In the Toolkit --


  • Guide to the Toolkit
  • Leagues in Action
  • I. Choosing a Role for Your League

    II. Grassroots Action Priorities

  • Climate Action
  • Price on Carbon
  • Our Children's Trust
  • Energy Efficient Buildings
  • Renewable Energy
  • Adapting to Climate Change
  • III. Basics of Climate Change

    IV. Engaging Individuals

  • Communicating About Climate Change
  • Preparing for a Meeting on Climate Change
  • Engaging Groups in Your Community
  • V. Promoting Public Policy

  • Community Action Models
  • Organizing For Community Action
  • Tips for Building Grassroots Support
  • League Action on Climate Change
  • International Action
  • VI. Resources


    Geothermal energy is heat energy from the earth. There are three main ways that this energy resource is used.

    Geothermal Electric Power Plants use steam from geothermal reservoirs to drive generator turbines and produce electricity. In the U.S., most of these plants are located in the Western states and Hawaii, where geothermal energy sources are located close to the surface.

    Direct-use heating systems use hot water from springs or reservoirs near the surface. As in ancient times, hot mineral springs are used for bathing, and hot spring water can be piped into buildings for heat. As an example, a direct heating system provides heat for 95 percent of the buldings in Reykjavik, Iceland. Industrial uses include food dehydration and milk pasteurization.  

    Ground-source heat pump systems take advantage of the Earth's relatively constant temperature to heat and cool buildings. The year-round 50- to 60-degree temperatures found just a few feet below the Earth's surface are warmer than the surface air in winter and cooler than the air in summer. A geothermal heat pump circulates a liquid through a system of pipes buried underground. In winter, the fluid collects heat from the ground and carries it into the building for distribution through a conventional duct system. In summer, the process is reversed as the fluid moves heat from the building back into the ground. 

    Potential. The Geothermal Energy Association (GEA) reports that the U.S. currently has almost 3,200 MW of installed geothermal capacity, more than any other country in the world. The majority of geothermal installed capacity is concentrated in California and Nevada, with additional plants also operating in Alaska, Hawaii, Idaho, Oregon, Utah, and Wyoming. In 2010, geothermal energy accounted for three percent of renewable energy-based electricity consumption in the U.S. The GEA projects continued strong growth in geothermal capacity in coming years.

    Benefits. Geothermal power plants can operate around the clock, regardless of the weather, to provide baseload power. The life-cycle GHG emissions of modern geothermal power plants are very low, and the plants use much less water on average than conventional generation technologies. Geothermal power plants have a very small land-use footprint, among the smallest, per kilowatt, of any power generation technology.   

    Geothermal heat pumps are considered to be one of the most efficient heating and cooling systems. They use 25-50 percent less electricity than conventional electric heating or cooling systems. In addition, geothermal heat pump systems can be used effectively in almost all parts of the country.

    Challenges. Geothermal plants are relatively small. Developing a plant requires expensive drilling, expertise in geology and hydrology, and specialized equipment.


    Previous <  > Next

    Last updated: 10/31/2013.