Distribution Power Generation

 In this article we will study about Distribution power generation . we will discuss in detail about the distribution power generation and also studied about advantages of DG system. we will know their introduction and function.

Distributed Power Generation

Electricity demand is growing in all the countries of the world. The electric utility installed capacity in the world, at present, is about 3100000 MW and to meet the increasing demand about 80000 MW of new capacity has to be added every year. In USA the utility capacity is about 850 GW AND AN AVERAGE OF 15000 MW of new installed capacity is needed every year meet the increase in demand as well as to replace about 6000 MW of old plants which are require to be retired every year. In India the utility installed capacity is about 118 GW at present and is expected to increase by at least 5% every year in the coming years. The situation in many other countries is almost similar.
Another phenomenon taking place everywhere is power system deregulation and opening up of competition. This system is likely to compel the generating companies to setup small generating plants close to the customers. This system of generating is called decentralized or distributes power generation (DG).  The significant applications of DG system include back up (stand by) generation utility grid enhancement, peak shaving, load management etc. it has been estimate that DG, in the world, would be about 20% in near future.
The DG system are small in size, less than 10 MW and typically 1or 2 MW they feed into the distribution system directly and may be installed by the utility or by big consumers. They may be of any type but are most likely to be solar plants or wind energy plants,

Advantages of DG System

Distributed generation system offer promise to help in modernization and improvement of electric distribution system. The advantages will accrue to the utility, consumer as well as commercial power producers and can be summarized as under:

(a) Advantage for utilities

  •   Transmission capacity relief
  •  Distribution capacity relief 
  • Hedge against high market prices 
  •  Grid investment deferments
  •  Improved grid asset utilization 
  •  Improved grid reliability 
  •  Var support 
  •  Voltage support
  •  Contingency reserves 
  •  Energy and load management

(b) Advantage for consumers

  • Efficient use of energy from combined heat and electricity 
  • Improved reliability by having back up generation 
  • Incentives from utility to provide capacity reserve 
  • Low cost electricity 
  • Clean energy 
  • Improve power quality 

(c) Advantage for commercial power producer

  • Power market (to sell electricity) 
  • Ancillary services market (reactive power, stand by capacity etc.)
  •     To summarize the above advantage tend towards evolution of a new modernized electric power system greater flexibility and security.

Energy sources of Distribution power generation system

Indicates the various distributed generation energy sources. These can be classified into conventional sources. These can be classified into conventional and non-conventional.
The conventional sources include combustion turbines, reciprocating engines, micro turbines and fuel cells. Natural gas and petroleum are used for these forms of distributed generation. However there is growing trend towards using non-conventional sources. This is, evidently, due to the fact that natural gas and petroleum sources are fast depleting and also due to growing environmental concerns. Biomass, solar and wind energy distributed generation system are being increasingly added to the grids and these trends will continue in future.

Energy sources                                            Typical Rating                                                                  

  1. Conventional                                                ----------------

  • Combustion turbine                                    1 to 30 MW   (Mega Watt )                  
  • Raciprocating  Engines                                10 KW  to 10 MW
  • Microturbines                                              1  KW   to 300 KW 
  • Fuel Cells                                                     1 KW   to  20 MW

    2. Non Conventional                                           ---------------

  • Biomass                                                        1 to 5 MW
  • Wind Turbines                                               1 KW to 1 MW 
  • Solar                                                              1 KW to 20 MW 
  • Photo voltaic                                                   1 KW to 1 MW 

The non-conventional energy sources have the disadvantage of high investment cost. A significant part of this investment cost is the cost of power electronic interface.

Function of Power electronic Interface

 The output voltage of a distributed generation system may be dc (in case of photovoltaic system and fuel cells) or ac (in case of wind energy system). However, it is mostly a variable voltage and has to be made compatible with grid voltage. Therefore a power electronic interface is always needed between distributed generation system and grid.
(1) Power conversion from a variable dc (or ac) voltage compatible with grid voltage and frequency. Moreover the output voltage of distributed generation may be more or less than grid voltage.
(2) Output power quality assurance with total harmonic distortion (THD), low voltage and frequency deviation and low flickering.
(3) Protection of distributed generation system and electrical power systems, from abnormal voltage, current, frequency and temperature condition with additional function as anti-islanding protection and electrical isolation etc.
(4)   Control of distributed generation system coupled with objectives like maximum power point tracking of PV array, maximum power extraction from wind energy system, optimum efficiency of fuel cell system etc.

Solar Energy for Distributed Generation

Solar Energy

When light radiation falls on a p-n junction, a voltage is generation. The primary power comes from the striking photons. The use of solar insolation to generate electricity is increasing constantly over the past few years. As the world‘s electricity demand is increasing the use of photovoltaic system connected to the utility grid are attracting more and more attention of power planners. As the costs of PV modules and power electronic interface are showing declining trends, PV system are likely to play major roles in supplying the future electricity demands of the world.
PV system is an all electrical system and has no moving parts. Life time of PV modules can be 25 years or more. However the power generation capacity gets reduced drastically due to ageing.
 Many photo voltaic technologies exist. Constant research and development activities are going on to reduce the cost of photo voltaic.
When photo-voltaic cells are connected in series we get a reasonably high voltage (about 40 V or so). However the weakest among these cells determines the current rating. Many series strings are connected in parallel to increase the current rating.

