"Geothermal energy harnesses the Earth's natural heat from beneath its surface to generate clean and sustainable power. This renewable resource utilizes hot water and steam to drive turbines, producing electricity with minimal environmental impact."

1. Geothermal Energy
KALPAJYOTI MAZUMDAR
Roll no. 236104005
PhD Scholar
Earth System Science and Engineering
Presented by-
CE 592 – Exploration Geoscience

2. Content
Introduction to Geothermal Energy
Where Geothermal energy is found
Extraction and uses
Direct and Indirect uses
Geothermal power plants
Geophysical methods in geothermal exploration
Advantages
Disadvantages
Geothermal provinces in India
Conclusion

3. It is simply the heat energy of the earth,
generated by various natural processes, such as :
• Heat from when the planet formed and accreted,
which has not yet been lost
•Decay of radioactive elements
•Friction
Geothermal = Geo (earth) & Thermal (heat)
Introduction
What is Geothermal Energy?

4. Where is Geothermal Energy Found?
• Found along major plate boundaries
where earthquakes and volcanoes are
concentrated
– Geysers
– Hot springs
– Fumaroles
– Geothermal reservoirs
Castle Geyser, Yellowstone
Hot Springs In Japan
Vigorous fumaroles in the summit crater of Mount Martin.
USGS photo taken August 26, 2006.

5. Geothermal
Site
Schematic

6. Plate Boundary:
 A good place to look for Geothermal
energy is in the vicinity of plate
boundaries.
 When they meet at convergent
boundaries, one plate is subducted
under the other, and the melting of
the subducted plate releases
significant amounts of fluids to
volcanic activity and its associated
heat energy.
 In the Atlantic and Pacific Oceans as well as adjacent onshore
areas, we have seen all types of plate boundaries with surface
expressions like volcanic island arcs and volcanic arcs (onshore).
Sometimes these volcanos are active, but often they are extinct with
accessible heat at some depth below.

7. The occurrence of geothermal resources is mainly in the following areas:
the high radioactive heat production zone,
the sedimentary basin and
the modern volcano zone as well as the inner-plate active tectonic zone
Geothermal resources in the high radioactive heat production zone is mainly due to the development
of many large-scale Mesozoic acid granitoids in the shallow surface of the Earth’s surface and crust.
This type of rock mass has high radioactivity heat production characteristics and can obtain good
geothermal resources under ideal heat production and overburdened thickness conditions.
Geothermal resources in the sedimentary basin are mainly due to the low thermal conductivity of the
thick depositional overburden, which prevents the heat loss from the deep heat source. In the modern
volcano zone geothermal resources are closely related to volcanic activity, mainly in areas with strong
volcanic activity. Under the action of tectonic activity, mantle-derived magma is partially melted and
magma diapir rises.

8. The Ring of Fire
Most geothermal activity occurs in the Ring of Fire
The Ring of Fire is a tectonic belt, about 40,000 km (25,000 mi) long and up to about 500 km (310 mi) wide, which circumscribes the
Pacific Ocean.

9. Extraction and Uses
The Lindal diagram shows how geothermal energy resources of different
temperatures can be used for a range of applications. Credit: Geoscience
Australia

10. Geothermal Hotspring Geothermal Greenhouse
Geothermal heat pump
Geothermal Pool

12. Indirect Application: Electricity Production
Geothermal Power Plants
• Require high temperatures (300 F – 700 F)
hydrothermal resources that may either
come from dry steam wells or hot water
wells
• There are three types of geothermal power
plants:
a. dry steam plants,
b. flash steam plants, and
c. binary cycle power plants

13. Dry Steam Plants
• Use steam piped directly from a
geothermal reservoir to turn the
turbogenerator
Image taken from saveonenergy.com

14. Flash Steam Plants
• Takes high pressure hot water from deep inside the earth and
converts it to steam to drive the generator turbines
• When the steam cools it condenses into water and is injected
into the earth to be used over and over again.
• Most geothermal plants are flash steam plants
• As with flash steam plants, these are only suitable for the
hottest geothermal reservoirs (generally associated with
volcanoes) and the gas is in direct contact with the power
plant so it’s chemistry is critical.

15. Flash Steam Power Plants are the most common form of geothermal power plant. The hot water
is pumped under great pressure to the surface. When it reaches the surface the pressure is
reduced and as a result some of the water changes to steam. This produces a ‘blast’ of steam.
The cooled water is returned to the reservoir to be heated by geothermal rocks again.
Image taken from saveonenergy.com

16. Binary Cycle Power Plants
A binary power plant uses hot geothermal fluid to
heat a secondary working fluid in a heat
exchanger. This working fluid turns to steam at a
lower temperature than pure water, and it’s vapor
can then be used to turn a turbine to produce
electricity.
The geothermal fluid is kept within a closed loop
and reinjected through an injection well to recharge
the geothermal reservoir.
A binary plant is used for lower temperature
reservoirs, with fluid less than 200oC.

