SAG in electrical power transmission.

What is  Sag.?

In electrical power transmission and mechanical design of overhead transmission line.

SAG.

A perfectly flexible wire of uniform cross-section, when string between the two supports at the same level, will form a catenary. However, if the sag is very small compared to the span, its shape approximation a parabola.

 The difference in level between the point of support and the lowest point on the conductor is known as sag 

The factors affecting the sag in an overhead line are given below.

1. Weight of the Conductor,

 This affect the sag directly. Heavier the conductor, greater will be the sag. In locations where ice formation takes place on the conductor, this will also cause increase in the sag.

2. Length Of the Span.

This also affect the sag. Sag is directly proportional to the square of the span length Hence other conditions, such as type of conductor, working tension, temperature etc. remaining the same a section with longer span will have much greater sag.

3. Working Tensile Strength.

The sag is inversely proportional to the working tensile strength of conductor if other conditions such as temperature, length of span remain the same. Working tensile strength of the conductor is determined by multiplying the ultimate stress and area of cross section and dividing by a factor of safety.

4. Temperature.

All metallic bodies expand with the rise in temperature and, therefore. The length of the conductor increases with the rise in temperature, and so does the sag.

Reference from .

Transmission and distribution of electrical power by-J.B.Gupta.

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WHAT IS REAL POWER IN ELECTRIC ENGINEERING

What Is Real Power?

Real Power: (P)

Real Power is the actual power which is really transferred to the load such as transformer, induction motors, generators etc. and dissipated in the circuit.

Alternative words used for Real Power (Actual Power, True Power, Watt-full Power, Useful Power, Real Power, and Active Power) and denoted by (P) and measured in units of Watts (W) 

i.e. The unit of Active or Real power is Watt where 1W = 1V x 1 A

Real Power in DC Circuits:

In DC Circuits, power supply to the DC load is simply the product of Voltage across the load and Current flowing through it.

i.e., P = V I because in DC Circuits, there is no concept of phase angle between current and voltage.

In other words, there is no frequency (f) or Power factor in DC Circuits.

Real Power in AC Circuits:

But the situation in Sinusoidal or AC Circuits is more complex because of phase difference (θ) between Current and Voltage. 

Therefore average value of power (Real Power) is P = VI Cosθ is in fact supplied to the load.

In AC circuits, When circuit is pure resistive, then the same formula used for power as used in DC as P = VI

Real Power Formulas:

• P = V I  (In DC circuits)

• P = VI Cosθ    (in Single phase AC Circuits)

• P = √3 VL IL Cosθ   or       (in Three Phase AC Circuits)
• P = 3 VPh IPh Cosθ

• P = √ (S2 – Q2) or

• P =√ (VA2 – VAR2) or

Real or True power = √ (Apparent Power2– Reactive Power2)
 or
• kW = √ (kVA2 – kVAR2)

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The History of 555 Timer IC – Story of Invention by Hans Camenzind

The 555 Timer IC is one of the renowned ICs, in the electronic circles. However, its history of invention is not known to many. This article takes you on a journey of 555 timer IC from the time of its creation to the present day time.

What is a 555 timer IC?

A 555 timer IC, is a multipurpose integrated circuit chip, that finds its application in timer, oscillation and pulse generation circuits. It is one of the prominent and popular inventions of the electronic world. A monolithic timing circuit, the 555 timer, is equally reliable and cheap like op-amps working in the same areas. It is capable of producing stabilized square waveform of 50% to 100% duty ratio.

The Birth of 555 Timer IC

Hans R. Camenzind, designed the first 555 timer IC in 1971, under an American company Signetics Corporation. It is this design work of his, that is most prominent in Hans’s distinguished career in the field of Integrated Circuit technology. In the summer of 1971, first design was reviewed, that used a constant current source and had 9 pins. After the review was passed, Hans thought of a new idea of replacing the constant current source by a direct resistance. This reduced the number of pins from 9 to 8, and enabled the chip to be fit in an 8 pin package instead of a 14 pin package. This new design was passed in the review in October 1971. The IC consists of 25 transistors, 2 diodes and 15 resistors. In order to define the timings, provision to attach R and C externally is provided.

