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MAE 136 Lectures 2, 3 & 4 Page 1

(Lectures 2, 3 & 4) Energy Resources and Usage; Fuels and Thermochemistry I, II & III

A. U.S. Energy Outlook (Attachment A PowerPoint Presentation)

B. International Energy Outlook (Attachment B

PowerPoint Presentation)

C. Background

1. Combustion and chemical reactions play a very important role in our everyday lives, inmany engineering applications, and in the study of energy and environment.

2. Combustion may be defined as the process of burning a substance in the presence of airor oxygen with the liberation of light and heat.

3. An example of an unwanted chemical reaction is shown below:

Smoke from the Station Fire rises over downtown Los Angeles Monday, Aug. 31, 2009. (AP Photo/Jon Vidar)

D. Representative Applications

1. Electric power plants (Coal, Gas)2. Transportation: Automobiles, Aircraft, Ships, Buses

a. Liquid fuels such as Gasoline, Diesel fuel, Jet Fuel, Ethanol, and Biodiesel)b. Gaseous fuels such as propane and natural gas

3. Rocket Motors (Liquid, Solid Propellants)
http://www.boston.com/bigpicture/2009/09/wildfires_in_southern_californ.html

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4. Energy Intensive Industries (CementCoal, SteelOil, Gas, GlassGas, AluminumOil, Gas, Pulp and PaperWood)

5. Household and Industrial Heating (Oil, Gas)6. Forest Fires7. Fuel Cells and Other Solid State Devices8. Chemical Reactions in the Human Body

E. Composition of Dry Air

1. Gaseous composition of dryair.

Constituent Chemical symbol Mole percent

Nitrogen N2 78.084

Oxygen O2 20.947

Argon Ar 0.934

Carbon dioxide CO2 0.0350

Neon Ne 0.001818

Helium He 0.000524

Methane CH4 0.00017

Krypton Kr 0.000114

Hydrogen H2 0.000053

Nitrous oxide N2O 0.000031

Xenon Xe 0.0000087

Ozone* O3 trace to 0.0008

Carbon monoxide CO trace to 0.000025

Sulfur dioxide SO2 trace to 0.00001

Nitrogen dioxide NO2 trace to 0.000002

Ammonia NH3 trace to 0.0000003

* Low concentrations in troposphere; ozone maximum in the30- to 40-km regime of the equatorial region.

Mackenzie, F.T. and J.A. Mackenzie (1995), OurChanging Planet. Prentice-Hall, UpperSaddle River, NJ, p 288-307. (After Warneck, 1988; Anderson, 1989; Wayne, 1991.http://eesc.columbia.edu/courses/ees/slides/climate/table_1.html.

2. For the purpose of simplifying the analyses slightly, it will be assumed that air consists of21 percent O2and 79 percent N2by volume. Thus, each mole of oxygen will beaccompanied by
http://eesc.columbia.edu/courses/ees/slides/climate/table_1.htmlhttp://eesc.columbia.edu/courses/ees/slides/climate/table_1.html

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Furthermore1 kmol O2+ 3.76 knol N2= 4.76 kmol of air

F. Chemical Reactions

A + B

CReactants Products

G. Burning of Hydrogen in Oxygen

1 H2 + aO2 bH2O

Conservation of Species:

H Balance: 2 + 0 = 2b b= 1

O Balance: 0 + 2a = b a= b/2 = a=

Therefore, the chemical reaction is

1 H2 + O2 1 H2O

The coefficients aand bare referred to as stoichiometric coefficients, i.e., the coefficientsin the theoretical equation. Most real reactions are not stoichiometric and depend on thequantity of reactants as well as pressure and temperature. Such situations require the study ofchemical equilibrium.

H. Burning of Hydrogen in Air

When hydrogen burns in air

1 H2 + (O2+ 3.76 N2) 1 H2O + d N2

N2Balance: (3.76) = d d= 1.88

and1 H2 + (O2+ 3.76 N2) 1 H2O + 1.88 N2

Although nitrogen remains inert in chemical reactions, it plays an important role in First Lawcalculations as will be seen.

I. Role of Air in Combustion Processes1. The theoretical air is the minimum amount of air that supplies sufficient oxygen for the

complete combustion of all the carbon, hydrogen, and any other elements in the fuel thatmay oxidize. When complete combustion is achieved, there is no free oxygen in theproducts.