 Hence these are Distribution Power Generation System . If you will find any incorrect in above article you must comment below in comment box.

If you want to know more about the Distribution power Generation you must sea this video.

Co-Generation Advantages, Co-generation Application

In this article we will know about  Co-generation advantages and their application .we will also know about the basic meaning of Co-Generation.we will also discuss about the topping and bottoming cycle.

Co-generation Advantages

Definition and Scope of Co-generation

Co-generation means sequential conversion of energy contained in fuel into two or more usable forms. In one manifestation the energy of coal is converted into heat in the boiler to produce steam. This steam is used to generate electrical energy and in addition provides heat for manufacturing process. In another manifestation gas is used in gas turbine to generate electrical energy. The remaining heat is used to produce steam in a heat recovery boiler. This steam is used for generating more electrical energy or is used as process steam for manufacturing process.
Co-generation advantages, application of cogeneration
Thus a conventional system uses energy of fuel to produce electrical energy for thermal energy (for manufacturing process) whereas a co-generation system produces both from the same primary fuel. A conventional system needs more fuel to give the same total energy output than a co-generation system. A co-generation system can be either an in plant power generation system or a reject heat utilization system.


Co-generation advantages, application of cogeneration

The implant power generation is used industries and is illustrated in. The industry needs both process steam and electricity. In conventional method steam is produced by a boiler and is electricity is either purchased from a utility or generated by a diesel generating set. If co-generation is used, the boiler is made to produce steam at a higher temperature and pressure than needed for manufacture purposes. This steam is a turbine generator set to produce electricity. The exhaust steam (from turbine) is used for manufacturing purpose.
The reject heat utilization system is used in power plants. Some steam is extracted from the turbine (at a suitable temperature and pressure) and supplied to a n adjacent industry for manufacturing purpose. This is illustrated.


 Co-generation Advantages

These are some Co-generation advantages  which are given below .

(a) Fuel economy. 

Co-generation result substantial economy in the consumption of primary fuels i.e. coal, oil, gas. The fuel economy results from higher thermodynamic efficiency of a co-generation system as compared to separate power producing systems and heat producing system. Moreover the extra fuel needed to generate electrically the same quality of steam produced for requirements is  only about 10%

(b) Lower capital costs.

 Many case studies have been conducted to estimate the costs per kW of installed capacity in power plants and the additional capital costs need to generate electricity by adopting co-generation systems. it is seen that an industry needing steam for processing has to invest in boilers. The extra investment needed to upgrade boiler so that electricity can also be generated is pretty small as compared to the cost of boiler. It has been estimated that incremental investment in co-generation system is only about 50% of the investment needed by an electric utility to supply the same power to industry. Thus co-generation result in enormous savings in capital costs.

(c) Low gestation period.

 A utility needs about 6 year to add a thermal generation system. However the installation of a co-generation system by an industry needs only about 3 years. The lower gestation period result in saving in interest, early utilization of facility, early return on investment and lesser chances of cost escalation of project.
Lower capital costs.
 Many case studies have been conductor to estimate the capital costs per kW of installed capacity in power plants and the additional capital costs needed to generate electricity by adopting co-generation systems it is seen that an industry needing steam for processing has to invest in boilers. The extra investment needed to upgrade boiler so that electricity can also be generation is pretty small as compared to the cost of boiler. It has been estimated that incremental investment in co-generation systems is only about 50% of the investment needed by an electric utility to supply the same power to industry. Thus co-generation result in enormous saving in capital costs. it most important co-generation advantage.

(d) Low gestation period. 

A utility needs about 6 year to add a thermal generation system. However the installation of a co-generation system by an industry needs only about 3 years. The lower gestation period results in saving in interest, early utilization of facility, early return on investment and lesser changes of cost escalation of project.
Saving to industry from power cuts and power supply interruption. In all developing countries including India the generation capacity is much less than the demand. The electricity supply authorities impose severe power cuts on industry especially when electricity demand for agriculture is high. Moreover the frequency and duration of supply interruptions are pretty large. The power cuts and supply interruption result in huge losses to industries. Many industries install diesel generating sets to keep their processes running. The generation cost per kW of these sets is very high. it is also co-generation advantages

If an industry opts for co-generation to meet its electricity demand, it will not face any power cuts. Moreover, a well designed co-generation scheme can be very reliable. Thus the industry will benefit in this respect also.

Co-Generation Technologies Advantage

The commercial co-generation technologies being presently used for topping cycles are steam turbine, gas turbine, combined cycle and diesel engine systems. In addition fluidized bed combustion (FBC), magneto-hydro-dynamic (MHD), fuel cells and some other conversion are being developed.these are also a type of Co-generation advantages.

(a) Steam turbine system. 