In 1972, Signetics Corp. then released its first 555 timer IC in 8 pin DIP and 8 pin TO5 metal can packages, as SE/NE555 timer and was the only commercially available timer IC at that time. Its low cost and versatility, made it an instant hit in the market. It was later on manufactured by 12 other companies and became the best selling product.

Although, there is a belief that this IC got its name from the three 5k resistors in its internal circuit, Hans R Camenzind revealed in his book, “Designing Analogue Chips”, that it was Signetics manager, Art Fury's, love for the number “555”, that led to the naming of the circuit.

The basic working tutorial of timer 555 IC has been discussed in our article “555timer- A complete guide”.

Applications of 555 Timer IC:

Through the years, electronic hobbyists and engineers have explored various areas where this IC can be used. From temperature measurement to voltage regulators to various multivibrators, this IC has found its prominent place in thousands of applications. The implementation of 555 TIMER IC depends on its operating mode. It is this versatility of 555Timer IC, that makes it useful for many applications.

Basically, a 555 timer IC has three operating modes.

Bi stable mode: The Schmitt trigger

Mono stable mode: One shot mode

Astable mode: Free running mode

555 timer as a multivibrator:

Depending on which type of multivibrator, (astable/monostable or bistable multivibrator) is to be used, the operating mode of 555 timer is selected. For example, if we want to design a monostable multivibrator, we will wire the 555 timer in the monostable mode.

These multivibrators are used in various two state devices such as relaxation oscillators, timers and flip flops.

555 timer IC as a PWM generator:

Using the variable “control” input , a 555 timer IC can be used to create a pulse width modulation (PWM) generator. The duty cycle here, depends on the analogue input voltage.

This operation of 555 timer can also be seen in Switched mode power supply (SMPS)circuit. As these SMPS circuits work on pulse width modulation (PWM) , the 555 timer turns to be the most prominent choice for the designers, as it is cheap and easy to incorporate in a circuit design. Here in these circuits, two timer ICs are used; one operates in astable mode and the other in PWM mode.

Another area where 555timer IC is implemented is in small DC-DC converter circuits. The 555 Timer when operating in astable mode, can produce a continuous stream of pulses of specified frequency. The IC output is fed to the converter to produce desired output voltages. These converter circuits have wide industrial applications.

Other circuits which use 555 timer include that of temperature measurement, moisture measurement waveform generators, various timer circuits, etc.

In recent times, the CMOS version of the IC is most commonly used. Among them, the popular ones are the ICs manufactured by MOTOROLA like MC1455. It can be directly used as a substitute to the original NE555 IC. This IC is pocket-friendly and costs around 0.28 US$.

The bipolar and the CMOS versions of 555 Timer IC

Ever since the first IC was manufactured, over 12 independent companies have fabricated the same. The original design had some design flaws like unbalanced comparators, large operating circuits, and sensitivity to temperature.

Hence, Hans R Camenzind, redesigned the existing IC to diminish the design flaws. The design of this IC was better than its original design. The improved IC was then sold by ZSCTI555 but could not create a buzz like the original 555timer IC did. Hence the original design continued to be a hit in the market.

However, the classic bipolar 555 IC version like NE555 IC, uses bipolar transistors, which dissipate large amount of power and produce high current spikes. Hence, these ICs could not be used in low power applications. This paved a way to the design of a new and version of the same, the CMOS version.

CMOS stands for “complementary metal-oxide semiconductor” and uses a combination of both n-type MOSFET (NMOS) and p-type MOSFET (PMOS), in enhancement mode. All the PMOS transistors have input from either the voltage source or from other PMOS, whereas, all the NMOS transistors have an input connected to ground or to other NMOS transistor. This composition leads to reduction in the power dissipation and lower current spikes.