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2. When the amount of air supplied is less than the theoretical air required, the combustionis incomplete. The result is CO and hydrocarbons in the products of combustion.

3. When the amount of air supplied is greater than the theoretical air required, there is freeoxygen in the products.

4. Although the nitrogen remains inert (except at very high temperature reactions), itstemperature does change and must be taken into consideration.

J. Air-Fuel Ratio, AF

1. For the reaction in Part H, the air-fuel ratio on a molar basis is

=

On a mass basis

2. The equivalence ratiois defined as the ratio of the actual fuel-air ratio to the fuel-air ratiofor complete combustion with the theoretical amount of air. The reactants are said toform a leanmixture when the equivalence ratiois less than unity, and a richmixturewhen it is greater than unity.

K. Burning of Hydrogen with 150 Percent Theoretical Air

Note that 150 percent theoretical air also corresponds to 50 percent excess air:

1 H2 + 1.5 (1/2) (O2+ 3.76 N2) H2O + eO2 + f N2

O Balance:

N Balance:

The reaction in this case is

and the molar air-fuel ratio is

=

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L. Fossil Fuels

1. OrganicAll compounds of carbon. Example: Coal.

2. Hydrocarbons (Liquid or Gas): Made up only of carbon & oxygen, CxHy .

Coal

Sedimentary Rock

Anthracite coal

Composition

Primary Carbon

Secondary hydrogen,

sulfur,

oxygen,

nitrogen

3. Coal

Coal is acombustibleblack or brownish-blacksedimentary rock usually occurring inrock strata in layers or veinscalled coal beds or coal seams. The harder forms, such asanthracite coal,can be regarded asmetamorphic rockbecause of later exposure toelevated temperature andpressure.Coal is composed primarily ofcarbon along withvariable quantities of other elements, chieflyhydrogen,sulfur,oxygen,andnitrogen.
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Classification of Coal (U.S. Department of Energy,

http://fossil.energy.gov/education, March 15, 2012)

Lignite: The largest portion of the world's coal reserves is made up of lignite, a

soft, brownish-black coal that forms the lowest level of the coal family. You can

even see the texture of the original wood in some pieces of lignite that is found

primarily west of the Mississippi River in the United States. Subbituminous: Next up the scale is subbituminous coal, a dull black coal. It

gives off a little more energy (heat) than lignite when it burns. It is mined mostly

in Montana, Wyoming and a few other western states.

Bituminous: Still more energy is packed into bituminous coal, sometimes called

"soft coal." In the United States, it is found primarily east of the Mississippi River

in midwestern states like Ohio and Illinois and in the Appalachian mountain range

from Kentucky to Pennsylvania.

Anthracite: Anthracite is the hardest coal and gives off a great amount of heat

when it burns. Unfortunately, in the United States, as elsewhere in the world,

there is little anthracite coal to be mined. The U.S. reserves of anthracite are

located primarily in Pennsylvania

Throughout history, coal has been a useful resource for human consumption. It isprimarily burned as afossil fuel for the production of electricity and/or heat, and is alsoused for industrial purposes such as refining metals. Coal forms when dead plant matteris converted intopeat,which in turn is converted intolignite,thenanthracite.Thisinvolves biological and geological processes that take place over a long period of time.

Coal, afossil fuel,is the largest source of energy for thegeneration of electricityworldwide, as well as one of the largest worldwideanthropogenic sources ofcarbondioxide releases. Grosscarbon dioxide emissions from coal usage are slightly more thanthose frompetroleum and about double the amount fromnatural gas.Coal is extractedfrom the ground bymining,either underground byshaft mining through the seams or inopen pits.Theenergy density of coal, i.e. itsheating value,is roughly 24 MJ/kg.

4. Petroleum (Energy Choi ces: A Gui de to Facts and Perspectives, ASME, NY 2010)

Petroleumor crude oilis a naturally occurring, dark, viscousflammable liquidconsisting of a complex mixture ofhydrocarbons of various molecular weights and otherliquidorganic compounds,that are found ingeologic formationsbeneath theEarth's

surface. Several fuels are obtained by refining petroleum and these include but are notlimited to gasoline, Diesel fuel, propane, and other fuels. Sour crude oiliscrude oilcontaining the impuritysulfur.

