Geothermal Energy What is Geothermal

Document Sample
Geothermal Energy What is Geothermal Powered By Docstoc

           Geothermal Energy

                  Clarence Prestwich

What is Geothermal?
 Heat from the Earth, or geothermal — Geo (Earth) +
 thermal (heat)
 Geothermal resources range from shallow ground to hot
 water and rock several miles below the Earth's surface, and
 even farther down to the extremely hot molten rock called

                        •The crust is broken into enormous slabs —
                        tectonic plates -that are actually moving very
                        slowly over the mantle, separating from, crushing
                        into, or sliding
                        (subducting) under one another.
                        •At these plate boundaries, and in other places
                        where the crust is thinned or fractured, magma is
                        closer to
                        the surface than it is elsewhere. over time, it
                        creates large regions of hot rock.
                        •If the magma emerges above ground its known as



History of Geothermal Energy in the
United States
 Human beings have used geothermal energy in North America for at least
 10,000 years. Paleo-Indians used hot springs for cooking, and for refuge and
 respite. Native Americans have a history with every major hot spring in the
 United States.
 1807- John Colter visited the Yellowstone area, leading to the designation
 "Colter's Hell". Also in 1807, settlers founded the city of Hot Springs,Arkansas
 1842-William Bell Elliot, a member of John C. Fremont's survey party,
  t bl              t i         ll just    th f h t is
 stumbles upon a steaming valley j t north of what i now S F              i
                                                               San Francisco,
 California. Elliot calls the area The Geysers-a misnomer-and thinks he has found
 the gates of Hell
 1852 - The Geysers is developed into a spa called The Geysers Resort Hotel..
 1862 - At springs located southeast of The Geysers, businessman Sam Brannan
 pours an estimated half million dollars into an extravagant development dubbed
 1892 - Folks in Boise, Idaho, feel the heat of the world's first district heating
 system as water is piped from hot springs to town buildings.

 1921 - John D. Grant drills a well at The Geysers with the intention of generating electricity.
 1930 - The first commercial greenhouse use of geothermal energy is undertaken in Boise, Idaho. In
 Klamath Falls, Charlie Lieb develops the first downhole heat exchanger (DHE) to heat his house.
 1940 - The first residential space heating in Nevada begins in the Moana area in Reno.
 1948 - Professor Carl Nielsen of Ohio State University develops the first ground-source heat pump.
 J.D. Krocker, an engineer in Portland, Oregon, pioneers the first commercial building use of a
 groundwater heat pump.
 1970 - The Geothermal Resources Council is formed to encourage development of geothermal
 resources worldwide. The Geothermal Steam Act is enacted
 1975 - The Energy Research and Development Administration (ERDA) is formed.
 1989 - The world's first hybrid (organic Rankine/gas engine) geopressure-geothermal power plant
 begins     ti    t Pl
 b i operation at Pleasant Bayou, Texas, using both the heat and th methane of a geopressured
                            tB       T       i b th th h t d the th            f            d
 1991 - The Bonneville Power Administration selects three sites in the Pacific Northwest for
 geothermal demonstration projects.
 1992 - Electrical generation begins at the 25-MW geothermal plant in the Puna field of Hawaii.
 1993 - A 23-MW binary power plant is completed at Steamboat Springs, Nevada.
 1994 - DOE creates two industry/government collaborative efforts to promote the use of
 geothermal energy to reduce greenhouse gas emissions.
 1995 - Integrated Ingredients dedicates a food-dehydration facility. A DOE low temperature
 resource assessment of 10 western states identifies nearly 9000 thermal wells and springs and 271
 communities collocated with a geothermal resource greater than 50ºC.


                             2000 - DOE initiates its GeoPowering the West program to
                             encourage development of geothermal resources in the
                             western U. S.
                             2001 - GeoPowering the West brings together
                             representatives from industry and agencies. Secretary of the
                             Interior Gail Norton convened a renewable energy summit
                             2002 - Organized by GeoPowering the West, geothermal
                             development working groups are active in five states —
                             Nevada, Idaho, New Mexico, Oregon, and Washington. 2003
                             2003 - The Utah Geothermal Working Group is formed.