An example of the CMOS version of 555 timer is LMC555 produced by texas instruments.

The Derivatives of 555 Timer IC:

Now we know what all a single 555 timer IC can do. This means a 555 timer can be used as an oscillator and as a pulse generator in the same circuit. For this purpose, numerous pin compatible derivatives, for both bipolar and CMOS versions of 555 Timer IC were produced by many companies, over the years.

The ICs are available either in round metal can package, or the more commonly seen 8 pin DIP package.

Packages – 555 Timer IC

A 14 pin package variation of 555 timer IC, called the 556 IC, was manufactured which had two 555 timer ICs in one chip. Here, the two ICs share a common ground and supply pin. The other 12 pins are allocated to the inputs and outputs of individual 555 timers.

LM556, a dual timer IC manufactured by texas instruments is one such IC. These IC s are ideal for sequential timing application.

Other derivative in 16 bit DIP package, the 558 and 559 had four ICs, in which DIS and THR were connected internally. The 558 IC , is a quad IC and is edge triggered. This eliminates the need of using coupling capacitor for sequential timing applications.

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An Introduction about Electrical Relays……

There are two basic classifications of relays:

• Electromechanical Relays 
• Solid State Relays 

One main difference between them is electromechanical relays have moving parts, whereas solid state relays have no moving parts.

Electromechanical Relays

Electromechanical relays are switches that typically are used to control high power electrical devices. Electromechanical relays are used in many of today's electrical machines when it is vital to control a circuit, either with a low power signal or when multiple circuits must be controlled by one single signal. 

Advantages of Electromechanical relays include lower cost, no heat sink is required, multiple poles are available, and they can switch AC or DC with equal ease.

Some of the electromechanincal relays are general purpose relays, power relay, contactor and time delay relay.

General Purpose Relay

Well known applications of general purpose relays are:

• Lighting controls,
• Time delay controls,
• Industrial machine controls, 
• Energy management systems, 
• Control panels, 
• Forklifts, 
• HVAC.

The general-purpose relay is rated by the amount of current its switch contacts can handle. Most versions of the general-purpose relay have one to eight poles and can be single or double throw. 

General Purpose Relays are cost-effective 5.1-15.1 Ampere switching devices used in a wide variety of applications.

These are found in computers, copy machines, and other consumer electronic equipment and appliances.

Power Relay

Power relays are used for many different applications, including:

• Automotive electronics
• Audio amplification
• Telephone systems
• Home appliances
• Vending machines

Power relays also contain a spring and an armature and one or many contacts. If the power relay is designed to normally be open (NO), when power is applied, the electromagnet attracts the armature, which is then pulled in the coil’s direction until it reaches a contact, therefore closing the circuit. If the relay is designed to be normally closed (NC), the electromagnetic coil pulls the armature away from the contact, therefore opening the circuit.

Power relay is used for switching a wide variety of currents for applications including everything from lighting control to industrial sensors.

The power relay is capable of handling larger power loads 10-45 amperes or more. They are usually single-pole or double-pole units.

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An Over view about MCCB (Moulded Case Circuit Breakers )

Molded Case Circuit Breakers

          Molded Case Circuit Breakers are electromechanical devices which protect a circuit from  Over-current and Short Circuit. It provides Short Circuit Protection and also Over-current and for circuits ranging from 63 Amps up to 3000 Amps.

             Their primary functions are to provide a means to manually and automatically open a circuit under overload or short circuit conditions. The over-current, in an electrical circuit, may result from short circuit, overload or faulty design.

          MCCB is an alternative to a fuse since it does not require replacement once an overload is detected. Unlike fuse, an MCCB can be easily reset after a fault and offers improved operational safety and convenience without incurring operating cost.

      Molded case circuit breakers generally have a  Thermal element for over-current and Magnetic element for short circuit release which has to operate faster.

