Geothermal Resources

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Geothermal Resources

There are a number of different resource potential estimates that have been developed. A few are listed below.

NREL Geothermal Favorability Map
NREL Supply Characterization and Representation

In 2011, NREL conducted an analysis to characterize and represent the supply of electricity generation potential from geothermal resources in the United States. The principal products were:

  • Capacity Potential Estimates - quantitative estimates of the potential electric capacity of U.S. geothermal resources
  • Cost Estimates - the cost to develop those listed geothermal resources
  • Geothermal Supply Curves - the two products were integrated to generate geothermal supply curves.


SMU Geothermal Maps

In 2011, the Southern Methodist University Geothermal Laboratory develops several geothermal resource maps (available at Google.org):

  • Heat Flow Maps depict the natural heat loss from the interior of Earth to the surface.
  • Temperature-at-Depth Maps illustrate the estimated temperature at a given depth and are developed using BHT data.
  • Geothermal Potential Estimates represent the amount of energy, typically expressed in megawatts (MW) that are available at a particular depth.


Geothermal Prospector

In 2010, NREL developed Geothermal Prospector, a web-based geographic information system (GIS) application, to support resource assessment and data exploration for the U.S. Department of Energy's (DOE) Geothermal Technologies Office. The Geothermal Prospector tool provides the information needed to allow users to determine locations that are favorable to geothermal energy development. This was in response to the recommendation by the Geothermal Technologies Program Blue Ribbon Panel Recommendations for DOE to focus efforts on accelerating near-term geothermal growth through exploration. The Geothermal Prospector hosts tools and datasets required to produce and disseminate both the exploration gap analysis and Enhanced Geothermal Systems (EGS) planning and analysis. All data created by NREL and served through the Geothermal Prospector is compatible with the National Geothermal Data System (NGDS), which provides comprehensive data from a wide variety of sources using standard data provision formats, including the Open Geospatial Consortium (OGC) Web Feature, Map, and Coverage Services (WFS, WMS, WCS).

USGS Resource Assessment

In 2008, scientists with the U.S. Geological Survey (USGS) completed an assessment of the geothermal resources in the U.S., which indicated:

  • Identified Geothermal Potential - mean electric power generation potential from identified geothermal systems is 9,057 Megawatts- electric (MWe), distributed over 13 states.
  • Undiscovered Geothermal Potential - mean estimated power production potential from undiscovered geothermal resources is 30,033 MWe.
  • EGS Geothermal Potential = an estimated 517,800 MWe could be generated through implementation of technology for creating geothermal reservoirs in regions characterized by high temperature, but low permeability, rock formations.


Canadian Geothermal Code for Public Reporting: Reporting of Exploration Results, Geothermal Resources and Geothermal Reserves 2010 Edition

In 2008, the Canadian Geothermal Energy Association established the Canadian Geothermal Code Committee and in conjunction with the Australian Geothermal Energy Group and the Australian Geothermal Energy Association developed the Canadian Geothermal Code for Public Reporting. The Canadian Code is largely adopted from the Australian Code (see below) and provides the foundation for its development; the most recent version was published in 2010.

Australian Code for Reporting of Exploration Results, Geothermal Resources and Geothermal Reserves: “The Geothermal Reporting Code”

In 2007, the Australian Geothermal Energy Group and the Australian Geothermal Energy Association established the Australian Geothermal Reporting Code Committee and in 2008 published the First Edition of the Geothermal Reporting Code. The updated Geothermal Reporting Code Second Edition was published in 2010. This document provides the framework and guidelines for public reporting of geothermal resources and reserves, similar to those established for the O&G and minerals extraction industries. The intent is to define a consistent methodology for reserve reporting to capital markets, investors and stakeholders in order to promote the credibility of the geothermal industry. The primary principles of this code are:

  • Transparency- Requires public reporting of geothermal exploration results, resource and/or reserve estimates to be clearly presented with sufficient information for investors to make rational, informed decisions. Terminology between a geothermal resource (inferred, indicated, measured) and a geothermal reserve (probable, proven) are delineated.
  • Materiality- Any and all relevant information related to a geothermal prospect which may materially impact 1) an investor's interpretation of the results or estimates, and 2) the geothermal prospect's economic value to the company, must be thoroughly disclosed and promptly reported.
  • Competence- All public reporting and disclosures must be verified and confirmed through a statement of consent by a qualified, experienced professional who is accountable to a professional Code of Ethics. The competent professional needs a minimum of five years of relevant experience to the particular type of geothermal play and must have a professional registration with the Australian Geothermal Energy Group's Register of Practicing Geothermal Professionals.
Diagram outlining the relationship between the increasing confidence associated with geological constraints on a geothermal prospect. The distinction between geothermal resources and geothermal reserves are shown versus 'Modifying Factors' as discussed in the Australian Geothermal Reporting Code (2010).