17. Image
taken
from
saveonenergy.com

18. Various methods of geothermal exploration using geophysical are reported in the literature. According to the basic approaches
used, they can be classified into two main groups:
1. Indirect and
2. Direct methods
1. Indirect or structural methods :
The indirect or structural methods give information on geological parameters which may reveal structures or geological
bodies that are important for the understanding of the geothermal system. These methods are classified as follows:
1.1 Seismic method
1.2 Magnetic measurement
1.3 gravimetric methods
Geophysical methods in Geothermal exploration

19. 1.1 Seismic method:
Seismic methods measure sound velocity distribution and anomalies in the earth as well as attenuation of the sound waves. Active
methods where an external source is used to create sound waves, such as explosions or hammer devices, while passive methods detect
the seismic activity in the earth and use that to get information on parameters that may be influential for the geothermal system.
In active measurements a distinction is made between refraction measurements and reflection measurements, depending on the
procedures. Active measurements give information on the density of the formations, the porosity and texture, boundaries and
discontinuities and fluid-filled zones and thus even temperature.
Passive methods use the natural seismic activity to delineate active faults and permeable zones (shear wave splitting) or to locate the
boundary between brittle and ductile crust, which can be indicative of depth to hear source. This can be important for the
understanding of the geothermal activity in the measured area.

20. 1.2 Magnetic measurements
Magnetic methods are widely used in geothermal exploration, often together with gravity measurements and seismic
refraction, in mapping geological structures. Magnetization of rocks is of two types: induced magnetization (MI), which has
the same direction as the ambient earth’s field; and permanent magnetization (MP), which often predominates in igneous
rocks and depends upon their properties and history.
In mineral exploration and its geo-environmental considerations, the secondary effects in rocks that host ore deposits
associated with hydrothermal systems are important and magnetic surveys may outline zones of fossil hydrothermal activity
1.3 Gravimetric method
The purpose of a relative gravity survey is to directly map the structure of the subsurface. Gravity is the attractive force
between two or more bodies of mass. The force is proportional to the mass of the object, and decreases with distance as seen in
the 1/R2 term of Eq.

21. The density contrast leads to a different gravitational force which is measured, and usually presented in mgal or 103
cm/s2. In order to obtain information about the subsurface density from the gravity measurement, it is necessary to make
several corrections to the measured value. The final corrected values of the gravity anomaly, is called Bouguer anomaly
and is given by :
Assuming these corrections have accurately accounted for the variations in gravitational acceleration, the Corrected
Bouguer Gravity can be assumed to be caused by variation density beneath the observation point .
An important additional application has been the use of precision gravity measurements for monitoring mass extraction
in geothermal systems with production.

22. 2. The direct methods give information on parameters that are influenced by the geothermal activity.
These methods are:
2.1 Geoelectrical method
A survey in the geophysical literature concerning geothermal exploration, and more particularly in electrical methods, reveals the existence of
various techniques and methodologies used. Electrical methods which are used in geothermal exploration measure the electrical resistivity
distribution of the ground in one or another way. From the resistivity distribution in the ground, structural and stratigraphic information can be
obtained.
Principle. The main principle is that electrical current is induced into the earth which generates an electromagnetic signal that is monitored at
the surface
An example is given by resistivity cross-section from the Krafla high-
temperature system in N-Iceland. It reflects well the low resistivity
close to the surface and the higher resistivity below associated with the
exploitable geothermal reservoir at 1–4 km depth. Below that an
extensive low-resistivity body may reflect partially molten magma
Reynolds RL, Rosenbaum JG, Hudson MR, Fishman NS. Rock magnetism, the distribution of magnetic minerals
in the earth’s crust, and aeromagnetic anomalies. In: Hanna W.F. editor. Geologic; 1990

23. 2.2 Thermal methods
In the thermal method, two distinct techniques can be distinguish: borehole or shallow probe methods for measuring thermal
gradient, which is useful itself, and with a knowledge of the thermal conductivity provides a measure of heat flow, and
airborne or satellite-based measurements, which can be used to determine the earth’s surface temperature and thermal inertia
of surficial materials, of thermal infrared radiation emitted at the earth’s surface
The heat exchange mechanism in the earth is important for interpretation of thermal methods. A distinction is made between:
 Conduction, which is based on atomic vibrations, and is important for transfer of heat in the earth’s crust;
Convection, which transfers heat by motion of mass, e.g. natural circulation of hot water; and
Radiation, which does not influence geothermal systems.