         MCCBs are manufactured such that end user will not have access to internal workings of the over-current protection device. Generally constructed of two pieces of heavy-duty electrically insulated plastic, these two halves are riveted together to form the whole. Inside the plastic shell is a series of thermal elements and a Spring-loaded trigger.

       When the thermal element gets too warm, from an over-current situation, the spring trips, which in turn will shut off the electrical circuit.

Types of MCCBs

Larger molded case circuit breakers have adjustable range setting on the face of the device. Molded case circuit breakers can range in size from 32 Amperes up to 3000 Amperes.

Molded Case Circuit Breakers have the following Specifications

• Current Rating - Amperes
• Current Setting Range - Amperes
• Short Circuit Rating - Kilo Amperes (KA)
• Operating Characteristics - Normal / Current Limiting Type

MCCBs are now available with a variety of Releases or Operating Mechanisms these are given below

• Thermal Magnetic Release
• Electronic Release
• Microprocessor Release
• Thermal Magnetic Release MCCB

               Thermal-magnetic circuit breakers use bimetals and electromagnetic assemblies to provide over-current protection. Their characteristic inverse time tripping under overload conditions is ideally suited for many applications varying from residential to heavy industrial loads. For higher level (short circuit) over currents, instantaneous trip characteristics allow molded case circuit breakers to interrupt with no intentional delay.

               The adjustable overload protection is from 70% to 100% of the nominal current and short circuit setting from 5 to 10 times of the rated current is possible.

              The minor disadvantage of the release is that operating characteristics of the breaker may vary depending on the ambient temperature.

Electronic Release MCCB

           Electronic or Static Release Molded Case circuit breakers use power electronic circuitry to provide over-current protection. The Continuous adjustable overload protection from 60% to 100% of the nominal current and short circuit setting from 2 to 10 times of the rated current is possible.

         The advantage of the release is that operating characteristics of the breaker is independent of the ambient temperature.

                This wide flexibility takes care of future increases in load capacity of an installation and ensures better planning at an optimum cost.

Microprocessor release MCCB

             Microprocessor release Molded Case circuit breakers use microprocessors to provide over-current protection. The Microprocessor release works on monitoring of current True R.M.S value. It is simulated and calculated from peak values, which installed microprocessor, can detect.

                There is high Flexibility through multiple adjustments of protection settings, High repeat accuracy and High reliability.

               Time delays can be provided for Short Circuit Release better discrimination and co-ordination using LCD display. System Diagnosis is possible as it stores the Trip history within the internal memory. Trip current indication is also available for understanding of type of fault and set-up programming at site.

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lab manual for diploma in electrical engineering semester 6 as per GTU syllabus

Lab manual 

Here is a lab manual for diploma in electrical engineering 
as per GTU syllabus 
of 
Semester 6 
Subject:- Installation commissioning  And maintenance 

click here to download  practicals.

practical 1CLICK

practical 2 Click

practical 3CLICK

practical 4CLICK

practical 5 Click

practical 6CLICK

practical 7CLICK

practical 8 CLICK

practical 9 Click.

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On Power System Stability the Impact Of Voltage Regulation

Voltage Tolerance Ranges

Voltage regulation, by definition, is the percentage change in secondary voltage from no-load to full-load conditions. The regulation is customarily specified at a specific power factor, as the power factor of the load affects the voltage regulation of the device or circuit.
Voltage regulation cannot be improved by the use of the conventional no-load tap changer on a transformer. The tap changer merely changes the transformer turns ratio, but does not significantly change the transformer impedance.

The regulation (percent change from no-load to full-load) will, therefore, not change.
The operating voltage range will, however, change and affect the performance of the utilization equipment.

Load flow studies should be performed and operating conditions (no-load, light-load, or full-load) examined to ensure that voltage tolerance ranges are not exceeded. If voltage tolerance ranges are exceeded, then one alternative is to adjust transformer taps to compensate for either high voltage, at no-load or light-load conditions, or low voltage, at full-load conditions.

