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					GEOTHERMAL POWER GENERATING TECHNOLOGY
   (NON-CONVENTIONAL ENERGY RESOURCE)

ABSTRACT:As the second-largest country of the world,                              found in "geothermal systems" which are regionally
undergoing explosive growth, India represents a unique and little-                localized geologic settings where the earth's naturally
tapped source of expertise on multifarious issues of economic and                 occurring heat flow is near enough to the earth’s surface
social development. Among many other problems of concern, the                     to bring steam or hot water to the surface.
development of alternative sources of energy is crucial to the
future wellbeing of India – indeed, of the globe. The increasing       GEOTHERMAL POWER GENERATION PLANTS:There are
demand of the energy has forced the mankind to find a way out          three types of geothermal power generation plants:
which will be efficiently and abundantly available source of
energy. This made the human race to think of the beneficiaries of                DRY STEAM POWER PLANT
non-conventional energy development in India. Today one of the                   FLASH STEAM POWER PLANT
latest trends of non-conventional energy development to be                       BINARY CYCLE POWER PLANT
implemented in our country is “GEOTHERMAL POWER                        DRY STEAM POWER PLANT:
GENERATING TECHNOLOGY”.Geothermal energy is a proven
resource for direct heat and power generation. In over 30 countries                Steam plants use hydrothermal fluids that are primarily
geothermal resources provide directly used heat capacity of 12,000     steam. The steam goes directly to a turbine, which drives a
MW and electric power generation capacity of over 8,000 MW. It         generator that produces electricity. The steam eliminates the need
meets a significant portion of the electrical power demand in          to burn fossil fuels to run the turbine. (Also eliminating the need to
several developing countries. Individual geothermal power plants       transport and store fuels!) This is the oldest type of geothermal
can be as small as 100 kW or as large as 100 MW depending on           power plant. It was first used at Lardarello in Italy in 1904, and is
the energy resource and power demand. Geothermal basically             still very effective. These plants emit on excess steam and very
means “earth’s heat”, which is used to produce power.The               minor amounts of gases.
Geothermal energy will avail a greater advantage of producing
power from the non-conventional source. In this method there are
more of advantages as compared to other non-conventional sources
of energy generation. Geothermal energy will be dearer to the
human race as it clean, reliable, flexible and economical form of
energy used for industries, commercial users, greenhouses,
aquaculture and many more applications. Use of this form of
energy can greatly minimize the impact, resulting in environmental
benefits for many states and local communities with growing
energy needs; also the use of geothermal energy keeps our
environment clean.

CONTENTS

          INTRODUCTION
          GEOTHERMAL POWER GENERATION PLANTS
          HOW GEOTHERMAL HEAT GET UPTO EARTH’S
           SURFACE
          USE OF GEOTHERMAL ENERGY TECHNOLOGY
          APPLICATIONS OF GEOTHERMAL ENERGY
           TECHNOLOGY
          IMPACTS OF GEOTHERMAL TECHNOLOGY                             FLASH STEAM POWER PLANTS:
                                                                                   Hydrothermal fluids above 360ºF (182ºC) can be used
          BENEFITS                                                    in flash plants to make electricity. Fluid is sprayed into a tank held
                                                                       at a much lower pressure than the fluid, causing some of the fluid
          CONCLUSION                                                  to rapidly vaporize, or "flash." The vapor then drives a turbine,
                                                                       which drives a generator. If any liquid remains in the tank, it can
           INTRODUCTION:The term geothermal comes from                 be flashed again in a second tank to extract even more energy.
           the Greek geo meaning earth and therein meaning heat
           thus geothermal energy is energy derived from the
           natural heat of the earth. The earth's temperature varies
           widely, and geothermal energy is usable for a wide
           range of temperatures from room temperature to well
           over 300° F. For commercial use, a geothermal
           reservoir capable of providing hydrothermal (hot water
           and steam) resources is necessary. Geothermal
           reservoirs are generally classified as being either low
           temperature (<150° C) or high temperature (>150° C).
           Generally speaking, the high temperature reservoirs are
           the ones suitable for, and sought out for commercial
           production of electricity. Geothermal reservoirs are
BINARY CYCLE POWER PLANTS:                                             much as 80% over fossil fuels. Direct use is also very clean,
Most geothermal areas contain moderate-temperature water (below        producing only a small percentage (and in many cases none) of the
400 degrees F). Energy is extracted from these fluids in binary-       air pollutants emitted by burning fossil fuels.
cycle power plants. Hot geothermal fluid and a secondary (hence,
"binary") fluid with a much lower boiling point than water pass        The Direct–Use Resource
through a heat exchanger. Heat from the geothermal fluid causes
the secondary fluid to flash to vapor, which then drives the                       In India the Geothermal is also applicable and many
turbines. Because this is a closed-loop system, virtually nothing is   surveys are being conducted to analyze the geothermal resources in
emitted to the atmosphere. Moderate-temperature water is by far        many parts of northern India.According to survey conducted in
The more common geothermal resource, and most geothermal               U.S low–temperature geothermal resources exist throughout the
power plants in the future will be binary-cycle plants.                western U.S., and there is tremendous potential for new direct–use
                                                                       applications. A recent survey of 10 western states identified more
                                                                       than 9000 thermal wells and springs, more than 900 low– to
                                                                       moderate–temperature geothermal resource areas, and hundreds of
                                                                       direct–use sites.The survey also identified 271 collocated sites –
                                                                       cities within 5 miles (8 kilometers) of a resource hotter than 122
                                                                       degrees F (50 degrees C) – that have excellent potential for near–
                                                                       term direct use. If these collocated resources were used only to
                                                                       heat buildings, the cities have the potential to displace 18 million
                                                                       barrels of oil per year!

