Geothermalenergy by sujit

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

 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
2
Thursday, May 14, 2015 Geothermal Energy

Geothermal comes from the
Greek words geo (earth)and
therme (heat).
Thus, geothermal energy means
heat inside the earth.

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.

 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.
Thursday, May 14, 2015 7Geothermal Energy

 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.

 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.

Direct use: District Heating System.
Electricity generation.
Heat pumps.

 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.

Hot Water Production
Piped Under Roads
In Greenhouses to Grow
Flowers,vegetables etc.
Industrial Uses: dry wood, pasteurize
milk, grow fish, etc.
Space Heating

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.

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

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.

 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.

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.

 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.

 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

 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.

 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.

 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.

 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.

 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.
Thursday, May 14, 2015 Geothermal Energy 25

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Geothermalenergy by sujit

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