Geothermal energy is heat energy generated and stored in the Earth. It originates from original formation of the planet and radioactive decay of minerals. Geothermal power plants tap into hot water or steam underground to generate electricity through turbines. There are three main types - dry steam, flash steam, and binary cycle plants. Geothermal energy is renewable but has high initial costs. It provides baseload power with very low emissions. India has geothermal potential in several provinces but development has been limited so far.

1. Geothermal Energy
By:
Mohammad Ahmad
Assistant Professor
REC Bijnor

2. Introduction
 Geo means earth and Thermal means heat,
geothermal means earth’sheat
 Geothermal energy is the energy contained as heat in
the earth’s interior.
 Geothermal energy is energy extracted from the heat
stored in theearth.
 Geothermal power uses the heat of magma below
the Earth's crust, which comes from radioactive
decay
 Earth’s geothermal energy originates from the
original formation of the Planet and from
radioactive decay of minerals.

3.  Earth’s radius is
approximately 6370 km
and it can be divided into
three zones
 Crust (7 km under
ocean, 20-65 km
under the continent)
 Mantle (2900 km , lies
under the crust)
 Core (centre, 4000oC)

5. History
 Prince Piero Ginori
Conti tested the first
geothermal power
generator. It
successfully lit four
lightbulbs. Later, in
1911,the world's
first commercial
geothermal power
station was built
there.

6. Some fact about Geothermal
 Why is geothermal energy a renewable resource?
Because its source is the almost unlimited amount of heat
generated by the Earth's core.
 Further, due to its low emissions geothermal energy is considered
to have excellent potential for mitigation of global warming.
 Economically Geothermal power requires no fuel, it is therefore
immune to fuel cost fluctuations.
 India has announced a plan to develop the country's first geothermal
power facility in Chhattisgarh
 Current worldwide installed
capacity is 10,715 megawatts(MW),
with the largest capacity in the United
States (3,086 MW).

8. Geothermal Reservoirs
 Reservoirs can be suspected in the areas where we find
 Geyser
 Boiling mud pot
 Volcano
 Hot springs

9. Where is geothermal energy available?
 Hydrothermal resources - reservoirs of steam or hot water -
are available primarily in the western states, Alaska, and
Hawaii.
 However, Earth energy can be tapped almost anywhere with
geothermal heat pumps and direct-use applications. Other
enormous and world-wide geothermal resources - hot dry rock
and magma,
 As the water rises to the surface, natural hot springs and
geysers occurs.
 The rising hot water & steam is trapped in permeable &
porous rocks to form a geothermal reservoir.
 Reservoirs can be discovered by
 Testing the soil
 Analyzing underground temperature

10. These regions are also seismically active with earthquakes and
magma movement, which breaks up rock structures and
allows water to circulate.

11. Geothermal Energy in India
 Geothermal provinces are estimated to produce 10,600
MW of power (experts are confident only to the extent
of 100 MW)
 Geothermal provinces in India: the Himalayas, Sohana,
West coast, Cambay, Son-Narmada-Tapi , Godavari, and
Mahanadi
 Reykjavík Geothermal will assist Thermax to set up a
pilot project in Puga Valley, Ladakh (Jammu &
Kashmir)
 First operational commercial geothermal power plant is
likely to come up in AP with a capacity of 25 MW by
Geosyndicate Pvt Ltd.

12. Extraction of Heat & Uses
The heat energy can be brought to earth surface
by following ways.
 Directly from hot springs/ geysers
 Geothermal heat pump
Uses are broadly classified as:-
 Direct use
 Indirect use : Electricity Generation
 Geothermal Heat Pump

14. Geothermal Heat Pump
For Space Heating/Cooling

15. Indirect Use: Electricity Generation
 Geothermal Energy, heats water that has seeped into underground
reservoirs. These reservoirs can be tapped for a variety of uses,
depending on the temperature of the water.
 The heat must be carried to the surface by fluid circulation, either
through magma conduits, hot springs, hydrothermal circulation, oil
wells, drilled water wells, or a combination of these.
 the geothermal gradient is 25-30°C per km of depth in most of the
world, and wells would have to be several kilometres deep to
permit electricity generation.
 The energy from high-temperature reservoirs (225°- 600°F) can be
used to produce electricity.

16. Layout of Plant

17. Process of Electricity Generation
 To harness energy, large holes have to be dug into the earth
until a geothermal hotspot is found.
 The water is sent through the injection well and reaches the
rocks and then hot water comes from the production well.
 The steam that comes out of the mixture might have
dissolved brine and some dust particles.
 Due to the high pressure when it reaches the topmost of the
earth surface it is converted into steam.
 The separator is the place where steam that comes from the
earth is made clean by removing the brine and dirt so that they
do not damage the turbine blades.

18. The high pressure and low pressure steam runs the
turbine.
The generator is coupled with turbine to produce
electricity.
The condenser is a phase changer where the steam
output of the turbine is given to the condenser and
gets converted to hot water.
 This hot water is then sent to the cooling tower
where it loses it heat and then sent to the
geothermal reservoir for further production of
steam.

