Geothermal Resources and Technologies
This page provides a brief overview of geothermal energy resources and technologies supplemented by specific information to apply geothermal systems within the Federal sector.
Geothermal energy is produced from heat and hot water found within the earth. Federal agencies can harness geothermal energy for heating and cooling air and water, as well as for electricity production.
Geothermal resources can be drawn through several resources. The resource can be at or near the surface or miles deep. Geothermal systems move heat from these locations where it can be used more efficiently for thermal or electrical energy applications. The three typical applications include:
Geothermal Heat Pumps (GHPs): GHPs use the ground, groundwater, or surface water as a heat source and heat sink as opposed to ambient air. Typical resource temperatures range from 40°F to 100°F (4°C to 38°C).
Direct-Use Applications: In direct-use applications, systems use hot water directly for space conditioning or process heat. This approach is most appropriate for low- to moderate-temperature hydrothermal resources.
Power Plant Electricity: Steam and binary geothermal power plants leverage heat from geothermal resources to drive turbines, which produce electricity.
Visit the Department of Energy's (DOE) Geothermal Technologies Office to learn more on geothermal energy basics and technologies.
Geothermal resources make a significant contribution to national renewable energy production. Because many of the existing geothermal resources are located on Federal lands, it is not surprising that 46% of the geothermal electricity generated is from resources on Federal lands.
Before conducting an assessment or deploying geothermal energy technologies, Federal agencies must evaluate a series of questions.
What are my energy goals?
Energy goals range from meeting regulatory requirements to powering remote applications to increasing energy security.
Regulatory Requirements: Electricity produced by geothermal technologies falls under the Energy Policy Act (EPAct) of 2005 definition of renewable energy and can be used to meet EPAct 2005 renewable energy requirements. While geothermal resources for thermal energy do not meet the EPAct 2005 renewable energy definition or requirements, it can reduce energy consumption intensity, which does play a role in other Federal laws and regulations.
Remote Power: Geothermal resources for thermal energy and electricity are generally not cost-effective or appropriate for remote applications.
Energy Security: Geothermal resources are viable renewable energy resources found in almost every community across the U.S. It is a predictable energy resource that can reduce utility peak demand for increased energy security.
What kind of energy do I use?
Federal agencies must understand what type of energy is used before determining if geothermal resources are applicable. Geothermal resources can be used for electricity or thermal energy applications.
When do I need the energy?
Geothermal energy is capable of producing electricity and thermal energy around the clock. It is a viable resource for most applications if deemed cost-effective based on energy load needs.
How much power do I use/need to produce?
Geothermal technologies generate varying amounts of electricity and thermal energy depending on the size of the technology deployment and geothermal resource itself. It is important to consult an expert for a professional evaluation to plan accordingly.
Where am I located?
Geothermal resources are available across the U.S., but vary greatly depending on exact location. For a broad overview of your facility's geothermal resources, the Department of Energy provides geothermal energy resource maps of the U.S.
Before initiating a geothermal energy project, resources in your area must be measured and verified. It is important to consult an expert for a professional evaluation before implementing geothermal energy projects.
Is this a building- or campus-scale project?
Geothermal technologies for thermal applications are ideally suited for facilities of almost any size. Geothermal power plants are suited more for large-scale or larger projects. Implementing a geothermal power plant for a standalone building or facility is typically not cost-effective.
Is my facility a good candidate for a GHP?
GHPs have proven to effectively save energy, but factors other than steady resource temperatures contribute to project feasibility. In general, it is best to consider GHP if several of the following conditions exist:
- New construction or existing facility with hydronic piping
- Major renovation when existing systems are obsolete
- High water table or moist, damp soil
- Ground-level parking area or open land for loop installation, or access to ground or other water
- Mixture of heating and cooling needs, including multiple zones (both core and perimeter), water heating, snow melting, and process applications
Can geothermal resources be used for industrial applications?
Direct-use geothermal applications can be used for multiple industrial applications, including heating for greenhouses, aquaculture (fish farming), crop drying, food dehydrating, laundries, sludge digestion, or other process heat applications.
What is my budget?
It is important to consult an expert for a professional evaluation to see if geothermal energy fits into your current budget. There are many examples of successful GHP installations at Federal agencies financed through energy savings performance contracts (ESPCs) and direct appropriations.
What resources are available for operations and maintenance?
Geothermal technologies require ongoing operations and maintenance. It is important to factor these operations and maintenance costs and staffing needs in any facility energy management plan.
Visit the project planning section for detailed information on planning and deploying renewable energy projects. Federal case studies are available to provide specific examples of viable geothermal energy projects.
Detailed information on geothermal energy resources and technologies is available through:
DOE Geothermal Technologies Office: Program providing information and resources on geothermal energy basics and technologies.
GHP Technology Focus: Describes GHP technologies and energy savings performance contracts.
Preliminary Screening for Project Feasibility and Applications for GHP Retrofits: Provides guidance on determining the feasibility of GHP retrofit projects and briefly discusses the most cost-effective scenarios for adding GHP systems.
Geothermal Energy Association: Composed of U.S. companies supporting the expanded use of geothermal energy and developing geothermal resources worldwide for electrical power generation and direct-heat applications.
Geothermal Resources Council: Serves as a focal point for continuing member professional development through outreach, information transfer, and education services.
International Ground Source Heat Pump Association: Non-profit, member-driven organization dedicated to the advancement of geothermal heat pump technology. Site includes a directory of geothermal businesses and resources.
Geothermal Heat Pumps: Provides an overview of how geothermal heat pumps use the earth to heat and cool buildings.
Geothermal Heat Pumps Deliver Big Savings for Federal Facilities: Technology Focus update on geothermal heat pump technologies and energy savings performance contracts (ESPCs).
Ground-Source Heat Pumps: Federal Technology Alert concentrating on ground-source heat pumps as a technology for reducing heating and air-conditioning costs.