Geothermal.docx

WESLEYAN UNIVERSITY-PHILIPPINES Mabini Extension, Cabanatuan City

COLLEGE OF ENGINEERING ELECTRONICS ENGINEERING

GEOTHERMAL POWER PLANT Prepared by: Ross Sonny Cruz John Jezzper Tan Irwin Nicolas Gonzales

November 27 2018

I.

Introduction Geothermal power plants are used in order to generate electricity by the use of geothermal energy (the Earth's internal thermal energy). They essentially work the same as a coal or nuclear power plant the main difference being the heat source. What is Geothermal Energy? Geo: (Greek) - Earth Thermal: relating to, using, producing, or caused by heat. Geothermal heat originates from Earth’s fiery consolidation of dust and gas over 4 billion years ago. At earth core – 4,000 miles deep – temperatures may reach over 9,000 degrees F. Geothermal energy is the energy stored in the form of heat beneath the earth's surface. 4 Layers of the Earth 1.) Crust 2.) Mantle 3.) Outer Core 4.) Inner Core

History The world’s first Geothermal power station (made by Prince Piero Ginori Conti) was built in 1911 in Larderello, in Southern Tuscany, Italy. Since Roman times steam and hot water springs emerging from this geologically active ground has been used for hot water and for bathing. In 1904 emerging steam was used to turn a small turbine which in turn powered four light bulbs – the first ever demonstration of geothermal electricity generation. In 1911 the Valle del Diavolo (Devil’s Valley) was chosen as the site of what would remain the world’s only geothermal power station for almost half a century. By 1913 a 250kW power station had been built which provided power for the Italian electric railway system.

II.

Principles Types of Geothermal Power Plant 1. Dry Steam Power Plant In dry steam power plant, direct steam from the geothermal reservoir is used to turn the turbine and generator to produce electricity. The temperature of the geothermal steam needed in this plant is atleast 150 degreee Celsius.

2. Flash Steam Power Plant In flash steam power plant, high pressure hot water from deep inside the earth is taken out and collected in a steam separator. This high pressure hot water comes to the surface by its own and its pressure keeps on decreases as it moves upward, this allows hot water to gets converter into steam. Steam gets separated in steam separator, and allowed to turn the turbine generator. When the steam cools, it is again injected back into the earth surface to be used again. Nowadays most of the geothermal power plants used are of flash steam plants. This power plant requires a temperature of atleast 180 degree Celsius for its operation. 3. Binary Cycle Power plant In binary cycle power plant, the heat of hot water is transferred to another liquid (called as secondary liquid). The heat of hot water causes another liquid to change into steam and then this steam is used to rotate turbine. It is the most recent developed power plant which may be operated at lowest temperature of atleast 57 degree Celsius. The secondary fluid (i.e. another liquid) used in this binary cycle geothermal power plant has

much lower boiling point than water. It works on both Rankine and Kalina cycle. The thermal efficiency of this power station is expected to be lie in between 10-13%. This power plant is called as binary, since here we are using two liquids (hot water and secondary liquid) for its working.

Principles:  Then the steam now, make to the surface of the earth, due to high pressure. (Geothermal power plants that uses steam only were dry steam power plant)  Other geothermal power plants seeps out both steam at the superheated fluid form the earth with the help of production wells, this steam and fluid is collected to spin the turbine which we attach a generator.  The steam spins the turbine, and the turbine spins the generator creating electricity, which will be step up for the power distribution.  Speaking in simple term it's all in the process of water heating and its transfer to steam which can be then used to drive a turbo-generator that generates electricity or this steam passes through heat exchangers and heats water creating necessary heat for central heating of households and industrial facilities.

III.

Schematic diagram, construction, and flow chart

Schematic of A common Geothermal Power Plant (Flash Steam Power Plant)

Parts of Geothermal Power Plant 1. Hydrothermal/Geothermal resources: It is a source which has both heat and water. In the earth crust we have both water and heat (magma). 2. Dry or hot water wells: These are the wells through which the dry steam and hot water from the earth is taken out. If dry steam is taken out than it is called as dry steam well and if hot water is taken out through it than it is called as hot water well. 3. Steam Separator: It is a separating device which is used to separate steam from hot water. 4. Turbine: It is rotating device which converts the kinetic energy of the fast moving steam into rotational energy (i.e. Mechanical energy). 5. Generator: It is coupled to the turbine shaft and converts mechanical energy of the turbine into electrical energy. 6. Steam Condenser: It condenses the exhaust steam from the turbine and changes it to water. 7. Injection Well: It is the well which is drilled in the earth to inject the condensed water again into the earth crust.

