What Is Geothermal Energy?
Geothermal energy is the natural heat of the Earth, which is transferred from the hot core of the planet to the much cooler surface by the conduction of heat through rocks. It is this same heat that produces the molten lava, hot ash, and gases that we see spewing from an erupting volcano. Geothermal energy can be harnessed by modern technology and brought to the surface as steam or hot water and converted to electricity.
Miles beneath the Earth’s surface lies one of the world’s largest energy resources—geothermal energy. Our ancestors have used geothermal energy for cooking and bathing since prehistoric times. Today, we use this enormous energy reservoir to supply millions of people with clean, low-cost electricity. Geothermal power plants use wells to pipe steam and hot water trapped underground to the surface to make electricity. The power plants produce electricity at 5¢ to 7.5¢ per kilowatt-hour. The Geysers Power Plant in northern California—the world’s largest geothermal power plant—generates more than 1700 megawatts of electrical power. Geothermal power plants are highly reliable and can operate 24 hours a day. Most power plants operate more than 95 percent of the time.
Abundant Power from Universal Geothermal Energy —An MIT chemical engineer explains why new technologies could finally make “heat mining” practical nearly anywhere on earth. By Kevin Bullis
A comprehensive new MIT-led study of the potential for geothermal energy within the United States has found that mining the huge amounts of heat that reside as stored thermal energy in the Earth’s hard rock crust could supply a substantial portion of the electricity the United States will need in the future, probably at competitive prices and with minimal environmental impact.
An 18-member panel led by MIT prepared the 400-plus page study, titled “The Future of Geothermal Energy” (PDF, 14.1 MB). Sponsored by the U.S. Department of Energy, it is the first study in some 30 years to take a new look at geothermal, an energy resource that has been largely ignored.
The goal of the study was to assess the feasibility, potential environmental impacts, and economic viability of using enhanced geothermal system (EGS) technology to greatly increase the fraction of the U.S. geothermal resource that could be recovered commercially.
Although geothermal energy is produced commercially today and the United States is the world’s biggest producer, existing U.S. plants have focused on the high-grade geothermal systems primarily located in isolated regions of the west. This new study takes a more ambitious look at this resource and evaluates its potential for much larger-scale deployment…
MIT-led panel backs ‘heat mining’ as key U.S. energy source
Gene Wescott, a geophysicist, and Professor Emeritus at the University of Alaska, Fairbanks has explored the possible use of geothermal energy in the Aleutian Islands to produce hydrogen for use in clean automobiles.
…Several decades ago, when the world was searching for new types of energy, Professor Wescott was dispatched from his campus in Fairbanks to a long string of islands that stretches for 1,100 miles from Alaska into the northern Pacific Ocean. The Aleutians are volcanic islands, many of them quite active today, and they are literally sitting on shallow beds of molten rock, surrounded by water.
The U.S. Department of Energy wanted to know if those desolate islands could be used to produce geothermal energy. The idea was that the hot areas beneath the surface might provide a continuous source of blistering hot water, which could in turn be flashed to steam and used to turn turbines and produce electricity. The precedent had been set in California and Iceland. California draws a small percentage of its electricity from geothermal power plants near San Francisco.
Energy for Centuries
So Wescott traveled out the Aleutians, drilling a few test wells along the way, and he found just what common sense would suggest should be there. The rocks beneath the surface were very, very hot.
But here’s the hitch: Why build power plants hundreds, or thousands, of miles away from any users? It isn’t practical to run power lines from the Aleutians all the way to the major population centers of the western United States, so what Wescott really found was an enormous source of energy where nobody could use it.
So the whole idea kind of died, except in the mind of Gene Wescott…
In recent years, Wescott has returned to the idea of building geothermal power plants in the Aleutians, and using that electricity to produce hydrogen. The hydrogen could be liquified, he says, and shipped to Asia or the west coast of the United States. One of the largest geothermal resources he found in his earlier research is near the major deepwater port of Dutch Harbor, making it almost seem as though providence planned the whole thing.
By Lee Dye
Special to ABCNEWS.com
Free From Oil- Scientist Dreams of World Fueled by Hydrogen
The volcanic heat energy within the Earth’s Ring of Fire could provide human civilization with more energy than all of the fossil fuels on the earth.
Geothermal Home Guide
Geothermal Energy Story
Geothermal Education Office
NREL — Geothermal Energy Basics
A Googol of Heat Beneath Our Feet
Mountains of Fire — by Kathy Svitil
The Earth at Work — by Kathy Svitil
U.S. DOE Geothermal Technologies Program
Heat Mining: A New Energy Source for the U.S.
The Plus Side of Volcanoes – Geothermal Energy
The U.S. How an Enhanced Geothermal System Works
Sandia National Laboratories Geothermal Research
Ring of Fire, Plate Tectonics, Sea-Floor Spreading, Subduction Zones, and Hot Spots
Experimental Geothermal Technology:
Hot dry rock goes supercritical:
Based on expertise gained during the development of the Laboratory’s Hot Dry Rock Project, Los Alamo’s geoscientist Donald W. Brown has proposed a method for producing geothermal energy using supercritical fluids such as carbon dioxide for the stimulation of the underground reservoir, production of the geothermal energy and heat transport. The Hot Dry Rock Project was a geothermal energy experiment that Los Alamos conducted between the years 1970 and 1996.
Brown’s process stimulates underground reservoirs by pumping a supercritical fluid into a formation to fracture the rock. Generally, this is done at depths ranging from about 5,000 feet to about 20,000 feet below the surface depending upon underground thermal conditions. At such depths, underground temperatures are in the range of roughly 200 to 600 degrees Fahrenheit in the western United States.
A supercritical fluid is a liquid that has been raised beyond a temperature and pressure at which the liquid and gas densities are equal — its critical temperature and pressure. For carbon dioxide, the supercritical conditions are a pressure of 1,074 pounds per square inch and a temperature of 88 degrees Fahrenheit.