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ENERGY SOURCES AND MANAGEMENT OF ELECTRICAL ENERGY

TOPICS➢ Present scenario ,future prospects and economic criteria

➢ Solar energy

➢ Bio energy

➢ Wind energy

➢ Geo-thermal and tidal energy

➢ Magneto hydro dynamic (MHD) Power generation

➢ Chemical energy sources

➢ Energy conservation and management

1)PRESENT SCENARIO

FUTURE ENERGY SCENARIO

2) SOLAR ENERGY

Solar energy is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture, molten salt power plants and artificial photosynthesis.

It is an important source of renewable energy and its technologies are broadly characterized as either passive solar or active solardepending on how they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light-dispersing properties, and designing spaces that naturally circulate air.

The large magnitude of solar energy available makes it a highly appealing source of electricity. The United Nations Development Programme in its 2000 World Energy Assessment found that the annual potential of solar energy was 1,575–49,837 exajoules (EJ). This is several times larger than the total world energy consumption, which was 559.8 EJ in 2012.

In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating global warming, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared"

HOW SOLAR ENERGY CONVERTED INTO ELECTRICAL

ENERGY

Light striking a silicon semiconductor causes electrons to flow, creating electricity. Solar power generating systems take advantage of this property to convert sunlight directly into electrical energy.

Solar panels (also called “solar modules“) produce direct current (DC), which goes through a power inverter to become alternating current (AC) — electricity that we can use in the home or office, like that supplied by a utility power company.

There are two types of solar power generating systems: grid-connected systems, which are connected to the commercial power infrastructure; and stand-alone systems, which feed electricity to a facility for immediate use, or to a battery for storage.

Grid-connected systems are used for homes, public facilities such as schools and hospitals, and commercial facilities such as offices and shopping centers. Electricity generated during the daytime can be used right away, and in some cases surplus electricity can be sold to the utility power company. If the system doesn’t generate enough electricity, or generates none at all (for example, on a cloudy or rainy day, or at night) electricity is purchased from the utility power company. Power production levels and surplus selling can be checked in real time on a monitor, an effective way to gauge daily energy consumption.

Stand-alone systems are used in a variety of applications, including emergency power supply and remote power where traditional infrastructure is unavailable.

APPLICATION OF SOLAR ENERGY

Solar water heater Solar furnaces

APPLICATION OF SOLAR ENERGY

Solar cooker Solar pumping

3)BIO-ENERGY

Bioenergy is renewable energy made available from materials derived from biological sources. Biomass is any organic material which has stored sunlight in the form of chemical energy. As a fuel it may include wood, wood waste, straw, manure, sugarcane, and many other by-products from a variety of agricultural processes. By 2010, there was 35 GW (47,000,000 hp) of globally installed bioenergy capacity for electricity generation, of which 7 GW (9,400,000 hp) was in the United States.

In its most narrow sense it is a synonym to biofuel, which is fuel derived from biological sources. In its broader sense it includes biomass, the biological material used as a biofuel, as well as the social, economic, scientific and technical fields associated with using biological sources for energy. This is a common misconception, as bioenergy is the energy extracted from the biomass, as the biomass is the fuel and the bioenergy is the energy contained in the fuel

There is a slight tendency for the word bioenergy to be favoured in Europe compared with biofuel in America

METHODS OF GENERATING ENERGY

FROM BIOMASS

Combustion

The most obvious way of extracting energy from biomass, the technology of direct combustion is well understood, straightforward and commercially available. Combustion systems come in a wide range of shapes and sizes burning virtually any kind of fuel, from chicken manure and straw bales to tree trunks, municipal refuse and scrap tyres. Some of the ways in which heat from burning wastes is currently used include space and water heating, industrial processing and electricity generation. One problem with this method is its very low efficiency. With an open fire most of the heat is wasted and is not used to cook or whatever. One method of improving this in developing countries is to build stoves out of mud and scrap iron.

Pyrolysis

A wide range of energy-rich fuels can be produced by roasting dry woody matter like straw and woodchips. The process has been used for centuries to produce charcoal. The material is pulverised or shredded then fed into a reactor vessel and heated in the absence of air. Pyrolysis can also be carried out in the presence of a small quantity of oxygen ('gasification'), water ('steam gasification') or hydrogen ('hydrogenation'). One of the most useful products is methane, which is a suilable fuel for electricity generation using high-efficiency gas turbines.