IV.

Utilization and Application Utilization and application of the geothermal energy is not limited by electricity production only, but it is also use in other applications like:

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Hot Springs

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Pasteurizing milk

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Medical Bathing

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Paper manufacturing

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Heating of household and

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Swimming pools

industrial facilities

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Drying timber

Future of the technology 

Geopressured Systems

Geopressured geothermal resources consist of hot brine, saturated with methane, found in large, deep aquifers under high pressure. The water and methane are trapped in sedimentary formations at a depth of about 3 km to 6 km, and the temperature of the

water is in the range of 90C to 200C. Three forms of energy can be obtained from geopressured resources: thermal energy, hydraulic energy from the high pressure, and chemical energy from burning the dissolved methane gas. The major region of geopressured reservoirs discovered to date is in the northern Gulf of Mexico.

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Magma Energy

Magma, the largest geothermal resource, is molten rock found at depths of 3 km to10 km and deeper. It has a temperature that ranges from 700C to 1,200C. The concept of using this heat source theorizes that thermal energy contained in magmatic systems could represent a huge potential resource of energy. In the U.S., for example, useful energy contained in molten and partially molten magma within the upper 10 km of Earth’s crust has been estimated at 5 to 50 x 10 to the 22 power J (50,000 to 500,000 quads). This technology is far from becoming commercially viably, however, says Sanyal. Not only is it extremely localized, but it also poses a host of technical challenges, including developing drilling and completion techniques as well as developing a technology for extracting heat from magma.

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Enhanced Geothermal Systems

This technology is still experimental, and several challenges—such as creating a pervasively fractured large rock volume, securing commercial well productivity, minimizing cooling, and minimizing water loss—will need to be overcome before it could become commercially viable. But, because it offers the promise of worldwide distribution, it offers the most potential, Sanyal says.

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Convective (“Hydrothermal”) Systems

Hydrothermal (or hot water) resources arise when hot water and/or steam is formed in fractured or porous rock at shallow-to-moderate depths (100 m to 4.5 km) as a result of either the intrusion in the earth’s crust of molten magma from the planet’s interior or the deep circulation of water through a fault or fracture. High-temperature hydrothermal resources (with temperatures from 180C to over 350C) are usually heated by hot molten rock. Low-temperature resources (with temperatures from 100C to 180C) can be produced by either process.

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Conductive Sedimentary Systems

Many sedimentary formations, including some that contain oil or gas, may be hot enough to serve as commercial geothermal reservoirs. Though no fracturing will be needed for this commercially unproven technology, it may require deeply drilled wells. Sanyal believes that this system could be commercially feasible if reservoir flow and capacity and temperature are high enough.

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Oil and Gas Field Waters

Hot water produced with deep drilling for oil or gas or from depleted oil/gas wells is being used more and more. But though it poses few technical challenges, the power cost using this process may not always be attractive.

VI.

References

Biggest Power Plants in the Philippines Pallinpinon Geothermal Power Plant – 192.5 MW (Negros Occidental) Malitbog Geothermal Power Station – 232.5 MW (Southern Leyte) Tiwi Geothermal Power Plant – 275 MW (Albay) Makiling – Banahaw Geothermal Power Plant – 480 MW (Laguna) Leyte Geothermal Production Field – 610.18 MW (Leyte) The Geysers Geothermal Complex California, USA The Geysers Geothermal Complex located about 121km north of San Francisco, California, is comprised of 18 power plants making it the biggest geothermal installation in the world. The complex has an installed capacity of 1,517MW and active production capacity of 900MW.

Calpine owns 15 power plants in the complex, with a combined net generating capacity of about 725MW, while two power plants are jointly owned by Northern California Power Agency and Silicon Valley Power, plus US Renewables Group, which owns the Bottle Rock Power plant. Ram Power is constructing a new 26MW geothermal power plant at the complex. The complex covers an area of approximately 78km². Production from the geothermal field commenced in 1960 and reached its peak in the 1980s. The turbine suppliers for the power plants in the complex include Toshiba and Mitsubishi Steam.