How viable is mine water for geothermal energy?
April 8, 2015 | By
Jaclyn Brandt
Students at Michigan Technological University (MTU) are researching the possibilities of using mine water for geothermal energy. The university, located in Houghton, Michigan, is home to the Keweenaw Research Center -- which houses one of the only 30 active mine water geothermal systems in the world.
The mine water in Keweenaw stays around 53 to 55 degrees Fahrenheit year round, which makes the location ideal for the technology. The water can be used to either heat or cool buildings using pipes, heat exchangers or heat pumps. The project was initiatied as a master's project by Michigan Tech graduate student Edward Louie, who explained that "With mine water, you can draw lots of heat... without it cooling down." The project resulted in a guidebook for utilities looking to produce geothermal energy from mine water. "A heat pump is simply a device that can move and concentrate heat with relatively little energy input," Louie said in a statement. "The efficiency of heat pumps has gotten better; their reliability has gotten better, but the technology itself is not from Star Trek." The technology is similar to a refrigerator, which concentrates the heat and removes it, while keeping the cold inside. Louie explained, "That's why the back of your fridge is warm, and that's why your freezer is freezing cold." That idea can be transferred to the heated water from the mine. The heat pump concentrates on a small amount of heated mine water to heat a building. "It's like the back of the fridge is placed in your house," Louie added. "So, it's dumping the heat in a warmer form into your house." The mine in Houghton was used for copper mining, which left the mine and its water fairly clean -- but not all mines were left in the same condition. Because of this, the researchers outlined closed loop systems in their guidebook. "Closed loop systems help protect equipment from corrosive mine water by exchanging heat outside a loop of corrosion resistant pipes placed inside the mineshaft," the university said in a statement. "The mine water itself is never pumped. In open loop systems, the mine water is pumped and makes contact with a metal heat exchanger. The advantage is increased efficiency and less piping, but the mine water has to be clean enough." The technology would take a similar approach to cooling a building -- pulling the cold out of the water. MTU explained that for every unit of energy used in the technology, they produce four -- or more -- units from it. "We hope to use geothermal as an educational resource," Jay Meldrum, director of the Keweenaw Research Center says. "It's also an area we want to continue doing research in." For more: © 2015 FierceMarkets, a division of Questex Media Group LLC. All rights reserved. http://www.fierceenergy.com/story/how-viable-mine-water-geothermal-energy/2015-04-08 |