The steam turbine system uses the equipment similar to that in a thermal plant i.e. boiler, steam turbine, generator and other auxiliaries. The fuel used may be oil, natural gas, coal, wood or other similar materials. The high pressure steam produced by the boiler drives a steam turbine which is coupled to generator. The low pressure exhaust from the steam turbine is used for industrial process applications, space heating etc. Back pressure steam turbines are generally preferred because they exhaust low pressure steam and are more efficient. The boiler used by industries for producing process steam is generally low temperature low pressure boilers. If such an industry opts for co generation, replacement of these boilers by those producing, high temperature, high pressure steam is invariable necessary.
Co-generation advantages, application of cogeneration
If an industry installs steam turbine equipment for co-generation, the pollution level is likely to increase. Sulfur oxides. Nitrogen oxides. Particulates and fly would pose problems and special pollution control measures would be necessary.
Case studies revealed an energy saving of about 13% if steam turbine co-generation system is installed. The steam-turbine system has the added advantage of fuel flexibility.

(b) Gas turbine system.

 A gas turbine system consists of compressor, combustion chamber, gas turbine and generator. Air is compressed by the compressor and supplied to combustion chamber. Fuel (oil or natural gas) is burnt in the combustion chamber and heats the compressed air. This hot pressurized gas expands in a turbine which drives the generator. The exhaust from the combustion chamber is used as process heat. If necessary the hot exhaust gases can be used to raise steam in a waste heat recovery boiler where the heat of the gases is transferred to water.
Due to scarcity and high cost of petroleum products, the cost of electricity generated by this cycle is rather high. Gas turbines need more maintains than steam turbines. Case studies have revealed an energy saving of about 25% if this cycle is used for co-generation system. it is most used co-generation advantages.

(c) Combined cycle system. 

This system is a combination of gas turbine and steam turbine systems. The gas turbine exhaust is used in waste heat boiler to raise steam. If necessary additional fuel is added to waste heat boiler. The steam, from the boiler, is used in a back pressure turbine which drives another alternator to produce electricity. The low pressure exhaust from steam turbine is used as process steam. This system has greater flexibility for topping steam. Case studies have indicated an energy saving of about 35% by a combined cycle co-generation system.
 hence these are co-generation technologies advantages.
For knowing more about the Co-generation advantages you must watch this video.



Topping  and Bottoming Cycles

The implant power generation (co-generation) system can be topping cycles or bottoming cycle.
In a topping cycle, fuel is burnt in the boiler to produce high temperature steam. This steam is expanded in a turbine coupled to a generator to give electric power. The reject heat from the turbine is used for manufacturing process. The reject heat from process is used to generate electrical power.
Thus in a topping cycle electrical energy is produced first whereas in bottoming cycle heat energy is used first. Generally the steam require for industrial process is at low temperature whereas high temperature steam is needed for electric power generation. Therefore only the topping cycle is used. The bottoming cycle has very limited utility.
The overall efficiency of a topping cycle is around 75% as compared to a combined efficiency of about 55% for two separate systems (for producing electrical energy and steam).
Hence these are Co-generation advantages if you will find any incorrect in above article you must comment below in comment box.

MHD Power Generation

In this article we will studied about the MHD Power generation . we will also know about how to generate MHD power. We will studied about the open cycle MHD power generation and Closed cycle MHD Power generation. we have also studied about advantages of MHD power generation.

MHD power generation , Open cycle and closed cycle MHD system

 MHD Power  Generation

Advantage of MHD Power Generation

MHD generation offers several advantages as compared to other methods of electric generation. Some of these are:

(1) The conversion efficiency of an MHD system can be around 50 percent as compared to less than 40 percent for the most efficient steam plants.

(2) Although the costs cannot be predicted very accurately, yet it has been reported that capital costs of MHD plants will be competitive with those of conventional steam plants.

(3) Because of higher efficiency, the overall generation cost of an MHD plant will be less. It has been estimated that the overall generation cost in an MHD plant would be about 20% less than in convection steam plants.

(4) The higher efficiency means better fuel utilization. The reduced fuel consumption would offer additional economic and social benefits and would also lead to conversion of energy resources.


MHD power generation , Open cycle and closed cycle MHD system

(5) The efficient heat utilization would decrease the amount of heat discharged to environment and the cooling water requirement would also be lower.

(6) The research studies at Aveo Everett Research Laboratories (USA) and other institutions have show that the use of precipitator not only recover the seed material but also effectively traps most other pollution agents. Show the pullulating emissions of an MHD plant and a conventional steam plant. Thus an MHD plant offers great benefits in environment aspects of electric energy generation.

(7) It is possible to utilize MHD for peak power applications and emergency service (upto 100 hour per year). It has been estimate that MHD equipment for search duties is simpler, has the capability of operating in large unit sizes and the ability to make rapid start to full load.