It is common to find crude oil containing some impurities. When the total sulfur level inthe oil is > 0.5 % the oil is called "sour". The impurities need to be removed before thislower quality crude can be refined intopetrol,thereby increasing the cost of processing.This results in a higher-priced gasoline than that made fromsweet crude oil.Thus sourcrude is usually processed intoheavy oil such asdiesel andfuel oil rather than gasoline to
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reduce processing cost. Sour oil can be toxic and corrosive, especially when the oilcontains high levels of hydrogen sulfide

Tar Sandsare a mixture of sand, clay, and bitumen which is a heavy crude oil. The oil is

difficult and expensive to produce because mining and retorting or steam assisted heating

of the reservoirs where it is found.

5. GasolineC8H18

Gasolineis a transparentpetroleum-derived liquid that is primarily used as a fuel ininternal combustion engines.It consists mostly oforganic compounds obtained by thefractional distillation of petroleum, enhanced with a variety of additives. (Some gasolinesalso containethanol as analternative fuel;for example, E10 contains 10 percent ethanol).In North America, the term "gasoline" is often shortened in colloquial usage to "gas",whereas most current or formerCommonwealth nations use the term "petrol". Undernormal ambient conditions its material state is liquid, unlikeliquefied petroleum gas or"natural gas".

Spark ignition engines are designed to burn gasoline in a controlled process calleddeflagration.But in some cases, the unburned mixture can autoignite, which results inrapid heat release and can damage the engine. This phenomenon is often referred to asengine knocking or end-gas knock. One way to reduce knock in spark ignition engines isto increase the resistance toautoignition,which is expressed by its octane rating.

Octane rating is measured relative to a mixture of2,2,4-Trimethylpentane (anisomer ofoctane)and n-heptane.In the US, octane ratings in unleaded fuels can vary between 86and 87 AKI (91-92 RON) for regular, through 89-90 AKI (94-95 RON) for mid-grade(European premium), up to 90-94 AKI (95-99 RON) for premium (European super).

Energy is obtained from the combustion of gasoline, the conversion of a hydrocarbon tocarbon dioxide andwater.The combustion of octane in air follows this reaction:

2 C8H18+ 25 (O2+ 3.76 N2) 16 CO2+ 18 H2O + 94 N2

Gasoline blends differ, and therefore actual energy content varies according to the seasonto season and producer by up to 4% more or less than the average, according to the USEnvironmental Protection Agency (EPA). On average, about 19.5 US gallons of gasolineare available from a 42-US-gallon (35 imp gal; 160 L) barrel of crude oil (about 46% byvolume), varying due to quality of crude and grade of gasoline. The remaining residue

comes off as products ranging from tar to naphtha. The EIA (2010) has recently postedon the Internet a detailed list of the contributors to the cost of a gallon of gasoline.

6. Kerosene - C12H26

Today, kerosene is mainly used infuel for jet engines (more technically Avtur,Jet A andJet A-1,Jet B,JP-4,JP-5,JP-7 orJP-8). One form of the fuel known asRP-1 is burnedwithliquid oxygen as rocket fuel. These fuel grade kerosenes meet specifications for
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smoke points andfreeze points.The combustion reaction can be approximated as follows,with the molecular formula C12H26(Dodecanese):

C12H26+ 18.5 (O2+ 3.76 N2) 12 CO2+ 13 H2O + 69.56 N2

7. Diesel Fuel C10H20to C15H28

Diesel fuelin general is any liquidfuel used indiesel engines.The most common is aspecificfractional distillate of petroleumfuel oil,but alternatives that are not derivedfrom petroleum, such asbiodiesel,biomass to liquid (BTL) orgas to liquid (GTL) diesel,are increasingly being developed and adopted. Diesel fuel is very similar toheating oil,which is used a fuel to heat homes and apartments and incentral heating.Petroleum-derived diesel is composed of about 75%saturated hydrocarbons (primarilyparaffinsincludingn,iso,andcycloparaffins), and 25%aromatic hydrocarbons (includingnaphthalenes andalkylbenzenes). The average chemical formula for common diesel fuelis C12H23, ranging approximately from C10H20to C15H28.

