Geothermal energy

1. 1Thursday, May 14, 2015 Geothermal Energy
SUJIT KUMAR ROY
ENVIRONMENTAL SCIENCE &
HAZARD STUDIES.
NOAKHALI SCIENCE &
TECHNOLOGY
UNIVERCITY

2.  What is geothermal energy
 Earth made of layer
 Temperature of earth crust
 History
 Locations
 Where we find geothermal energy
 Use of geothermal energy
 Direct heating
 Electricity generation
 Heat pumps
 Environmental impact
 Advantage
 Disadvantage
 Bangladesh and geothermal energy
 Conclusion
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Thursday, May 14, 2015 Geothermal Energy

3. Geothermal comes from the
Greek words geo (earth)and
therme (heat).
Thus, geothermal energy means
heat inside the earth.
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5. At the center is a core of iron.
Around that is an outer core of
iron and rock so hot the rock is
melted.
The liquid rock is called
magma.
The next layer is a mixture of rock
and magma called the mantle.
The shell of the earth – with the
oceans and mountains - is called
the crust.
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7.  For thousands of years,
civilizations have used naturally
warm spring water for various
purposes like bathing and cleaning,
but was also used to heat living
spaces.
 Geothermal energy was first used
to produce electricity in Italy in the
early 20th century. The first
working prototype was small and
constructed by Prince Gionori
Conti in 1905.
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9.  Ring of Fire.
 Over 20 countries:
 Iceland
 U.S.
 Italy
 France
 China
 Japan, etc.
 The United States is the country
with the greatest geothermal
energy production.
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10.  Even though geothermal
energy is underground, there
are visible features on the
surface.
 These include volcanoes,
hot springs, and geysers.
 The most active geothermal
resources are usually found
where earthquakes and
volcanoes are concentrated.
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11. Direct use: District Heating System.
Electricity generation.
Heat pumps.
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12.  Use hot water from
springs or reservoirs
near the surface.
 Hot water near the
earth's surface can
be piped directly
into buildings and
industries for heat.
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13. Hot Water Production
Piped Under Roads
In Greenhouses to Grow
Flowers,vegetables etc.
Industrial Uses: dry wood, pasteurize
milk, grow fish, etc.
Space Heating
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14. Dry Steam Power
Plant:
 Uses the superheated,
pressurized steam
(180°-350°C).
Process:
 The steam is sent
directly to a turbine,
which drives the
generator and
produces electricity.
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15. Binary Cycle Power Plant:
 Most geothermal areas contain
moderate-temperature water
(below 400°F).
Process:
 Hot geothermal fluid and a
secondary fluid with a much
lower boiling point than water
pass through a heat exchanger.
 Heat from the geothermal
fluid causes the secondary
fluid to flash to vapor, which
then drives the turbines
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16. Flash Steam Power Plants:
 Hydrothermal fluids above 360°F
(182°C) can be used in flash plants
to make electricity.
Process:
 Fluid is sprayed into a tank held
at a much lower pressure than the
fluid.
 This causing some of the fluid to
rapidly vaporize, or "flash."
 The vapor then drives a turbine,
which drives a generator.
 If any liquid remains in the tank,
it can be flashed again in a
second tank to extract even more
energy.
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17.  Hot Geothermal Fluids Near Surface (<1-2 mi.)
Preferably in Excess of 300°F, but Electrical Generation
Is Occurring at Temps. In the Low 200’s°F.
 Proximity to Population Base.
 Low Mineral and Gas Content.
 Location on Private Land.
 Proximity to Transmission Lines.
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18. Utilizes constant
temperature of upper 10
feet of the Earth’s
surface.
Similar to ordinary heat
pumps, but they rely on
more stable source than
air.
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19.  Most Basic Form of Geothermal Usage
 What – takes advantage of stored heat of near surface
soil / water (Const. temp of 55-75 °F)
Winter Months – uses ground as a “heat source”
 Transfers heat from warm subsurface to facility.
Summer Months – uses ground as a “heat sink”
 Transfers heat from facility to ground.
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20.  Overall, geothermal power is a
 Sustainable
 Flexible
 Environmentally-friendly resource.
 Main disadvantages:
 Emission of pollutant gases into atmosphere
 Emission of toxic compounds to surface level
 Possible cause of land instability
 Reliant on electricity power sources
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21.  The practice of extracting fluid from deep earth can cause
dissolved (non-condensable) gases to escape into the
atmosphere.
 Major: CO2, CH4, NH3, H2S.
 Minor: Hg vapor, C6H6 , benzene.
 Implications:
 Climate change
 Acid rain
 Health risks
 A relatively minor source of greenhouse gases.
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22.  Potentially infinite energy supply.
 Used successfully in some countries such as
New Zealand and Iceland.
 In Iceland half of the geothermal energy is
used to produce electricity and half is used for
heating.
 Used directly for heating.
 Less costly than oil energy.
 Conserve fossil fuel.
 Does not contribute to global warming.
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23.  Can be expensive to set up and only works in areas of
volcanic activity.
 Geothermal and volcanic activity might calm down,
leaving power stations redundant.
 Dangerous elements found underground must be disposed
of carefully.
 The steam contains Hydrogen sulfide gas , which has the
odor of rotten egg and is an unpleasant form of air
pollution.
 It is not a free source of heat.
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24.  There exist 6000 MW maximum electricity shortage during
hot summer days and also in the harvesting and irrigation
season.
 In this circumstances there is no alternative of renewable
energy and Bangladesh have a great opportunity to generate
electricity from geothermal energy to overcome this power
crisis.
 North-east region of this country is suitable for planting
geothermal power plant.
 So the geothermal energy is a great opportunity for
eliminating this electricity shortage.
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25.  Geothermal energy is limited so we have to use it
very carefully.
 Hot, dry rock (HDR) is widespread and offers
new resources in areas where geyser activity is
unknown.
 Direct low-temperature heat transfer for home
systems is practical as long as low maintenance is
designed into the system.
 Geothermal energy likely to remain at 1% of
world energy.
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