                              Renewable Energy Cost Trends
                                                             Levelized cents/kWh in constant $20001

                                               40                                    100
                                                                      Wind                                                  PV
                               COE cents/kWh

                                               30                                        80

                                               0                                         0
                                               1980   1990   2000   2010   2020          1980        1990     2000   2010    2020

                10                                             70                                             15
                                                 Geothermal    60                 Solar thermal                                         Biomass
COE cents/kWh

                8                                                                                             12
                6                                              40                                             9
                                                               30                                             6
                2                                              10                                             3
                0                                               0                                             0
                1980      1990                 2000  2010 2020 1980        1990   2000        2010     2020   1980    1990       2000    2010   2020

                     Source: NREL Energy Analysis Office (
                     1These graphs are reflections of historical cost trends NOT precise annual historical data.

                     Updated: October 2002

                        What are the benefits of using
                        geothermal energy?
                             Several attributes make it a good source of energy.
                                               First, it's clean. Energy can be extracted without burning a
                                               fossil fuel Geothermal fields produce only about one-sixth of
                                               the carbon dioxide that a relatively clean natural-gas-fueled
                                               power plant produces, and very little if any, of the nitrous oxide
                                                  sulfur bearing gases          plants
                                               or sulfur-bearing gases. Binary plants, which are closed cycle
                                               operations, release essentially no emissions.
                                               Geothermal energy is available 24 hours a day, 365 days a year.
                                               Geothermal power plants have average availabilities of 90% or
                                               higher, compared to about 75% for coal plants.
                                               Geothermal power is homegrown, reducing our dependence on
                                               foreign oil.


Is geothermal energy a renewable
 The source is the almost unlimited amount of heat generated
 by the Earth's core. Even in geothermal areas dependent on a
 reservoir of hot water, the volume taken out can be
 reinjected, making it a sustainable energy source.

Where is geothermal energy available?
 Hydrothermal resources - reservoirs of steam or hot water -
 are available primarily in the western states, Alaska, and
 Earth energy can be tapped almost anywhere with
                               direct use
 geothermal heat pumps and direct-use applications.
 Other enormous and world-wide geothermal resources - hot
 dry rock and magma, for example - are awaiting further
 technology development.

What are the environmental impacts of
using geothermal energy?
 Geothermal technologies offer many environmental advantages
 over conventional power generation:
   Emissions are low. Only excess steam is emitted by geothermal flash
   plants. No air emissions or liquids are discharged by binary
   geothermal plants, which are projected to become the dominant
   technology in the near future.
   Salts and dissolved minerals contained in geothermal fluids are usually
   reinjected with excess water back into the reservoir at a depth well
   below groundwater aquifers. This recycles the geothermal water and
   replenishes the reservoir.
   Some geothermal plants do produce some solid materials, or sludges,
   that require disposal in approved sites. Some of these solids are now
   being extracted for sale


What is the visual impact of
geothermal technologies?
 District heating systems and geothermal heat pumps are
 easily integrated into communities with almost no visual
 impact. Geothermal power plants use relatively small
 acreages, and don't require storage, transportation, or
 combustion of fuels. Either no emissions or just steam are
 visible. These qualities reduce the overall visual impact of
 power plants in scenic regions.

Is it possible to deplete geothermal
 The long-term sustainability of geothermal energy
 production has been demonstrated at the Lardarello field
 in Italy since 1913, at the Wairakei field in New Zealand since
 1958, and at The Geysers field in California since 1960.
 Pressure and production declines have been experienced at
                p                                 p
 some plants, and operators have begun reinjecting water to
 maintain reservoir pressure. The City of Santa Rosa,
 California, pipes its treated wastewater up to The Geysers to
 be used as reinjection fluid, thereby prolonging the life of the
 reservoir while recycling the treated wastewater.


