Geothermal Energy, Tapping the
Earth’s Internal Heat
Kalyn Smith
Emily Hoffman
2nd period
Goals of Geothermal Energy
• Heat and cool buildings
• Produce electricity
• Help mitigate global warming if widely
deployed in place of fossil fuels
A geothermal energy plant
http://www.treehugger.com/geothermal-power-plant-i01.jpg
Potential to the World
• Very high efficiency
• Moderate net energy
at accessible sites
• Lower CO2
emissions than fossil
fuels
http://www.treehugger.com/files/2008/06/ge
othermal-energy-doe-90-millioninvestment.php
Potential to the World
• Low cost at favorable
sites
• Low land use and
disturbance
• Moderate
environmental impact
http://www.wateryear2003.org/en/ev.phpURL_ID=4930&URL_DO=DO_TOPIC&URL_S
ECTION=201.html
How is Geothermal Energy Generated?
• Temperatures hotter than the sun’s surface
are continuously produced inside the earth by
a slow decay of radioactive particles
• People around the world use geothermal
energy to produce electricity and heat their
homes by digging deep wells and pumping the
heated water or steam to the surface
Where is geothermal energy found?
•
•
•
•
•
Geothermal reservoirs
Volcanoes
Fumaroles
Hot springs
Geysers
http://www.terrapass.com/images/blogposts/
volcano.jpg
Most geothermal energy…
• Is found along major plate boundaries where
earthquakes and volcanoes are concentrated
• The Ring of Fire
• The most common method that scientists use
to find geothermal reservoirs is drilling a well
and testing the temperature deep
underground.
The Ring of Fire
http://upload.wikimedia.org/wikipedia/comm
ons/0/09/Pacific_Ring_of_Fire.png
The United States and Geothermal
Energy
• Most of the geothermal reservoirs in the U.S. are located in
the western states and Hawaii.
• California generates the most electricity from geothermal
energy.
• "The Geysers" dry steam reservoir in northern California is
the largest known dry steam field in the world and has been
producing electricity since 1960.
• The U.S. leads the world in electricity generation with
geothermal power.
• 7 states have geothermal power plants
• In 2008 U.S. geothermal power plants produced 0.4% of total
electricity in the United States.
Geothermal energy in the U.S.
Uses of Geothermal Energy
• Direct use and district heating systems
• Electricity generation power plant
– Require water or steam at very high temperatures
(300 F – 700 F)
• Geothermal heat pumps
– use stable ground or water temperatures near the
Earth's surface to control building temperatures
above ground.
Direct use of geothermal energy
• Use hot water from springs/reservoirs near
the surface
• District heating systems are a common way to
heat buildings using geothermal energy, which
is accomplished by piping hot water near the
earth’s surface directly into buildings for heat
• Industrial applications of geothermal energy
include food dehydration, gold mining, and
milk pasteurizing
Geothermal power plants
• Use hydrothermal resources that have two common
ingredients: water and heat.
• Require high temperatures (300 F – 700 F)
hydrothermal resources that may either come from dry
steam wells or hot water wells
• These resources can be used by drilling deep wells and
pumping the steam or hot water to the surface
• The wells are 1 – 2 miles deep
• There are three types of geothermal power plants: dry
steam plants, flash steam plants, and binary cycle
power plants
Dry steam plants
• Use steam piped directly from a geothermal
reservoir to turn the generator turbines
http://www1.eere.energy.gov/geothermal/ima
ges/drysteam.gif
Flash Steam Plants
• Takes high pressure hot water from deep
inside the earth and converts it to steam to
drive the generator turbines
• When the steam cools it condenses into water
and is injected into the earth to be used over
and over again.
• Most geothermal plants are flash steam plants
http://www.alchemydes.com/samples/flashste
am_chart.gif
Binary cycle power plants
• Transfers the heat from geothermal hot water
to another liquid.
• The heat causes the second liquid to turn to
steam which is used to drive a generator
turbine.
http://www.digtheheat.com/geothermalpics/b
inary_plant.gif
Energy efficient and cost effective
• According to the
EPA are the most
energy efficient,
cost effective, and
environmentally
clean systems for
temperature
control
http://homeimprovement.resourcesforattorne
ys.com/images/geothermal_heat_pumps.jpg
Geothermal energy and the
environment
• Geothermal power plants do not burn fuel to
generate electricity so their emission levels
are very low
• Release less that 1% of carbon dioxide
emissions of a fossil fuel plant
• Use scrubber systems to clean the air of
hydrogen sulfide
• Emits 97% less acid rain-causing sulfur
compounds than fossil fuel plants
Geothermal energy plant piping
http://www.teara.govt.nz/files/p5432chh.jpg
Disadvantages
• Hard to find a suitable location due to the
large area that the geothermal piping
consumes
• It is possible for an extraction site to suddenly
stop producing steam
• Harmful gases can escape from deep within
the earth
• The initial cost and design is costly
BIBLIOGRAPHY
• http://tonto.eia.doe.gov/kids/energy.cfm?pag
e=geothermal_home-basics-k.cfm
• http://www.energyquest.ca.gov/story/chapter
11.html
• http://www.energy-consumersedge.com/pros_and_cons_of_geothermal_en
ergy.html