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acid
rain:
common name for any precipitation (rain, snow, sleet, hail,
fog) having a high amount of sulfuric acid and/or nitric acid
or having a pH lower than 5.6. Normal rain has a pH of 5.6 -
5.7. Accumulation of acids in lakes and rivers damages or kills
plant and animal life. Acid rain also dissolves building materials
and leaches nutrients out of soil resulting in crop damage.
Fossil fuel power plants are a major source of acid rain.
agriculture:
the growing (farming) of plants, flowers, trees, grains, and
other crops. Greenhouses can be heated with hot water from geothermal
reservoirs. In some places pipes of hot water are buried under
the soil. Geothermal heat is also used to dry crops.
aquaculture:
the farming of fish and other water-dwelling organisms in freshwater
or seawater. Geothermal water is used to help speed the growth
of fish, prawns and alligators. China is probably has more aquaculture
operations than any other country.
aquifer: a
large permeable body of underground rock capable of yielding
quantities of water to springs or wells. Aquifers provide about
60 percent of American drinking water. Underground aquifers
of hot water and steam are called geothermal reservoirs.
balneology:
using hot spring mineral water for therapy. This is perhaps
the oldest use of natural geothermal waters.
boiling point:
temperature at which a single substance, such as water, changes
from a liquid to a gas (steam) under normal atmospheric pressure.
The boiling point at which water transitions to steam is 212°F
(100°C). Some liquids boil at a lower temperature than
water -- a principle utilized in binary power plants. Boiling
point is also affected by pressure. The greater the pressure,
the higher the boiling point. This principle is put to work
in geothermal (flash) power plants when superheated (hotter
than boiling) geothermal water is brought up wells. The hot
water flashes to steam when the pressure is released as it reaches
the surface. This phenomenon also occurs naturally, resulting
in such features as geysers.
caldera: a
bowl-shaped landform, created either by a huge volcanic explosion
(which destroys the top of a volcano) or by the collapse of
a volcano's top.
carbon dioxide
(CO2): a gas produced
by the combustion of fossil fuels and other substances. CO2
also occurs naturally in large amounts in molten magma, which
is involved in the explosive eruption of volcanoes. See Greenhouse
Effect.
chemical energy:
energy inherent in the chemical bonds which hold molecules together.
Examples are coal and oil, which have energy potential that
is released upon combustion.
combustion: the
burning of gas, liquid, or solid, in which the fuel is oxidized,
producing heat and often light.
condense:
to change from a gas to drops of liquid. Water-cooled geothermal
power plants use cooling towers to cool the used steam and condense
it back to water for injection back to the edge of the reservoir.
In binary power plants, an organic liquid is first vaporized
(with heat from geothermal water) to drive a turbine, then cooled
and condensed back to a liquid and recycled again and again
in a closed loop.
conduction:
the transfer of heat as a result of the direct contact of rapidly
moving molecules through a medium or from one medium to another,
without movement of the media. The heat from geothermal water,
for instance can be conducted through metal plates or pipes
to heat other water for district heating systems or a second
organic liquid for use in binary power plants.
continental drift:
the theory that the continents have drifted apart when a
supercontinent, Pangaea, broke apart. See Plate Tectonics.
convection currents:
the currents caused by hot air or fluid rising and falling.
Hot air or fluid expands and is therefore less dense than its
cooler surroundings, thus it rises; as it cools it contracts,
becomes more dense and sinks down creating something of a rolling
motion. These motions are thought to be party of the dynamic
geologic processes that drive the movement of crustal plates.
See Plate Tectonics
core (outer and
inner): the extremely hot center of the Earth. The outer
core is probably molten rock and is located about 3,200 miles
(5,100) kilometers down from the earth’s surface; the inner
core may be solid iron and is found a the very center of the
Earth- about 4,000 miles (6,400 kilometers) down.
crust: the
solid outermost layer of the Earth, mostly consisting of rock,
and ranging from 3 - 35 miles (4.8 - 56 kilometers) thick, comprises
the topmost portion of the lithosphere (see lithospheric plates).
Earth's crust insulates us from the hot interior.
cultivate:
to grow and tend (plants or crops), farm.
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dehydrate:
to free from moisture in order to preserve; to dry fruits,
vegetables or lumber, for instance. A factory in in Nevada,
for example uses geothermal heat to dehydrate onions and garlic
for restaurants.
density: the
amount of mass in a given volume of something. Two objects can
be the same size, but have different densities because one of
the objects has more mass "packed" into the same amount of space.
Objects are smaller when they are cold, larger when hot.
direct use: use
of geothermal water and it's heat to grow fish, dry vegetable,
fruit and wood products, heat greenhouses and city buildings,
or provide hot water for spas.
district heating
system: a heating system that provides heat to a large number
of buildings all from a central facility. In geothermal district
heating systems, one or more wells can serve entire districts.
earthquake:
the vibration or movement of the ground caused by a sudden shift
along faults (cracks) in the earth's crust; most earthquakes
occur at the places where tectonic plates edges meet.
electric current:
the continuous flow of electrons; often referred to as electricity.
electrical energy:
energy of electric charges or electric currents.
electron:
the smallest part of an atom (atoms are the tiny particles of
which all substances are made). Electrons may be freed from
atoms to produce an electric current.
energy conversion
the changing of energy from one form to another. One of
the many examples are heat energy being converted into mechanical
energy, and then mechanical energy into electrical energy, as
is done in steam-driven electric power plants.
energy efficiency:
the measure of the amount of energy which any technology can
convert to useful work; technology with a higher energy efficiency
will require less energy to do the same amount of work.
energy resource:
a source of useable power which can be drawn on when needed.