Types of Geothermal
 Power Plants Generate Electricity from Geothermal
 Direct-Use Piped Hot Water Warms Greenhouses
 and Melts Sidewalk Snow
 Geothermal Heat Pumps (GHPs) Use Shallow round
 Energy to Heat and Cool Buildings


Geothermal Power
 In the United States, geothermal energy has been used to generate
 electricity on a large-scale since 1960. The US leads the world in
 installed geothermal capacity with 3086.6 megawatts (MW) currently
 online in nine states. Seven geothermal projects in five different states
 were brought online in 2009.
 Heat from the Earth—geothermal energy—heats water that has seeped
 into underground reservoirs.
 These reservoirs can be tapped for a variety of uses, depending on the
 temperature of the water.
 The energy from high temperature reservoirs (225º–600ºF) can be used
 to produce electricity.
 There are currently three types of geothermal power plants:
   Dry steam
   Flash steam
   Binary cycle

What makes a site good for geothermal
electric development?
 Hot geothermal fluid with low mineral and gas content,
 shallow aquifers for producing and reinjecting the fluid,
 location on private land to simplify permitting, proximity to
 existing transmission lines or load, and availability of make-
 up water for evaporative cooling. Geothermal fluid
  p               p               g
 temperature should be at least 300º F, although plants are
 operating on fluid temperatures as low as 210º F.


April 2010 Geothermal Power Capacity On-Line

Dry Steam Power Plants

 Dry steam plants use steam from underground wells to rotate a
 turbine, which activates a generator to produce electricity. There
 are only two known underground resources of steam in the
 United States: The Geysers in northern California and Old
 Faithful in Yellowstone National Park. Since Yellowstone is
 protected from development, the power plants at The Geysers are
 the only dry steam plants in the country
 It was first used at Lardarello in Italy in 1904, and is still very
 The Geysers in northern California, the world's largest single
 source of geothermal power.
 These plants emit only excess steam and very minor amounts of


Power Plant at The Geyers

Flash steam

 The most common type of geothermal power plant, flash
 steam plants use waters at temperatures greater than 360ºF.
 As this hot water flows up through wells in the ground, the
 decrease in pressure causes some of the water to boil into
 steam. The steam is then used to power a generator, and any
 leftover water and condensed steam is returned to the
 Fluid can also be sprayed into a tank held at a much lower
 pressure than the fluid, causing some of the fluid to rapidly
 vaporize, or "flash.“ If any liquid remains in the tank, it can
 be flashed again in a second tank to extract even more


                                             Flash Plant Imperial valley,

Flash Plant Dixie valley, NV

      Binary cycle plants
        Binary cycle plants use the heat from lower-temperature
        reservoirs (225º–360ºF) to boil a working fluid, which is
        then vaporized in a heat exchanger and used to power a
        generator. The water, which never comes into direct contact
        with the working fluid, is then injected back into the ground
                         g                j                    g
        to be reheated.
        Moderate-temperature water is by far the more common
        geothermal resource, and most geothermal power plants in
        the future will be binary-cycle plants.


                                              Binary plant Big Island of
                                              Hawaii. Provides 25% of the
                                              island needs

Binary plant Soda Lake, NV

     Enhanced Geothermal Systems
       The natural hydrothermal resource is dependent on the
       coincidence of substantial amounts of heat, fluids, and
       permeability in reservoirs all in the same location, and the
       present state of knowledge suggests that this coincidence is
       not commonplace. Lots of heat not so much water.
       An alternative to dependence on naturally occurring
       hydrothermal reservoirs involves engineered hydrothermal
       reservoirs in hot rocks. This alternative is known as
       "Enhanced Geothermal Systems," or EGS.