MHD Power Generation ( Open cycle and working fluid)

MHD system may be an open cycle system or a closed cycle system. In an open cycle system the working fluid is used on the once through basis. The working fluid after generating electrical energy is discharge to the atmosphere through a stack. In a closed cycle system the working fluid is recycled to the heat source and thus used again and again. The operation of MHD generators directly on combustion products is an open cycle system. The working fluid is air. In closed cycle system helium or argon is used as the working fluid. The use of a nuclear reactor using solid fuel element for providing the heat energy for an MHD process requires that the working fluid should have the following three properties (i) it should be capable of providing heat transfer under reactor operating condition (ii) it should not require excessive compressor work (iii) it should not be rendered active within the reactor. Helium, most nearly, fulfill all these requirements.

MHD Power Generation Closed cycle 

 The MHD generator resembles a rocket engine surrounding by a huge magnet. The fuel, coal (or natural gas ) is burnt to produce hot gas. The hot  gas is then seeded with a small amount of an ionized alkali metal (cesium or potassium) to increase the electrical conductivity of the gas. The gas expands through the rocket like generator surrounded by powerful magnet. During the motion of the gas positive and negative ions move to the electrodes and constitute an electric current. The rejected gas passes through an air heater for preheating the inlet air. The seed material is recovered for successive use. The nitrogen and sulphur are removed (for pollution control) and the gases are discharged to the atmosphere. The developed view of an MHD channel          
For efficient practical realization an MHD system must have following features:



MHD power generation , Open cycle and closed cycle MHD system
MHD power generation feature are these...

(1) Air superheating arrangement to heat the gas to around 2500 C so that the electrical conductivity of the gas is increased.

(2) The combustion chamber must have low heat losses.

(3) Arrangement to add a low ionization potential seed material t other gas to increase its conductivity.

(4) Water cooled but electrically insulating expanding duct with long life electrodes.

(5) A magnet capable of producing high magnetic flux density (5to 7 teslas).

(6) Seed recovery apparatus-necessary for both environment and economic reasons

MHD Power Generation Open loop Cycle system

The closed cycle inert gas MHD system was conceived around 1965. Ti was thought that in this in this method all the advantage of the open cycle system would be retained and the main disadvantages of the open cycle system (viz. very high temperature requirements and a very chemically active flow) could be removed. As the name suggest, the working fluid, in a closed cycle, is circulated in a closed loop. The working fluid is helium or argon with cesium seeding.


MHD power generation , Open cycle and closed cycle MHD system
The working fluid is a mixture of atomic gases, without rotational and vibration modes. That interacts readily with thermal electrons. Therefore it is possible in closed cycle system to maintain the conduction electron in the flow at a higher temperature than the bulk gas. Since electron density tent to be governed temperature rather than gas temperature we can get substantially higher electron density and electrical conductivity than would exist at the same temperature in combustion gas flow.

The possibility of using a nuclear heat source with a closed cycle MHD system has also been investigated. However its feasibility has yet not been established.
Hence these are MHD power generation and their open cycle and closed loop cycle system . if you find any incorrect in above article you must comment below in comment box.

If you want to know more about the MHD power generation you must watch this video.

Earth Energy Application

In this article we will know about the earth energy and their application.

Introduction of Earth Energy

Earth is in state of thermal equilibrium. Energy received from the sun is lost at night. The small amount of energy generate by the decay of unstable isotopes of Uranium, Thorium etc. is dissipated form’s earth interior to oceans and atmosphere.

Heat generation within earth is around 2700 GW. The temperature difference within the earth depends on:

(1) The thermal properties of earth’s interior their radical and lateral variation.
(2)   Movements of fluid or solid rock materials occurring at rates of more than a few millimeters per year.

Earth energy and application

A potential geothermal source region should have high thermal gradient which is defined as:

                      Thermal gradient = Heat flux / Thermal Conductivity

Thermal gradient will be night if either heat flux is high or thermal conductivity is low. The heat energy in earth’s interior is due to radioactivity. Regions of higher radioactivity have higher heat flux and are potential geothermal sites.

Surface of the earth consist of about one dozen tectonic plates e.g. American plate, African plate, Arabian plate, Indian plate, Philippine plate, pacific plate etc. Each of these plates has thickness around 100 km and thousand of kilo meters of area. Earth’s interior is unable to lose heat, by conduction, as rapidly as it is generated by radioactivity. This lead to convective instabilities which mean that these plates are continuously in motion with respect to each other. 

A variety of processes along the margins of the plates lead to partial melting at depths between 15 to 200 km. the molten masses penetrate the surrounding rock and rise towards earth at rates varying from a few cms per day to a few cms per year thus result in volcanic activity. The molten masses which do not reach earth’s surface come to rest in the middle or upper part of the earth’s crust at depth less than 20 km. These liquid magmas may have temperature around 1000 C. The crystallization of these liquid magmas produces intrusive igneous bodies. The cooling and crystallization of igneous bodies gives rise to local heat flux.

 This heat flux constitutes the geothermal energy which may be used for variety of purpose including electricity generation. These local heat fluxes continue for thousands of years and form an inexhaustible source of energy. The majority of active geothermal areas tend to concentrate around the margins of major lithosphere plates.

