Discovery Guides Areas


Geothermal Energy: Drilling Beneath the Surface of Our Energy Dilemma
(Released September 2009)

  by Ethan Goffman  


Key Citations




Resources News Articles
Historical Newspapers

News Articles

  1. Geothermal: Old Energy, New Promise

    Earth Explorer, 02-01-1995

    If you lived in Reykjavík, the capital of Iceland, you would attend a school warmed against the Arctic cold by heat from inside the earth. If you lived in Japan, you might eat fish from tanks heated by conditions found kilometers beneath the earth's crust. Iceland and Japan both have ready access to geothermal energy.

    Geothermal energy may be either in the form of dry heat or hot water. Deep in the planet's core, radioactive atoms such as uranium, potassium, and thorium have decayed for many billions of years. This has generated heat intense enough to melt solid rock. Because the earth's crust is a poor conductor of heat, this heat has largely remained deep underground near where it was produced. Like heat from a wood stove in a large room, the heat produced in the core gradually diminishes with distance. If you could stick a thermometer into the earth's core, the temperature may be as high as 6,600°C (12,000°F). If you stuck it into the mantle, the layer between crust and core, the temperature might register between 3,700°C and 1,000°C (6,700°F and 1,800°F). A few kilometers under the earth's surface, the temperature ranges from a few dozen to several hundred degrees Celsius. . . .

    Copyright 1995, Enteractive, Inc.

    For full-text documents see ProQuest's eLibrary

  2. Tapping into Nature for Power

    Blair, Pam. Bulletin. Northwest Public Power Association. 06-01-2005

    In North America, the first human use of geothermal resources - heat from the earth - occurred more than 10,000 years ago, with the settlement of Paleo-Indians at hot springs.

    While people still soak in those shallow pools, developers are now probing more than 10 miles below the surface in search of geothermal energy hot enough and plentiful enough to generate electricity.

    In the United States, most high and medium-temperature geothermal reservoirs are located in the Western states, Alaska and Hawaii. At temperatures between 250 and 700 degrees Fahrenheit, the natural hot water and steam from the earth can be used to turn turbine generators, producing electricity.

    Water from reservoirs with temperatures of 70 to 300 degrees Fahrenheit is used directly to heat greenhouses and water at health spas; grow catfish, trout, alligators, tilapia and tropical fish; dry food and timber products; wash wool; dye cloth; manufacture paper; pasteurize milk; extract gold and silver from ore; provide space heating; and prevent sidewalks from freezing in winter.

    Copyright Northwest Public Power Association Jun 2005.

    For full-text documents see ProQuest's eLibrary

  3. Examining Geothermal Energy

    Fischer, James R; Price, Richard; Finnell, Janine. Resource. 04-01-2006

    geo.ther.mal adj. having to do with the heat of the earth's interior

    Geothermal energy is used in three separate types of applications that utilize very different technologies. Two of these applications - heat pumps and direct use - are thermal applications, while the third type is used for generating electrical power.

    Heat pumps

    Geothermal heat pumps can be used throughout the nation for heating and cooling buildings. Geothermal heat pumps take advantage of soil and near-surface rocks, from 1.5 to 15 m (5 to 50 ft) deep, which have a nearly constant temperature and provide a heat source in the winter and a heat sink in the summer. Fluid is circulated through a loop of piping that is run underground to create a heat exchanger. An indoor system extracts the energy from the fluid for heating or adds energy to the fluid for cooling - replacing both a furnace and an air conditioner.

    Geothermal heat pumps are more expensive to install than conventional heating and cooling systems, but because monthly energy bills are lower, they are less costly in the long run - often paying for themselves with energy savings within five years. . . .