Anaerobic Digestion

Biogas is produced when wet sewage sludge, animal dung or green plants are allowed to decompose in a sealed tank under anaerobic (oxygen-free) conditions. Feedstocks like wood shavings, straw and refuse may be used, but digestion takes much longer. Each kilogram of organic material (dry weight) can be expected to yield 450-500 litres of biogas. The residue left after digestion is a potentially valuable fertilizer or compost. Fermentation: Ethanol (ethyl alcohol) is produced by the fermentation of sugar solution by natural yeasts. Suitable feedstocks include crushed sugar beet and fruit. Sugars can also be manufactured from vegetable starches and cellulose by pulping and cooking, or from cellulose by miling and treatment with hot acid. After about 30 hours of fermentation, the brew cantains 6-10 per cent alcohol, which can be removed by distillation as a fuel.

Gasification

This process, usually using wood produces a flammable gas mixture of hydrogen, carbon monoxide, methane and other non flammable by products. This is done by partially burning and partially heating the biomass (using the heat from the limited burning) in the presence of charcoal (a natural by-product of burning biomass). The gas can be used instead of petrol and reduces the power output of the car by 40%. It is also possible that in the future this fuel could be a major source of energy for power stations.

Fermentation

If the biomass used is (or can be converted into) mostly sugar, then yeast can be added. The fermentation that follows produces alcohol which is a very high energy fuel that makes it very practicle for use in cars. This has been tried succesfully in Brazil.

WET AND DRY PROCESSES

4) WIND ENERGY

Wind power is the use of air flow through wind turbines to mechanically power generators for electric power. Wind power, as an alternative to burning fossil fuels, is plentiful, renewable, widely distributed, clean, produces no greenhouse gas emissions during operation, consumes no water, and uses little land.The net effects on the environment are far less problematic than those of nonrenewable power sources.

Wind farms consist of many individual wind turbines, which are connected to the electric power transmission network. Onshore wind is an inexpensive source of electric power, competitive with or in many places cheaper than coal or gas plants.Offshore wind is steadier and stronger than on land, and offshore farms have less visual impact, but construction and maintenance costs are considerably higher. Small onshore wind farms can feed some energy into the grid or provide electric power to isolated off-grid locations.

Wind power gives variable power, which is very consistent from year to year but has significant variation over shorter time scales. It is therefore used in conjunction with other electric power sources to give a reliable supply. As the proportion of wind power in a region increases, a need to upgrade the grid, and a lowered ability to supplant conventional production can occur. Power-management techniques such as having excess capacity, geographically distributed turbines, dispatchable backing sources, sufficient hydroelectric power, exporting and importing power to neighboring areas, or reducing demand when wind production is low, can in many cases overcome these problems.In addition, weather forecasting permits the electric-power network to be readied for the predictable variations in production that occur.

As of 2015, Denmark generates 40% of its electric power from wind, and at least 83 other countries around the world are using wind power to supply their electric power grids. In 2014, global wind power capacity expanded 16% to 369,553 MW. Yearly wind energy production is also growing rapidly and has reached around 4% of worldwide electric power usage,11.4% in the EU.

WIND ENERGY CONVERSION SYSTEM

A wind energy conversion system includes upper and lower wind turbines having counter-rotating blade assemblies supported for rotation about a vertical rotation axis, with each blade assembly carrying a rotor for rotation past a stator to produce an electrical output. The wind turbines are supported by a tower at an elevated position above the ground. Each wind turbine produces torque, and the wind energy conversion system provides for balancing the torques to avoid a net torque on the tower. Adjustment mechanisms are provided for adjusting blade pitch and for adjusting the size of an air gap between a stator and a rotor that comes into alignment with the stator as the rotor rotates therepast. The wind energy conversion system provides a hood for supplying intake air to a wind turbine and an exhaust plenum for exhausting air from the wind turbine, with the hood and the exhaust plenum being directionally positionable.

WIND MILLS

A windmill is a mill that converts the energy of wind into rotational energy by means of vanes called sails or blades.Centuries ago, windmills usually were used to mill grain (gristmills), pump water (windpumps), or both. The majority of modern windmills take the form of wind turbines used to generate electricity, or windpumps used to pump water, either for land drainage or to extract groundwater

HOW DOES A WIND TURBINE GENERATE

ELECTRICITY?

Wind power converts the kinetic energy in wind to generate electricity or mechanical power. This is done by using a large wind turbine usually consisting of propellers; the turbine can be connected to a generator to generate electricity, or the wind used as mechanical power to perform tasks such as pumping water or grinding grain. As the wind passes the turbines it moves the blades, which spins the shaft. There are currently two different kinds of wind turbines in use, the Horizontal Axis Wind Turbines (HAWT) or the Vertical Axis Wind Turbines (VAWT). HAWT are the most common wind turbines, displaying the propeller or ‘fan-style’ blades, and VAWT are usually in an ‘egg-beater’ style

5) GEO THERMAL ENERGY The Earth's heat-called geothermal energy-escapes as steam at a hot springs in Nevada. Credit:

Sierra Pacific

Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.

