Page 96 - North American Clean Energy September October 2015

geothermal energy

Tapping into Mine Water Geothermal

Unused waste product is a useful resource

by Allison Mills

Mine water is often considered not only a waste, but also a serious danger to human and “It’s just like the radiator in your car,” says Jay Meldrum, the director of the Keweenaw
environmental health. With millions of miles of abandoned tunnels in the United States Research Center. “Only the heat from the mine shaft water is what we are using.”
illed with potentially acidic and heavy metal enriched water, the task of cleaning it up is Within the building loop, a water-glycol mix circulates and runs through 18 heat pumps
daunting. However, this expensive hazard can also be a proitable resource.
throughout the center’s main building. he heat from the mineshaft water acts as a pre-

Communities around the world have tapped into mine water reservoirs for geothermal heater to bring the temperature of the refrigerant up to the mineshaft temperature,
heating and cooling. But to date, there are fewer than 30 existing systems, despite mine approximately 55°F. he higher the temperature, the better performance of the heat pump.
water’s prevalence. One is at the Keweenaw Research Center just north of Houghton, “We hope to use geothermal as an educational resource,” Meldrum says, adding they’re
Michigan.
working with the National Park Service to install an exhibit in the Calumet Visitor Center.

In Michigan’s Keweenaw Peninsula, a legacy of copper mining—long since boomed and “It’s also an area we want to continue doing research in.”
busted—is being reworked into a geothermal and alternative energy future. Researchers
and students at Michigan Technological University and Keweenaw Research Center have Cost is always a concern
established an interdisciplinary team to manage an active mine water geothermal system, One challenge is the double-whammy of high electric prices and cheap natural gas in the

reine its mechanics and develop community outreach materials.
region. Chris Green, who directly manages the Keweenaw Research Center’s mine water
geothermal system, also points out that while it’s a cleaner technology, it is still dependent
Collaboration is key
on electricity. Green hopes to combine solar and mine water geothermal to make the
Michigan Tech graduate student Edward Louie spearheaded the project as part of his system more carbon neutral, but the problem is the large initial investment required. In

master’s work in energy policy, and put together a guideline for communities across the an economically depressed area like the Keweenaw Peninsula, the only green most people
country interested in mine water geothermal projects.
seem to care about is in their wallets.
Locally, Louie and other student researchers collaborated with the village of Calumet to Still, with some of the nation’s highest electricity rates—second only to Hawaii—the
assess the extensive mine tunnel network under the town. In a place that gets more than appeal of solar is big, and geothermal is competitive with propane and fuel oil heating,

an average of 200 inches of snow every year, using geothermal for heat is important.
which are fairly common in the region.
A lot of heat can be drawn from mine water without it cooling down, because the mine With so few active systems in the world, the Keweenaw Research Center is a unique
water in the Keweenaw stays around 53°F to 55°F. hese year-round temperatures can then resource for people living in the region. Tapping into the mine water is also a tribute to

be used to heat or cool buildings using simple technology, standard in most geothermal the area’s history, says Richelle Winkler, a community and environmental sociologist at
systems, but the key is having a good heat pump.
Michigan Tech who works with the Keweenaw Research Center crew.
“Using the mine water for geothermal energy creates an opportunity to recast
Heat pumps - an old technology for a modern application
community identity,” Winkler says. “Which both celebrates the mining heritage, and

“A heat pump is simply a device that can move and concentrate heat with relatively little promotes progress forward in an environmentally sustainable way.”
energy input,” Louie says, adding the equipment has been around since the 1970s. “he With so much room for expansion, the Keweenaw could become a hub for mine water
eiciency of heat pumps are has gotten better, their reliability has gotten better, but the geothermal. And through the guidebook, Winkler and her collaborators could help shape a
technology itself is not from Star Trek.”
widespread environmental problem into a solution and resource.

In a geothermal heating system, the heat pump concentrates a relatively small amount
of heat from the mine water, which remains much warmer than the winter outside air,
Waste product to useful energy
into comfortable temperatures for heating a building. For cooling, the heat pump works in he guidebook project was funded by a People, Prosperity and Planet (P3) grant through
reverse, dumping cooler air into the building. And for every unit of energy used to power the Environmental Protection Agency (EPA). he student researchers on the project,

the heat pump to do this exchange, the pump can move four, and sometimes more, units of spanning ields from mechanical energy, policy, chemistry, and communications, presented
heat.
their work in Washington, DC this April. hey received an honorable mention, plus won
Geothermal systems are inherently lexible, depending on location and the quality of the a special award for having the most interdisciplinary and community engaged work.
mine water. In the Keweenaw, where pure copper was dug up, the mine water is relatively hey will be presenting at the American Institute of Chemical Engineers conference in

clean. In other areas, mine water is laden with heavy metals and acid, which corrodes November.
equipment. hat makes implementing the systems challenging, but not impossible. Louie For him, Green says the success of the project so far comes from turning a waste product
and his team outline several open- and closed-loop systems in the mine water geothermal into a useful system. He also says it its into the current ideal of locally produced energy.
guidebook.
“Everyone used to generate their own power—how do we return to that?” he asks. “his

Closed-loop systems help protect equipment from corrosive mine water by exchanging mine water is just sitting below the surface and it’s an unused resource. We can change that.”
heat outside a loop of corrosion resistant pipes placed inside the mineshaft. he mine
water itself is never pushed through the heat pumps. At the Keweenaw Research Center, Allison Mills is a rock and dance geek, working as a science writer at Michigan
they pipe the mine water up from 300 feet below the surface, an open-loop system. Tech, and occasional freelancer for EARTH Magazine.

hrough a big heat exchanger, the mine water cools or heats a closed-loop system within
the building.
www.aee-mtu.org/geothermal-calculator-guidebook

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