Geothermal energy involves harnessing the Earth's internal heat by extracting hot water or steam from underground reservoirs and using it to generate electricity or provide direct heating. Various technologies exist for geothermal power generation including dry steam, flash steam, and binary cycle plants. While geothermal energy has significant environmental benefits compared to fossil fuels, some concerns exist around the potential local impacts of geothermal development projects.

1. GEOTHERMAL
ENERGY

2. Geothermal Energy:
Introduction
 What is geothermal energy?
 Geothermal energy- energy that comes from
the ground; power extracted from heat stored
in the earth
 Geo: earth
 Thermal: heat

4. Geothermal Energy Generation
Direct
 Small scale uses
 Heating homes
 Hot springs
 Greenhouse heating
 Food dehydration
plants
 Agriculture
 Crop drying
 Milk pasteurization
Electrical
 Dry steam
 Flash steam
 Binary cycle

5. How Direct Uses Work
•Direct Sources function by sending water down a well to be heated by the
Earth’s warmth.
•Then a heat pump is used to take the heat from the underground water to the
substance that heats the house.
• Then after the water it is cooled is injected back into the Earth.

6. How Geothermal Works
 Earth’s core heat
 Water → steam → drive electrical generators
 Turbines
 Geothermal production of energy is 3rd
highest among renewable energies. It is
behind hydro and biomass, but before solar
and wind
 Area specific
 Geothermal energy is localized

7. Dry Steam/Flash Steam/Binary
Cycles
 Each uses the heat from underground in some
manner to generate energy
 Different combinations of water temperatures
create different effects(water or air cooled
system)
 How Geothermal Energy Works

8. Generation of Electricity is
appropriate for sources >150o
C
Dry Steam Plants: These were the first type of plants created. They use
underground steam to directly turn the turbines.

9. Flash Steam Plants: These are the most common plants. These systems pull
deep, high pressured hot water that reaches temperatures of 3600
F or more to
the surface. This water is transported to low pressure chambers, and the
resulting steam drives the turbines. The remaining water and steam are then
injected back into the source from which they were taken.

11. Binary Cycle Plants: This system passes moderately hot geothermal water
to heat exchanger past a liquid, usually an organic fluid or secondary
liquid, namely isobutene, iso-pentane or ammonia–water mixture present
in an adjacent, separate pipe. Due to this double-liquid heat exchanger
system, it is called a binary power plant, that has a lower boiling point.
The resulting steam from the organic liquid drives the turbines. This
process does not produce any emissions and the water temperature
needed for the water is lower than that needed in the Flash Steam Plants
(2500
F – 3600
F).
Casa Diablo

14. Different Geothermal Energy
Sources
•Hot Water Reservoirs: As the name implies these are reservoirs of hot
underground water. There is a large amount of them in the US, but they
are more suited for space heating than for electricity production.
•Natural Stem Reservoirs: In this case a hole dug into the ground can
cause steam to come to the surface. This type of resource is rare in the
US.
•Geopressured Reservoirs: In this type of reserve, brine completely
saturated with natural gas in stored under pressure from the weight of
overlying rock. This type of resource can be used for both heat and for
natural gas.

15. •Normal Geothermal Gradient: At any place on the planet, there is a normal
temperature gradient of +300
C per km dug into the earth. Therefore, if one
digs 20,000 feet the temperature will be about 1900
C above the surface
temperature. This difference will be enough to produce electricity. However,
no useful and economical technology has been developed to extracted this
large source of energy.
•Hot Dry Rock: This type of condition exists in 5% of the US. It is similar to
Normal Geothermal Gradient, but the gradient is 400
C/km dug underground.
•Molten Magma: No technology exists to tap into the heat reserves stored in
magma. The best sources for this in the US are in Alaska and Hawaii

16. Ground Heat Collectors
This system uses horizontal loops filled with circulating water at a depth of 80
to 160 cm underground.
Borehole Heat Exchange
This type uses one or two underground
vertical loops that extend 150 meters
below the surface.

17. Hot Dry Rocks: The simplest models have one injection well and two
production wells. Pressurized cold water is sent down the injection well
where the hot rocks heat the water up. Then pressurized water of
temperatures greater than 2000
F is brought to the surface and passed
near a liquid with a lower boiling temperature, such as an organic liquid
like butane. The ensuing steam turns the turbines. Then, the cool water
is again injected to be heated. This system does not produce any
emissions. US geothermal industries are making plans to commercialize
this new technology.

20. Geothermal Energy: History
 1926: a deep geothermal well was used to
heat greenhouses.

21. Example of a Power Plant in Larderello Today

22. Geothermal Energy: History
 1960: Pacific Gas and Electric has
first successful geothermal electric
power plant in US at The Geysers
 Turbine lasted more than 30 years

23. United States and Geothermal

24. United States and Geothermal
 The US is now the world’s largest geothermal
producer
 Current bills are being processed to give
research towards geothermal projects $500
million
 Pushing large scale production

25. Can Geothermal Energy run
out?
• 100% renewable
 Earth’s core is always going to be heated
 As long as there is a way to extract the energy from
the heat, the energy will always be available

26. Environmental Effects/ Benefits
 Remarkable
difference of
environmental
effects compared to
fossil fuels
 Leaves almost no
footprints
 Most hardware used
to extract
geothermal energy
is underground
 Minimal use of
surface
(http://www.geothermal.nau.edu/about/enviro
ment.shtmlNorthern Arizona University.
2009 Oct 27)

27. Environmental Effects/Benefits
(http://www.geothermal.nau.edu/about/envi
roment.shtml> Northern Arizona
University. 2009 Oct 27)
 Easy to operate
 Open up economy
 Much more efficient
use of land
Power Source Land
Requirement
(ac/mW)
Geothermal 1-8
Nuclear 5-10
Coal 19

30. Environmental Effects/
Disadvantages
 Fluids drawn from the
deep earth carry a mixture
of gases
 Pollutants contribute to
global warming and acid
rain
 Construction of Plants can
adversely affect land
stability
 Sources may hold trace
amounts of toxic
chemicals/mineral deposits
 Loud Noises
 Initial start up cost
(expensive)
(http://www.geothermal.nau.edu/about/enviroment.
shtml> Northern Arizona University. 2009 Oct
27)
Operation Noise Level (dBa)
Air drilling 85–120
Mud drilling 80
Discharging wells after drilling
(to remove drilling debris)
Up to 120
Well testing 70–110
Diesel engines (to operate
compressors and provide
electricity)
45–55
Heavy machinery (e.g., for earth
moving during construction)
Up to 90

31. Opposition to Geothermal
Energy
 Not everyone agrees that geothermal energy is a
solution to our energy crisis
 Too costly
 Noise
 Use of fresh water
 Land surveying
 The technology is not quite there
 Some people just believe that our fossil fuels will
“never” run out
 Don’t believe that fossil fuels are finite

32. Conclusion
 Overall, geothermal appears to be a sound
solution to energy needs
 Geothermal energy has the ability to expand
 Few environmental effects
 Very cost efficient
 Geothermal is RENEWABLE

33. FIND THE EATABLE?