GEOTHERMAL ENERGYINTRODUCTION

By

J. VivekM.E. Solar Energy

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CONTENTS What is geothermal energy Geothermal reservoir How it is used

i. Direct useii. Power productioniii. Heat pumps

Advantages and disadvantages

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GEOTHERMAL ENERGY

Geothermal energy is defined as, getting heat energy from the earth. It is consider as one of the renewable energy because the heat is flow from the interior of the earth continuously.

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EARTH TEMPERATURE GRADIENT

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GEOTHERMAL RESERVOIRThe heat from the Earth’s core continuously flows outward and heat the outer layer of the rock called mantle. When it come to molten state then it is called magma. Magma can reach just below the earth surface.Rain water sometimes go down through the geological fault lines or crack and it is super heated by magma, then hot water reservoir is formed. It is known as geothermal reservoir.

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USES Geothermal direct use Geothermal electricity production Geothermal heat pumps.

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GEOTHERMAL DIRECT USE

Direct use is suitable for low temperature applications(200 to 1500C). Hot water from geothermal resources can be used for a number of purposes.

In modern direct-use systems, a well is drilled into a geothermal reservoir to provide a steady stream of hot water. 

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DIRECT USE APPLICATIONS Drying crops Industrial processes, such as

pasteurizing milk, the drying of vegetable and fruit products

Spas

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Geothermal power production

There are three commercial types of geothermal power plants.

Flash power plants Dry steam power plants Binary power plants

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Flash power plants Steam with water is extracted from

the geothermal reservoir Heated water under high pressure is

separated in a surface vessel (called a steam separator) into steam and hot water.

The steam is delivered to the turbine, and the turbine powers a generator. The liquid is injected back into the reservoir

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Flash Power Plant

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DRY STEAM POWER PLANTS Dry steam is extracted directly

from the geothermal reservoir.(1800 – 2200C)

Steam is used to run the turbines that power the generator, and no separation is necessary because wells only produce steam.

Steam is condensed and pumped back into the ground

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Dry Steam Power Plant

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BINARY POWER PLANTS

Low temperature rang 100 – 1500C Use low boiling fluids like iso butane

and iso pentane. Hot water from the reservoir heat the

working fluid and it will vaporized. This vapor is used to run the turbine.

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Binary Power Plant

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HOT DRY ROCK TECHNOLOGY This technology is used, where rock

under earth is have enough heat but there is no water reservoir.

Here reservoir is formed manually. Water supply in to hot rocks and

steam is produced. Then it is extracted through pipe

and used for required applications.

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GEOTHERMAL HEAT PUMPS

The upper 10 feet of the Earth, maintains a nearly constant temperature between 50° and 60°F (10°-16°C).

This ground temperature is warmer than the air above it in the winter and cooler than the air in the summer. Geothermal heat pumps take advantage of this resource to heat and cool buildings.

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ADVANTAGES Low emission Low running cost Less area is required Renewable Power can produce continuously.

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Disadvantages Limited capacity Installation cost is high Limited location Requires careful selection of

materials.

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