Capacitors of either switched or fixed configurations can also be used to correct the voltage range profile of a distribution system.

Often, for large complex systems, the use of switched capacitors is the only realistic solution for a voltage range that is too wide. In this instance, capacitors are switched off-line when the load is light, so that the voltage does not become too high.

As the load increases, capacitors are switched on-line to prevent the voltage from becoming too low.

For maximum benefit, capacitors should be located close to the load that is causing the problem, however, this is often not technically or economically feasible.

Synchronous motors can also be used to good advantage on large power systems if the 0.8 power factor design is purchased, rather than the less expensive unity power factor motor. The 0.8 power factor synchronous motor can be used to improve voltage levels on its utilization bus in the same manner as capacitors.

Control of the operating voltage range can also be achieved by the use of transformers with on-load tap changers and line regulators.

Both devices use multi-tap devices, in combination with voltage sensing and control apparatus, to adjust the transformer ratio or regulator ratio by actively switching taps as the steady-state load changes. These devices are usually used by utilities in the primary distribution system and provide the final distribution circuits with a voltage range within the Range A limits of ANSI C84.1.

Unless the site distribution system is unusually large and complex, and the daily load fluctuations quite large, these devices are not applied to electrical distribution systems on facilities.

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TYPES OF BUS BAR SYSTEM

TYPES OF BUS BAR SYSTEM

1 Single Busbar System

Single busbar system is as shown below in figure 

Single Busbar System

a. Merits

1. Low Cost

2. Simple to Operate

3. Simple Protection

b. Demerits

1. Fault of bus or any circuit breaker results in shut down of entire substation.

2. Difficult to do any maintenance.

3. Bus cannot be extended without completely deenergizing substations.

c. Remarks

1. Used for distribution substations up to 33kV.

2. Not used for large substations.

3. Sectionalizing increases flexibility.

2 Main & Transfer Bus bar System

Main & Transfer Bus is as shown below in figure 

a. Merits

1. Low initial & ultimate cost

2. Any breaker can be taken out of service for maintenance.

3. Potential devices may be used on the main bus.

b. Demerits

1. Requires one extra breaker coupler.

2. Switching is somewhat complex when maintaining a breaker.

3. Fault of bus or any circuit breaker results in shutdown of entire substation.

c. Remarks

1. Used for 110kV substations where cost of duplicate bus bar system is not justified. 

3 Double Bus bar Single Breaker system

Double Bus Bar with Double Breaker is as shown below in figure 

a. Merits

1. High flexibility

2. Half of the feeders connected to each bus

b. Demerits

1. Extra bus-coupler circuit breaker necessary.

2. Bus protection scheme may cause loss of substation when it operates.

3. High exposure to bus fault.

4. Line breaker failure takes all circuits connected to the bus out of service.

5. Bus couplers failure takes entire substation out of service.      

c. Remarks

Most widely used for 66kV, 132kv, 220kV and important 11kv, 6.6kV, 3.3kV

Substations.

