NRRI  >  Minnesota`s Geothermal Energy Production

Last Update Thu Oct 25 08:16:00 CDT 2012

Minnesota`s Geothermal Energy Production

Objective Progress / Results

To (1) Collect downhole temperatures from over 100 water wells and exploration drill holes; (2) Collect, analyze, and describe 100 granite samples; and (3) Issue a final report with the new heat flow and temperature vs. depth maps.A final report was submitted to the Office of Energy Security and was accepted. It is available on the NRRI Minerals website. Additional funds from the American Association of State Geologists-DOE still remain. These funds will be used to process additional samples for thermal conductivity and radionuclide analyses. Unanalyzed samples from the previous project, and new samples collected during the new EDA REE project will be processed and sent to Dr. William Gosnold at the University of North Dakota Grand Forks for additional analyses, with the data to be added to the National DOE Geothermal Database and also sent to the National Heat Flow database at Southern Methodist University (SMU) in Texas.

Background

Enhanced Geothermal Systems (EGS) for future energy recovery are primary technologies needed for future electrical power and/or thermal heat production systems. The U.S. DOE in their 2007 study conducted by MIT concludes EGS extraction is one of the most promising clean energy technologies that can be used nationwide. EGS could provide 100 GWe (gigawatt - electric) or more of cost-competitive generating capacity in the next 50 years at sites throughout the U.S.A. where geothermal heat transfer conditions, rock stability, and appropriate hydrothermal environments are present at depths greater than 5 km. However, the heat flow and temperature versus depth maps in the DOE-MIT report indicate that temperatures at depth in Minnesota are very cold, based on four data points within Minnesota and about 90 data points under Lake Superior. All but one of these data points were collected 2.5 meters under lakes. Temperatures at shallow depths are affected by climate, and recent research shows that temperatures begin to stabilize at about 300ft. or 100m, which eliminates all but one of the previous data points.

Previous Activity / Results

Over 800 sites were searched for wells to probe. Fifty-eight wells were probed that were reduced to 36 new data points. Radionuclide data collection was completed. Downhole temperature data, radionuclide data from granite samples, and thermal conductivity data from 180+ samples were used to produce new heat flow data. The new map illustrates warmer temperatures at shallower depths, less than the 10kms required to find 150 deg C water. In portions of Otter Tail and Wilkin counties, the depth to 150 deg C occurs at about 7.0-7.5kms. In the southwest Minnesota counties of Murray, Nobles, Pipestone, and Rock, these temperatures were found at a depth of about 8.0-8.5 km. Additional sample collection is needed to refine these data to see if shallower depths might produce these temperatures.

Start Date 11/02/2009
End Date 06/30/2012

Principal Investigator

Steven Hauck CoPI

Donald Fosnacht PI