Fuels

FOSSIL FUELS 85% of the worlds commercial energy

COALOILNATURAL GASFOSSIL FUELS 85% of the worlds commercial energy OILNATURAL GAS

Fuel is a substance which, when burnt, i.e. on coming in contact and reacting with oxygen or air, produces heat. Thus, the substances classified as fuel must necessarily contain one or several of the combustible elements : carbon, hydrogen, sulphur, etc. In the process of combustion, the chemical energy of fuel is converted into heat energy.

The following are the element which are found in fuels:CoalHydrogenCompounds of carbon & hydrogenSulphurNitrogenOxygenMoistureAsh, impurities and other incombustible matter

SOLID FUELS AND THEIR CHARACTERISTICSSolid fuels are mainly classified into two categories, i.e. natural fuels, such as wood, coal, etc. and manufactured fuels, such as charcoal, coke, briquettes

Advantages(a) They are easy to transport.(b) They are convenient to store without any risk of spontaneous explosion.(c) Their cost of production is low.(d) They posses moderate ignition temperature.

Disadvantages(a) Their ash content is high.(b) Their large proportion of heat is wasted.(c) They burn with clinker formation.(d) Their combustion operation cannot be controlled easily.(e) Their cost of handling is high.

Coals and their CharacteristicsIt is commonly adopted view that coal is a mineral substance of vegetable origin. The large deposits of coal in India are in Bengal, Bihar and Madhya Pradesh. Most of the Indian coal is of low grade variety and coal washing to obtain low ash metallurgical coal is unavoidable. Over 30% of coal output is consumed by railways, another similar proportion is used by industry including iron and steel works. This leaves barely 40% of coal mined for use of the power supply undertakings.

Analysis of CoalTwo commonly used tests are : Proximate analysis and Ultimate analysis of coal. Calorific value of coal is defined as the quantity of heat given out by burning one unit weight of coal in a calorimeter.

Proximate Analysis of Coal: This analysis of coal gives good indication about heating and burning properties of coal. The test gives the composition of coal in respect of moisture, volatile matter, ash and fixed carbon.

Ultimate Analysis of Coal:This analysis of coal is more precise way to find the chemical composition of coal with respect to the elements like carbon, hydrogen, oxygen, nitrogen, sulphur and ash. The broad range in which the constituents of coal vary by weight as determined by ultimate analysis are given below :

(A) WOOD: The most commonly used and easily obtainable solid fuel is wood. It is the oldest type of fuel which man had used for centuries after the discovery of the fire itself. In India, wood is used in almost every village, as well as in small towns and cities. In some parts of country such as Kashmir and Mysore, wood is used for industrial purposes as well.

(B) Peat: It is mixture of moisture(it may be as high as 90%) and decayed vegetable matter. It burns fully without smoke or soot formation. It is generally used as a fuel for gas producer plants.

(c) Coal: it includes all forms of coal from lignite to anthracite, which are formed from peat in the earth crust due to pressure and heat over a period of millions of year. During its formation the peat looses moisture, hydrogen, nitrogen, sulphur and volatile matter progressively while its carbon content and the heating value of the fuel increases.

The coal have been divide into two main group:Gondwana coal field: these coal are situated in the region of maharastra, bihar, mp, orrisa, AP and bengal. In these coal fields the coal is bituminous and sub-bituminous quality.

Tertial coal field: These coal field are situated in TN,Rajasthan, Assam and kashmir having mostly lignite variety of coal.

(D) Charcoal: Charcoal is a produce derived from destructive distillation of wood, being left in the shape of solid residue. Charcoal burns rapidly with a clear flame, producing no smoke and developing heat of about 6,050 cal/kg. During the process of formation of charcoal, will recover by products like methyl alcohol, acetic acid, acetone, gaseous compound and tar. It has no sulphur content and it can burn easily without smoke and produces 25,500 kJ/kg calorific value of heat.

(E) Coke and its Characteristics: It is obtained from destructive distillation of coal, being left in the shape of solid residue. Coke can be classified into two categories : soft coke and hard coke. Soft coke is obtained as the solid residue from the destructive distillation of coal in the temperature range of 600-650oC. It contains 5 to 10% volatile matter. It burns without smoke. It is extensively used as domestic fuel. Hard coke is obtained as solid residue from the destructive distillation of coal in the temperature range of 1200-1400oC. It burns with smoke and is a useful fuel for metallurgical process.

(F) Briquettes and their Characteristics: The term briquettes is used in respect of the dust, slack and other small size waste remains of lignite, peat, coke, etc. compressed into different shapes of regular form, with or without binder. Dust and rubble result in considerable percentage during mining, transportation, etc. and the briquetting industry is, therefore, an important step towards the saving of fuel economy.

LIQUID FUELS AND THEIR CHARACTERISTICSThe liquid fuels can be classified as follows :(a) Natural or crude oil, and(b) Artificial or manufactured oils.

