geothermalenergy by sujit

Monday, May 1, 2023 Geothermal Energy 1

GEOTHERMAL ENERGY

SUJIT KUMAR ROY

ENVIRONMENTAL SCIENCE & HAZARD

STUDIES.

NOAKHALI SCIENCE &

TECHNOLOGY UNIVERCITY

Monday, May 1, 2023 Geothermal Energy

Agenda : 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


What is Geothermal?

Geothermal comes from the Greek words geo (earth)and therme (heat).

Thus, geothermal energy means heat inside the earth.


The Earth Is Made of Layers


The Earth Is Made of Layers

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.


Temperature Of Earth Crust


History of Geothermal energy

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.


Most geothermal activity occurs in an area called the Ring of Fire.


Locations 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.

http://upload.wikimedia.org/wikipedia/commons/0/09/Pacific_Ring_of_Fire.png


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.

Where Can We Find Geothermal Energy?


Use Of Geothermal EnergyDirect use: District Heating System.Electricity generation.Heat pumps.


Direct District Heating System

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.


Use Of Direct HeatHot Water ProductionPiped Under Roads In Greenhouses to Grow

Flowers,vegetables etc.Industrial Uses: dry wood, pasteurize

milk, grow fish, etc.Space Heating


Electricity GenerationDry 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.


Electricity GenerationBinary 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

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Electricity GenerationFlash 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.

Geothermal Energy


What Makes a Good Geothermal Reservoir for Generating Electricity?

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.


Heat Pumps

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.


The Use Geothermal Heat Pump

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.


Environmental Impact

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


Atmospheric Pollution 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.


OVER ALL ADVANTAGE : 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.


OVER ALL DISADVANTAGE :

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.


Bangladesh and geothermal energy 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.

Monday, May 1, 2023 Geothermal Energy

Conclusion: Geothermal 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.

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