19. MainComponentsof a
Geothermal PowerPlant
 Injection Well
 ProductionWell
 Separator
 Heat Exchanger
 SteamTurbine
 Condenser
 Generator

20. TYPES OFGEO-THERMAL POWER PLANT
• Direct Dry Steam Power Plant
• Flash Steam Cycle Power Plant
• Binary Cycle Power Plant

21. DIRECT DRY STEAM
Vapour Dominated
 The oldest type of Geothermal power plant used, operating at California,
Italy, and Japan.
 Steam plants use hydrothermal fluids that converted into steam at 165ºC
at LOW pressure.
 Steam goes directly to a turbine, which drives a generator that produces
electricity.
 Steamiscondensedandpumpedbackinto theground
 Steam eliminates the need to burn fossil fuels to run the turbine.
 These plants emit only excess steam and very minor amounts of gases.
 Canachieve1kWhper6.5kgof steam
 A55MWplant requires100kg/sofsteam

22. DIRECT DRY STEAM

23. FLASH CYCLE Power Plant
Liquid dominated: High temperature
 Commonly used geothermal power plant.
 Operating at Hawaii, Nevada, Utah & some other places
 At high pressure, and a temperature around 182°C, the fluid
remains in liquid state inside the earth, however, when it reaches to
surface of the earth, it converted into a mixture of water and steam.
 This Fluid is sprayed into a Flash tank held at a much lower
pressure than the fluid and hence separated the water and steam.
 The vapour then drives a turbine, which drives a generator.
 If any liquid remains in the tank, it can be flashed again in a
second tank (double flash) to extract even more energy.

24. FLASHCYCLE

25. BINARY CYCLE POWER PLANT
Liquid dominated: Low temperature
 Low temperature (100o -150oC ) fluid is used in it.
 A heat exchanger is required in it.
 Hot geothermal fluid and a secondary fluid such as iso-butane
with a much lower boiling point (10oC) than water pass
through a heat exchanger.
 Heat from the geothermal fluid causes the secondary fluid to
flash to vapour, which then drives the turbines.
 Because this is a closed-loop system, nothing is emitted to
the atmosphere.
 Most efficient for future.

26. BINARYCYCLE

27. Injection Well
 The basic concept is to inject, or
recycle the fluid back to the reservoir
to complete the loop.
 if the water is to be used for any
other purpose than electricity
generation, the supply can be taken
from the injection wells
Production Well
 The function of this production/
extraction well is only to pump up
the hot liquid from the reservoir.
 This well serves as the feed to the
separator.

28. Separator
 The purpose served by the
Vapor-liquid separator(Or
simply the separator) is to
separate the vapor-liquid
mixture.
 Steam containsnon
condensable gases
including Hydrogen
sulphide
 Separator are used forthe
purpose to remove these gases

29. SteamTurbine
 Specially designed steamturbine areused for geothermal power plants
 Steam can be corrosive due to many non condensable gases e.g.
Hydrogensulphide
 Toprotect rotor bladesandnozzlesfrom corrosion specialcoatingsandmaterialsare
used
 The generation and transmission side of geothermal power plants is similar to
conventional power plants

30. Cost
 Direct use of geothermal energy is absolutely cheaper than
other energy sources.
 The initial investment is high.
 But after certain time period, the cost of electricity
becomes comparable to other resources of energy.
 Rs. 2.772 to Rs. 4.4352 per kWh (unit)
 Cost of electricity generation depends upon certain factors:
 Temperature and depth of resource
 Type of resource (steam, liquid, mix)
 Available volume of resource
 Size and technology of plant

31. Applications
• Providing Heat For Residential And
Commercial Use.
• Electricity Generation
• Food Processing
• Paper processing
• Aquaculture
• Horticulture

32. • Geothermal energy is
also used to heat
sidewalks and roads to
prevent freezing in the
winter.
• Most recently, the
Netherlands began
using geothermal
energy to keep bike
lanes from freezing in
the wintertime.

33. Merits of Geothermal Energy
 It is a renewable source of energy.
 By far, it is non-polluting and environment friendly.
 There is no wastage or generation of by-products.
 Geothermal energy can be used directly. In ancient times, people used this
source of energy for heating homes, cooking, etc.
 Maintenance cost of geothermal power plants is very less.
 Geothermal power plants don't occupy too much space and thus help in
protecting natural environment.
 Unlike solar energy, it is not dependent on the weather conditions.
 Geothermal heating system can replace fossil fuel heating system in a
particular area.

34. Demerits
 Only few sites have the potential of Geothermal Energy.
 Most of the sites, where geothermal energy is produced, are
far from markets or cities, where it needs to be consumed.
 There is always a danger of eruption of volcano.
 Installation cost of the power plant is very high.
 There is no guarantee that the amount of energy which is
produced will justify the capital expenditure and operations costs.
 It may release some harmful, poisonous gases that can escape
through the holes drilled during construction.