8. Ethane

C2H6Ethaneis achemical compound withchemical formula C2H6. Atstandard temperatureand pressure,ethane is a colorless, odorlessgas.Ethane is isolated on an industrial scalefromnatural gas,and as a byproduct ofpetroleum refining.Its chief use is aspetro-chemical feedstock forethyleneproduction.

The completecombustion of ethane releases 1559.7 kJ/mol, or 51.9 kJ/g, of heat, andproducescarbon dioxide andwater according to thechemical equation

C2H6+ 3.5 (O2+ 3.76 N2) 2CO2+ 3H2O + 13.16 N2

9. Propane C3H8

Propaneis a three-carbonalkane with the molecular formula C3H8, normally a gas, butcompressible to a transportable liquid. Aby-product ofnatural gasprocessing andpetroleum refining, it is commonly used as a fuel forengines,oxy-gas torches,barbecues,portable stoves,and residentialcentral heating.

A mixture of propane andbutane,used mainly as vehicle fuel, is commonly known asliquefied petroleum gas (LPG or LP gas). It may also contain small amounts ofpropyleneand/orbutylene.Anodorant,such asethanethiol orthiophene,is added so that people caneasily smell the gas in case of a leak.

Propane undergoescombustion reactions in a similar fashion to other alkanes. In thepresence of excess oxygen, propane burns to form water andcarbon dioxide.

C3H8+ 5 (O2+ 3.76 N2) 3 CO2+ 4 H2O + 18.8 N2

When not enough oxygen is present for complete combustion, incomplete combustionoccurs when propane burns and formscarbon monoxide andcarbon as well as carbon
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dioxide and water. Unlikenatural gas,propane is heavier than air (1.5 times as dense). Inits raw state, propane sinks and pools at the floor. Liquid propane will flash to a vapor atatmospheric pressure and appears white due to moisture condensing from the air.Whenproperly combusted, propane produces about 50 MJ/kg. Thegross heat of combustion ofonenormal cubic meter of propane is around 91 MJ.

10. Butane C4H10

Butaneis a gas with the formula C4H10that is analkane with fourcarbonatoms.Butanesare highly flammable, colorless, easilyliquefiedgases.When oxygen is plentiful, butaneburns to formcarbon dioxide and water vapor; when oxygen is limited, carbon (soot)orcarbon monoxide may also be formed.

2 C4H10+ 13 (O2+ 3.76 N2) 8 CO2+ 10 H2O + 48.88 N2

The maximumadiabatic flame temperature of butane withair is 2,243 K (1,970 C or3,578 F).

Butane lighter in use Butane lighter, showing liquid butane reservoir

The most common use of butane is aslighter fuel for a common lighter orbutane torch.Butane gas is sold bottled as a fuel for cooking and camping. When blended withpropaneand other hydrocarbons, it is referred to commercially asLPG,for liquefied petroleumgas. It is also used as a petrol component, as a feedstock for the production of basepetrochemicals in steam cracking, as fuel for cigarettelighters and as apropellant inaerosol sprays such asdeodorants.
http://en.wikipedia.org/wiki/Natural_gashttp://en.wikipedia.org/wiki/Higher_Heating_Valuehttp://en.wikipedia.org/wiki/Normal_cubic_meterhttp://en.wikipedia.org/wiki/Alkanehttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Liquefyhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Soothttp://en.wikipedia.org/wiki/Adiabatic_flamehttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Lighterhttp://en.wikipedia.org/wiki/Butane_torchhttp://en.wikipedia.org/wiki/Propanehttp://en.wikipedia.org/wiki/Liquified_petroleum_gashttp://en.wikipedia.org/wiki/Lighterhttp://en.wikipedia.org/wiki/Propellanthttp://en.wikipedia.org/wiki/Aerosol_sprayhttp://en.wikipedia.org/wiki/Deodoranthttp://en.wikipedia.org/wiki/File:The_Green_Lighter_1_ies.jpghttp://en.wikipedia.org/wiki/File:Ec-hasslau.de_010.jpghttp://en.wikipedia.org/wiki/Deodoranthttp://en.wikipedia.org/wiki/Aerosol_sprayhttp://en.wikipedia.org/wiki/Propellanthttp://en.wikipedia.org/wiki/Lighterhttp://en.wikipedia.org/wiki/Liquified_petroleum_gashttp://en.wikipedia.org/wiki/Propanehttp://en.wikipedia.org/wiki/Butane_torchhttp://en.wikipedia.org/wiki/Lighterhttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Adiabatic_flamehttp://en.wikipedia.org/wiki/Soothttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Liquefyhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Alkanehttp://en.wikipedia.org/wiki/Normal_cubic_meterhttp://en.wikipedia.org/wiki/Higher_Heating_Valuehttp://en.wikipedia.org/wiki/Natural_gas