    Copyright American Society of Agricultural Engineers Apr 2006

    For full-text documents see ProQuest's eLibrary

  4. Science and Technology: Blowing hot and cold; Geothermal energy

    The Economist. 09-16-2006

    Geologists are getting more juice out of the ground

    GOLDILOCKS, the fussy, blonde, larcenous heroine of an English children's story, liked her porridge neither too hot, nor too cold, but just right. Most engineers looking for underground sources of steam to generate geothermal power have similar tastes. If the steam is much colder than 150 degrees C, it will start to condense into water before it can be used to turn a turbine. On the other hand, steam hotter than 400 degrees C, although richer in energy, is harder to find and to handle. Two new projects, however, aim to push back both these limits.

    Geothermal power stations tap aquifers heated by contact with hot rocks in volcanic regions--or, in hot but dry spots, they pump water past such rocks to heat it up. The temperature of the steam produced varies, depending on how hot the source is and how much heat it loses on its way to the surface.

    Not all geothermal activity is hot enough to bring water to the boil. The Chena hot springs, in Alaska, for example, are just right for bathers, at a porridge-like 43 degrees C, but not much use for traditional geothermal power generation. Even within the spa's wells, the water is only 74 degrees C. Nonetheless, its owners, in conjunction with United Technologies, an engineering conglomerate, have worked out how to generate power from the tepid flow--the coldest ever used in a geothermal plant.

    Copyright 2006 The Economist Newspaper Ltd.

    For full-text documents see ProQuest's eLibrary

Historical Newspapers

  1. GETTING POWER FROM VOLCANOES; Italians Using Heat of Tuscan Steam Vents

    Boston Daily Globe (1872-1922). Boston, Mass.: Dec 1, 1918. pg. 44, 1 pgs

    Abstract (Summary) The present enormous price of coal in Italy has resulted in the realization of an idea which at first thought seemed but a dream, but which has been developed in a marvelons manner and is assuming considerable inportance; this is. . . .

    Original Newspaper Image (PDF)

  2. California Taps New Power; Cheap Power

    By Floyd McCracken. Christian Science Monitor. Boston, Mass.: Jun 26, 1962. pg. 13, 1 pgs

    Abstract (Summary) The region of southern California is promised a source of cheap electrical power and a chemical industry of some importance by the chance discovery of a 25-square-mile pocket of high-intensity geothermal energy. The area lies within easy reach of oil-well drills.

    Original Newspaper Image (PDF)

  3. Earth's Inner Heat Expected to Be Major U.S. Power Source; GEOTHERMAL

    GEORGE GETZE. Los Angeles Times (1886-Current File). Los Angeles, Calif.: Dec 1, 1972. pg. B1, 2 pgs

    Abstract (Summary) The U.S. has lagged in developing one of the world's greatest natural resources, the earth's internal heat, according to Joseph Barnea, director of the resources and transport division of the United Nations.

    Original Newspaper Image (PDF)

Taken from ProQuest's Historical Newspapers.


  1. Dynamic modeling and control of hybrid ground source heat pump systems

    by Chen, Chang, M.A.Sc., Concordia University (Canada), 2008 , 178 pages

    Abstract (Summary)
    Ground source heat pump (GSHP) systems are one of the fastest growing applications of renewable energy in the world with annual increases of 10% over the past decade. GSHPs are potentially more efficient than conventional air-to-air heat pumps as they use the relatively constant temperature of the geothermal energy to provide heating or cooling to conditioned rooms at desired temperature and relative humidity. More importantly, GSHP systems can in fact achieve significant energy savings year round, compared to conventional HVAC systems.

