Evaluation of Geothermal Energy Potential in Mississippi Counties of the Black Warrior Basin
Cary R. Lindsey
Department of Geosciences, Mississippi State University, P.O. Box 5448, Starkville, Mississippi 39762
Geothermal energy is a virtually renewable energy source available to varying degrees in the subsurface globally (Blodgett and Slack, 2009). Geothermal is clean, consistently available, and with the right technology, will continue to become less expensive as high-polluting fossil fuels rise in cost. To date, most geothermal sites in the United States are located in the western half of the country because surficial evidence of geothermal activity, such as hot springs, is most common there. The availability of new technologies, such as Enhanced Geothermal Systems (EGS) and the geothermal binary power plant, and the ever-increasing cost of fossil fuel, a need exists for reassessment of the geothermal potential in areas that were previously thought to have little to none.
One advancement that makes the reassessment of Mississippi so important is binary cycle power. The binary technology can use water at temperatures as low as 135°C. Using binary technology, water can be pumped from the ground and used to heat a binary fluid such as isobutane, which boils at just a few degrees above room temperature. The steam created turns a turbine that creates electricity. The steam is then condensed back into liquid form and used repeatedly. Mississippi geology may offer the conditions needed for this binary system.
Generation of geothermal power produces virtually no carbon emissions, yet the last comprehensive assessment of Mississippi’s geothermal potential was in the mid 1970s (Luper, 1978). The assessment included only about 40 of Mississippi’s 82 counties. Whereas geothermal maps have been created since then, most of the data used have been derived from this study by the U.S. Department of Energy with limited modification and from a very limited number of well-log readings. Currently, the only active geothermal project in Mississippi is a hydrocarbon companion system developed by Gulf Coast Green Energy, dubbed the Green Machine (Jennejohn, 2010).
In an effort to better assess the geothermal energy potential in Mississippi, this study focused on the counties of the Black Warrior Basin Province of north and northcentral Mississippi. Despite showing evidence of elevated geothermal gradients amenable to geothermal energy extraction, this area has received only cursory evaluation. The primary method for assessing the area will be the mathematical adjustment of recorded bottom-hole temperatures (BHT) found on well logs from the Mississippi Oil and Gas Board’s (2012) online database using the Harrison et al. (1983, as cited in Blackwell, 2004) correction followed by a second correction used by researchers at Southern Methodist University (Blackwell and Richards, 2004). The temperature correction factor is as follows: ...
AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012