Transcript of a seminar report on geothermal energy
- 1. Chapter 1 INTRODUCTION 1.1 ABSTRACT Electricity is produced
by geothermal in 24 countries, five of which obtain 15-22% of their
national electricity production from geothermal energy. Direct
application of geo- thermal energy (for heating, bathing etc.) has
been reported by 72 countries. By the end of 2004, the worldwide
use of geothermal energy was 57 TWh/yr of electricity and 76 TWh/yr
for direct use. Ten developing countries are among the top fifteen
countries in geothermal electricity production. Six developing
countries are among the top fifteen countries reporting direct use.
China is at the top of the latter list. It is considered possible
to increase the ins-talled world geothermal electricity capacity
from the current 10 GW to 70 GW with present technology, and to 140
GW with enhanced technology. Enhanced Geothermal Systems, which are
still at the experimental level, have enormous potential for
primary energy recovery using new heat-exploitation technology to
extract and utilise the Earth's stored thermal energy. Present
investment cost in geothermal power stations is 2-4.5 million
euro/MWe, and the generation cost 40-100 euro/MWh.2 Direct use of
geothermal energy for heating is also commercially competitive with
con- ventional energy sources. Scenarios for future development
show only a moderate increase in traditional direct use
applications of geothermal resources, but an exponential increase
is foreseen in the heat pump sector, as geothermal heat pumps can
be used for heating and/or cooling in most parts of the world. CO2
emission from geothermal power plants in high-temperature fields is
about 120 g/kWh (weighted average of 85% of the world power plant
capacity). Geothermal heat pumps driven by fossil fuelled
electricity reduce the CO2 emis-sion by at least 50% compared with
fossil fuel fired boilers. If the electricity that drives the
geothermal heat pump is produced from a renewable energy source
like hydropower or geothermal energy the emission savings are up to
100%.3 Geothermal energy is available day and night every day of
the year and can thus serve as a supplement to energy sources which
are only available intermittently. Renewable energy sources can
contribute significantly more to the mitigation of climate change
by cooperating than by competing. 1.2 INTRODUCTION Electricity is
produced by geothermal in 24 countries, five of which obtain 15-
22% of their national electricity production from geothermal
energy. Direct applicati- on of geothermal energy (for heating,
bath ing etc.) has been reported by 72 countries. By the end of
2004, the worldwide use of geothermal energy was 57 TWh/yr of
electricity and 76 TWh/yr for direct use. Ten developing countries
are among the top fifteen countries in geothermal electri-city
production. Six developing countries are among the top fifteen
countries report-ing direct use. China is at the top of the latter
list. It is considered possible to in-crease the installed world
geothermal elec-tricity capacity from the current 10 GW to 70 GW
with present technology, and to 140 GW with enhanced technology.
Enhanced Geothermal Systems, which are still at the experimental
level, have enormous potential for primary energy recovery using
new heat-exploitation tech- nology to extract and utilise the
Earths stored thermal energy. Present investment cost in geothermal
power stations is 2-4.5 million euro/MWe, and the generation cost
40-100 euro/MWh. 1
- 2. Direct use of geothermal energy for heating is also
commercially competitive with conventional energy sources.
Scenarios for future development show only a moderate increase in
traditional direct use applications of geothermal resources, but an
exponential increase is foreseen in the heat pump sector, as
geo-thermal heat pumps can be used for heating and/or cooling in
most parts of the world. CO2 emission from geothermal power plants
in high-temperature fields is about 120 g/kWh (weighted average of
85% of the world power plant capacity). Geothermal heat pumps
driven by fossil fuelled electricity reduce the CO2 emission by at
least 50% compared with fossil fuel fired boilers. If the
electricity that drives the geothermal heat pump is produced from a
renewable energy source like hydropower or geothermal energy the
emission savings are up to 100%. Geothermal energy is available day
and night every day of the year and can thus serve as a supplement
to energy sources which are only available intermit-tently.
Renewable energy sources can con- tribute significantly more to the
mitigation of climate change by cooperating than by competing. The
most important source of informa-tion for this contribution is a
position pa-per of the International Geothermal Asso-ciation (IGA)
presented at the IPPC Meet-ing on Renewable Energy Sources
(Frid-leifsson et al., 2008). The cost analysis is based on a very
detailed Geothermal Energy Association paper (GEA, 2005). 1.3
PRESENT STATUS Although geothermal energy is catego-rised in
international energy tables am-ongst the new renewables, it is not
a new energy source at all. People have used hot springs for
bathing and washing clothes since the dawn of civilisation in many
parts of the world. An excellent book has been published with
historical records and stories of geothermal utilisation from all
over the world (Cataldi et al., 1999). Electricity has been
generated com-mercially by geothermal steam since 1913, and
geothermal energy has been used on the scale of hundreds of MW for
five decades both for electricity generation and direct use. The
utilisation has increased rapidly during the last three decades.
