Geothermal potential of abandoned underground industrial mineral mines in Ohio
Wolfe, Mark E.1, Timothy E. Leftwich1, and Dina L. Lopez2
1Ohio
Department of Natural Resources, Division of Geological Survey, Columbus, Ohio
mark.wolfe@dnr.state.oh.us;
2Department
of Geological Sciences, Ohio University, Athens, Ohio
Geothermal heat pump technology (GHPT), using water sources such as those in abandoned
mines, offers substantial savings in energy use while reducing greenhouse gas emissions. GHPT
doesn't require the considerable above-ground infrastructure as other forms of alternative energy
such as wind turbines and solar panels. However, a major hurdle to GHPT implementation is a
lack of public awareness. Abandoned underground mines (AUMs) are often considered a
geohazard, but consideration of the low-temperature geothermal potential should not be ignored.
The Ohio Department of Natural Resources, Division of Geological Survey (Ohio Geological
Survey) has been gathering information on abandoned underground mines in Ohio for many
years. Significant data is contained in final maps submitted when mines are abandoned. More
than 7,000 Ohio mine maps have been scanned and georeferenced, mine outlines digitized, and
databases created with information such as mine identifier, commodity mined, date abandoned,
operator, elevation, and geology. The AUM information is easily accessible as an interactive map
on the Ohio Geological Survey website. The majority of AUMs in Ohio produced coal, but there
are more than 170 abandoned underground industrial mineral mines in the state. Many of these
industrial mineral abandoned underground mines (IM-AUMs) are flooded and due to the high
specific heat capacity of water, they represent a potentially significant low-temperature
geothermal energy resource. Abandoned uranium, silver, and tin mines in Germany; a copperzinc mine in Norway; and a lead mine in the United States, along with several coal mines
worldwide, have successfully used low-temperature mine waters and heat-pump technology for
heating and cooling of buildings. Geothermal energy feasibility studies have been completed for
two gold and two copper mines in Canada, eight iron-ore mines and a uranium mine in Germany,
a copper mine in Hungary, a copper mine in the United States, and a silver mine in Norway, but
research of geothermal energy potential of IM-AUMs is not documented in the literature. Such IMAUMs are often located in areas of high-population density that would benefit from a nearby
source of low-temperature geothermal energy.
The Ohio AUM database was queried by commodity type (limestone, clay, shale, or gypsum) and
whether a mine is located below local drainage—an indication of partial or complete flooding,
which is a requirement for heat exchange using mine water. The results of the query indicated 23
abandoned underground clay mines in seven counties, four abandoned underground limestone
mines in three counties, and six abandoned underground gypsum mines in two counties were
below local drainage and likely flooded. The query results were highlighted on the AUM
interactive map; further evaluation using the “Zoom-in” tool and overlaying color aerial photos
and/or topographic maps determined nearby homes or businesses that could potentially utilize
the low-temperature geothermal energy for space heating. If a particular AUM was determined to
justify additional research, a scan of the abandoned mine map was opened by clicking on the
“Identify Feature” button. Additional detailed mine information, such as size and orientation of
rooms and pillars, thicknesses of geologic units, original shaft or slope locations, and other
surface features, assisted in determining mine water volumetrics, heat storage capacity, and
hydrogeologic regime.
Application of the methodology for evaluating geothermal energy potential for IM-AUMs in Ohio
resulted in identification of six clay mines, four gypsum mines, and two limestone mines suitable
for further investigation. Clay mine Py-335, located immediately north of the town of Shawnee in
Perry County, covers an area of more than 200 acres (81 hectares) and has a small factory
overlying the northeast portion of the mine. Clay mine Sk-150, in the northern portion of the city of
Massillon in Stark County, covers an area greater than 100 acres (40 hectares) and has two
businesses overlying the central portion of the mine and a neighborhood of homes to the
immediate south. The additional four abandoned underground clay mines had deficiencies, such
as a lack of nearby homes and businesses and small sizes, but may hold potential for future
development under specific circumstances. The abandoned gypsum mines, in Ottawa County,
offer interesting possibilities, particularly for future development. Located near Sandusky Bay,
State Route 2, and the Port Clinton airport, these mines cover an area in excess of 700 acres
(283 hectares). The underground gypsum mine maps are generally very good, offering detailed
information, such as mine profiles. The two abandoned limestone mines are located near
population centers in Summit and Lawrence Counties, contain significant water storage
capacities, have detailed geologic information available, and offer excellent opportunities for lowtemperature geothermal development.
Adaptive reuse of AUM sites for low-temperature geothermal energy has proven to be a viable
option in abandoned coal and metal mines worldwide and should be a consideration in the final
underground industrial mineral mine closure process. Site-specific information, including drill-hole
and core data, geologic reports, and mine water level, temperature, and quality analyses, can
help support decisions to perform detailed feasibility studies. Partnering with possible geothermal
energy users in proximity to IM-AUMs, including creation of a Geo-utility, may have positive
economic benefits for mine operators and surrounding communities.