       The logical steps necessary to complete an economically-viable EGS
       operation are:
         Finding a site.
         Creating the reservoir.
         Completing a wellfield
         Operating the reservoir
         Operating the facility
       EGS reservoirs are made by drilling wells into hot rock and fracturing
       the rock sufficiently to enable a fluid (water) to flow between the wells.
       The fluid flows along permeable pathways, picking up in situ heat, and
       exits the reservoir via production wells. At the surface, the fluid passes
       through a power plant where electricity is generated. Upon leaving the
       power plant, the fluid is returned to the reservoir through injection
       wells to complete the circulation loop


Utah Geothermal Area

      Utah has two geothermal electric plants:
         the 23-megawatt Roosevelt Hot Springs
         facility near Milford run by Utah Power and CalEnergy Corp., and the
         Utah Municipal Power Association's Cove Fort Station, which is located
         north of Beaver, Utah.

Power plants in Utah
                               Blundell 2 - Milford

                               Blundell 1 - Milford
Thermo Hot Spring –
Sulfurdale/Cove Fort


 Geothermal water contains varying concentrations of dissolved minerals and salts.
 Sometimes the minerals are extracted and put to good use.
  At reservoirs with higher concentrations, have the potential for clogging and corroding
 power plant equipment.
  Most geothermal reservoirs contain varying amounts of dissolved gases such as
 hydrogen sulfide. Modern geothermal technology ensures that geothermal power plants
 capture these gases
                                        y       g
 Geothermal reservoirs must be carefully managed so that the steam and hot water are
 produced no faster than they can be naturally replenished or supplemented.
 Geothermal power plants run day and night, so they provide reliable baseload electricity.
 Most geothermal power plants can increase their output of electricity to provide more
 power at times of greater demand. But geothermal power plants can’t be used
 exclusively for peaking power;
 If geothermal wells were turned off and on repeatedly, expansion and contraction
 (caused by heating and cooling) would damage the wells.

Direct Use of Geothermal Energy
 Geothermal reservoirs of low-to moderate temperature water —
 68°F to 302°F - This resource is widespread in the United States
 and provide direct heat for residential, industrial, and commercial
    Balneology (hot spring and spa bathing)
    Agriculture (greenhouse and soil warming)
    Aquaculture (fi h prawn and alligator farming)
    A      lt (fish,            d lli t f i )
    Industrial Uses (mining, product drying and warming)
 In addition, spent fluids from geothermal electric plants can be
 subsequently used for direct use applications in so-called
 "cascaded" operation.
 Direct use of geothermal energy in homes and commercial
 operations is much less expensive than using traditional fuels.
 Savings can be as much as 80% over fossil fuels.

Direct-use systems
 Typically include three components:
    A production facility — usually a well — to bring the hot water
    to the surface;
    A mechanical system — piping, heat exchanger, controls — to
                             p       process;
    deliver the heat to the space or p
    A disposal system — injection well or storage pond — to
    receive the cooled geothermal fluid.
 A 1996 survey found that these applications were using
 nearly 5.8 billion megajoules of geothermal energy each year
 — the energy equivalent of nearly 1.6 million barrels of oil!


Native Americans used hot springs. Some tribes considered hot springs to be
neutral territory where no wars were allowed. 2000-2005 Geothermal Eduation


   Green houses
      There are thirty-eight greenhouses, many covering several
      acres, are raising vegetables, flowers, houseplants, and tree
      seedlings in 8 western states.
      Using geothermal resources instead of traditional energy
      sources can saves about 80% of fuel costs Which would
      equate to about 5% to 8% of total operating costs.
      The relatively rural location of most geothermal resources
      also offers advantages, including clean air, few disease
      problems, clean water, a stable workforce, and, often, low


       Milgro Nurseries near Newcastle, Iron County

covering over 24 acres, growing chrysanthemums, poinsettia, calilysis and tulips.

          Milgro is the largest potted plant grower in the U.S. and in
          addition to its 1,000,000-sq ft geothermally-heated facility in
          Newcastle, it also maintains substantial conventionally-heated
          operations near Los Angeles.