Energy resources are often classified as renewable or non-renewable.
energy: the
ability to do work, such as making things move and heating them
up. Energy can take many forms, including electrical, chemical,
radiant, mechanical and heat.
Environmental
Protection Agency (EPA): Federal government agency that
makes and enforces standards for pollution control; designed
to protect the environment.
eruption:
the explosive discharge of material such as molten rock and
gases, or hot water (as from volcanoes or geysers).
fault: a crack
or break in the Earth’s crust along which movement has
occurred, often resulting in earthquakes.
fracture:
a crack in the Earth’s crust along which no movement has
occurred.
fumarole:
a small hole or vent in the Earth's surface, found near volcanic
areas, from which steam or gases shoot out.
generator:
a machine that converts mechanical power into electricity by
spinning copper wires (conductors) within a magnetic field.
geothermal (ground
source) heat pump: a space heating/cooling system which
moves heat from and to the earth, as opposed to making heat
using a fuel source. Geothermal heat pumps take advantage of
the almost constant temperature just a few feet underground
-- usually warmer than the air in winter and cooler than the
air in summer.
geothermal reservoir:
a large volume of underground hot water and steam in porous
and fractured hot rock. The hot water in geothermal reservoirs
occupies only 2 to 5% of the volume of rock, but if the reservoir
is large enough and hot enough, it can be a powerful source
of energy. Geothermal reservoirs are sometimes overlain by a
layer of impermeable rock. While geothermal reservoirs usually
have surface manifestations such as hot springs or fumaroles,
some do not.
geothermal phenomena:
an observable event at the surface, whose occurrence is the
result of the Earth’s internal heat; includes volcanoes,
geysers, hot springs, mud pots and fumaroles.
geothermal power
plant: a facility which uses geothermal steam or heat to
drive turbine-generators to produce electricity. Three different
types make use of the various temperature ranges of geothermal
resources: dry steam, flash and binary.
geothermal resource:
the natural heat, hot water, and steam within the Earth
geothermal water:
water heated by the natural heat inside the Earth.
geyser: a
natural hot spring that sends up a fountain of water and steam
into the air; some geysers "spout" at regular intervals and
some are unpredictable.
global warming/greenhouse
effect: the trapping of heat in the atmosphere. Incoming
solar radiation goes through the atmosphere to the Earth's surface,
but outgoing radiation (heat) is absorbed by water vapor, carbon
dioxide, and ozone in the atmosphere. At certain levels this
is beneficial because it keeps the planet warm enough for life
as we know it. However, an increase in the normal amount of
carbon dioxide and other gases may contribute to a human-caused
warming trend that could have serious effects on global climate,
the global ecosystem, and food supplies.
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health
spa: an establishment (often commercial) which is visited
by guests seeking therapy and relaxation; many center around
hot mineral springs or use hot water from geothermal wells.
heat exchanger:
a device in which heat is transferred by conduction through
a metal barrier from a hotter liquid or gas, to warm a cooler
liquid or gas on the other side of the metal barrier. Types
of heat exchangers include "shell and tube," and "plate."
heat transfer:
the transmission of heat. There are three forms of heat transfer:
"conduction," "convection," and "radiation." See these terms.
hot spot: areas
of volcanic activity found in the middle of lithospheric plates,
caused from an upwelling of concentrated heat in the mantle.
Hot spots remain stationary while the plates move over them,
often leaving a chain of extinct volcanoes as the plate moves
away from the hot spot; examples include the Hawaiian Islands
and Yellowstone National Park.
hot springs:
a natural spring that puts out water warmer than body temperature
and therefore feels hot; may collect in pools or flow into streams
an lakes. A geothermal phenomenon.
hydrothermal:
hydro means water and thermal means heat. Literally hydrothermal
means hot water. Steam and hot water reservoirs are hydrothermal
reservoirs. Hot dry rock resources and magma resources are not
considered to be hydrothermal resources.
impermeable: does
not allow liquids to pass through easily -- certain rock types
and clay soil are impermeable.
injection well:
a well through which geothermal water is returned to an underground
reservoir after use. Geothermal production and injection wells
are constructed of pipes layered inside one another and cemented
into the earth and to each other. This protects any shallow
drinking water aquifers from mixing with deeper geothermal water.
lava: molten
magma that has reached the Earth's surface.
magma: hot,
thick, molten (liquid) rock found beneath the Earth’s surface;
formed mainly in the mantle.
mantle: the
semi-molten interior of the Earth that lies between the core
and the crust making up nearly 80% of the Earth’s total
volume; extends down to a depth of about 1800 miles (2,900 kilometers)
from the surface.