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11. Natural Gas (Primarily MethaneCH4with lesser amounts of ethane, propane, andnitrogen). [Reference: Energy Choices: A Guide to Facts and Perspectives, ASME,

New York 2010]

Natural Gasis a clear gas that is found in formations in the earth and most of the time

with crude oil and produced through wells drilled into the formations in the earth and

most of the time with crude oil and produced through wells drilled into the formation.Pressures, depths, composition heating value, and corrosiveness vary with each source.

Natural gas is typically found associated with oil at depths of about a mile or greater.

Natural gas is primarily methane, and a typical composition is methane CH470-90

percent, ethane C2H6, propane C3H6, and Butane C4H10. The gas must be processed

before it can be used. The produced gas may also contain hydrogen sulfide H2S, which is

highly toxic, and is referred to as sour gas. Production of sour gas requires special

processing and safety procedures.

Natural Gas from Shale (http://chevron.com,March 17, 2012). According to

Chevron, natural gas is an efficient energy source and the cleanest-burning fossil fuel.

Natural gas extracted from dense shale rock formations has become the fastest-growing

source of gas in the United States and could become a significant new global energy

source. Although the energy industry has long known about huge gas resources trapped in

shale rock formations in the United States, it is over the past decade that energy

companies have combined two established technologieshydraulic fracturing (fracking)

and horizontal drillingto successfully unlock this resource. Methane is the main

primary constituent innatural gas,and probably the most abundant organic compound on

earth. The relative abundance of methane makes it an attractivefuel.However, because it

is agas atnormal conditions,methane is difficult to transport from its source.

Main reactions with methane are:combustion,steam reforming tosyngas,andhalogenation.In general, methane reactions are difficult to control. Partial oxidation tomethanol,for example, is challenging because the reaction typically progresses all theway tocarbon dioxide andwater even with incomplete amounts of oxygen. Like otherhydrocarbons, methane is a very weak acid.

The combustion of methane may be written as

CH4+ 2 (O2+ 3.76 N2) CO2+ 2 H2O + 7.52 N2

Natural gas is a cleaner burning fuel than either coal or gasoline, and with plentifulsupplies in the United States at the present time, it is a very popular fuel. In fact, Bennett(2012) in a recent article in the Wall Street Journalhas written about U.S. automakersmoving toward equipping pickup trucks powered by natural gas.
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M.Biofuels

Biomass is produced directly or indirectly from photosynthesis with the basic chemicalreaction written in simplified form as

CO2+ H2O + SunlightCH2O (carbohydrate) + O2

In this reaction carbohydrates are produced. As we know, living animals breathe oxygen andgive off CO2, while plant life takes in CO2and gives off O2. Clearly, plant and otherorganisms need each other to survive and to maintain a balance of O2and CO2in theatmosphere.

There are two ways to produce biofuels. The first is to use crops that contain high sugarcontent such as sugar cane, sugar beets, sorghum or starch such as corn, wheat, and barley.Yeast fermentation is then used to produce ethanol. The second way is to grow plants such asoil palms, soybeans, rapeseeds, sunflowers, and other plants that contain a high concentrationof vegetable oil to produce biodiesel.

Biomass may be defined as living or dead biological material which can be used as a sourceof energy. Biofuels are made from biomass.

1. Wood

Woodis a hard, fibrous tissue found in trees. It has been used for hundreds of thousandsof years for bothfuel and as a construction material. It is an organic material, a naturalcomposite ofcellulose fibers (which are strong in tension) embedded in amatrix ofligninwhich resists compression. At the present time the most important use of wood in theEuropean Union is for heating. In France more than 40 percent of the individual homesuse wood for space heating.