4 Double Bus bar with Double breaker System

 Double Bus Bar with Double breaker system is as shown below in figure 

a. Merits

1. Each has two associated breakers

2. Has flexibility in permitting feeder circuits to be connected to any bus

3. Any breaker can be taken out of service for maintenance.

4. High reliability

b. Demerits

1. Most expensive

2. Would lose half of the circuits for breaker fault if circuits are not connected to both the buses.

c. Remarks

1. Not used for usual EHV substations due to high cost.

2. Used only for very important, high power, EHV substations.

5 Double Main Bus & Transfer Busbar System

Double main bus & transfer bus system is as shown below in figure

a. Merits

1. Most flexible in operation

2. Highly reliable

3. Breaker failure on bus side breaker removes only one ckt. From service

4. All switching done with breakers

5. Simple operation, no isolator switching required

6. Either main bus can be taken out of service at any time for maintenance.

7. Bus fault does not remove any feeder from the service

b. Demerits

1. High cost due to three buses

c. Remarks

1. Preferred by some utilities for 400kV and 220kV important substations.

6 ONE & HALF BREAKER SCHEME

a. Merits

1. Flexible operation for breaker maintenance.

2. Any breaker can be removed from maintenance without interruption of load.

3. Requires 1 1/2 breaker per feeder.

4. Each circuit fed by two breakers.

5. All switching by breaker.

6. Selective tripping.

b. Demerits

1. One and half breakers per circuit, hence higher cost

2. Any breaker can be removed from maintenance without interruption of load.

c. Remarks

1. Used for 400kV & 220kV substations.

2. Preferred.

7 RING OR MESH ARRANGEMENT

a.      Merits

Bus bars gave some operational flexibility.

b.      Demerits

1. If fault occurs during bus maintenance, ring gets separated into two sections.

2. Auto-reclosing and protection complex.

3. Requires VT’s on all circuits because there is no definite voltage reference point.

4. Breaker failure during fault on one circuit causes loss of additional circuit because of breaker failure.

These VT’s may be required in all cases for synchronizing live line or voltage indication

c.       Remarks

 Most widely used for very large power stations having large no. of incoming and outgoing lines and high power transfer.

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A Bit of an Introduction about Geo-Thermal Energy

Introduction of Geo-Thermal Energy

Geothermal energy is energy extracted from heat stored in the earth. This geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface. It has been used for space heating and bathing since ancient times, but is now known for both heating as well as for generating electricity.

Geothermal power is cost effective, reliable, and environmentally friendly, but has previously been geographically limited to areas near tectonic plate boundaries. Recent technological advances have significantly expanded the range and size of viable resources, especially for direct applications such as home heating.

Geo-thermal Potential

Geothermal energy has shown signs of considerable growth over the last few years. Global geothermal installed capacity (for electricity) has escalated from 7,972 MWe in 2000 to around 9,700 MWe in the year 2007 (generating about 0.3% of global electricity demand) and is expected to reach around 13,600 MWe by 2012.

The US continues to be the world leader in terms of total installed capacity of geothermal energy and the generation of electric power from geothermal energy.

By mid 2008, worldwide installed capacity of geothermal energy for electricity generation had crossed the 10 GW mark. Worldwide, about 30 GW of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications. If heat recovered by ground source heat pumps is included, the non-electric use of geothermal energy is estimated at more than 100 GWt (gigawatts of thermal power) and is used commercially in over 70 countries.

Geothermal (ground-source) heat pumps (GHPs) have become a major growth area of geothermal energy use in the United States, Canada and Europe. The number of GHPs has steadily increased over the past 10 years. By 2008, an estimated 800,000 equivalent 12 kW (3.4 ton) units have been installed in the United States and about 50,000 in Canada.

Geo-thermal Locations

Geothermal energy supplies more than 10,000 MW to 24 countries worldwide and now produces enough electricity to meet the needs of 60 million people. The Philippines, which generates 23% of its electricity from geothermal energy, is the world’s second biggest producer behind the U.S. Geothermal energy has helped developing countries such as Indonesia, the Philippines, Guatemala, Costa Rica, and Mexico. The benefits of geothermal projects can preserve the cleanliness of developing countries seeking energy and economic independence, and it can provide a local source of electricity in remote locations, thus raising the quality of life. 

Iceland is widely considered the success story of the geothermal community. The country of just over 300,000 people is now fully powered by renewable forms of energy, with 17% of electricity and 87% of heating needs provided by geothermal energy. Iceland has been expanding its geothermal power production largely to meet growing industrial and commercial energy demand. In 2004, Iceland was reported to have generated 1465 gigawatt-hours (GWh) from geothermal resources; geothermal production is reached 3000 GWh in 2009. 

