Geothermal Resource Assessment: A Case Study Of Spatial Variability And Uncertainty Analysis For The States Of New York And Pennsylvania

Abstract

Historically, the Northeastern United States has not been carefully explored for geothermal resources mainly because of its low-grade category, which does not make it feasible for electricity generation in today's energy markets. Advanced technologies, such as Enhanced Geothermal Systems (EGS), have shown potential for using low-grade resources for both direct thermal use for heating and cooling and combined heat and power applications (CHP) (Tester et al., 2006; Tester et al., 2010). Interest in geothermal has fluctuated over the last 40 years, since uncertainties in resource maps, coupled with expected high drilling costs often minimize the viability of low-grade geothermal resources relative to the cost of current alternatives, such as natural gas. Research in this area continues to be done with the hope of exploiting the many economic, social, and political benefits this renewable energy has to offer. This thesis develops and compares methods for the assessment of geothermal characteristics of a region and their estimates of the uncertainty in the assessments. In addition, this thesis uses such methods to provide an assessment of the geothermal characteristics of the New York - Pennsylvania region for which drill-log information is available. This thesis has 5 major sections corresponding to 9 chapters. Chapters 1 and 2 provide an introduction to the thesis and the analysis. Chapter 3 discusses methods for developing thermal resource characteristics. Specifically, bottom-hole temperature (BHT) corrections and equations used to describe geothermal gradient, average thermal conductivity, surface heat flow, and temperature-at-depth are discussed. Chapters 4 and 5 provide an analysis of the geology and available well data for the Appalachian Basin of New York and Pennsylvania. Chapter 5 recommends methods for the detection of anomalies or outlying values within large datasets. Chapters 6 and 7 recommend methods for the assessment of geothermal characteristics for the Appalachian Basin of New York and Pennsylvania, as well as estimates of the uncertainty in the assessment. Chapter 8 provides a comparison of the estimates reported in Chapter 6 and 7 and reports the performance of each method. Chapter 9 provides the conclusions of the thesis and the analysis.