A Demonstration System for Capturing Geothermal Energy from Mine Waters beneath Butte, MT Geothermal Project
Last modified on July 22, 2011.
|Project Title||A Demonstration System for Capturing Geothermal Energy from Mine Waters beneath Butte, MT|
|Project Type / Topic 1||Recovery Act – Geothermal Technologies Program: Ground Source Heat Pumps|
|Project Type / Topic 2||Topic Area 1: Technology Demonstration Projects|
|Project Description|| Butte, Montana, like many other mining towns that developed because of either hard-rock minerals or coal, is underlain by now-inactive water-filled mines. In Butte’s case, over 10,000 miles of underground workings have been documented, but as in many other mining communities these waters are regarded as more of a liability than asset. Mine waters offer several advantages:
- The volume of water available for heat exchange is immense compared to that obtainable from wells, which are the most common source of groundwater for heat exchange. - Mine waters can commonly be accessed by using mine shafts, rather than drilling wells, thus attaining substantial savings in the initial installation costs. - Mine waters beneath Butte are abnormally warm, which provides large efficiency advantages during Butte’s long heating season. Success of this project would extend to large regions where warm, but not hot, geothermal waters are abundant and typically are being utilized only for small applications such as hot pools or spas, if at all. Cooler waters in many mines could similarly be used, particularly where cooling needs dominate.
Engineering estimates state that the heating costs for the Natural Resource Building could be reduced by more than half simply by preheating incoming air with mine waters, and environmental benefits are gained from decreased NOx, SOx, and CO2 emissions as opposed to burning fossil fuels. Heat pumps should add to that efficiency. The completed building will be instrumented and monitored to document energy use, enable evaluation of real versus projected energy savings, and offer engineering classes and researchers the opportunity for hands-on data for modeling various building systems. Efficiencies attained at this site can be used to demonstrate potential economic and environmental benefits available to the city of Butte as well as sites throughout the U.S. The public outreach effort would include publications and presentations available on-site and at appropriate off-site venues. Increased public awareness of the benefits of Montana Tech’s system should result in greater willingness for others to invest in such systems, whether installed as ground loops, wells, or in mines, and consequent decreased consumption of fossil fuels and attendant emissions.
|Objectives||Install a heat-pump system in Montana Tech’s new Natural Resources Building that will (a) provide efficient, geothermally based, climate control for the building, and (b) demonstrate the efficacy of using mine waters for heat pump systems. At a minimum, the system capacity will be in the 50- to 100-ton range, but could be larger if economics warrant.|
|Awardees (Company / Institution)||Montana Tech of The University of Montana|
|Funding Opportunity Announcement||DE-FOA-0000116|
|DOE Funding Level (total award amount)||$1,072,744.00|
|Awardee Cost Share||$1,082,753.00|
|Total Project Cost||$2,155,497.00|
|Principal Investigator(s)||Dr. W. Franklin Gilmore, Chancellor, Montana Tech of The University of Montana|
|Targets / Milestones||Mine waters will be accessed via an existing shaft, a closed loop installed, and heat pumps will then provide the necessary boost to heat and cool the building. The water in the mine is 78F (25C); nearly 20 years of continuous pumping at a nearby mine indicates that mine-water temperatures are stable and ample heat is available for long-term use. The details of the system are still being assessed; important decisions to be made include where the heat exchanger and heat pumps should be located in the system, and whether to convert all or only parts of the building heating system to geothermal capability. The natural-gas-fired steam system presently installed will be redundant to the geothermal system, so that direct comparisons can be made on comparative costs of the systems.|
|Location of Project||Butte, MT|
|Impacts||Successful application of techniques could allow replication to buildings across campus and in City of Butte, including county court house, the Federal court building, World Museum of Mining, and numerous privately owned historic buildings.|
|Funding Source||American Recovery and Reinvestment Act of 2009|
|References||EERE Geothermal Technologies Programs|