Advantages(a) They posses higher calorific value per unit mass than solid fuels.(b) They burn without dust, ash, clinkers, etc.(c) They can be stored indefinitely without any loss.(d) They are clean in use and economic to handle.(e) They require less excess air for complete combustion.

Disadvantages(a) The cost of liquid fuel is relatively much higher as compared to solid fuel.(b) Costly special storage tanks are required for storing liquid fuels.(c) There is a greater risk of five hazards, particularly, in case of highly inflammable and volatile liquid fuels.(d) They give bad odour.

Classification of PetroleumThe chemical nature of crude petroleum varies with the part of the world in whichit is found. They appear, however, to be three principal verities.

Paraffinic Base Type Crude PetroleumThis type of petroleum is mainly composed of the saturated hydrocarbonsfrom CH4 to C35 H72 and a little of the napthenes and aromatics. Thehydrocarbons from C18 H38 to C35 H72 are sometimes called waxes.

Asphalitc Base Type Crude PetroleumIt contains mainly cycloparaffins or napthenes with smaller amount ofparffins and aromatic hydrocarbons.

Mixed Base Type Crude PetroleumIt contains both paraffinic and asphaltic hydrocarbons and are generally richin semi-solid waxes.

Diesel Fuel and its CharacteristicsThe diesel fuel or gas oil is obtained between 250-320oC during the fractionaldistillation of crude petroleum. This oil generally contains 85% C. 12% H. Itscalorific value is about 11,000 kcal/kg.

Kerosene Oil and its CharacteristicsKerosene oil is obtained between 180-250oC during fractional distillation of crude petroleum.

Heavy Oil and its CharacteristicsIt is a fraction obtained between 320-400oC during fractional distillation of crudepetroleum. This oil on refractionation gives :(a) Lubricating oils which are used as lubricants.(b) Petroleum-jelly (Vaseline) which is used as lubricants in medicines and in cosmetics.(c) Greases which are used as lubricants.(d) Paraffin wax which is used in candles, boot polishes, wax paper, tarpolin cloth and for electrical insulation purposes.

GASEOUS FUELS AND THEIR CHARACTERISTICSGaseous fuel include the natural gas and the prepared gases of fixed composition like acetylene (C2H2), methane (CH4), ethylene(C2H4) etc or the industrial gases like coke oven gas, blast furnace gas, producer gas etc

AdvantagesGaseous fuels due to erase and flexibility of their applications, possess thefollowing advantages over solid or liquid fuels :(a) They can be conveyed easily through pipelines to the actual place of need, thereby eliminating manual labour in transportation.(b) They can be lighted at ease.(c) They have high heat contents and hence help us in having higher temperatures.(d) They are clean in use.(e) They do not require any special burner.(f) They burn without any shoot, or smoke and ashes.(g) They are free from impurities found in solid and liquid fuels.

Disadvantages(a) Very large storage tanks are needed.(b) They are highly inflammable, so chances of fire hazards in their use is high.

Natural Gas and its Characteristics:Natural gas is generally associated with petroleum deposits and is obtained from wells dug in the oil-bearing regions. The approximate composition of natural gas is :

CH4 = 70.9%, C2H6 = 5.10%, H2 = 3%, CO + CO2 = 22%The calorific value varies from 12,000 to 14,000 kcal/m3. It is an excellent domestic fuel and is conveyed in pipelines over very large distances.

Liquid Petroleum gas:Propane and Butane gases are obtained from oil and gas well. During refining process of petroleum, considerable amount of propane and butane is produced. Propane gas liquefies at 8.8bar and butane at 2.1bar at atmospheric temprature of 21.1 deg C

Nuclear EnergyEnergy from disintegrating atomic nuclei has a tremendous potential to do good for the people of the world. About 17% of the energy in the world comes from nuclear power plants.

All atoms of the same element have the same number of protons and electrons but the number of neutrons may differ. Atoms of the same element that differ in the number of neutrons are called isotopes. Since the positively charged protons in the nucleus repel one another energy is needed to hold the protons and neutrons together. However, some isotopes of some atoms are radioactive, that is the nucleus of these atoms are unstable and decompose. Neutrons, electrons, and protons are released during this decomposition releasing a great deal of energy. Only certain kinds of atoms are suitable for the development of a nuclear chain reaction. The two materials most commonly used are uranium-235 and plutonium-239.

NUCLEAR FISSION A reaction in which an atomic nucleus of a radioactive element splits by bombardment from an external source, with simultaneous release of large amounts of energy, used for electric power generation

NUCLEAR FUSION

Nuclear Reactors A nuclear reactor is a device that permits a controlled fission chain reaction. In the reactor, neutrons are used to cause a controlled fission of heavy atoms such as Uranium 235 (U-235). U-235 is a uranium isotope used to fuel nuclear fission reactors.

