Geothermal Sources

Geothermal Sources
By Debbie Pollitt, eHow Contributor
Print this article
Nearly 90 percent of Icelandic residents use geothermal energy for heat.
Geothermal energy is literally the natural heat of the Earth — earth (geo) heat (therme) — and a renewable resource that can be used to heat buildings and generate electricity. The heat is continuously produced deep within the Earth’s core, will never run out and can be redeemed as steam or hot water. U.S. geothermal projects rose by 12 percent in 2010 and, as of 2011, nine states produce geothermal power.
Billions of years ago when the Earth was forming, large amounts of energy were caught in the middle of the planet, bonding molecules of iron and nickel together to make the Earth’s core. The core is about 4,000 miles beneath the surface on top of which are two more layers — the mantle and the crust. High temperatures are continuously produced and the deeper the layer within the Earth, the hotter the heat. Geothermal energy comes from the intense heat and is caused by the slow decay of radioactive particles, a process that happens naturally in all rocks.
Hot Spots
The Earth’s crust keeps the heat of the mantle beneath the surface but when the heat becomes so intense that it breaks through the crust, it creates patches of geothermal energy known as hot spots. Hot spots can be in the form of volcanoes or geysers. Yellowstone National Park, for example, is home to many geysers, the most famous of which is Old Faithful. Cracks and openings in the crust create ventilation points ensuring that the mantle is able to keep the Earth’s surface continuously heated. This kind of geothermal energy emerges less explosively in the form of steam, creating springs and wells of heated water.
Geothermal energy is potentially everywhere but finding it is easier said than done. Volcanoes, springs and geysers are useful indicators of geothermal reservoirs and scientists may find clues by analyzing local soil and water sources but otherwise the most reliable way to locate them is to dig deep and drill. The world’s hottest geothermal area is the Pacific Ocean’s “Ring of Fire” while America, New Zealand, Iceland and Indonesia are also countries rich in geothermal sources. U.S. geothermal systems include the Geyser’s region of Northern California, Southern California’s Imperial Valley and the Yellowstone areas of Idaho, Montana and Wyoming. Hawaii, Arkansas and Texas also have significant geothermal activity.
Advantages of Geothermal Energy
It’s a very clean source of energy as nothing has to be burnt to produce the steam to turn the turbines. Using geothermal energy produces fewer greenhouse gas emissions than other energy sources. It is available around the clock, every day of the year and is capable of reducing America’s reliance on foreign oil imports. Geothermal plants can produce cheap electricity and although the initial construction and start-up costs are high, the long-term costs are low compared to conventional power plants. There are no transportation costs and the supply is reliable, predictable and stable.
Read more: Geothermal Sources |

Geothermal Energy

Geothermal Energy
Geothermal energy is the heat from the Earth. It’s clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth’s surface, and down even deeper to the extremely high temperatures of molten rock called magma.
Almost everywhere, the shallow ground or upper 10 feet of the Earth’s surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water.
The Earth’s heat-called geothermal energy-escapes as steam at a hot springs in Nevada. Credit: Sierra Pacific
In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii. Wells can be drilled into underground reservoirs for the generation of electricity. Some geothermal power plants use the steam from a reservoir to power a turbine/generator, while others use the hot water to boil a working fluid that vaporizes and then turns a turbine. Hot water near the surface of Earth can be used directly for heat. Direct-use applications include heating buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk.
Hot dry rock resources occur at depths of 3 to 5 miles everywhere beneath the Earth’s surface and at lesser depths in certain areas. Access to these resources involves injecting cold water down one well, circulating it through hot fractured rock, and drawing off the heated water from another well. Currently, there are no commercial applications of this technology. Existing technology also does not yet allow recovery of heat directly from magma, the very deep and most powerful resource of geothermal energy.
Many technologies have been developed to take advantage of geothermal energy – the heat from the earth. NREL performs research to develop and advance technologies for the following geothermal applications:
Geothermal Electricity Production
Generating electricity from the earth’s heat. [learn more]
Geothermal Direct Use
Producing heat directly from hot water within the earth. [learn more]
Geothermal Heat Pumps
Using the shallow ground to heat and cool buildings. [learn more]