    2000-2005 Geothermal Eduation Office

 About 20% of U.S. fish and seafood consumption is now
 farm-raised, aquaculture is becoming a recognized segment
 of the livestock complex.
 There are twenty-eight active aquaculture operations using
 geothermal energy in 10 states
 Highly dependent upon the quantity and quality of water


     Closeup of a prawn grown in a research project with
     geothermally heated water at the GeoHeat Center,
     Oregon Institute of Technology. 2000-2005 Geothermal
     Eduation Office

Multiple varieties of fish

Alligator farming Buhl, Idaho &
Alamosa springs, CO


Fish Breeders of Idaho Inc., Hagerman, Idaho
     This site is ideal for warm water species. The wells (expect one) are near the
     top of the canyon; so, water flows down a quarter mile with an 80 ft drop.
     Raceways are interspersed with rocky brook-like channels that help add oxygen
     utilized by the fish.
     Stocking starts with the water flow at the top with channel catfish, followed by
     lower oxygen tolerant blue catfish (350,000 - 400,000 lb/yr combined), to
     even more tolerant tilapia (100,000 - 200,000 lb/yr) near the bottom, then to
     settling ponds where solid waste is removed More oxygen is added and water
     cooled in the rocky brook on its way to the river. Starting in 1994, in the lower
     portion, water is diverted to alligator houses (1,000 6-footers/yr) and outdoor
     ponds for 1,000 lb 10 - 14 ft breeding stock. The alligators are fed dead fish
     from this site and from the numerous nearby cold water fish farms (trout).
     Since the fish are cleaned on site, the alligators are also fed the entrails.
     In winter, about 1,000 gpm of cold water from shallow springs is mixed with
     geothermal to maintain correct growing temperatures. In summer, 4,000 -
     5,000 gpm is obtained from an irrigation canal.

   Industrial and Commercial Uses

     Industrial applications include food dehydration, laundries,
     gold mining, milk pasteurizing, spas, and others.
     Dehydration, or the drying of vegetable and fruit products, is
     the most common industrial use of geothermal energy. The
     earliest commercial use of geothermal energy was for
                                 g               gy
     swimming pools and spas. In 1990, 218 resorts were using
     geothermal hot water.


This plant in Brady, Nevada, provides dried onions
to Burger King.

          2000-2005 Geothermal Education Office

District and Space Heating

 In the U.S., more than 120 operations, with hundreds of
 individual systems at some sites, are using geothermal energy for
 district and space heating.
 District systems distribute hydrothermal water from one or more
 geothermal wells through a series of pipes to several individual
             buildings,               buildings.
 houses and buildings or blocks of buildings
 Space heating uses one well per structure.
 Geothermal district heating systems can save consumers 30% to
 50% of the cost of natural gas heating.
 The potential for district heating in the western U.S. was
 published in a 1980s inventory which identified 1,277 geothermal
 sites within 5 miles of 373 cities in 8 states.

                                                  Pipes of geothermal water can
                                                  be installed under sidewalks and
                                                  roads to keep them from icing
                                                  over in winter, like this sidewalk
                                                  in Klamath Falls, Oregon.

          2000-2005 Geothermal Education Office


                  District heating Boise, Id

Direct-use growth in the United States

Regulatory/Environmental Issues:
 Geothermal fluids in Utah are regulated as “a special kind of
 underground resource.” The use of or injection of the fluid
 constitutes a beneficial use of the waters of the state and as
 such water rights are required from the State Division of
 Water Rights.
  In addition, rights to a geothermal resource or fluids are
 based upon the principle of “correlative rights” conveying the
 right of each landowner to produce his equitable share of
 underlying resources. Well construction and permitting is
 regulated by the Division of Water Resources of the
 Department of Natural Resources.


Geothermal heat pumps
 Have been in use since the late 1940s. Geothermal heat pumps (GHPs) use the constant
 temperature of the earth as the exchange medium instead of the outside air temperature.
 This allows the system to reach fairly high efficiencies (300%-600%) on the coldest of
 winter nights, compared to 175%-250% for air-source heat pumps on cool days.
 The technology relies on the fact that the Earth (beneath the surface) remains at a
 relatively constant temperature throughout the year, warmer than the air above it during
 the winter and cooler in the summer, very much like a cave. The ground, in other words,
 acts as a heat source in winter and a heat sink in summer.
 There                    l 0 000       h      l heat           ll d h
 Th are approximately 50,000 geothermal h pumps installed in the United S       d States
 each year

 The system includes three principal components:
    Geothermal earth connection subsystem
    Geothermal heat pump subsystem
    Geothermal heat distribution subsystem.