Heat Extraction

The extraction of heat from the earth’s interior needs a natural or artificial heat exchange. In many geothermal areas natural sub-surface water circulating system bring out this heat giving rise to hot springs. A schematic representation of geothermal system 
Kilometer or so an impermeable crystalline magma above the magma is the impermeable crystalline rocks which are overlain by localized pockets of permeable rocks. One such localized pocket is show in this figure. The localised pockets are bounded by fracture zones or fault alone which some relative motion of rock has occurred. Water circulated long fault lines. As it goes down and moves in the earth’s interior (path ABCDE) it is heated by the permeable layer which is in turn heated by conduction of heat from the magma. The hot water comes out through another fault and forms a hot spring.

Earth energy and application

Depending on the temperature and depth of the permeable rocks, the natural hydro thermal system can be divided into three categories. 

(1) Dry Steam System. The temperature of the permeable rock is very high. The whole of the water is converted into steam which gets superheated by the time it comes out of the surface. The Larderello (Italy) and Geysers (California) fields are dry steam systems.

(2) We Steam system. The temperature of permeable rock is not very high. By the time water comes out, only a part of it gets converted to steam. Therefore eruption gives water steam mixture.

(3) Hot Water System. The temperature of the permeable rock is rather low. The surface eruption provides hot water.

For proper exploitation of geothermal energy for electricity generation, extensive survey by geological and geophysical methods is necessary. When the area have been located after hese surveys, it is necessary to drill a number of holes at carefully selected sites. The cost of drilling the wells increases with the depth. The wells at Geysers field (California) are 2km deep, 51 cm diameters at top 22cm diameter at bottom.

The dry Steam of the high temperature dry steam system can be directly taken to the steam turbine and used for generating electricity.
The wet steam fields in the world have been estimated to be about twenty times more abundant than the dry steam fields. The wet systems yield about 20 per cent (by weight) and the remaining quantity of hot water. It is necessary to separate the steam and water at the surface before the steam can be used to drive the turbine. Generally, in such system, the steam is used for electricity generation and the hot water for other miscellaneous purpose. In New Zealand the hot water of a wet steam field is being used for industrial processes by a paper mill. In Iceland such water is used for industrial purposes and house hold heating. Similar is the case in Japan, USSR and Hungary. In Chile a project is being developed for using the steam, from a wet steam geothermal field for electricity generation and distillation of the hot water to yield fresh water and valuable minerals.

Hence these are Earth energy application if you will find any incorrect in above article you must comment below in comment box. 

If you want to know more about the Earth Energy and application you must watch this video.

General Description Of Pumped Storage Plants

In this article we will know about the pumped storage plants. We have also studied about the how pumped storage plants are use full for hydel power plant.

General Description Of Pumped Storage Plants

A pumped storage plant is a special type of plant meant to supply peak loads. During peak load period, water is drawn from the head water pond through the penstock and generates power for supplying the peak load. During the off-peak period, the same water is pumped back from the tail water pond to the head water pond so that this water may be used to generate energy during the next peak load period. Thus, the same water is used again and again and extra water is needed only to take care of evaporation and seepage. Generally the pumping of water from the tail water pond to the head water pond is done at night when loads are low. The plant generates energy for supplying peak loads during day time. The off peak pumping maintains the firm capacity of the pumped storage plant. The reservoir capacity should be such that the plant can supply peak load for 4 to 11 hours. A general arrangement of pumped storage plant .

Pumped Storage Plant Advantage, Application

The earlier pumped storage installations used a separate pumped of pumping the water back into the head water pond. A recent development is a reversible turbine pump. During peak loads, the turbine drives the alternator and the plant generates electrical energy. During low loads, the alternator runs as a motor and drives the turbine which now works as a pump for pumping the water into the head water pond. This arrangement reduces the capital cost of the plant. The power for driving the motor is taken from the system. 

PUMPED STORAGE PLANTS FOR SUPPLYING PEAK LOADS

Every pumped storage scheme reduces dual conversion of energy, the efficiency being around 60 to 70 percent. The fact that the energy gained from a pumped storage plant is always less than the energy input, should not obscure the fact that this apparent loss to the system is negligible when compared with the substantial savings in fuel which are made when these plants are used in a mixed system. The most obscures economies are in the replacement of standby thermal plants and in the fact that the existing thermal plants can be run with fewer and less rapid load changes.

Pumped Storage Plant Advantage, Application

Modern generation systems are a mixture of hydro, steam and nuclear power stations so that energy can be generated most economically. If hydro contribution is small, the steam and nuclear stations have to be of sufficiently large capacity. The steam and nuclear plants operate more economically when run continuously at or near full load. At the time of low loads the excess energy generated by stem and nuclear plants can be used for driving the motor of the pumped storage scheme. The pumped storage plant would in turn supply peak loads. Thus the capacity of the steam and nuclear plants need be only for supplying the base loads and hence much less than what it would be if they were to meet the whole demand. In addition the steam and nuclear plants can be worked at almost unity load factor which ensures their most economic operation. 