mechanical energy:
the energy an object has because of its motion or position
and the forces acting on it.
megawatt (MW):
a unit of power, equal to a thousand kilowatts (kW) or one million
watts(W). The watt is a unit of power (energy/time), the rate
energy is consumed or converted to electricity.
mineralized:
containing minerals; for example, mineralized geothermal water
contains dissolved minerals from inside the Earth.
molecules:
extremely tiny particles of which all materials are made .
mud pot (paint
pot): thermal surface feature which occurs where there is
not enough water to support a geyser or hot spring even though
there may be some hot water below. Steam and gas vapors bubble
up through mud formed by the interaction of gases with rock.
natural gas:
a gas mixture (mostly methane) trapped underground in many places
near the surface of the Earth; a fossil fuel.
nitrogen oxides
(Nox): formed in combustion; appear as yellowish-brown clouds;
can irritate lungs, cause lung diseases, lead to formation of
ozone (which is harmful in the lower atmosphere, but necessary
as protection from UV rays in the upper atmosphere).
nonrenewable resource:
resources that are not replaced or regenerated naturally within
a period of time that is useful; this includes fossil fuels,
uranium and other minerals.
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Pangaea:
the huge supercontinent which scientists think may have existed
250 million years ago. All of the continents may have at one
time been joined together to make this huge land mass.
particulates (particulate
matter): dust, soot, smoke and other suspended matter; can
be respiratory irritants. Particulate matter smaller than 10
microns (pm10) has been found to be particularly harmful to
health.
pasteurize:
to use high temperatures to destroy disease-causing bacteria.
permeable:
able to transmit water or other liquids; for example, rock with
tiny passageways between holes, fractured rock, and gravel are
permeable.
plate tectonics:
the study of the movement of large crustal plates (lithospheric
plates) of the Earth’s shell. The earth's shell is broken
into several pieces (12 large ones and several smaller ones).
These plates move toward and away from one another at about
the rate our fingernails grow. The process that creates the
dynamic movement of the plates includes the convection of magma
in the mantle and lithosphere. Plate tectonics helps to explain
continental drift, seafloor spreading, volcanic eruptions and
other geothermal phenomena, earthquakes, mountain formation
and the distribution of some plant and animal species.
porous: full
of small holes (pores); able to be filled (permeated) by water,
air, or other materials.
power plant:
a central station where electricity is produced using turbines
and generators.
pressure:
the force exerted over a certain area. Our atmosphere exerts
pressure on the surface of the earth, and layers of rock exert
pressure on those below them.
radiant energy:
energy (heat) that is transferred by rays or waves, especially
electromagnetic waves, through space or another medium. Radiation.
renewable resource:
a resource that can be used continuously without being used
up (because it regenerates itself within a useful amount of
time). Examples include
water (small hydro) and wind power, solar energy, and geothermal
energy.
rift zone:
long narrow fractures in the crust found along ocean floor or
on land, from which lava flows out; often associated with spreading
centers from which tectonic plates are diverging, such as the
mid-Atlantic Ridge.
Ring of Fire:
a belt of intense volcanic, geothermal and earthquake activity
found all around the Pacific Rim caused by plate tectonic activity.
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steam:
the vapor form of water that develops when water boils. Steam
is made of very tiny heated water particles (molecules) which
are bouncing around and bumping into each other at very high
speeds. These heated water molecules are also spreading out
and expanding in every direction they can. If we confine or
trap water in a container, with a pipe as an opening, and heat
the water to steam, it will create great pressure in the container
and will rush out the pipe with a great deal of force. This
force (the "power" of steam) can be put to work turning a turbine
connected to an electricity generator.
subduction boundary:
one of two types of converging plate boundaries which occurs
when one plate plunges under another overriding plate.
sulfur oxides
(Sox): pungent, colorless gases (including sulfur dioxide
(SO2); formed primarily by the
combustion of fossil fuels; may damage the respiratory tract,
as well as plants and trees.
sustainable:
material or energy sources which, if managed carefully, will
provide the needs of a community or society indefinitely, without
depriving future generations of their needs.
therapeutic:
the treatment of disease or other disorder; something that may
benefit health. (Geothermal) hot springs are often thought of
as therapeutic.
transmission lines:
wires that transport electricity over long distances.
turbine: a
machine with blades that are rotated by the forceful movement
of liquid or gas, such as air, steam or water or a combination.
vaporize:
to change into the gas form anything which is normally a liquid
or a solid; the term is most commonly is used in reference to
water (which vaporizes to steam).
volcano:
an opening in the Earth's crust from which lava, steam, and/or
ashes erupt (or flow), either continuously or at intervals.
voltage: the
measure of the amount of force that "pushes" an electric
current..
water phases:
the change of water from one state to another. The change from
ice to liquid is melting; the reverse process is freezing. The
change from liquid to gas is evaporation and the product is
water vapor; the change from water vapor to liquid is called
condensation. Evaporation and condensation are both important
functions in geothermal phenomena and in geothermal technology.
Watt (W):
the measure of the amount of current flowing through a wire
at a given time.
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