Geothermal Capacity Growth

By Herman K. Trabish
More than 128 megawatts of geothermal capacity came on-line in the U.S. in 2012, the second largest annual capacity addition since 2005.
By comparison, the U.S. will install more than three gigawatts of solar this year, and the U.S. wind industry may hit 12 gigawatts. That’s why a developer recently called U.S. geothermal “sort of nichey.”
Competition from historically low natural gas prices was, as one developer put it, “the threat” in 2012. But geothermal leaders expect gas price volatility to end its own threat. Geothermal’s bigger challenge might come from utility-scale solar and wind. Those resources win the majority of utility contracts, though geothermal offers the same long-term price certainty.
In any case, here are the high points of the U.S. geothermal year.
Top Twelve Geothermal Projects
One: Hydroshearing at AltaRockEnergy’s Newberry Crater project in Oregon appeared to be successful. Microseismic events were recorded, indicating hot rock at 500 meters had been fracked with high pressure cold water. Hydroshearing, AltaRockEnergy hopes, will allow control of the seismic activity caused by Enhanced Geothermal System (EGS) fracking. If it proves safety, geothermal would no longer be restricted to conventional hydrothermal wells but could produce anywhere there are hot rocks and water.
Two: U.S. Geothermal Project of the Year award winner Hudson Ranch I was the first plant to go on-line in California’s Salton Sea area in twenty years. Th 49.9-megawatt EnergySource project brought the area’s installed capacity to almost 330 megawatts and renewed interest in its economically recoverable 1,400 megawatt to 2,000 megawatt potential, especially because of the nearby, newly built Sunrise Powerlink transmission line.
Three: Chevron (CVX), a silent partner in Hudson Ranch I, announced it would return to active development in the U.S. market and is looking for projects of ten megawatts or more.
Four: Phase one of Ball State University’s $45 million ground-source heat pump (GHP) system went active in 2012. When complete, the system will heat and cool the 5.5 million square feet of Ball State’s 47 buildings, eliminating coal-fired boilers and saving the university $2 million per year.
(Click to enlarge)
Five: Connected to Hudson Ranch I is startup SIMBOL’s demonstration facility for pre-reinjection extraction of precious metals from geothermal brine. SIMBOL’s harvest of a grade of lithium currently available in few other places offers a valuable revenue stream because of lithium’s value in the rapidly expanding electric car battery market.
Six: Geothermal systems are natural sources of greenhouse gas emissions, a 2012 study from the Geothermal Energy Association (GEA) reported as California’s emissions trading market opened, but they contain little carbon dioxide, minute amounts of methane, and little or no nitrogen oxide.
Seven: Utah Geological Survey testing discovered a new type of high-temperature energy reservoir in the Utah-Arizona-Nevada Black Rock desert basin that showed a potential equivalent to California’s Geysers, the Calpine Corp. (CPN) fields that produce a third of the world’s geothermal energy.
Eight: The DOE-funded Geothermal Technologies Program offered $1 million awards to each proposal promising to “reduce the levelized cost of electricity from new hydrothermal development to $0.06 per kilowatt-hour by 2020 and Enhanced Geothermal Systems (EGS) to $0.06 per kilowatt-hour by 2030.”
(Click to enlarge)
Analysts predict the 2012 geothermal marketplace will approach $13 billion. As of May 2012, approximately 11,224 megawatts of installed geothermal power capacity was on-line globally.
According to Ormat Technologies (ORA) CEO Dita Bronicki, the major international geothermal markets are still Ethiopia, Kenya and Tanzania in Africa, Indonesia, Japan, and the Philippines in the Asia-Pacific, the Caribbean Islands, El Salvador, and Nicaragua in Central America, Argentina, Chile, and Peru in South America, and Germany, Canada and Turkey.
Nine: In Nicaragua, RAM Power (RAMPF.PK) went on-line in phase one of its San Jacinto-Tizate flash steam plant. Phase two may also be in operation by the end of 2012. The site could ultimately produce 270 megawatts for twenty years.
Ten: The U.S. Agency for International Development and the U.S. Geothermal Energy Association launched the two-year, $1.5 million East Africa Geothermal Partnership (EAGP) to help put U.S. geothermal to work developing East Africa’s estimated 10,000 to 15,000 megawatts of potential, and German development agency KfW launched the $67 million East African Geothermal Risk Mitigation Facility, an exploration partnership with the African Union Commission.
Eleven: Japan’s drive to replace its nuclear industry with renewables got boosts, according to the Geothermal Resources Council’s Ian Crawford, when the government approved geothermal exploration in national parks, expected to open 1,000 megawatts of the nation’s 23,000 megawatt potential, and when recreational hot springs owners acknowledged that geothermal, using binary technology that transfers the source water heat to a pressurized working fluid and reinjects the cooled water, does not threaten vital water resources.
Twelve: To reduce dependence on imported natural gas, Western Europe moved toward geothermal energy for heating. A U.K.-Iceland MOU would initiate the building of a sub-North Sea cable, the longest in the world, to deliver Icelandic geothermal resources. Germany, the Netherlands and France also initiated efforts in 2012 to increase use of geothermal heating.