Advantages Of Pumped Storage Plant

Pumped storage plants have very important advantage. Some of these are:
  
(i)
Peak loads can be supplied at a lesser cost that that incurred when these loads are supplied by steam and nuclear plants.

(ii) Standby capacity is available on short notice. Power engineers in utilities having pumped storage installations have long realized the benefit of quick switching on and off capacity of these installations. Pumped storage plants need a starting time of only 2 to 3 seconds and can be loaded fully in about 15 seconds. In the event of an outage on a unit, a pumped storage plant can be called upon to meet the generation deficiency (occurring due to the outage) thus ensuring reliable supply and avoiding the necessary of load shedding.

(iii) The load factor of steam and nuclear plants is increased thus ensuring their efficient and economic operation.

(iv) Since the base loads plants needs not be used to supply peak loads. The forced and maintenance outages of these plants are likely to be reduced.

(v) In the event of an extra demand coming up suddenly on the system, these plants can be immediately switched on to meet this extra demand.

(vi) Because of their ability to take up loads in a very small time, the use of pumped storage plants reduces the spinning reserve requirement of the systems.

(vii) They can be used for load for frequency control.       

Types Of Pumped Storage Installation

Pumped storage plants offer many benefits. However their feasibility and economics should be critically evaluated at the planning stage. During the power system planning studies, three types of pumped storage installation can be considered: 

(i) High head, daily daily/weekly cycle, peaking plants close to the load center.

(ii) Low/medium head, seasonal cycle plants, far-away from load center (peaking or non-peaking types). 

(iii) Medium head, daily/weekly cycle peaking plants at an existing cascade of reservoirs.

Hence these are basic description of pumped storage plant if you will find any incorrect in above article you must comment below in comment box.

Classification of Hydro-electric power plant

In this article we will know about the classification of hydro-electric plants. We will know about various types of hydro electric plant.
 Classification of Hydro-electric power plant
 The classification of hydro-electric plant can be classified According to various steps 
 1. Flow of water
 Hydro plants can be classified, according to the extent of water regulation available, into following types:
According to flow of water , the classification of hydroelectric plant given below .

1. Run of river plant without poundage.

        2. Run off river with poundage

3.  Reservoir plants
Classification of hydro-electric plants, different type hydro-electric plant
                                

1. Run of River plant Without poundage


 These plants are located such that they use water as it comes, without any poundage or storage. There is no control on flow of water. During period of high flows or low loads, water is wasted. During lean flow periods, the plant capacity is very low. High flows or low. As such these plants have very little firm capacity. In such sites, the water is mainly used for irrigation or navigation and power plant is only incidental. Such plants can be built at a considerably low cost but the head available and the amount of power generation are generally low. Their principal aim is to use whatever high flows, these plants can supply a substantial portion of base load. flow is available of energy generation and thus save coal that would otherwise be necessary for the steam plants. During the period of The generation capacity to be installed for such plants requires a careful consideration. The 72 MW plants of Louisville Gas and Elect. Company on Ohio River in U.S.A. is an example of this type of plant. it is main types of hydro-electric power plants.

2. Run off river plants with poundage. 

Poundage refers to storage at the plant to take care of hour to hour fluctuations in load on the station. Poundage increases the firm capacity of the station provided the floods do not raise the tail race water level thus reducing the effective water head and plant output. Such plants can serve as base load or peak load plants depending on the stream flow. When plenty of water is available, these plants can be used as base load plants. When stream flow decreases, these plants can be made to work as peak load plants. Show these two operated in operation of such plants. Thus these plants offer maximum conservation of coal when operated in conjunction with steam plants the 252 MW Hydro Plant and Safe Harbor Plant in U.S. A are example of this type of plants.

3. Reservoir plants.

 Most of the hydro-electric plants, everywhere in the world, belong to this category. When water is stored in a big reservoir behind a dam, it is possible to control the flow of water and use it most effectively. Storage increases the firm capacity of the plant. The plant can be used as a base load plant or as a peak load plant depending on the water stored in the reservoir, the rate of inflow and the system load. Grand Coulee of reservoir plants. In U S A, KRASNOYARKS plant in USSR and BHAKRA plant in India are notable examples of reservoir plants.. it is basic classification of hydro-electric power plants.

2. Classification of According to load


Classification of hydro-electric plants, different types of hydro-electric plant
  According to load, hydro plants can be classified as base load plants, peak load plants and pumped storage plant.

(1)    Base load plants.

 They feed the base load of the system. Thus they supply almost constant load throughout and operate on a high load factor. Base load plants are usually of large capacity. Run off river plants without poundage and reservoir plants are used as base load plants. For a plant to be used as base load plant, the unit cost of energy generated by the plant should be low.
it is also main types of hydro-electric plant.

(2)    Peak load plants.


 They are meant to supply the peak load of the system. Run off river of plants with poundage can be used as peak load plants during lean flow periods. Reservoir plants can, of course, be used as peak load plants also. Peak load plants have large seasonal storage. They store water during off-peak periods and are run during peak load periods. They operate at a low load factor. A special type of peak load plant is pumped storage plant.

