Geothermal energy is heat generated and stored in the Earth. It can be extracted and used to heat buildings through geothermal heat pumps or to generate electricity in geothermal power plants. There are three main types of geothermal power plants - dry steam, flash steam, and binary cycle plants - which convert geothermal reservoirs of steam or hot water into electricity using turbines. Geothermal energy has advantages of being renewable and reducing carbon emissions, but also has disadvantages like potential induced seismic activity and greenhouse gas emissions from geothermal reservoirs.

1. Geothermal Energy
Done by: Sanaz Hussain and Epshita Tarannum

2. Index
What is geothermal energy?
Different uses of geothermal energy.
Dry steam power plant.
Flash steam power plant.
Binary cycle power plant.
Ground source heat pump(GSHP)
Advantages
Disadvantages

3. What is geothermal energy?
Geothermal energy is the heat
energy generated and stored in the
Earth. The geothermal energy of
the Earth’s crust originates from
the original formation of the planet
and from radioactive decay of
materials.
Geothermal energy is a non-
conventional source of energy
which in other words means it is
renewable.
The Blue Lagoon is a geothermal spa in Iceland

4. Different Uses of Geothermal Energy:
 Geothermal energy can be extracted and converted into different forms of
energy so that we can use it in our day to day life. Geothermal energy is
mainly used for –
• Heating water- [Geothermal heat pump(GHP)]
• Air conditioning-[Geothermal heat pump(GHP)]
• Electricity generation-[Geothermal power plants]
 Geothermal energy is converted into electrical energy in geothermal power
plants. Geothermal power plants mainly follow 3 working principles:
• Dry steam
• Flash steam
• Binary cycle

5. Dry steam power
plant:
Steam is directly generated from
geothermal reservoirs and
transferred to a turbine which is
connected to a generator. The
steam causes the turbine to rotate
and the generator produces
electricity. After rotating the
turbine the steam goes to the
condenser where it is converted
into water (condensate) and
injected back to the Earth through
the injection well. However dry
steam power plants cannot be built
everywhere because it requires
natural dry steam hydrothermal
reservoirs which are very rare.

6. Flash steam power
plant:
Power plants using this
working principle are made
where there is an
availability of geothermally
heated water at a high
temperature of 350°
Fahrenheit. This water is
called brine. Brine is
transferred to a tank where
it is converted into steam.
The steam rotates the
turbine which is connected
to a generator and
electricity is produced.
After that, the waste brine
injected back to the Earth.

7. Binary cycle
power plant:
This working principle is
used where there is an
availability of geothermally
heated water at a lower
temperature of 100°
Fahrenheit. The hot water is
passed to heat exchanger
where a mixture vapor is
generated which runs the
turbine. The vapor is cooled
by a condenser and recycled.
The waste water is injected
back to the Earth

9. Geothermal Heat Pumps or Ground Source Heat
Pump (GSHP)-
• A geothermal heat pump or ground source heat pump (GSHP) is a central heating
and cooling system that transfers heat to or from the ground.
• Earth acts as a very large store of heat energy. It can be used as a heat source in
winter, or a heat sink in summer. The ground can be used to moderate the
temperature in buildings standing on it.
• A ground source heat pump provides a clean way to heat buildings, free of all carbon
emissions on site. It can make use of solar energy stored in the ground to provide one
of the most energy-efficient ways of heating buildings. Solar recharge of the ground is
an integral part of ground source energy which is used to increase the efficiency of
ground source heat pumps.
• The only energy used by a ground source heat pump is electricity to power the
compressor and the circulation pumps which transfer heat energy from the ground
into the building. A well designed ground source heat pump installation will deliver
three or four times as much thermal energy (heat) as is used in electrical energy to
drive the system.

12. Advantages -
• There is no combustion involved and no emission of potentially
dangerous gases. No fuels are required.
• Heat pumps can also provide cooling in summer, as well as heating in
winter. Ground source heat pumps are the only renewable energy
technology that can benefit from the thermal energy storage properties of
the ground to recycle heat from summer to winter
• Ground Source Heat Pumps save money. Heat pumps are much cheaper
to run than direct electric heating systems.
• GSHPs require less maintenance than combustion based heating
systems. They also have a longer life than combustion boilers.

13. Disadvantages
• Potential emissions of greenhouse gases below the earth surface might
migrate to the earth surface and the atmosphere which can lead to an
increase in pollution level. Such emissions are higher in areas near
geothermal power plants.
• Construction of geothermal power plants can affect the stability of
land. In January 1997, the construction of a geothermal power plant in
Switzerland triggered an earthquake with a magnitude of 3.4 on the
Richter scale.
• Geothermal heat pumps have to be powered in order to function which
leads consumption of more energy in turn.

14. Quiz-
• What is geothermal energy ?
• Name two advantages of geothermal energy.
• Give example of a liquid that can be used as secondary liquid in binary cycle power
plant.
• Name two disadvantages of geothermal energy.
• Do you think we should use geothermal energy for the future? Why?

15. Bibliography
• https://openei.org/wiki/Definition:Ground_Source_Heat_Pumps
• https://www.azocleantech.com/article.aspx?ArticleID=335
• http://www.gshp.org.uk/Geothermal_Heat_Pumps.html

16. Thank You!:)