requests for more information.) 

Barriers for these projects — especially the first to get off the ground — include permitting, licensing, and performing environmental impact assessments. Commercial developers will have to work with regulators at the federal, state, and local levels, Sidorstov said. Plus, participating in an electricity market, like MISO or PJM, would require working with the system operator for interconnection and getting into the queue to become part of the market.

“The first attempt to permit and license a facility like this is going to be a chore. … The developer will have to really be diligent and learn quite a few things,” Sidorstov said. “It will create many legal issues because there are some new things that need to be fleshed out.”

The Michigan Tech study says the first PUSH projects will help “chart the course” for federal, state, and local rules and regulations, including for siting, mine remediation, post-mining land use, and environmental safety.

“The bad news is that it is a lengthy process — and I would say appropriately so because this is a large facility,” Sidorstov said. “The good news is that there are already some exceptions and streamlining of licensing for closed-loop systems” because they are designed not to release water back into the environment. 

Economic and energy justice boon

In June, the U.S. Department of Energy issued a request for information to aid its development of a $500 million program to fund clean energy projects at current or former mine sites. The funding comes from the federal infrastructure law and names PSH as one of the innovative project ideas that could be replicated across the country. The agency expects to begin accepting project proposals next year for funding. 

“Such investment shows that people think it is a good idea to solve these problems while also reclaiming and rehabilitating brownfields, instead of cutting up remaining greenfields,” Scarlett said. He says “Michigan Tech is uniquely suited to guide some of these demonstration projects,” and his team is working on their responses to the DOE’s request.

DOE notes that PUSH projects could result in economic development for underserved communities near mines. They could also provide energy justice for communities that bear higher energy cost burdens, experience disproportionately high pollution from energy generation and transmission, and have lower access to reliable energy — especially renewable energy. Scarlett says most post-mining communities “face a triad of problems.”

“When mines go bust and the extraction cycle closes, the communities end up in an economic recession or depression. That leads to demographic collapse as people leave the community and they end up with an overbuilt town,” Scarlett said. “There’s often an ecological legacy on the landscape that is discouraging for other kinds of investment. … Interconnected with those other two is the cultural malaise that comes from feeling abandoned as the global economy moves on.”

Building PUSH in abandoned mines would bring jobs to disinvested areas while promoting greater clean energy use and environmental stewardship. It could also encourage future investments in communities that have become economically disadvantaged.

“It’s not just about being the necessary enabler for renewable electricity; it’s also something that gives post-mining communities the opportunity to thrive,” Sidorstov said.

Michigan Tech’s PUSH feasibility analysis is only as good as the data, and the team admits the data on domestic abandoned mines is thin. Addressing that is their next step. 

They recently entered into an agreement with the Michigan Department of Energy, Great Lakes, and Environment to update and improve its decades-old database of abandoned mines. The researchers will improve the GIS database’s mapping capabilities and will expand its planning and environmental management functionality for use by industry and private landowners who are investigating energy technologies for abandoned mines.

“We’ve been able to show in Negaunee that it can work and it will be profitable,” Scarlett said. “But doing hard things like this requires a mixture of political will, social will, and economic will. There has to be private interest and public interest, and the biggest challenge is getting all the different interests to align — especially for something that nobody’s done before.”