(3)    Pumped storage plant.


 It is special type of plant meant to supply peak load. 

3. Classification of electric plant According to Head                      

Classification of Hydro-electric power plants, different types of hydro-electric plant

(1)    Low head plants.

   When head is less than 30 m, the plant is called a low plant. A dam or barrage across the river creates the necessary head. The power plant is located near the dam. And, therefore, no surge tank is need. Either one half of the barrage has regulating gates for discharge of surplus water while the plant is in front of the second half or the plant is constructed by the side of the river. Francis or Kaplan turbines are used. it is main types of hydro-electric plant

(2)    Medium head plants.

 The plants operating at head between 30 and 100 m. An open channel brings water from main reservoir to the fore-day from where pen stocks carry water to the turbines. Francis or Kaplan turbines are used.

(3)    High head plants. 

The plants operating at heads above 100m are generally  classified as high head plants. The civil works for these plants include reservoir, tunnel, surge tank and penstock. Generally Francis are used   for heads below 200m and penstock turbines for turbines for still higher heads.

If you will find any incorrect in above article you must comment below in comment box.

Solar Energy Collectors, Types of Solar Energy Collectors

In this article we will know about the solar energy collectors . we also know about the types of solar energy collectors.

Solar Energy Collectors

The first step in the solar energy utilization is the collection of this energy. This is done through collectors whose surfaces are designed for high absorptive and low emissivity.
Solar energy collectors, types of solar energy collector
these are following types of solar energy collectors. which is shown below.

1.  Flat Plate Collector.

 A flat collector consists of the following basic element:. it is very efficient type solar energy collector.
1. A flat plate upon which the short wave solar radiation falls and is absorbed and converted into heat energy.

2. An insulated container to eliminate or substantially reduce thermal losses from the collection system.

3. One or more plates of glass or transparent plastic to reduce the upward heat loss from the collection surface.

 4. Tubes or channels to circulate the liquid required to remove the heat energy from the collector to the strong tank.

A flat plate collector is shown in Fig. Solar radiation passes through the transparent cover and is absorbed by the collector plate. A fluid flowing in a passage in contact with the collector is heated and the heat from the fluid is extracted for use. The circulating pump keeps a continuous circulation of the fluid through collector and strong tank. In the storage tank, is working as heat ex changer, fluid heats water which is used for the desire purpose. The efficiency of the collection and conversion process depends on the heat loss to surroundings which in turn depends on the temperature at which the collectors work. The cover plate is transparent to incoming radiation but opaque to infra red radiation of the collector and thus reduces the heat losses. Treating the collector surface with special coating reduces the heat losses still further. These coating can be
 (1) particles of copper oxide about 1 u m in diameter, 
(2) semi- conductor like silica 
(3) layered coatings of calcium oxide and magnesium oxide. 

These coating have a high ratio of absorptive emissivity (about 10 to 15 or so) but are very expensive. Al though a variety may be used for the heat transfer in the collector flow channels. All practical system to date have used water or water ethylene glycerol solution, the letter additive being used primarily to avoid problem due to the freezing of liquid in the tube under subzero temperature conditions. it is very simple and less costly type solar energy collectors.
Solar energy collectors, types of solar energy collector
 Flat plate collector with honey comb structure. There is a growing interest in the use of honey comb cellular structure of various shapes. Some of which are shown in fig. 15.8.their excellent strength to weight ratio they have many application in aircraft and aerospace industries. Many materials like aluminum, glass, plastics etc. are used in the manufacture
Of these structures. It has found that collectors with honey comb cellular structures are more efficient and their use has been proposed in solar heat collectors. The process of heat transfer is a multi mode phenomenon and all the three modes, conduction, con- vection and radiation, should be considered in assessing the overall performance of any structure. In term of conduction affect the cellular surface. May be envisages as an extended surface used to increase the heat transfer area. In terms of convection effects, structure has been found to modify the convection transport from a heated body and in terms of radiation effects, they have been proposed for the creation of artificial black bodies and specials forms of terminal traps. An inclined flat plate solar collector with honey comb structure is shown in diagram.

2.  Concentrating Collectors

 In spite of the methods of reducing heat losses the maximum temperature at which a flat plate collector works is quite low, around 100 C IN summer and around 40c in winter. Concentrating collectors are more effective but very closely. Parabolic- at around can be   reflector used up to 30000 c However its direction has to be adjusted to follow the direction of sun rays.

A hemostat (b) is often used to reflect the radiation directly on the object to be heated. A combination of heliostat and parabolic reflector may also be used. The heliostat reflects the sun’s rays to the reflector. The heliostat can be adjusted to account for the change in sun’s position. it is very useful type solar energy collector .
Solar energy collectors, types of solar energy collector
The reflective surface of a heliostat usually consist of back silvered low iron glass or metalized plastic. These are fixed to light and mechanically stiff back up structures. The reflective surface is generally made up several small segments to allow better control of the flatness than a large single surface. These segments are also easily replaced in case of damage. The heliostats elements are mounted on that are fixed perpendicularly to a horizontals elevation members. Azimuth ally are elevations movements are made by separated drive mechanisms which typically consist of electric motor driven gears connected to the axes.