Charcoalis usually obtained by heating wood in the absence of oxygen. It is 85-98percent carbon and has a higher energy density than wood and burns hotter and cleanerthan wood. Before the advent of fossil fuels, charcoal was used extensively as a fuel andas a metallurgical reducing agent.

Curkeet (2011) presented an overview on the combustion characteristics of Wood. Woodas a fuel goes back to the beginning of recorded history, and it has been used to cook,heat, and in other ways. All wood is made up of primarily Cellulose, Hemi-Cellulose andLignin:

Cellulose(C6H10O5)x

Hemi-Cellulosexylose, mannose, galactose, rhamnose, and arabinose(sugars).

Lignin - C9H10O2, C10H12O3, C11H14O4

These constituents are all essentially complex hydrocarbons which form chains and
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fibers with lignin acting as an adhesive binding it all together. All common wood is madeup of roughly 50 3% Carbon, 6 1% Hydrogen, and 443% Oxygen with the restinorganic ash. Softwoods tend toward higher Carbon and lower Oxygen content thanhardwoods. When burned completely about the wood mass is converted to CarbonDioxide and about to water. This process liberates (heating value) about 8600 Btu perpound (20MJ/kg) of heat energy for hardwoods and 9000 Btu/lb (21MJ/kg) for

softwoods. Complete combustion of wood produces only carbon dioxide (CO2) and water(H2O). There is no visible smoke, no creosote, and no harmful emissions. It releases thefull heating potential of the fuel. Natural wood has no significant sulfur or metals content.

Incomplete combustion results in production of significant levels of CO, and manyhydro- carbons. These unburned components represent lost heating value, pollutantemissions, and potential creosote formation.Since ideal combustion is never achieved,50100 percent excess air is always required to approach 100% combustion. So the realchemical reaction looks more like

A CAHBOC+ u (O2+ 3.76 N2) d CO2 + g O2+ h N2+ j H2O + k CXHY

When wood is freshly cut it can have very high moisture content. Even trees that havebeen dead for years can have a moisture content as high as 50% or more. To maximizeheating efficiency and minimize poor combustion and emissions, it is essential toproperly dry or season fuel wood.

Forest fires are undesirable occurrences that involve the burning of trees (wood), brush,and anything in the path of the fire. Such fires can inflict great damage over a larger areaand spew pollutants in the environment. Two photos of recent forest fires in the LosAngeles area are shown below.

A vehicle travels past a wall of flames at the Station Fire in the Acton, California area northof Los Angeles, August 30, 2009. (REUTERS/Gene Blevins)#
http://www.boston.com/bigpicture/2009/09/wildfires_in_southern_californ.html#photo5http://www.boston.com/bigpicture/2009/09/wildfires_in_southern_californ.html#photo5

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Spot fires glow after the Station Fire burned through August 30, 2009 in Acton, California. (Justin Sullivan/Getty Images) #

2. Biodiesel

Biodiesel can be produced from soybeans, algae, jatrophra curcas, sunflowers, rapeseed,mahua trees, and other biomass. Algae grows in almost any damp or wet environment,and ponds, canals, trenches, and other objects that hold water provide an idealenvironment for algae growth. Japtropha trees/bushes are native to Africa, Asia, and the

Americas but are now grown worldwide. The mahua tree is native to the Indiansubcontinent.

Pure biodiesel (B-100) from soybeans (Wikipedia, April 3, 2012)
http://www.boston.com/bigpicture/2009/09/wildfires_in_southern_californ.html#photo32http://www.boston.com/bigpicture/2009/09/wildfires_in_southern_californ.html#photo32

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Hansen (2008) has presented some interesting data on Diesel and Biodiesel fuels. Histechnical definition of Biodiesel is

Biodiesela fuel comprising mono-alkyl esters of long chain fatty acidsderived from vegetable oils or designated B100, and meeting therequirements of ASTMD 6751.