    A hybrid ground source heat pump (HGSHP) system is designed in this study to heat and cool an office building all the year round. Dynamic models of each component of the heat pump system are developed for simulations of heat transfer between each component of the HGSHP system and for control strategy design and analysis. A detailed multiple-load aggregation algorithm (MLAA) is adapted from the literature to precisely account for and calculate the transient heat conduction in vertical ground heat exchangers with different yearly, monthly, and daily pulses of heat. Feedback PI controllers for heat pump units and On/Off controllers for boiler and cooling tower are designed and utilized to match anticipated building loads and to analyze transient response characteristics of such outputs as water flow rate and air flow rate of heat pumps, return water temperature and supply air temperature of heat pumps, water temperatures of ground loops and heat exchangers, water temperature of boiler or cooling tower, and fuel flow rate of boiler. Control strategies for the HGSHP system in both heating and cooling modes of operation are also introduced to study the system responses. With the usage of On/Off controllers and well-tuned PI controllers, as well as optimal control strategies for heating and cooling operations, the HGSHP system is expected to give better operating performance and efficiency. As a result, noticeable energy savings can be achieved in both heating and cooling modes of operation.

    For full-text documents see ProQuest's Dissertations & Theses Database

  2. Geologic setting of the Central Alaskan Hot Springs Belt: Implications for geothermal resource capacity and sustainable energy production

    by Kolker, Amanda M., Ph.D., University of Alaska Fairbanks, 2008 , 205 pages

    Abstract (Summary)
    The Central Alaskan Hot Springs Belt (CAHSB) is a vast stretch of low-temperature hydrothermal systems that has the potential to be a geothermal energy resource for remote communities in Alaska. Little exploration has occurred in the CAHSB and the resource is poorly understood. A geothermal power plant was installed in 2006 at Chena Hot Springs (CHS), one of the 30-plus hot springs in the CAHSB. This, in addition to the multiple direct use projects at CHS, could serve as a model for geothermal development elsewhere in the CAHSB. This dissertation evaluates the geologic setting of the CAHSB and explores the implications for resource capacity and sustainable energy production. The local geology and geochemical characteristics of CHS are characterized, with a focus on identifying ultimate heat source responsible for the hot springs. A radiogenic heat source model is proposed and tested for the entire CAHSB, wherein the anomalously radioactive plutons that are associated with nearly every hot spring are providing the source of heat driving the geothermal activity. This model appears to be feasible mechanism for the observed heat transfer. This implies that CAHSB "reservoir" fluids are probably low-temperature. It also suggests that individual hydrothermal systems are small-scale and localized features, unlike the types of hydrothermal systems that are conventionally exploited for energy (i.e., those that derive their heat from magmatic or deep crustal sources, which have higher reservoir temperatures and larger spatial extent). In this context, the individual capacity of several CAHSB resources close to communities is assessed, and a preliminary evaluation of the sustainability of the power production scheme at CHS is given. As another approach to the question of sustainability, this dissertation explores the ways in which external benefits of geothermal energy can influence the economics of a project. In sum, producing geothermal energy from CAHSB resources is somewhat risky at the present time, though it may be less risky than continued use of diesel fuel. The risks of geothermal development could be greatly reduced by rapid and immediate exploration efforts to collect much-needed data about CAHSB geothermal resources.

    For full-text documents see ProQuest's Dissertations & Theses Database

  3. Hydrogen production using geothermal energy

    by Hand, Theodore W., M.S., Utah State University, 2008 , 94 pages

    Abstract (Summary)
    With an ever-increasing need to find alternative fuels to curb the use of oil in the world, many sources have been identified as alternative fuels. One of these sources is hydrogen. Hydrogen can be produced through an electro-chemical process. The objective of this report is to model an electrochemical process and determine gains and or losses in efficiency of the process by increasing or decreasing the temperature of the feed water. In order to make the process environmentally conscience, electricity from a geothermal plant will be used to power the electrolyzer. Using the renewable energy makes the process of producing hydrogen carbon free. Water considerations and a model of a geothermal plant were incorporated to achieve the objectives.

    The data show that there are optimal operating characteristics for electrolyzers. There is a 17% increase in efficiency by increasing the temperature from 20°C to 80°C. The greater the temperature the higher the efficiencies, but there are trade-offs with the required currents.

    For full-text documents see ProQuest's Dissertations & Theses Database


  • Geothermal Energy Association

  • GeoExchange

  • Geothermal Technologies Program, U.S. Department of Energy