Geothermal energy made up 0.21% of the energy (and 1.9% of renewable energy) used in the United States in 2018 and 0.39% of electricity generated in the United States in 2019.
What is geothermal energy and how is it used?
Geothermal power plants use hot water or steam, sometimes reaching 700 degrees Fahrenheit (about 370 degrees Celsius), drawn from reservoirs below the Earth’s surface — or in fewer instances, has been injected underground for this purpose. When steam (converted from water or drawn from the Earth) is allowed expand, the steam’s force turns a turbine, which spins a generator to produce electricity.
Other systems use heat from the Earth more directly. Geothermal heat pumps use heat from the ground or water to heat and cool buildings. Still other systems pipe hot water directly into buildings to warm them.
The United States produces more energy from geothermal sources than any other country, as the necessary heat, water, and geologic permeability exist at shallow enough depths in many areas. But some countries rely far more heavily on this source. (Geothermal energy heats most households in Iceland, for example, and fueled 44% of Kenya’s electricity in 2016.)
States in the West have the greatest geothermal resources, and seven states had geothermal plants as of 2019: California, Nevada, Utah, Oregon, Hawaii, Idaho, and New Mexico, in order of most electricity produced from geothermal resources. In 2019, California produced more than 70% of U.S. geothermal energy.
What are the advantages and disadvantages of geothermal energy?
Geothermal systems demand high initial development costs, and few geothermal facilities have been built in recent years in the United States.
Geothermal resources are often far from cities where the most energy is used, which can require the construction of new transmission lines.
Geothermal power plants generate energy continuously, providing a consistent flow of energy and stabilizing energy grids.
The Business Council for Sustainable Energy’s 2020 Sustainable Energy in America Factbook includes recent information on the U.S. energy sector, such as market details, data on emerging technologies, and historical trends.
The U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) published the 2018 Renewable Energy Fact Book, which is the most recent edition and includes summary information on the different types of renewable energy sources. The Fact Book was prepared by the National Renewable Energy Laboratory, which also gives information about each of the major renewable energy sources. The EERE also describes technologies and research in different methods of renewable electricity generation, including solar, geothermal, wind, and water.
The International Energy Agency (a Paris-based autonomous intergovernmental organization) produced the report Global CO2 Emissions in 2019, which provides helpful international context about global energy trends and development. A report from the International Renewable Energy Agency (IRENA), Renewable Power Generation Costs in 2019, breaks down the prices tied to different renewable energy technologies and processes on a global scale.