                                                                                  Tapping the Resource

                                                                       Direct–use systems typically include three components:
HOW GEOTHERMAL HEAT GET UP TO EARTH'S
SURFACEThe heat from the earth's core continuously flows
outward. It transfers (conducts) to the surrounding layer of rock,
                                                                                 A production facility – usually a well – to bring the hot
                                                                                  water to the surface;
the mantle. When temperatures and pressures become high enough,
some mantle rock melts, becoming magma. Then, because it is                      A mechanical system – piping, heat exchanger, controls
lighter (less dense) than the surrounding rock, the magma rises                   – to deliver the heat to the space or process; and
(convects), moving slowly up toward the earth's crust, carrying the
heat from below. Sometimes the hot magma reaches all the way to                  A disposal system – injection well or storage pond – to
the surface, where we know it as lava. But most often the magma                   receive the cooled geothermal fluid.
remains below earth's crust, heating nearby rock and water                       A disposal system – injection well or storage pond – to
(rainwater that has seeped deep into the earth) - sometimes as hot                receive the cooled geothermal fluid.
as 700 degrees F. Some of this hot geothermal water travels back
up through faults and cracks and reaches the earth's surface as hot
springs or geysers, but most of it stays deep underground, trapped      Greenhouse and Aquaculture FacilitiesGreenhouses and
in cracks and porous rock. This natural collection of hot water is     aquaculture (fish farming) are the two primary uses of geothermal
called a geothermal reservoir.                                         energy in the agribusiness industry. Most greenhouse operators
                                                                       estimate that using geothermal resources instead of traditional
                                                                       energy sources saves about 80% of fuel costs – about 5% to 8% of
THE FUTURE OF GEOTHERMAL ELECTRICITY:Steam and                         total operating costs. The relatively rural location of most
hot water reservoirs are just a small part of the geothermal           geothermal resources also offers advantages, including clean air,
resource. The Earth's magma and hot dry rock will provide cheap,       few disease problems, clean water, a stable workforce, and, often,
clean, and almost unlimited energy as soon as we develop the           low taxes.
technology to use them. In the meantime, because they're so
abundant, moderate-temperature sites running binary-cycle power
plants will be the most common electricity producers.                  Industrial and Commercial Uses

                                                                       Industrial applications include food dehydration, laundries, gold
USE OF GEOTHERMAL ENERGY TECHNOLOGY AND                                mining, milk pasteurizing, spas, and others. Dehydration, or the
RESOURCES: Direct Use of Geothermal Energy                             drying of vegetable and fruit products, is the most common
                                                                       industrial use of geothermal energy. The earliest commercial use of
Geothermal reservoirs of low-to moderate-temperature water –           geothermal energy was for swimming pools.
68ºF to 302ºF (20ºC to 150ºC) – provide direct heat for residential,
industrial, and commercial uses. This resource is widespread in        APPLICATIONS            OF       GEOTHERMAL              ENERGY
the U.S., and is used to heat homes and offices, commercial            TECHNOLOGY:
greenhouses, fish farms, food processing facilities, gold mining
operations, and a variety of other applications. Spent fluids from     The three main applications of Geothermal Energy
geothermal electric plants can be subsequently used for direct use
applications in so-called "cascaded" operation.Direct use of           PowerPlants
geothermal energy in homes and commercial operations is much
less expensive than using traditional fuels. Savings can be as         Power plant technologies are being used to convert hydrothermal