24. 3. Other methods
3.1 Remote sensing
Satellite and airborne imagery can map zones of secondary mineral precipitation associated with emerging geothermal fluids
and attributes such as heat flux. Aerial photography and terrain mapping with laser ranging also illuminate surface structural
features associated with geologic settings
3.2Gamma-ray spectrometry
Gamma ray logs send rays into the walls of the well and collect information about relative rock types. This is important for
differentiating between sandstones, which are good sources of fluids, and shale, which has low porosity and permeability and
can surround other rock layers and trap fluids

25. Advantages
• Very high efficiency/high net yield
• Very reliable (runs 24 hrs. a day)
• Very clean – no air pollution or GHGs
• Renewable and sustainable
• Conserves fossil fuels
• Can help decrease dependence of foreign oil
• No transportation involved

26. Disadvantages
• Can’t provide our current energy needs
• Can only be used in certain geologically active areas
• Water contains minerals that can be corrosive and difficult
to dispose of safely
• Harmful gases can escape from deep within the earth
• Piping system requires large areas of land
• Initial costs can be high

27. Geothermal
province in India
https://www.mapsofindia.com/maps/nonconventional/geothermal.htm
Examples of Geothermal Fields in India
1.Puga geothermal field
2.Chhumathang geothermal field
3.Manikaran geothermal field
4.Beas valley
5.Satluj and spiti valley
6.Tapoban geothermal field, Chamoli, Uttarakhand and Alaknanda Valley
7.Tatapani geothermal field
8.Salbardi region
9.Anhoni- Samoni area
10.Unkeshwar
11.Godavari Graben
12.Andaman-Nicobar region
13.Damodar Valley basins
14. Western thermal province
15. Cambay geothermal region
16.Konkan geothermal provinces
17. Sohna thermal region
18.Tuwa and Chhabsar geothermal fields, Gujarat
19.Lasundra geothermal province

28. Geothermal Energy in India:
 Geothermal provinces are estimated to produce 10,600 MW of power.
 Main Geothermal provinces in India: the Himalayas, Sohana, West coast, Cambay, Son-Narmada,
Godavari and Mahanadi
 First operational commercial geothermal power plant is likely to come up in AP with a capacity of 25
MW by Gepsyndicate Pvt Ltd.
 NTPC signed a Memorandum of understanding with Chhattisgarh State for Renewable Enenrgy
Development.

31. The world’s first geothermal power plant in Larderello, Italy, is a dry steam plant. It was built in 1911
and used to power the Italian railway system and the nearby villages of Larderello and Volterra. The plant
has expanded over the years and now produces around 800MW of electricity!

32. General Scenario:
 Systematic efforts to explore the geothermal energy resources commenced in 1973
 Identification of 340 hot springs and 7 proven geothermal provinces in India
 At present there are no operational geothermal plants in India
On going project in India:
 Magneto-telluric investigations in Tattapani geothermal area in Madhya Pradesh
 Magneto-telluric investigation in Puga geothermal area in Ladakh region, Jammu & Kashmir

33. Conclusion
Geothermal heating system can replace fuel heating system in particular area.
Annual coast for common heating purposes can be reduced by more than 60%.
Continued energy shortages have created added interest in geothermal energy for power generation.
Potential exists to provide all energy requirements in the U.S
Geothermal energy appears to be a partial solution to our energy needs.

34. References:
Books:
1. Godfrey, Boyle, Renewable Energy : power for a sustainable future, second edition, Indian Edition,
Oxford University Press,2004,,pp. 342-381
2. Tanseem Abbasi & S.A. Abbasi, Renewable Energy Sources: Their impacts on global warming and
pollution, Eastern Economy Edition, PHI Learning Pvt. Ltd., New Delhi,, pp. 168-190
 Sites:
1. https://www.energy.gov/eere/geothermal/geothermal-
basics#:~:text=Geothermal%20energy%20is%20heat%20energy,depths%20below%20the%20Earth's%20surface
2. https://education.nationalgeographic.org/resource/geothermal-energy/
3. https://www.eia.gov/energyexplained/geothermal/use-of-geothermal-energy.php
4. https://www.researchgate.net/publication/350823763_Geothermal_Energy_A_Review
5. https://www.researchgate.net/publication/318665334_Geothermal_energy

35. Thank You
Thank You