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Geothermal Research Project

The Connecticut and Massachusetts Geological Surveys collaborated on a National Geothermal Data Project funded by the US Department of Energy through the Association of American State Geologists.  The goal was
  • to develop information to assist in locating State geothermal resources and
  • provide data for better design of Enhanced Geothermal Systems in bedrock and unconsolidated sediments. 
Project Details
Bedrock units suspected capable of producing radiogenic heat at depth were the primary focus of this study. Additional bedrock units were analyzed to provide a regional view of the geothermal potential across the State. A total of 55 bedrock units were targeted and 242 samples were collected for this study.  Using the Surficial Materials and Quaternary Maps of Connecticut, 20 units were targeted for the collection of 100 sediment samples.
Rock chemistry, density and thermal conductivity of the bedrock samples were used to calculate heat production, heat flow, and thermal profiles at depth. Thermal conductivity measurements were made and physical profiles of sediment (grain size, sand, silt, clay percent, bulk density, porosity) were created.
From these data, a geothermal resource map series has been compiled. The series includes heat production, inferred heat flow, thermal conductivity, and thermal profile maps for bedrock, and a thermal conductivity map for sediments. These maps will assist geothermal contractors in site plan and system design.  All data and mapping are available through the National Geothermal Data System.  
Connecticut Maps
Heat Production - Shows the location of surface outcrop samples from which heat production values were obtained.  Heat production values (hpvs) were determined using concentrations of radiogenic (K, U, Th) and measured sample density. Heat production and inferred heat flow maps summarize model results for bedrock units. 
Inferred Heat Flow - Shows the location of surface outcrop samples from which heat flow is inferred.  The typical sample size is between 0.2 to 1.0 kg.  An infered heat flow can be obtained from the empirical linear relationship between heat flow and heat production.
Bedrock Thermal Conductivity (TC) - Shows the location of outcrop samples from which thermal conductivity measurements were obtained. Heat flow values were determined using the calculated hpvs for the samples and hpvs of average crustal material of New England. TC mapping of sediments depict favorable areas for geothermal installations, and may be used in design of various ground source heat pump systems. 
Surficial Materials Thermal Conductivity - Shows the location of surficial material samples from which thermal conductivity measurements were obtained. 
Thermal profile maps depict models of inferred temperature increases at depth, providing estimates for 3, 4, 5, and 6 km at specific locations, and provide depths needed to achieve desired temperature for either EGS or larger direct heat applications. Thermal profiles at depths from 3 to 6 km were generated using hpv, heat flow, and TC values for each sample. Results indicate that areas with highest heat flow values are in southeastern CT bedrock. 
Inferred Temperature Maps at:
Project Sponsors and Partners
Department of Energy AASG Arizona Geological Survey Massachusetts Geological Survey
Content last updated October 6, 2014