Advantages:Generating electricity by nuclear energy saving is an important pollutant gases (CO2and others) that would be generated if this energy would be generated from the burning of fossil fuels.Currently more fossil fuels which are produced so that in the not too distant future these resources will be exhausted or the prices would rise making them inaccessible to most consumed of the population.Another advantage is in the amount of fuel needed; with little fuel large amounts of energy are obtained. This saves on raw materials but also in transport, handling extractionnuclear fuel. The cost of fuel is 20% of the cost of energy generated.Production of electric energy is continuous. A nuclear power plant is generating electricity for almost 90% of the hours of the year.

Disadvantage: Major drawback is the generation of nuclear waste and the difficulty to manage and it takes many years to lose itsradioactivityand danger.Nuclear reactors, once constructed, have an expiration date. After this date must be dismantled, so that in the main countries producing nuclear energy to maintain constant the number of operating reactors should be built about 80 new nuclear reactors the next ten years.Nuclear power plants are targets for terrorist organizations.

Hydroelectric power (often called hydropower) is considered a renewable energy source. A renewable energy source is one that is not depleted (used up) in the production of energy. Through hydropower, the energy in falling water is converted into electricity without using up the water.Hydel Energy

Hydropower energy is ultimately derived from the sun, which drives the water cycle. In the water cycle, rivers are recharged in a continuous cycle. Because of the force of gravity, water flows from high points to low points. There is kinetic energy embodied in the flow of water.

Humans first learned to harness the kinetic energy in water by using waterwheels.A waterwheel is a revolving wheel fitted with blades, buckets, or vanes.Waterwheels convert the kinetic energy of flowing water to mechanical energy.

Mechanical energy is a form of kinetic energy, such as in a machine. Mechanical energy has the ability to do work. Any object that is able to do work has mechanical energy.

The mechanical energy produced by the turbine is converted into electric energy using a turbine generator. Inside the generator, the shaft of the turbine spins a magnet inside coils of copper wire. It is a fact of nature that moving a magnet near a conductor causes an electric current. How a Hydroelectric Power System Works

Advantages:Environmental Benefits of Hydro No operational greenhouse gas emissions Savings (kg of CO2 per MWh of electricity): Coal 1000 kg Oil 800 kg Gas 400 kg No SO2 or NOXNon-environmental benefits flood control, irrigation, transportation, fisheries and tourism.Disadvantage:The loss of land under the reservoir.Interference with the transport of sediment by the dam.Problems associated with the reservoir.Climatic and seismic effects.Impact on aquatic ecosystems, flora and fauna.

Solar EnergyOriginates with the thermonuclear fusion reactions occurring in the sun.

Power TowersPower tower in Barstow, California.

Direct Conversion into ElectricityPhotovoltaic cells are capable of directly converting sunlight into electricity.A simple wafer of silicon with wires attached to the layers. Current is produced based on types of silicon (n- and p-types) used for the layers. Each cell=0.5 volts.Battery needed as storageNo moving parts Not wear out, but because they are exposed to the weather, their lifespan is about 20 years.

Advantages

All chemical and radioactive polluting byproducts of the thermonuclear reactions remain behind on the sun, while only pure radiant energy reaches the Earth.Energy reaching the earth is incredible. By one calculation, 30 days of sunshine striking the Earth have the energy equivalent of the total of all the planets fossil fuels, both used and unused

Disadvantages

Sun does not shine consistently.Solar energy is a diffuse source. To harness it, we must concentrate it into an amount and form that we can use, such as heat and electricity. Addressed by approaching the problem through: 1) collection, 2) conversion, 3) storage.

Wind Power

Wind Power Wind power is good renewable, clean and free source of energy for power productionReduce dependence on fossil fuels including imported oilsReduce emission of greenhouse gas and other pollutantOne major concern is the noise can be improvedIntermittency and variability of the wind

Advantages: The wind blows day and night, which allows windmills to produce electricity throughout the day. (Faster during the day) Energy output from a wind turbine will vary as the wind varies, although the most rapid variations will to some extent be compensated for by the inertia of the wind turbine rotor. Wind energy is a domestic, renewable source of energy that generates no pollution.Disadvantages:The strength of the wind is not constant and it varies from zero to storm force. This means that wind turbines do not produce the same amount of electricity all the time.Wind turbines are noisy.Large wind farms are needed to provide entire communities with enough electricity.

Bio Gas PlantBiofuel is basically an Eco-friendly fuel that is generated from recently deceased biological matter. A fuel can be considered as a biofuel only when it comprises of more than 75% of renewable materials. Many people confuse fossil fuels and recently deceased biological matter. You should keep in mind that fossil fuels like oil are composed of biological matter that has been dead for a very long time. Hence, fossil fuels are usually linked to global warming.

Ozone layer

Global Warming