News - July 2013 - Geothermal innovations Workshop in Cincinnati Ohio

On July 16, Cincinnati Ohio was the location of American Ground Water Trust’s sixth Geothermal Heating and Cooling Innovations workshop in 2013.  It is the third offering in the local area since 2007 when AGWT began this outreach initiative highlighting the connections between low-temperature geothermal and groundwater.Jeff Quinn (left) and Greg Wells

Greg Wells of Jackson Geothermal and Jeff Quinn of Baroid IDP spoke on the importance of “ground proofing” the loop design using formation thermal conductivity (FTC) tests.  Thermal conductivity is the physical property of a material that determines how easily heat can pass through it.  A FTC test determines an in-situ average value for the total composite length of rock exposed in the borehole that will contain the high-density polyethylene (HDPE) loop pipe at a specific location in the loop field.  FTC tests are also used to document important design parameters including overburden soil and rock types, rock layer thicknesses, depth to groundwater, groundwater quality and quantity and the competency of the subsurface geology with regard to faults and potentially unstable zones that could impact drilling progress and require special drilling methods.  FTC tests should be completed in borings that will eventually be part of the loop field.  The FTC boreholes should be drilled to the design depth of the loop field in order to match the composite composition of the rock and soil material that will be in contact with the loop pipe.  As a general rule, a FTC test should be completed when the cost of the FTC test is equal to or less than the cost difference between the low and the high end loop design cost estimates according to the range of possible thermal conductivity values for the project area.  If difficult drilling conditions may be encountered then the potential extra cost of the drilling may also be added to the loop cost differential as a comparison to the cost of the FTC test in the cost benefit analysis. 

A CD of the presentations (PDF format) offered at the Cincinnati Geothermal workshop is available for a small fee that supports the education programs of the American Ground Water Trust.  Send an email to the Trust for more information.