Geothermal resources have been identified in some 90 countries and
there are quan-tified records of geothermal utilisation in 72
countries. Summarised information on geothermal use in the
individual countries for electricity production and direct use
(heating) is available in Bertani (2005) and Lund et al. (2005),
respectively. Electricity is produced by geothermal energy in 24
countries. Five of these countries obtain 15-22% of their national
electricity pro-duction from geothermal (Costa Rica, El Salvador,
Iceland, Kenya and the Philip-pines). In 2004, the worldwide use of
geothermal energy was about 57 TWh/yr of electricity, and 76 TWh/yr
for direct use. The installed electric capacity in 2004 was 8,933
MWe. The world geothermal electricity pro-duction increased by 16%
from 1999 to 2004 (annual growth rate of 3%). Direct use in-creased
by 43% from 1999 to 2004 (annual growth rate of 7.5%). Only a small
fraction of the geothermal potential has been developed so far, and
there is ample opportunity for an increased use of geo-thermal
energy both for direct applications and electricity production
(Gawell et al. 1999). The installed electrical capacity achi-eved
an increase of about 800 MWe in the three year term 2005-2007,
following the rough standard linear trend of approxi-mately 200/250
MWe . 2
- 3. Geothermal energy has until recently had a considerable
economic potential only in areas where thermal water or steam is
found concentrated at depths less than 3 km in restricted volumes,
analogous to oil in commercial oil reservoirs (Cataldi, 1999,
Fridleifsson, 1999). This has changed in the last two decades with
the development of power plants that can economically uti-lise
lower temperature resources (around 100C) and the emergence of
ground source heat pumps using the earth as a heat source for
heating or as a heat sink for cooling, depending on the season.
This has made it possible for all countries to use the heat of the
earth for heating and/or cooling, as appropriate. It should be
stressed that heat pumps can be used basically everywhere. CHAPTER
2 GEOTHERMAL RESERVOIRS 2.1 WHAT IS RESERVOIR 3
- 4. A geothermal reservoir is a volume of rocks in the
subsurface which exploitaton in terms of heat can be economically
profitable. It should be noted that for producing the heat from the
subsurface is necessary the presence of a transport fluid (usually
water), and that drilling to an enough depth to reach the optimum
operation temperatures is also necessary. These factors and the
technical and other concerns entail costs which increase with
depth. The temperature of the fluid and the possible applications
are important to sort reservoirs. Thus, four types of geothermal
reservoirs can be defined: 2.1.1 High temperature: These reservoirs
provide enough heat to make electricity from steam profitably. High
temperature reservoirs are generally more than 150 C, and are
located in areas of thin lithospheric thinness or active volcanism.
Within the group of high-temperature geothermal reservoirs there
are "Hot Dry Rock" (HDR) geothermal reservoirs, which are exploited
by the techniques called "stimulation of geothermal reservoirs"
(EGS: Enhanced Geothermal System). They consist of fracturing a
mass of deep rock to create a geothermal reservoir allowing the
circulation of fluids inside it. These reservoirs not require high
thermal gradients, but a very specific geological context. Although
the implementation of such reservoir is still experimental (i.e.
Soultz-sous-Frets, in France) in Catalonia have been granted some
exploration permits. 2.1.2 Middle temperature: Despite these
reservoirs have a lower temperature compared to the high
temperature ones, they allow extracting sufficient heat to produce
electricity (but with lower performances) using a volatile fluid.
The reservoirs usually reach temperatures between 100 and 150 C,
and are located in areas with favourable structural and geological
contexts and geothermal gradients higher than the average. Their
direct use may be in heating mode and their main applications are
in district heating systems and industrial processes. 2.1.3 Low
temperature: The temperature of these reservoirs is between 100 and
30 C. They are located in areas with a favourable geological
context including deep aquifers; the geothermal gradient is like
the average in the region. Their exploitation involves pumping hot
groundwater from the aquifer and re-injecting it after it has
delivered the heat and is cold again. These are used in direct
applications and for district heating systems and industrial
processes. 2.1.4 Very low temperature: The temperature of these
reservoirs is below 30 C. In these, the underground is used as a
heat exchanger, by means of a heat pump in a closed circuit. Their
applications are in domestic and agricultural air conditioning
systems. These kinds of reservoirs may be anywhere, because their
efficiency is just determined by the underground thermal inertia in
normal (average) geothermal gradient conditions. 4
- 5. Geothermal heat pumps (GHPs) are one of the fastest growing
applications of renewable energy in the world today (Ry-bach,
2005). They represent a rather new but already well-established
technology, utilising the immense amounts of energy stored in the
earths interior. This form for direct use of geothermal energy is
based on the relatively constant ground or gro-undwater temperature
in the range of 4C to 30C available anywhere in the world, to
provide space heating, cooling and domestic hot water for homes,
schools. CHAPTER 3 USES OF GEOTHERMAL ENERGY 3.1 OVERVIEW
Geothermal reservoirs of low-to moderate-temperature water 68F to
302F (20C to 150C) provide direct heat for residential, industrial,
and commercial uses. This resource is widespread in the United
States, and is used to heat homes and offices, 5
- 6. commercial greenhouses, fish farms, food processing
facilities, gold mining operations, and a variety of other
applications. In addition, spent fluids from geothermal electric
plants can be subsequently used for direct use applications in
so-called "cascaded" operation. Direct use of geothermal energy in
homes and commercial operations is much less expensive than using
traditional fuels. Savings can be as much as 80% over fossil fuels.
Direct use is also very clean, producing only a small percentage
(and in many cases none) of the air pollutants emitted by burning
fossil fuels. 3.2 THE DIRECT-USE RESOURCE Low-temperature
geothermal resources exist throughout the western U.S., and there
is tremendous potential for new direct-use applications. A survey
of 10 western states identified more than 9,000 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!
3.3 ACCESSING THE RESOURCE Direct-use systems typically include
three components: Production facility usually a well to bring the
hot water to the surface; Mechanical system piping, heat exchanger,
controls to deliver the heat to the space or process; and Disposal
system injection well or storage pond to receive the cooled
geothermal fluid. 3.4INDUSTRIAL AND COMMERCIAL USES Industrial
applications include food dehydration, laundries, gold mining, milk
pasteurizing, spas, and others. Dehydration, or the drying of
vegetable and fruit products, is the most common industrial use of
geothermal energy. The earliest commercial use of geothermal energy
was for swimming pools and spas. In 1990, 218 resorts were using
geothermal hot water. 6
- 7. 3.6GEOTHERMAL ELECTRICITY PRODUCTION Most power plants need
steam to generate electricity. The steam rotates a turbine that
activates a generator, which produces electricity. Many power
plants still use fossil fuels to boil water for steam. Geothermal
power plants, however, use steam produced from reservoirs of hot
water found a couple of miles or more below the Earth's surface.
There are three types of geothermal power plants:dry steam, flash
steam, and binary cycle. Dry steam power plants draw from
underground resources of steam. The steam is piped directly from
underground wells to the power plant, where it is directed into a
turbine/generator unit. There are only two known underground
resources of steam in the United States: The Geysers in northern
California and Yellowstone National Park in Wyoming, where there's
a well-known geyser called Old Faithful. Since Yellowstone is
protected from development, the only dry steam plants in the
country are at The Geysers. Flash steam power plants are the most
common. They use geothermal reservoirs of water with temperatures
greater than 360F (182C). This very hot water flows up through
wells in the ground under its own pressure. As it flows upward, the
pressure decreases and some of the hot water boils into steam. The
steam is then separated from the water and used to power a
turbine/generator. Any leftover water and condensed steam are
injected back into the reservoir, making this a sustainable
resource. Binary cycle power plants operate on water at lower
temperatures of about 225-360F (107-182C). These plants use the
heat from the hot water to boil a working fluid, usually an organic
compound with a low boiling point. The working fluid is vaporized
in a heat exchanger and used to turn a turbine. The water is then
injected 7
- 8. back into the ground to be reheated. The water and the
working fluid are kept separated during the whole process, so there
are little or no air emissions. 3.7GEOTHERMAL HEAT PUMPS (GHPS)
Geothermal heat pumps take advantage of the Earths relatively
constant temperature at depths of about 10 ft to 300 ft. GHPs can
be used almost everywhere in the world, as they do not share the
requirements of fractured rock and water as are needed for a
conventional geothermal reservoir. GHPs circulate water or other
liquids through pipes buried in a continuous loop, either
horizontally or vertically, under a landscaped area, parking lot,
or any number of areas around the building. The Environmental
Protection Agency considers them to be one of the most efficient
heating and cooling systems available. Animals burrow underground
for warmth in the winter and to escape the heat of the summer. The
same idea is applied to GHPs, which provide both heating and
cooling solutions. To supply heat, the system pulls heat from the
Earth through the loop and distributes it through a conventional
duct system. For cooling, the process is reversed; the system
extracts heat from the building and moves it back into the earth
loop. It can also direct the heat to a hot water tank, providing
another advantage free hot water. GHPs reduce electricity use 3060%
compared with traditional heating and cooling systems, because the
electricity which powers them is used only to collect, concentrate,
and deliver heat, not to produce it. 3.8 HEATING USES Geothermal
heat is used directly, without involving a power plant or a heat
pump, for a variety of applications such as space heating and
cooling, food preparation, hot spring 8
- 9. bathing and spas (balneology), agriculture, aquaculture,
greenhouses, and industrial processes. Uses for heating and bathing
are traced back to ancient Roman times. (2) Currently, geothermal
is used for direct heating purposes at sites across the United
States. U.S. installed capacity of direct use systems totals 470 MW
or enough to heat 40,000 average-sized houses. The Romans used
geothermal water to treat eye and skin disease and, at Pompeii, to
heat buildings. Medieval wars were even fought over lands with hot
springs. The first known "health spa" was established in 1326 in
Belgium at natural hot springs. And for hundreds of years, Tuscany
in Central Italy has produced vegetables in the winter from fields
heated by natural steam. CHAPTER 4 TYPES OF GEOTHERMAL PLANT 4.1
GEOTHERMAL POWER PLANT Geothermal power comes from the slow decay
of radioactive minerals such as uranium, which causes the rocks to
become magma. Tectonic plate movement causes the movement of magma
up from the edges, forming a reservoir in which geothermal steam
and hot water can be recovered through wells. 9
- 10. Geothermal energy uses heat to produce steam, which in turn
powers a generator to produce electricity. Geothermal energy is
generated deep in the ground, in the form of hot molten rock, or a
Magma formed from the collapse of radioactive materials like
uranium. This energy becomes available to us at the borders of
tectonic plates, when rubbing together and sliding under the
another, causing the magma to break from the edges and pushed to
the Earths surface forming a geothermal reservoir. 4.2 DRY STEAM
POWER PLANT The first is the dry steam power plant which is used to
generate power directly from the steam generated inside the
earth.In this case, we do not need additional heating boilers and
boiler fuel, as steam or water vapour fill the wells through rock
catcher and directly rotates the turbine, which activates a
generator to produce electricity. This type of power plant is not
common since natural hydrothermal reservoirs dry steam are very
rare. There are four commercial types of geothermal power plants:
a. flash power plants, b. dry steam power plants, c. binary power
plants, and d. flash/binary combined power plants. 10
- 11. 4.3 FLASH STEAM POWER PLANT The most common type of
geothermal power plant, flash steam plants use waters at
temperatures greater than 360F. As this hot water flows up through
wells in the ground, it is collected in a flash tank where drop in
pressure causes the liquid to boil into steam.The steam is
separated from the liquid which is then used to run turbines which
in turn generate power. The condensed steam is returned to the
reservoir 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. Fluid is sprayed
into a tank held at a much lower pressure than the fluid, 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 (double flash)
to extract even more energy. 4.4 BINARY STEAM POWER PLANT This type
of plant uses high temperature geothermal water to heat another
fluid which has a lower boiling point than water. This fluid
vaporizes to steam, drives the turbines, then condenses to liquid
to begin the cycle again. The water, which never comes into direct
contact with the working fluid, is then injected back into the
ground to be reheated. Since the most resources are with lower
temperature the binary steam power plants are more common. 11
- 12. Most geothermal areas contain moderate-temperature water
(below 400F). Energy is extracted from these fluids in binary-cycle
power plants. Hot geothermal fluid and a secondary (hence,
"binary") 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.
Because this is a closed-loop system, virtually nothing is emitted
to the atmosphere. Moderate-temperature water is by far the more
common geothermal resource, and most geothermal power plants in the
future will be binary-cycle plants. Recent advances in geothermal
technology have made possible the economic production of
electricity from geothermal resources lower than 150C (302F). Known
as binary geothermal plants, the facilities that make this possible
reduce geothermal energys already low emission rate to zero. Binary
plants typically use an Organic Rankine Cycle system. The
geothermal water (called geothermal fluid in the accompanying
image) heats another liquid, such as isobutane or other organic
fluids such as pentafluoropropane, which boils at a lower
temperature than water. The two liquids are kept completely
separate through the use of a heat exchanger, which transfers the
heat energy from the geothermal water to the working fluid. The
secondary fluid expands into gaseous vapor. The force of the
expanding vapor, like steam, turns the turbines that 12
- 13. power the generators. All of the produced geothermal water
is injected back into the reservoir. 4.5 SITE SELECTION OF
GEOTHERMAL PLANT 4.5.1 SLOPE Slope refers to how steep the surface
of the land is. Steep slopes are a limitation for GPP development,
not only because of the cost and transportation but also water that
can find pathway from the drain to flow on the surface. Basically
the slope limitations for any development are slight if the slope
is less than 8%, moderate if the slope is 8-15% and severe if the
slope is greater than 15%. In this study, topography counter map of
the study area was used to create a slope binary factor map to use
in the GM-GPP (Fig. 3). To identify suitable areas based on the
slope the study area is divided into two features; less than 15%
and more than 15%. The area with less than 15% slope is 149 km2
which in selected as suitable areas for GPP based on slope. 4.5.2
RIVERS River limitations refer to the location of rivers and
potential for flooding by streams or rivers around GPP in the study
area. On the other words, the area without river, stream or big
tributary drainage with their buffer can be assumed as a suitable
area for GPP based on the river. There are 82 km river in the study
area. 47 km of these rivers which is called khiav chay, is a
beautiful river, runs north from Mt. Kasra, between the two
villages of Moil (to the east) and Dizo (to the west), to
meshkinshahr city on the middle of wide Darreh Rud valley had a
calciummagnesium hardness of only 80 mg/l and temperature 7.5C
(Fig. 3). This valley has 120-280 meter depth that surrounded by
steep slope therefore the selected area in the West side of the
river were not selected because plumbing geothermal fluid from the
wells which all located in the East side of the river is not
economic. In this study, 200 m buffer size was given around the
rivers data layer to identify river limitation areas. The areas
beyond this limitation are suitable area for GPP based on the
river. 4.5.3 FAULTS In geology, faults are discontinuities (cracks)
in the earth's crust that have been 13
- 14. responsible for many destructive earthquakes.Blewitt et al.
(2003) indicated that at a regional scale, geothermal plumbing
systems might be controlled by fault planes. Therefore fractures
and faults play an important role in geothermal fields, as fluid
mostly flows through fractures in the reservoir rocks. In the
current study for avoiding of risk-taking of faults, 200 meter
buffer size was applied by using the ArcMap Buffer tool and a
certain area is selected as potential hazard area based on faults
and fractures. The made fault limited factor map was used in GM-GPP
to identify suitable area by avoiding fault risks. In this scale
there are 42 faults and fractures in the study area. 4.5.4
SOCIOECONOMICAL DATASET Socioeconomic study and conditions are
usually hard to identify and investigate, as they are related to
the human beings and their characteristics, which usually differ
widely within the same community and from one community to another.
In the study area among the socioeconomic parameters, maybe
population center, access road and land use can affect the GPP site
selection project. Based on the land use data layer all around the
study area is suitable for GPP construction. For this reason land
use data layer did not appear in the model. 4.5.5 POPULATION CENTER
The location and distribution of Villages, single buildings, agro
nomads camping, sheep farming, stadium and sport centers, burial
grounds, mosques and etc considered as population center data
layer. To avoid of selection or affect these areas, 500 meter
buffer size applied around these features to make the population
center limited data layer. The clip tool in ArcInfo between the
population center limited map and study area map was applied to
make the suitable area based on the population centers or factor
map which was used in the GM-GPP. There are three villages in the
study area located in the southern, northern and eastern parts
respectively. The Valezir village is located in the northern part
and comprises about 50 families. The second village is Dizo in the
north-western part of the area comprising about 30 families and the
third and largest village is Moil that is located in the
south-eastern part of the area with more than 400 families whose
dominant occupation is sheep keeping and cultivation . 4.5.6 ACCESS
ROAD One of the important parts of every socioeconomic study is the
condition of road network. In the study area 16 km asphalt road
provides access to the field from Meshkinshahr city to the village
of Moil, then to the geothermal site south of the village by 14 km
paved road (Fig.3). In the GPP site selection project 100 meter
buffer size was applied around the road features to make the
restricted road map. By using clip tool, factor map without this
restricted area was made to use in the siting model. 4.5.7 HOT
SPRINGS hot springs are evidence of a subsurface heat source and
the temperature of springs has correlation with amount of heat
flow. Those locations where hot springs rise to the surface are
geothermal potential prospected areas because it is assumed that
the 14
- 15. probability of the occurrence of a geothermal resource is
higher than that in the surrounding area. There are 7 hot springs
(Fig. 3) including hottest one in the country which is called
Geynarjeh with 86C located in the study area. With regard to the
chemical and physical characteristics of the thermal waters, they
have been traditionally used for recreational and balneological
purposes in the form of swimming and bathing pools as a fundamental
version of direct-heat utilization of geothermal energy in the
region (Saffarzadeh and Noorollahi, 2005). The clip tool was
applied between the study area and limited hot springs map with 100
meter buffer size to make the hot spring factor map to use in the
model. CHAPTER 5 GEOTHERMAL ENERGY IN INDIA 5.1 OVERVIEW India has
reasonably good potential for geothermal; the potential geothermal
provinces can produce 10,600 MW of power (but experts are confident
only to the extent of 100 MW). But yet geothermal power projects
has not been exploited at all, owing to a variety of reasons, the
chief being the availability of plentiful coal at cheap costs.
15
- 16. However, with increasing environmental problems with coal
based projects, India will need to start depending on clean and
eco-friendly energy sources in future; one of which could be
geothermal. It has been estimated from geological, geochemical,
shallow geophysical and shallow drilling data it is estimated that
India has about 10,000 MWe of geothermal power potential that can
be harnessed for various purposes. Rocks covered on the surface of
India ranging in age from more than 4500 million years to the
present day and distributed in different geographical units. The
rocks comprise of Archean, Proterozoic, the marine and continental
Palaeozoic, Mesozoic, Teritary, Quaternary etc., More than 300 hot
spring locations have been identified by Geological survey of India
(Thussu, 2000). The surface temperature of the hot springs ranges
from 35 C to as much as 98 C. These hot springs have been grouped
together and termed as different geothermal provinces based on
their occurrence in specific geotectonic regions, geological and
strutural regions such as occurrence in orogenic belt regions,
structural grabens, deep fault zones, active volcanic regions etc.,
Different orogenic regions are Himalayan geothermal province,
Naga-Lushai geothermal province, Andaman-Nicobar Islands geothermal
province and non-orogenic regions are Cambay graben, Son-Narmada-
Tapi graben, west coast, Damodar valley, Mahanadi valley, Godavari
valley etc. Puga Valley (J&K) Tatapani (Chhattisgarh) Godavari
Basin Manikaran (Himachal Pradesh) Bakreshwar (West Bengal) Tuwa
(Gujarat) Unai (Maharashtra) Jalgaon (Maharashtra) 16
- 17. 5.2 CURRENT PROJECT There are no operational geothermal
plants in India. Geothermal Field Estimated (min.) reservoir Temp
(Approx) Status Puga geothermal field 240oC at 2000m From
geochemical and deep geophysical studies (MT) Tattapani Sarguja
(Chhattisgarh) 120oC - 150oC at 500 meter and 200 Cat 2000 m
Magnetotelluric survey done by NGRI Tapoban Chamoli (Uttarakhand)
100oC at 430 meter Magnetotelluric survey done by NGRI Cambay
Garben (Gujrat) 160oC at 1900 meter (From Oil exploration borehole)
Steam discharge was estimated 3000 cu meter/ day with high
temprature gradient. Badrinath Chamoli (Uttarakhand) 150oC
estimated Magneto-telluric study was done by NGRI Deep drilling
17
- 18. required to ascertain geothermal field Geothermal Field
Reservoir Temp (Approx) Status Surajkund Hazaribagh (Jharkhand)
110oC Magneto-telluric study was done by NGRI. Heat rate 128.6
mW/m2 Manikaran Kullu (H P) 100oC Magneto-telluric study was done
by NGRI Heat flow rate 130 mW/m2 Kasol Kullu (H P) 110oC
Magneto-telluric study was done by NGRI 5.3 COST,PRICE AND
CHALLENGE Unlike traditional power plants that run on fuel that
must be purchased over the life of the plant, geothermal power
plants use a renewable resource that is not susceptible to price
fluctuations. New geothermal plants currently are generating
electricity from 0.05$ to 0.08$ per kilowatt hour (kwh).Once
capital costs .Once the capital costs have been recovered price of
power can decrease below 0.05$ per kwh. The price of geothermal is
within range of other electricity choices available today when the
costs of the lifetime of the plant are considered. Most of the
costs related to geothermal power plants are related to resource
exploration and plant construction. Like oil and gas exploration,
it is expensive and because only one in five wells yield a
reservoir suitable for development .Geothermal developers must
prove that they have reliable resource before they can secure
millions of dollar required to develop geothermal resources 18
- 19. 5.3.1 DRILLING Although the cost of generating geothermal
has decreased by 25 percent during the last two decades,
exploration and drilling remain expensive and risky. Drilling Costs
alone account for as much as one-third to one-half to the total
cost of a geothermal project. Locating the best resources can be
difficult; and developers may drill many dry wells before they
discover a viable resource. Because rocks in geothermal areas are
usually extremely hard and hot, developers must frequently replace
drilling equipment. Individual productive geothermal wells
generally yield between 2MW and 5MW of electricity; each may cost
from $1 million to $5 million to drill. A few highly productive
wells are capable of producing 25 MW or more of electricity. 5.3.2
TRANSMISSION Geothermal power plants must be located near specific
areas near a reservoir because it is not practical to transport
steam or hot water over distances greater than two miles. Since
many of the best geothermal resources are located in rural areas ,
developers may be limited by their ability to supply electricity to
the grid. New power lines are expensive to construct and difficult
to site. Many existing transmission lines are operating near
capacity and may not be able to transmit electricity without
significant upgrades. Consequently, any significant increase in the
number of geothermal power plants will be limited by those plants
ability to connect, upgrade or build new lines to access to the
power grid and whether the grid is able to deliver additional power
to the market. 5.3.4 BARRIERS 19
- 20. Finding a suitable build location. Energy source such as
wind, solar and hydro are more popular and better established;
these factors could make developers decided against geothermal.
Main disadvantages of building a geothermal energy plant mainly lie
in the exploration stage, which can be extremely capital intensive
and high-risk; many companies who commission surveys are often
disappointed, as quite often, the land they were interested in,
cannot support a geothermal energy plant. Some areas of land may
have the sufficient hot rocks to supply hot water to a power
station, but many of these areas are located in harsh areas of the
world (near the poles), or high up in mountains. Harmful gases can
escape from deep within the earth, through the holes drilled by the
constructors. The plant must be able to contain any leaked gases,
but disposing of the gas can be very tricky to do safely. 5.5
GEOTHERMAL COMPANIES Panx Geothermal LNJ Bhilwara Tata Power
Thermax NTPC Avin Energy Systems GeoSyndicate Power Private Limited
5.6 RD&D PRIORITIES In the case of geothermal energy, several
topics are identified as being key to its advancement in the global
market place. These are related to cost reduction, sustainable use,
expansion of use into new geographical regions, and new
applications. The priorities are categorized as general or specific
to RD&D. General priorities: Life-cycle analysis of geothermal
power generation and direct use systems. Sustainable production
from geothermal resources. Power generation through improved
conversion efficiency cycles. Use of shallow geothermal resources
for small-scale individual users. Studies of induced seismicity
related to geothermal power generation (conventional systems and
enhanced geothermal systems. Specific RD&D priorities:
Commercial development of EGS. Development of better exploration,
resource confirmation and management tools. Development of deep
(>3 000 m) geothermal resources. Geothermal co-generation (power
and heat). CHAPTER 6 ADVANTAGE AND DISADVANTAGE 6.1 ADVANTAGES
20
- 21. 1) It is a renewable source of energy. 2) By far, it is
non-polluting and environment friendly. 3) There is no wastage or
generation of by-products. 4) Geothermal energy can be used
directly. In ancient times, people used this source of energy for
heating homes, cooking, etc. 5) Maintenance cost of geothermal
power plants is very less. 6) Geothermal power plants don't occupy
too much space and thus help in protecting natural environment. 7)
Unlike solar energy, it is not dependent on the weather conditions.
6.2 DISADVANTAGES 1) Only few sites have the potential of
Geothermal Energy. 2) Most of the sites, where geothermal energy is
produced, are far from markets or cities, where it needs to be
consumed. 3) Total generation potential of this source is too
small. 4) There is always a danger of eruption of volcano. 5)
Installation cost of steam power plant is very high. 6) There is no
guarantee that the amount of energy which is produced will justify
the capital expenditure and operations costs. 7) It may release
some harmful, poisonous gases that can escape through the holes
drilled during construction. 6.3 LIMITATIONS 6.3.1 NOT WIDESPREAD
SOURCE OF ENERGY Since this type of energy is not widely used
therefore the unavailability of equipment, staff, infrastructure,
training pose hindrance to the installation of geothermal plants
across the globe. Not enough skilled manpower and availability of
suitable build location pose serious problem in adopting geothermal
energy globally. 6.3.2 HIGH INSTALLATION COSTS To get geothermal
energy, requires installation of power plants, to get steam from
deep within the earth and this require huge one time investment and
require to hire a certified installer and skilled staff needs to be
recruited and relocated to plant location. Moreover, electricity
towers, stations need to set up to move the power from geothermal
plant to consumer. 6.3.3 CAN RUN OUT OF STEAM Geothermal sites can
run out of steam over a period of time due to drop in temperature
or if too much water is injected to cool the rocks and this may
result huge loss for the companies which have invested heavily in
these plants. Due to this factor, companies have to do extensive
initial research before setting up the plant. 6.3.4 SUITED TO
PARTICULAR REGION It is only suitable for regions which have hot
rocks below the earth and can produce steam over a long period of
time. For this great research is required which is done by the
companies before setting up the plant and this initial cost runs up
the bill in setting up the geothermal power plant. Some of these
regions are near hilly areas or high up in mountains. 21
- 22. 6.3.5 MAY RELEASE HARMFUL GASES Geothermal sites may
contain some poisonous gases and they can escape deep within the
earth, through the holes drilled by the constructors. The
geothermal plant must therefore be capable enough to contain these
harmful and toxic gases. 6.3.6 TRANSPORTATION Geothermal Energy
cannot be easily transported. Once the tapped energy is extracted,
it can be only used in the surrounding areas. Other sources of
energy like wood, coal or oil can be transported to residential
areas but this is not a case with geothermal energy. Also, there is
a fear of toxic substances getting released into the atmosphere.
Now that we have gone through the disadvantages of geothermal
energy, lets go through it advantages too and understand why it is
Here look at some of the advantages of geothermal energy. CHAPTER 7
CONCLUSION Geothermal energy is a renewable en-ergy source that has
been utilised econo-mically in many parts of the world for decades.
A great potential for an extensive increase in worldwide geothermal
utilisa-tion has been proven. This is a reliable energy source
which serves both direct use applications and electricity
generation. Geothermal energy is independent of weather conditions
and has an inherent storage capability which makes it especi-ally
suitable for supplying base load power in an economical way, and
can thus serve as a partner with energy sources which are only
available intermittently. The rene-wable energy sources can
contribute sig-nificantly to the mitigation of climate change and
more so by working as part-ners rather than competing with each
other. Presently, the geothermal utilisation sector growing most
rapidly is heat pump appli- cations. This development is expected
to continue in the future making heat pumps the major direct
utilisation sector. The main reason for this is that geothermal
heat pumps 22
- 23. can be installed economically all over the world. One of
the strongest arguments for putting more emphasis on the
development of geo- thermal resources worldwide is the limited
environmental impact compared to most other energy sources.
Geothermal heating system can replace fossil fuel heating system in
a particular area. Annual costs 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.
CHAPTER 8 REFERENCES http://www.mav.com/Disadvantages_micro air
vehicle.php http://energyalmanac.ca.gov/renewables/micro air
vehicle/types.html http://en.wikipedia.org/wiki/micro air vehicle
http://mav.org/Basics.aspx http://www.micro air
vehicle-future.com/mav.php
http://www.portal.state.pa.us/portal/server.pt/community/types_of_energy/4568/
geothermal/471158//mav http://www.mavworld.com/rea/tech//air
energy/geoelectricity
http://www.powerscorecard.org/tech_detail.cfm?resource_id=3
http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-
micro air vehicle-works.html
http://lsa.colorado.edu/essence/texts//micro air vehiclel.html
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