Geothermal Energy
Intro to Geothermal Energy
 “Geothermal” comes from Greek words geo, meaning
“earth,” and therme, meaning “heat.”
 Geothermal Energy is the heat produced from the
Earth’s core. The core’s heat radiates to the upper
mantle.
 The core can reach up to 9,000°F.
 The mantle’s temperature can vary
between 900 and 1600°F.
Different Forms of Geothermal
 Direct Energy
 Geothermal Heat Pump
 Geothermal Power Plant
Direct Energy
 Near-surface hot springs or geothermal reservoirs pump
hot water to the surface.
 Pipes pull a hot resource up to the surface, a heat
exchanger takes heat from the resource, and the unused
water is injected back into the ground.
 For example, direct energy is used in hot spring pools
like Warner Springs.
Geothermal Heat Pump
 Dirt underground is a
constant 50°F to 60°F.
 Water enters the
building through pipes
called “loops” and is
converted to heat or
cool the building.
 Used in the Midwest and
back east to heat and
cool buildings.
use underground steam to drive turbines which generate
electricity.
Three types of
Geothermal Power Plants:
1. Steam Plants

Steam directly from a reservoir spins turbines in
generators, creating electricity.
2. Flash Steam Plants

300°F to 700°F water is pumped from an underground
well. The water turns into steam powers a generator.
3. Binary Cycle Plants

Geothermal resource goes into a heat exchanger. The
heat heats a second liquid, which boils and and creates
steam to turn turbines.
How Does Geothermal Energy Get
to the Earth’s Surface?
 The core’s heat radiates outward into the mantle.
 The heat melts the mantle’s rock into magma.
 This magma does either of two things:
1. Reaches all the way to the surface, turning into lava flows.
2. Stays below the surface, heating rock and water around it.
 The mass of heated minerals and water below the surface is
known as a geothermal reservoir.
 To create electricity, the geothermal resource must be brought
to the surface so the heat can be extracted.
Lava
SURFACE
CORE
HEAT
Geothermal
Reservoir
MANTLE
Water and Rock
Where the energy comes from:
The superheated fluid is an
important natural resource.
It’s “the resource” for power.
 It’s “scrubbed” to get clean steam.
 The steam drives turbines and generates electricity.
Why use geothermal?
 It is a renewable energy- Clean and Green!
 It can be used instead of fossil fuels.
 Burning fossil fuels is detrimental to the earth’s
ecosystem, causing global warming.
 Using Geothermal Energy protects the Earth’s
atmosphere!
 Geothermal is more reliable
than sun or wind.
Global Warming
How is Electricity Generated?
 Most commercial electrical power is based on spinning a
wire coil in a magnetic field.
 Mechanical energy
(motion) is converted
into electrical energy.
 Most power plants use fossil fuels such as coal or gas to
drive turbines to generate electricity.
From Steam to Usable Electricity
Renewable Energy Generation
 Geothermal plants use steam from
fluid that is super-heated by magma
deep under the earth’s surface.
 Instead of steam, windmills use wind
and dams use water to drive the
turbines.
Reinjection
 Reinjection is the process of returning the geothermal fluid
that was taken from the mantle back into the underground.
 Excess steam is condensed back into fluid and is also returned
to the mantel.
 This is what makes the geothermal resource renewable.
 The geothermal fluid will be reheated in the mantle and can
be used again.
 If a power plant decides not to use the process of reinjection,
it runs the risk of diminishing the underground resource.
Reinjection Process Explained
Geothermal Energy in History
 10,000 years ago- Paleo-Indians used hot springs for
cooking and bathing.
 1830- Hot Springs, Arkansas- Asa Thompson charges
money for hot springs bath. First commercial usage.
 1900- Hot spring water is pumped to homes in Klamath
Falls, Oregon.
 1904- First Geothermal power
plant in Larderlello, Italy
History (cont.)
 1921-Drilling at The Geysers with intention of producing
electricity
 Unsuccessful at first
 A year later, successful as the first US geothermal power
plant
 1960- USA’s first large scale geothermal electricity
generating plant
 By Pacific Gas & Electric
 1970- Geothermal Resources Council is formed
 1977- US Department of Energy (DOE) is formed
 Geothermal Energy and Mineral Corporation
 Nevada corporation founded in 1968
How Energy Gets to You!
 Gemcor owns the land
containing the steam
wells
 Cal Energy operates the
power plant, converting
the geothermal resource
into electricity.
 Southern California Edison
transports and sells the
electricity.
GEMCOR
CAL
ENERGY
SOCAL
EDISON
Gemcor Today and in the Future
 With help from Cal Energy, Gemcor’s resource
produces 166 Megawatts (MW) of electricity.
 Two new sites at Black Rock are planned to open,
which will add 200 MW of electricity to Gemcor’s
production.
 The next slide will show a video tour of Gemcor’s
first production plant.
Gemcor Plant - Outside
Gemcor Plant - Control Room
End
Thank You