It takes one bushel of soybeans to produce about 1.5 gallons of Biodiesel or 100 kgsoybeans to produce about 10 liters of Biodiesel. (As an interesting data point, the WallStreet Journal listed the Cash Price of soybeans at $ 14.24 per bushel on April 12, 2012).Hansen represents Diesel fuel as C16H34. Thus, burning Diesel fuel in air thestoichiometric chemical reaction gives

C16H34+ 24.5 (O2+ 3.76 N2)17 H2O + 16 CO2+ 92.12 N2

1kg 14.9 kg 3.1 kg

The stoichiometric air-fuel ratio 14.9 to 1. Now, Hansen states that the soybeanBiodieselfuel moleculeis

C19H36O2

Thus, 1 kg Biodiesel + 12.5 kg air produces 2.8 kg CO2, i.e., Biodiesel produces about 10percent less CO2than does Diesel fuel. Finally Hansen has presented the chart belowwhich compares the energy density (heating value) of various fuels including bothBiodiesel and Ethanol.

.

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3. Ethanol C2H5OH

Ethanol, Halperin (2006), is formed when an H atom in ethane, C2H6, is replaced by anOH radical to produce C2H5OH. Halperin (2006) has discussed the characteristics ofethanol. It is a clear colorless liquid with a pleasant smell. Except for alcoholicbeverages, nearly all the ethanol used industrially is a mixture of 95% ethanol and 5%

water, which is known simply as 95% alcohol. Although pure ethyl alcohol (known asabsolute alcohol) is available, it is much more expensive and is used only when definitelyrequired.

Ethanol, C2H5OH is the primary biofuel used in the world. Brazil and the United Statesaccount for more than two-thirds of the global ethanol production. Brazil uses sugar caneand the United States uses corn. Brazil is able to produce ethanol at a very competitiveprice, about 40 percent less expensive than that obtained from corn is the U.S., and 70percent less than the ethanol produced from sugar beets or cereal crops in Europe.Developing crops to produce biofuels requires both land and water. In that regard, Brazilis in a very favorable position with about 18 percent of the worlds freshwater resources.

The fuel is derived from plants such as corn, sugarcane, and switch grass among others.In the case of corn, it is first ground into a fine powder, mixed with water, heated, anenzyme is then added to convert the mixture into sugars before yeast is added to fermentit. The resulting liquid has an alcohol content of 10 percent. A distillation process thenseparates the alcohol from the rest of the mixture before the remaining water is removed.The result is essentially pure alcohol. At the present time ethanol is more expensive as afuel than gasoline. At present commercial corn-based ethanol comes from corn in theU.S. One of the more exciting ethanol prospects on the horizon is cellulosic ethanol,which can be made from a number of plant by-products, including cornstalks. Althoughit's unlikely to be commercially available for at least a few years, cellulosic ethanoleventually could help substantially reduce costs.

The stoichiometric reaction of ethanol with air is

C2H5OH + 3 (O2+ 3.76 N2) 2CO2+ 3H2O + 11.28 N2

and the higher and lower heating values of ethanol are 29, 670 kJ/kg and 26,800 kJ/kg,respectively. Gies (2010) has written about the environmental effects of ethanol in theNew York Times.
http://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Oxygen

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4. Black Liquor

In the pulp and paper industry black liquoris the spent cooking liquor from theKraftprocess when digestingpulpwood intopaper pulp removinglignin,hemicelluloses andother extractives from the wood to free thecellulose fibers. Approximately 7 tons ofblack liquor are produced in the manufacture of one ton of pulp.

Black liquor is an aqueous solution of lignin residues, hemicellulose, and theinorganicchemicals used in the process. The black liquor contains 15 percent solids by weight ofwhich 10 percent are inorganic and 5% are organic. Normally the organics in black liquorare 40-45 percent soaps, 35-45 percent lignin and 10-15 percent other organics.

Theorganic matter in the black liquor is made up of water/alkali soluble degradationcomponents from the wood.Lignin is degraded to shorter fragments with sulphur contentat 1-2 percent and sodium content at about 6 percent of the dry solids.Cellulose andhemicellulose is degraded to aliphatic carboxylic acid soaps and hemicellulose fragments.The extractives givetall oil soap and crudeturpentine.The soaps contain about 20percent sodium.