Earth Connection

 Using the Earth as a heat source/sink, a series of pipes,
 commonly called a "loop," is buried in the ground near the
 building to be conditioned. The loop can be buried either
 vertically or horizontally. It circulates a fluid (water, or a
 mixture of water and antifreeze) that absorbs heat from, or
 relinquishes heat to, the surrounding soil, depending on
 whether the ambient air is colder or warmer than the soil.

Heat Pump Subsystem

 For heating, a geothermal heat pump removes the heat from
 the fluid in the Earth connection, concentrates it, and then
 transfers it to the building. For cooling, the process is


   Heat Distribution Subsystem

    Conventional ductwork is generally used to distribute heated
    or cooled air from the geothermal heat pump throughout the

   Residential Hot Water

    Geothermal heat pumps can be used to provide domestic hot
    water when the system is operating
    Excess heat from the geothermal heat pump's compressor is
    transferred to the house's hot water tank.
    Provides no hot water during the spring and fall when the
    geothermal heat pump system is not operating
    Manufacturers are beginning to offer "full demand" systems
    that use a separate heat exchanger to meet all of a
    household's hot water needs. These units cost-effectively
    provide hot water as quickly as any competing system.

Types of Geothermal Heat Pump Systems
    There are four basic types of ground loop systems.
      open loop option.
      open-loop option
    All of these approaches can be used for residential and
    commercial building applications.


Closed-Loop Systems Horizontal
 This type of installation is generally most cost-effective for
 residential installations, particularly for new construction
 where sufficient land is available. It requires trenches at least
 four feet deep. The most common layouts either use two
 pipes, one buried at six feet, and the other at four feet, or
 two pipes placed side-by-side at five feet in the ground in a
 two-foot wide trench. The Slinky™ method of looping pipe
 allows more pipe in a shorter trench, which cuts down on
 installation costs and makes horizontal installation possible in
 areas it would not be with conventional horizontal


 Large commercial buildings and schools often use vertical systems
 because the land area required for horizontal loops would be
 Vertical loops are also used where the soil is too shallow for
 trenching, and they minimize the disturbance to existing
 Holes (approximately four inches in diameter) are drilled about 20
 feet apart and 100–400 feet deep. Into these holes go two pipes
 that are connected at the bottom with a U-bend to form a loop.
 The vertical loops are connected with horizontal pipe (i.e.,
 manifold), placed in trenches, and connected to the heat pump in
 the building.



 If the site has an adequate water body, this may be the lowest
 cost option. A supply line pipe is run underground from the
 building to the water and coiled into circles at least eight feet
 under the surface to prevent freezing. The coils should only
 be placed in a water source that meets minimum volume,
 depth, and quality criteria.


Open-Loop System
 This type of system uses well or surface body water as the
 heat exchange fluid that circulates directly through the GHP
 Once it has circulated through the system, the water returns
 to the ground through the well, a recharge well, or surface
 Practical only where there is an adequate supply of relatively
 clean water, and all local codes and regulations regarding
 groundwater discharge are met.

Ground loop


   Economic Analysis:
Installed Geothermal HVAC Capital Cost:
   $3,235,000 ($13.87/ft2)($149.30/m2)
Conventional HVAC Capital Cost Bid:
   $3,963,363 ($17.00/ft2)($183.00/m2)
Annual HVAC Energy Cost ( (2001-2002):)
   $141,333 ($0.61/ft2)($6.57/m2)
Annual HVAC Energy Cost of Comparable Conventional School:
   $200,500 ($0.86/ft2) ($9.26/m2)
Annual HVAC Energy Savings:
Estimated Simple Payback Period:


Shared By: