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GEOTHERMAL RESOURCES-THE FUTURE ENERGY

PRESENTED B Y

P. VENK ATAK UM AR CH. VENK ATESH

III/IV EEE III/IVEEE

Email:pvk_eee254@yahoo.com Email:venki_chunduri@yahoo.com

Cell#9963851850 cell#9849456549

ST.ANN’S COLLEGE OF ENGINEERING&TECHNOLOGY

CHIRALA

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ABSTRACT:

Geothermal energy is a powerful energy source, right under our feet.

The internal heat which drives this form of electrical energy production is derived from the upper mantle of the earth

. Electrical energy production by the use of steam turning a turbine is common, but the use of earth’s internal heat is what makes this form of energy production possible.

To do this, a large power plant has to be used.

We can generate geothermal energy by drilling deep holes into the earths crust, pumping cold water through one end, and then by the time it rises back to the surface, the water can be hundreds of degrees Celsius, which we then use as steam to drive a turbine which drives a generator, creating power.

Geothermal energy is one of the best natural energies around.

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INTRODUCTION:

Indian geothermal provinces have the capacity to produce 10,600 MW of power- a figure which is five time greater than the combined power being produced from non-conventional energy sources such as wind, solar and biomass. But yet geothermal power projects have not seen the sunlight due the availability of 192 billion tones of recoverable coal reserves They are often described as clean and green forms of energy because of their minimal environmental impact compared to fossil fuels. Examples are the use of sunshine, wind, flowing water, biological- and geothermal processes. Because its source is the almost unlimited amount of heat generated by the Earth's core. Even in geothermal areas dependent on a reservoir of hot water, the volume taken out can be reinjected, making it a sustainable energy source.

HOT SPOTS:

Indian has 400 medium to high enthalpy geothermal springs, clustered in seven province shown in Figure 1. The most promising provinces are i) The Himalaya, ii) Sohana, iii) Cambay, iv) Son-Narmada-Tapi (SONATA) and v) the Godavari. With the recent volcanic eruption, the Barren Island, a part of the Andaman-Nicobar chain of islands, is added to the above list. Total power generating capacity of these provinces is estimated to be of the order of 10,000 MW. The chart below summarizes the temperatures, heat flow values and geothermal gradients of the geo thermal provinces of India

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HOW DOES GEOTHERMAL

ENERGY COME TO THE

SURFACE?

• Flow of magma up into volcanoes, which discharge it as lava

• Flow of underground water, or steam, naturally heated deep in the Earth

• Flow of water, or steam, injected and retrieved by human effort

NEW INNOVATIVE TECHNIQUES FOR FINDING "HIDDEN" GEOTHERMAL SYSTEMS:

Geothermal Exploration and Drilling can be done using these techniques:

Ø Reconnaissance for Hidden Resources

Ø Basin and Range Exploration

Ø Innovative Geothermal Exploration Techniques

Ø 3-D Magnetotelluric Modeling

Ø Geothermal Resource Exploration and Definition Solicitation

Ø High-Temperature Instrumentation

Ø Well bore Integrity and Lost Circulation

Ø Hard-Rock Drill Bit Technology

Ø Cost Database and Simulators

Ø Diagnostics-while-Drilling (DWD)

Ø Acid-Resistant Cements

Ø Cement Structural Response Analysis

GEOTHERMAL POWER PLANTS:

Geothermal power plant technologies being used to convert hydrothermal fluids to electricity. The conversion technologies are dry steam, flash, and binary cycle. The type of conversion used depends on the state of

the fluid (whether steam or water) and its temperatur e. Steam plants : They use very

hot (more than 300° F) steam and hot water resources. The steam either comes directly from the resource, or the very hot, high-pressure water is depressurized ("flashed") to produce steam. The only significant emission from these plants is steam (water vapor). Minute amounts of carbon dioxide, nitric oxide, and sulfur are emitted, but almost 50 times less than at traditional, fossil-fuel power plants.

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Binary plants :

They use lower-temperature, but much more common, hot water resources (100° F – 300° F). The hot water is passed through a heat exchanger in conjunction with a secondary (hence, "binary plant") fluid with a lower boiling point usually a hydrocarbon such as isobutane or isopentane. The secondary fluid vaporizes, which turns the turbines, which drive the generators. The remaining secondary fluid is simply recycled through the heat exchanger. The geothermal fluid is condensed and returned to the reservoir. Because binary plants use a self-contained cycle,

nothing is emitted. Energy produced by

binary plants currently costs about 5 to 8 cents per kWh. Because these lower-temperature reservoirs are far more common, binary plants are the more prevalentamounts of gases.

SIGNIFICANCE OF

GEOTHEMAL ENERGY :

In 1997, 'Kyoto protocol' says that industrialized countries will reduce emission of Green House Gases (GHGs) by at least 5% compared to 1990 levels by the period extending from

2008 to 2012. Consequence to the Kyoto protocol, all the industrial countries are encouraging development of new renewable energy technologies. Geothermal energy is gaining importance as alternate source of energy. Geothermal energy based power production over the world has gone up from 5800 MW to 8400 MW from 1998 to 1999. Thus all the countries, except India, have started using geothermal energy to generate power and support a variety of industries. Nearly 70% of India's power production is based on coal due to the availability of huge coal reserves in the country. Excessive use of this source, without the use of strategies to mitigate its effects, will have deteriorating effect on the quality of human life. In another decade, according to the World Bank, emission of CO2, SO2 and Nx will exceed 1500 million tones, 1900 kilo tones and 1200 kilo tones respectively. This means CO2 emissions will be 775 million metric tones per year as compared to 1000 million metric tones per year produced in the entire European Union! This may lead to severe droughts, especially in developing countries like India, and reduce supplies of clean, fresh water to the point where there are major threats to public health. With global water resources already under severe strain from rapid population growth and expanding economic activity, the danger is clear.

Though India has been exempted from signing the Kyoto protocol, in future it has to be a part of this convention and reduce emission of CO2-which means reduction in usage of coal and other fossil fuels.

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This is the time for India to launch its geothermal energy resources programme in a big way to implement clean development mechanism (CDM). The country has enormous resources, which are lying untapped. World funding organizations and developed countries, which are using extensively geothermal energy, are keen to promote this energy sources to reduce GHGs by India.

WHY GEOTHERMAL ENERGY:

There is no doubt that the cost of electricity produced from coal is far less expensive compared with other fuels. The present day cost of one unit of power is less than a rupee in the case of coal based power while liquid fuel based power costs about Rs. 2 per unit and hydro power costs about Rs. 1.50. But the expenditure spent to meet the consequences (like disposal of fly ash; treating the coal with high ash content etc) is high which automatically increases one rupee a unit to several rupees. Now a time has come to look into those alternate energy sources which were not viable a decade ago due to non availability of technical know-how. At present 1.5 percent of total power generation capacity comes from non-conventional energy sources like wind, solar and bio-mass. In the next fifteen years, according to the World Bank report, this energy supply could increase by seven times and above from non-conventional energy sources

Systems for use of geothermal energy have proven to be extremely reliable and flexible. Geothermal plants are modular and can be transported conveniently to any site. Both baseline and peaking power can be generated.

Construction time can be as little as 6 months for plants in the range 0.5 to 10 MW and as little as 2 years for clusters of plants totaling 250 MW or more. One such binary power plant in operation at Wineagel Developers geothermal site in California, USA, generating 750 kW is shown in figure 2. This plant consists of two binary units with a gross efficiency of 8.5% and a capacity factor of 109%. Several such plants exists in China across Indian's border. The Yangbajain Geothermal Power Station in Tibet has an installed generating capacity of 25 MW ranking 10th in the world

WHY INDIA IS NOT ABLE TO CASH AND BE THE WORLD BEST PROCESSED FOOD EXPORTERS?

One of the India’s proudest accomplishment has been achieving self sufficiency in food production and that the country’s produces a wide variety of agricultural products at prices that are below world’s values in most cases India is one of the world’s major food producers but accounts for less than 1.5percent of international food trade . There is large scope for us companies to invest in food processing and packaging sector which is growing annually at 15 to 20%. If such is the situation then REASONS :

The problem lies in inadequate infrastructure like cold storage, dehydration facility etc. About 75-80 percent of vegetables and fruits in India perish due to high water content. This industry requires about US$6 billion in investment in the next five years to create necessary infrastructure, expand production and storage facilities using state-of-art technology to match international standards. Because of lack of such facilities products worth US$2.5 billion is wasted yearly out of which the

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farm products accounts for US$ 1.5 billion.

Using conventional energy to minimize wastage is expensive today and is going be the same or more expensive in future with ever increasing cost of conventional fuels.The cost of conventional fuel makes the finished product very expensive. To compete with international market and to promote the product in the local market, the amount spent in such process should be minimum. This can be accomplished by using the country’s available geothermal energy resources. To give an example, the table below gives a comparative statement of cost involved in dehydrating fruits using conventional energy and geothermal energy.

PRODUCT TIME(Hr) GEOTHERMAL CONVENTION

AL PINEAPPL E 18 90 4950 APPLE (Slices) 16 810 4500 APPLE (CUBES) 16 810 4500 BANANA 1 7 24 1350 5625

Courtesy: M/s Eco-Fruit Agro Industry, Gautimala, Central America: Cost in Rs.

Most food-processing and greenhouse operators over the world estimate that using geothermal resources instead of conventional energy sources saves about 80% of fuel costs – about 5% to 8% of total operating costs. Worldwide, the installed capacity of direct geothermal utilization is about 9000 MW and the energy used is about 31,200 GWh/yr distributed among 38 countries .

THE PROCESS INVOLVED IN CONVERTING GEOTHERMAL

ENERGY TO ELECTRICAL ENERGY:

Unlike other power plants that rely on coal or other fossile fuels to create electricity for homes and business geothermal resources to generate electricity. The natural heat of the earth creates geothermal resources .This heat comes from molten rock called magma located at earth’s core deep below the

geothermal resources. This heat comes from molten rock called magma located at earth’s core deep below the geothermal Resource.

Over thousands of years rain water seeps through cracks in the earth’s surface and collects in underwater reservoir heated fluid . to reach the superheated fluid wells are drilled 5000 to 10000 feet below the surface of the earth .these wells, called production wells brings the superheated fluid to the earth’s surface where it can be used to generate electricity for homes and business

FLASHES WATER TO STEAM:

This geothermal power plant uses crystallizer reactor clarifier technology, a process that turns the geothermal superheated fluid into steam while remaining solids from it . the steam while removing solids from it . the

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steam is used to drive a turbine and generator electricity. All remaining geothermal fluids are injected back into the reservoir for reuse under its own pressure, superheated fluid from the geothermal resource flows naturally to the surface through production wells. as the liquid flows towards the surface the pressure decreases causing a small portion of fluid still within the well to separate or “flash” into steam . at the surface the superheated fluid and steam mixture flows through surface pipe lines and into a well head separator. Inside the separator the pressure of the superheated fluid is reduce. this causes a large amount of the superheated fluid to rapidly vapourise and flash into high pressure steam . the geothermal fluid that is not flashed into steam in the well head separator flows to a second vessel called a standard-pressure crystallizer where additional amount of standard pressure steam is produced . the flash process continues in the low pressure

TURBINES AND GENERATORS:

Turbines are the primary piece of equipment used to transform geothermal energy into mechanical energy. Pressurised steam created from the geothermal superheated fluid flows through pipe lines to large steam turbine. The force and energy in the steam is used to spin the turbine blades. The turbines turn a shaft directly connected to an electrical generator. An electrical charge is created when magnets rotate within the generator. Large copper bars carry the electrical charge to a step up transformer outside the plant. Within the transformer the voltage is increased before the power is sent to the power lines that carry it to homes and business.

SUSTAINING RESOURCES:

Geothermal energy is a sustainable resource because with proper

management a geothermal resource can remain a renewable source of energy. Water trapped deep within the earth will naturally replace the superheated fluid that is drawn from the geothermal resource through surface wells. However it is possible to deplete the geothermal resource by removing fluid faster than it can be naturally replaced. To help prevent this steam used in the geothermal power plant passes through a condenser that turns it back into fluid. At this stage it is possible to recover minerals from the geothermal fluid before it is injected back into the earth. This condensed fluid along with the fluid that did not flash to steam is injected back into the underground reservoir. Magma naturally reheats the fluid so it can be reused again.

The system works by capturing steam from wells and converting that power into energy. It has the advantage of delivering energy 24 hours a day, not intermittently. This technology injects all the geothermal liquid back into the ground. That means there are no emissions, and geothermal wells are not depleted. In most other plants, geothermal steam is just released into the atmosphere, eventually depleting the steam available to the power plant. With this method, that steam is put back into the ground, so the water can be reheated and re-released, sustaining the geothermal plants. This method uses air cooling instead of water cooling, allowing its system to be used in places with water shortages.

ADVANTAGES OF GEOTHERMAL ENERGY:

1 So the first advantage of using geothermal heat to power a power station is that, unlike most power

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stations, a geothermal system does not create any pollution. It may once in a while release some gases from deep down inside the earth, that may be slightly harmful, but these can be

contained quite easily.

2 The cost of the land to build a geothermal power plant on, is usually less expensive than if you were planning to construct an; oil, gas, coal, or nuclear power plant. The main reason for this is land space, as geothermal plants take up very little room, so you don't need to purchase a larger area of land. Another factor that comes into this is that because geothermal energy is very clean ,you may receive tax cuts, and/or no environmental bills or quotas to comply with the countries carbon emission scheme (if they have one

We can use it repeatedly without depleting it.

No contribution to global warming, No polluting emissions

Low cost applications when counting all costs

Saving on health and its costs

DISADVANTAGES:

It can only be used in some areas around the world, where the crust is thin and hot rocks are near the surface. Sometimes the hot water that is pumped to the surface contains pollutants such as sulphur.

THE FUTURE FOR GEOTHERMAL ENERGY :

The outlook for geothermal energy use depends on at least three factors: the demand for energy in general; the

inventory of available geothermal resources; and the competitive position of geothermal among other energy sources.

The Demand for energy will continue to grow. Economies are expanding, populations are increasing (over 2 billion people still do not have electricity), and energy-intensive technologies are spreading. All mean greater demand for energy. At the same time, there is growing global recognition of the environmental impacts of energy production and use from fossil fuel and nuclear resources

The Inventory of accessible

geothermal energy is sizable. And with more exploration, the inventory can become larger. The entire world resource base of geothermal energy has been calculated in government surveys to be larger than the resource bases of coal, oil, gas and uranium combined. The geothermal resource base becomes more available as methods and technologies for accessing it are improved through research and experience.

Thus the geothermal energy is the best renewable source of energy.

REFERENCES: www.indiacore.com www1.eere.energyhttp://www.sustaina bleenergy.qld.edu.au/sources/geo.htm l http://geothermal.marin.org/ http://edugreen.teri.res.in/explore/ren ew/geo.htm

Geothermal energy - Energy from the earth's core

http://www.eia.doe.gov/kids/energyfa cts/sources/renewable/geothermal.ht ml

The energy story - geothermal energy

http://www.energyquest.ca.gov/story/ chapter11.html

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http://www.scienceonline.co.uk/energ y/renewable-energy.html#geothermal

References

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