    239
fluids to electricity. The type of conversion used depends on the             Easy on the land. The land area required for
                                                                              geothermal power plants is smaller per megawatt than
state of the fluid (whether steam or water) and its temperature.
                                                                              for almost every other type of power plant. Geothermal
                                                                              installations don't require damming of rivers or
DirectUse                                                                     harvesting of forests -- and there are no mine shafts,
                                                                              tunnels, open pits, waste heaps or oil spills.
Geothermal reservoirs of low-to moderate-temperature water —
68°F to 302°F (20°C to 150°C) — provide direct heat for
                                                                             Reliable. Geothermal power plants are designed to run
residential, industrial, and commercial uses. This resource is                24 hours a day, all year. A geothermal power plant sits
                                                                              right on top of its fuel source. It is resistant to
widespread in the U.S., and is used to heat homes and offices,
                                                                              interruptions of power generation due to weather,
commercial greenhouses, fish farms, food processing facilities,               natural disasters or political rifts that can interrupt
                                                                              transportation of fuels.
gold mining operations, and a variety of other applications.
                                                                             Flexible. Geothermal power plants can have modular
GeothermalHeatPumps
                                                                              designs, with additional units installed in increments
The geothermal heat pump, also known as the ground source heat
                                                                              when needed to fit growing demand for electricity.
pump, is a highly efficient renewable energy technology that is
gaining wide acceptance for both residential and commercial
                                                                             Helps    Developing     Countries   Grow.    Geothermal
buildings. Geothermal heat pumps are used for space heating and
                                                                              projects can offer all of the above benefits to help
cooling, as well as water heating. Its great advantage is that it
                                                                              developing countries grow without pollution. And
works by concentrating naturally existing heat, rather than by
                                                                              installations in remote locations can raise the standard
producing heat through combustion of fossil fuels.
                                                                              of living and quality of life by bringing electricity to
                                                                              people far from "electrified" population centers.


IMPACTS OF GEOTHERMAL TECHNOLOGY:                                        CONCLUSION:

            All energy development and production impacts the
environment to some degree. But the use of geothermal energy can                So from the above presented information it has been
greatly minimize these impacts, resulting in environmental benefits
for many states and local communities with growing energy needs.         clear that   “GEOTHERMAL POWER                GENERATING
The use of geothermal energy helps keep our air and water clean.         TECHNOLOGY” is a latest & good form of non
The use of geothermal energy also greatly minimizes the amount
of resulting solid waste and land required for energy production.        conventional energy which will be a substitute to the
When local communities use geothermal power plants, they can             conventionally    produced     energy.   In    this      modern
easily:
                                                                         technological sphere of life the geothermal energy would

                Meet clean air standards                                become the best and abundantly available form of energy.

                Minimize     solid   waste    and    recover/recycle    By this method the energy is produced with very less amount
                 minerals                                                of environmental pollution in a more efficient way. The
                Meet water quality and conservation standards           energy produced here can be used for a numerous
                Minimize land use and impact.                           applications. It also provides employment to a huge number
                                                                         of people. So with the benefits of this geothermal technology
BENEFITS:
                                                                         this form of energy can provide power to a considerable

           Clean. Geothermal power plants, like wind and solar          amount of loads
            power plants, do not have to burn fuels to manufacture
            steam to turn the turbines. Generating electricity with
            geothermal energy helps to conserve nonrenewable             REFERENCES:
            fossil fuels, and by decreasing the use of these fuels, we
            reduce emissions that harm our atmosphere. There is no
            smoky air around geothermal power plants -- in fact              ENERGY FOR THE FUTURE,(Eds Sir Denis Rooke),
            some are built in the middle of farm crops and forests,           Ian Fells and John Horlock, Published by E& FN SPON
            and share land with cattle and local wildlife.
                                                                              ,The Royal Society,1995.




    240
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   http://ces.iisc.ernet.in/energy/paper/ires/solarenergy.ht
    ml




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posted:8/26/2012
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