According to some experts, the most likely value for the technical potential of geothermal resources suitable for electricity generation is 240 GWe (This is about 5% of total global installed capacity for electricity in 2008). Theoretical considerations, based on the conditions in Iceland and the USA, reveal that the magnitude of hidden resources is expected to be 5-10 times larger than the estimate of identified resources. If this is the case for other parts of the world, the upper limit for electricity generation from geothermal resources is in the range of 1-2 TWe.

Prominent countries worldwide with geothermal potential:

• Russia 
• Japan 
• Eastern China 
• Himalayan Geothermal Belt 
• The Philippines 
• Indonesia 
• New Zealand 
• Canada 
• United States 
• Mexico 
• Central American Volcanic Belt 
• Andean Volcanic Belt 
• The Caribbean 
• Iceland and other Atlantic Islands 
• Northern Europe 
• Eastern Europe 
• Italy 
• Eastern and Southern Mediterranean 
• East Africa Rift System

Geothermal Energy - How it works

There are three main types of geothermal energy in use currently:

• Direct Use Heating Systems – these use hot water from springs or reservoirs near the earth’s surface.
• Electricity from Geothermal Energy – Electricity generation in power plants require water or steam at very high temperature. Geothermal power plants are generally built where geothermal reservoirs are located within a mile or two of the surface. Thus, these plants use the geothermal heat for generating steam that run a turbine to produce electricity.
• Geothermal Heat Pumps – These heat pumps use stable temperatures under the ground to heat and cool buildings.

Applications of Geothermal Energy

Geothermal Electricity Production

Geothermal Electricity: This geothermal power plant generates electricity for the Imperial Valley in California.

This geothermal power plant generates electricity for the Imperial Valley in California. Credit: Warren Gretz

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 360°F (182°C). 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°-360°F (107°-182°C). 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 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.

Small-scale geothermal power plants (under 5 megawatts) have the potential for widespread application in rural areas, possibly even as distributed energy resources. Distributed energy resources refer to a variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system.

In the United States, most geothermal reservoirs are located in the western states, Alaska, and Hawaii.

Geothermal Direct Use

Geothermal Direct Use: Geothermally heated waters allow alligators to thrive on a farm in Colorado, where temperatures can drop below freezing.

Geothermally heated waters allow alligators to thrive on a farm in Colorado, where temperatures can drop below freezing. Credit: Warren Gretz

When a person takes a hot bath, the heat from the water will usually warm up the entire bathroom. Geothermal reservoirs of hot water, which are found a couple of miles or more beneath the Earth's surface, can also be used to provide heat directly. This is called the direct use of geothermal energy.

Geothermal direct use dates back thousands of years, when people began using hot springs for bathing, cooking food, and loosening feathers and skin from game. Today, hot springs are still used as spas. But there are now more sophisticated ways of using this geothermal resource.

In modern direct-use systems, a well is drilled into a geothermal reservoir to provide a steady stream of hot water. The water is brought up through the well, and a mechanical system - piping, a heat exchanger, and controls - delivers the heat directly for its intended use. A disposal system then either injects the cooled water underground or disposes of it on the surface.

Geothermal hot water can be used for many applications that require heat. Its current uses include heating buildings (either individually or whole towns), raising plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes, such as pasteurizing milk. With some applications, researchers are exploring ways to effectively use the geothermal fluid for generating electricity as well.

In the United States, most geothermal reservoirs are located in the western states, Alaska, and Hawaii.

Indian Geo-thermal Energy Program

Potential

It has been estimated from geological, geochemical, shallow geophysical and shallow drilling data it is estimated that India has about 10000 MWe of geothermal power potential that can be harnessed for various purposes.^[iv]

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.

Potential Sites:

•  Puga Valley (J&K)
•  Tatapani (Chhattisgarh)
•  Godavari Basin Manikaran (Himachal Pradesh)
•  Bakreshwar (West Bengal)
•  Tuwa (Gujarat)
•  Unai (Maharashtra)
•  Jalgaon (Maharashtra)

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HOPE This information will help you to gain your knowledge about Geothermal Energy..

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