Almost everywhere, the shallow ground or upper 10 feet of the Earth's surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water.

In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii. Wells can be drilled into underground reservoirs for the generation of electricity. Some geothermal power plants use the steam from a reservoir to power a turbine/generator, while others use the hot water to boil a working fluid that vaporizes and then turns a turbine. Hot water near the surface of Earth can be used directly for heat. Direct-use applications include heating buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk.

Hot dry rock resources occur at depths of 3 to 5 miles everywhere beneath the Earth's surface and at lesser depths in certain areas. Access to these resources involves injecting cold water down one well, circulating it through hot fractured rock, and drawing off the heated water from another well. Currently, there are no commercial applications of this technology. Existing technology also does not yet allow recovery of heat directly from magma, the very deep and most powerful resource of geothermal energy.

TIDAL ENERGY

Tidal power or tidal energy is a form of hydropower that converts the energy obtained from tides into useful forms of power, mainly electricity.

Although not yet widely used, tidal energy has potential for future electricity generation. Tides are more predictable than the wind and the sun. Among sources of renewable energy, tidal energy has traditionally suffered from relatively high cost and limited availability of sites with sufficiently high tidal ranges or flow velocities, thus constricting its total availability. However, many recent[when? clarification

needed] technological developments and improvements, both in design (e.g. dynamic tidal power, tidal lagoons) and turbine technology (e.g. new axial turbines, cross flow turbines), indicate that the total availability of tidal power may be much higher than previously assumed, and that economic and environmental costs may be brought down to competitive levels.

Historically, tide mills have been used both in Europe and on the Atlantic coast of North America. The incoming water was contained in large storage ponds, and as the tide went out, it turned waterwheels that used the mechanical power it produced to mill grain.[1] The earliest occurrences date from the Middle Ages, or even from Roman times.[2][3] The process of using falling water and spinning turbines to create electricity was introduced in the U.S. and Europe in the 19th century.[4]

The world's first large-scale tidal power plant was the Rance Tidal Power Station in France, which became operational in 1966. It was the largest tidal power station in terms of output until Sihwa Lake Tidal Power Station opened in South Korea in August 2011. The Sihwa station uses sea wall defense barriers complete with 10 turbines generating 254 MW

STEAM GENERATION AND ELECTRICITY

GENERATION

The steam-electric power station is a power station in which the electric generator is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser. The greatest variation in the design of steam-electric power plants is due to the different fuel sources.

Almost all coal, nuclear, geothermal, solar thermal electric power plants, waste incineration plants as well as many natural gas power plants are steam-electric. Natural gas is frequently combusted in gas turbines as well as boilers. The waste heat from a gas turbine can be used to raise steam, in a combined cycle plant that improves overall efficiency.

Worldwide, most electric power is produced by steam-electric power plants, which produce about 86% of all electric generation The only other types of plants that currently have a significant contribution are hydroelectric and gas turbine plants, which can burn natural gas or diesel. Photovoltaic panels, wind turbines and binary cycle geothermal plants are also non-steam electric, but currently do not produce much electricity

HOW ELECTRICITY IS GENERATED FROM

GEOTHERMAL ENERGY

When the geothermal resource produces a saturated or superheated vapor, the steam is collected from the production wells and sent to a conventional steam turbine . Before the steam enters the turbine, appropriate measures are taken to remove any solid debris from the steam flow, as well as corrosive substances contained in the process stream (typically removed with water washing). If the steam at the wellhead is saturated, steps are taken to remove any liquid that is present or forms prior to the steam entering the turbine. Normally, a condensing turbine is used; however, in some instances, a backpressure turbine is used that exhausts steam directly to the ambient.[

The steam discharges to a condenser where it is condensed at a subatmospheric pressure (typically a few inches of Hg). The condenser shown in Fig. 1 is a barometric condenser. In a barometric condenser, the cooling water is sprayed directly into the steam, with the cooling water and condensate being pumped to a cooling tower where the condensing heat load is rejected to the ambient. Some plants use surface condensers where the latent heat from the condensing steam is transferred to cooling water being circulated through the condenser tubes. With a surface condenser, the cooling water and condensate are typically pumped to the cooling tower in separate streams. The steam condensate provides a makeup water source for the evaporative heat rejection system. Any excess condensate, together with the tower blowdown, is injected back into the reservoir.

