In summer 2025, Dr. James “Jim” Tinjum, professor in the Sustainable Systems Engineering (SSE) MEng Program at UW-Madison, traveled to Butte, Montana to explore the modern application of geothermal energy. The purpose of this trip was to assess the use of warm water in a deep mine shaft for heating the adjacent Mike Mansfield Federal Building and U.S. Courthouse. The mine shaft (“Steward Shaft”) is from the early mining operations in Butte and is roughly 500 feet away from the building. This project is being federally funded by the U.S. General Services Administration (GSA) and is currently in the preliminary design phase.
The ultimate goal of the project is both ambitious and innovative: repurpose the Steward Shaft as the heat reservoir for a geothermal heat pump system as part of the modernization of geothermal energy.
Preliminary findings from the June visit are promising. Jim and his colleagues confirmed a steady water temperature of 88°F (31.4°C) down to 1300 feet (396 meters), indicating an excellent and consistent geothermal resource. While logistical constraints remain—such as gaining full access through the closed upper portion of the shaft—several alternative system designs, including the Darcy System, Genesis ‘in-well’ heat exchangers, and a closed-loop concentric system are being evaluated to harness this energy efficiently.
Jim reflected on the magnitude of this project, saying, “When you are sitting at the shaft a mile high it is crazy to think about how deep these shafts actually go—how they extend almost to sea level.”
This initiative is not only a powerful example of applied research beyond Wisconsin’s borders, but it also connects directly to Jim’s first-of-its-kind Geothermal Energy course, launching this spring as part of the SSE program. This course will cover topics such as thermodynamics of heat flow in porous media (soil and rock), direct-use thermal energy systems, and high-temperature water to electricity. The course ultimately addresses the global urgency to reduce greenhouse gas emissions through innovative, low-carbon energy solutions that are resilient and economically efficient.
Learn more about our SSE Program and SSE course offerings here.
Example SONAR image showing the dimensions and integrity of two of the mine shaft compartments.