Helios tats have been found to be very suitable as collectors for solar power plants. Their cost is one of the key costs in the total cost of the plant. It is expected that better manufacturing processes and mass production will reduce their cost. hence it is main type of solar energy collector.

 SOLAR PONDS. 

Non-convective solar ponds have been suggested for collecting solar energy on a large scale. A solar pond is a shallow body of water, about 1 metre deep containing dissolved salts to generate a stable density gradient (fresh water on top on denser salt water at bottom). Some of the incident solar energy entering the pond surface is absorbed throughout the depth and the remainder which penetrates the pond is absorbed at the black bottom. If the pond had only fresh water (or water of the same density) the lower layers would heat up, expand and rise to the surface. Because of convective maxing and heat loss at the surface only a small temperature rise in water would be realized. The convection can be eliminated by initially creating a sufficiently strong salt concentration gradient. In this case the thermal expansion in the bottom lower layers is insufficient to destabilize the pond. With convection nearly eliminated the heat loss from the lower layer is only by conduction. Because of its relatively low thermal conductivity water acts as insulator and permits temperatures up to 90%c to be developed in the bottom layers. solar pond is use full for solar energy collector to produce electricity,

Solar energy collectors, types of solar energy collector

One way to extract heat from solar ponds is to place pipes in the lower layers and circulate water through these pipes. A simpler and more efficient approach is to take advantage for stable density stratification and use method of selective withdrawal, a technique often use for water quality control in large reservoirs. A sink placed in stably stratified liquid withdraws the liquid from a thin horizontal layer, just as one would draw a single card from a deck. This flow is quite different from one that would occur if the density of water were the same throughout. The phenomenon of selective withdrawal provides means by which, firstly, the stable density gradient required in the upper insulating layer can be corrected and maintained at secondly the hot lower layer can be removed, passed through a heat ex changer and returned at a lower temperature to the bottom of the bottom of the pond. It is sometimes desirable to separate physically the bottom layer from the upper layer by a thin zone transparent partition, generally made of plastic.

The use of solar ponds has been suggested for salt production, space heating and power generation using organic fluid Rankin cycle engines which can operate relatively low source temperatures.  

Hence these are solar energy collector if you find any incorrect in above article you must comment below in comment box.

If you want to know more about the solar energy collectors you must watch this video.


Photo-Voltaic Cell Working

 In this article we will know about the photo-voltaic cell working and their application . we will know brief working of photo-voltaic cell.

Photo-Voltaic Cell working
It is possible to covert solar energy directly into electric energy by photo-voltaic process. The photo-voltaic effect is the generation of an EMF as a result of the absorption of ionizing radiation. Energy conversion devices which are used to convert sunlight to electricity by photo-voltaic effect are known as photo voltaic cells. Thus a solar cell is a transducer which converts the sun’s radiant energy directly into electricity and is basically a semi conductor diode capable of developing a voltage of 0.5 -1v and a current density of 20-40mA per 2cm depending on the materials used and the sun light conditions.

The photo –voltaic effect can be observed in nature in a variety of materials but the materials having the best performance in sun light are the semi conductors. When photons of the sun light are absorbed in a semi –conductor, they create free electrons (and holes) with higher energies than the electrons which provide the bonding in the crystal. Once these free electron holes to flow pairs are created, there must be an electric field to induce these higher energy electrons and holes to flow out of semi conduction to do useful work. In typical solar cell this is done by the use of p---n junction. It is known that an electric field exists across a p—n junction and this field sweeps the electrons in one direction and holes in the other. so these are basic working of photo-voltaic cell.

A typical solar cell is shown in diagram.  active area of solar cell is less than full front surface area because of the need to position opaque conductors on top the cell to collect the generated current. Practical top contact structure are generally in the form of comb to like grids so designed as to strike a balance between reduced active area and reduced series resistance brought about the increasing the contact coverage. An anti reflection coating is often employed to improve the coupling of light into the semi-conductor. The solar cell has to be encapsulated to protect it from atmospheric degradation.so it is overall working of photo voltaic cell. for better know about photo-voltaic cell we must need to know about working of solar cell.

 Solar cell working

 Many types of solar cells have been proposed. The two types available commercially are single crystal silicon cells and cadmium sulfide/cumbrous sulfide cells. Single crystal silicon is the most highly developed material for photo voltaic conversion. The physical properties of single crystal silicon are well understood and the raw material is abundant. Single crystal silicon cells have efficiency around 10to 14 per been used for many years as power sources for space craft in sizes from a few watts to over 20KV per satellite. However they are still very costly and many attempts have been initiated in France, Japan, USA, West Germany etc. to reduce the cost.
    Hence these are photo-voltaic cell working if you will find any incorrect in above article you must comment below in comment box. thanks
If you want to know more about the photo voltaic cell working you must sea this video.