Hydrothermal resources typically contain varying amounts of dissolved minerals and gases that impact both the design and operation of the energy conversion systems. In power cycles where steam is extracted from the geothermal resource and expanded in a condensing turbine, the cycle design must account for the removal of the noncondensable gases extracted from the resource with the steam. If not removed, these gases accumulate in the condenser, raising the turbine exhaust pressure and decreasing power output. When hydrogen sulfide is present in the process steam, it also accumulates in the condenser, though a portion partitions or dissolves in the condensate or cooling water. When the hydrogen sulfide levels are sufficiently high so that some abatement process of the condensate or cooling water is required, surface condensers are typically used to minimize the quantity of water that has to be treated. In addition, the noncondensable gas stream containing hydrogen sulfide must also be treated prior to being released to the atmospher

6) MAGNETO HYDRO DYNAMICS POWER

GENRATION

A magnetohydrodynamic generator (MHD generator) is a magnetohydrodynamic device that transforms thermal energy and kinetic energy into electricity. MHD generators are different from traditional electric generators in that they operate at high temperatures without moving parts. MHD was developed because the hot exhaust gas of an MHD generator can heat the boilers of a steam power plant, increasing overall efficiency. MHD was developed as a topping cycle to increase the efficiency of electric generation, especially when burning coal or natural gas. MHD dynamos are the complement of MHD propulsors, which have been applied to pump liquid metals and in several experimental ship engines.

An MHD generator, like a conventional generator, relies on moving a conductor through a magnetic field to generate electric current. The MHD generator uses hot conductive plasma as the moving conductor. The mechanical dynamo, in contrast, uses the motion of mechanical devices to accomplish this. MHD generators are technically practical for fossil fuels, but have been overtaken by other, less expensive technologies, such as combined cycles in which a gas turbine's or molten carbonate fuel cell's exhaust heats steamto power a steam turbine.

Natural MHD dynamos are an active area of research in plasma physics and are of great interest to the geophysics and astrophysics communities, since the magnetic fields of the earth and sunare produced by these natural dynamos.

CHEMICAL ENERGY SOURCES

FUEL CELL A fuel cell is an electrochemical cell that converts the chemical energy from a fuel into electricity

through an electrochemical reaction of hydrogen fuel with oxygen or another oxidising agent.[1] Fuel cells are different from batteries in requiring a continuous source of fuel and oxygen (usually from air) to sustain the chemical reaction, whereas in a battery the chemical energy comes from chemicals already present in the battery. Fuel cells can produce electricity continuously for as long as fuel and oxygen are supplied.

The first fuel cells were invented in 1838. The first commercial use of fuel cells came more than a century later in NASA space programs to generate power for satellites and space capsules. Since then, fuel cells have been used in many other applications. Fuel cells are used for primary and backup power for commercial, industrial and residential buildings and in remote or inaccessible areas. They are also used to power fuel cell vehicles, including forklifts, automobiles, buses, boats, motorcycles and submarines.

There are many types of fuel cells, but they all consist of an anode, a cathode, and an electrolyte that allows positively charged hydrogen ions (protons) to move between the two sides of the fuel cell. At the anode a catalyst causes the fuel to undergo oxidation reactions that generate protons (positively charged hydrogen ions) and electrons. The protons flow from the anode to the cathode through the electrolyte after the reaction. At the same time, electrons are drawn from the anode to the cathode through an external circuit, producing direct current electricity. At the cathode, another catalyst causes hydrogen ions, electrons, and oxygen to react, forming water. Fuel cells are classified by the type of electrolyte they use and by the difference in startup time ranging from 1 second for proton exchange membrane fuel cells (PEM fuel cells, or PEMFC) to 10 minutes for solid oxide fuel cells (SOFC). Individual fuel cells produce relatively small electrical potentials, about 0.7 volts, so cells are "stacked", or placed in series, to create sufficient voltage to meet an application's requirements.In addition to electricity, fuel cells produce water, heat and, depending on the fuel source, very small amounts of nitrogen dioxide and other emissions. The energy efficiency of a fuel cell is generally between 40–60%; however, if waste heat is captured in a cogeneration scheme, efficiencies up to 85% can be obtained.

A related technology is flow batteries, in which the fuel can be regenerated by recharging.

The fuel cell market is growing, and in 2013 Pike Research estimated that the stationary fuel cell market will reach 50 GW by 2020

APPLICATION OF FUEL CELL

Fuel Cell Today categorises the use of fuel cells into three broad areas: portable power generation, stationary power generation, and power for transportation. We also include a category for fuel and infrastructure, relating to the production, distribution, storage and dispensing of fuels for fuel cells, as this is crucial to implementing fuel cell technology.