The residual lignin components currently serve for hydrolytic or pyrolytic conversion orjust burning only. Hemicellulosis may undergo fermentation processes, alternatively

Current Status

New waste-to-energy methods to utilize the energy in the black liquor have beendeveloped. The use ofblack liquor gasification has the potential to achieve higher overall
http://en.wikipedia.org/wiki/Kraft_processhttp://en.wikipedia.org/wiki/Kraft_processhttp://en.wikipedia.org/wiki/Pulpwoodhttp://en.wikipedia.org/wiki/Pulp_(paper)http://en.wikipedia.org/wiki/Ligninhttp://en.wikipedia.org/wiki/Hemicellulosehttp://en.wikipedia.org/wiki/Cellulosehttp://en.wikipedia.org/wiki/Inorganic_compoundhttp://en.wikipedia.org/wiki/Inorganic_compoundhttp://en.wikipedia.org/wiki/Organic_compoundhttp://en.wikipedia.org/wiki/Ligninhttp://en.wikipedia.org/wiki/Cellulosehttp://en.wikipedia.org/wiki/Hemicellulosehttp://en.wikipedia.org/wiki/Tall_oilhttp://en.wikipedia.org/wiki/Turpentinehttp://en.wikipedia.org/wiki/Black_liquor_gasificationhttp://en.wikipedia.org/wiki/Black_liquor_gasificationhttp://en.wikipedia.org/wiki/Turpentinehttp://en.wikipedia.org/wiki/Tall_oilhttp://en.wikipedia.org/wiki/Hemicellulosehttp://en.wikipedia.org/wiki/Cellulosehttp://en.wikipedia.org/wiki/Ligninhttp://en.wikipedia.org/wiki/Organic_compoundhttp://en.wikipedia.org/wiki/Inorganic_compoundhttp://en.wikipedia.org/wiki/Inorganic_compoundhttp://en.wikipedia.org/wiki/Cellulosehttp://en.wikipedia.org/wiki/Hemicellulosehttp://en.wikipedia.org/wiki/Ligninhttp://en.wikipedia.org/wiki/Pulp_(paper)http://en.wikipedia.org/wiki/Pulpwoodhttp://en.wikipedia.org/wiki/Kraft_processhttp://en.wikipedia.org/wiki/Kraft_process

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energy efficiency than the conventional recovery boiler while generating an energy-richsyngas from the liquor. The syngas can be burnt in agas turbinecombined cycle toproduce electricity .

The heavy or strong black liquor introduced to the recovery furnace ranges from 6080percent solids by weight. The organic fraction of the solids is principally derived from the

hemicellulose and the lignin removed from the cellulose strands of the wood chips. Theinorganic fraction of the solids is primarily Na2CO3, sodium hydrosulfide (NaHS), andoxidized sulfur compounds. Black liquor also contains various chemical elements whichenter the process with the wood, as impurities in makeup limestone and salt cake, and ascontaminants in makeup water. These elements include K, Cl, Al, Fe, Si , manganese, Na,Mg, and phosphorous.

The heating value of black liquor is a strong function of the carbon content and rangesfrom about 12,000 to 17,500 kJ/kg, corresponding to carbon content of 28 to 44 percentCarbon, respectively.

N. Municipal Solid Waste (MSW)

MSW typically consists, as collected, of about 50 percent combustible material such aspaper, plastics, wood, and rubber. About 25 percent is noncombustible, and another 25percent is moisture. The energy content of MSW material is about 5,000 Btu/lb. Waste-to-energy (WTE) plants can significantly reduce the volume of MSW before disposal inlandfills. These plants also generate electricity that helps to offset the financial burden ontaxpayers who ultimately pay for the waste disposal.

WTE plants now incorporate the latest technology to reduce pollutant emissions below thepoint of endangering public health. Regulatory requirements instituted in 1992 are among themost stringent for any combustion technology because of the variable nature of solid waste.

Current operating WTE plants contribute a very small share of the total U.S. energy needs.But if all the MSW were combusted (after recycling 30 percent), plants with the latesttechnology would contribute 3-4 percent of the total U.S. energy needs. There is significantuse of modern waste-to-energy technology to produce electrical power in the U.S.

O. Analysis of Combustion Products

1. Dry basis: Fractional analysis of all components, except for water vapor.

2. Wet basis: Fractional analysis of all components including water vapor.
http://en.wikipedia.org/wiki/Energy_conversion_efficiencyhttp://en.wikipedia.org/wiki/Syngashttp://en.wikipedia.org/wiki/Gas_turbinehttp://en.wikipedia.org/wiki/Combined_cyclehttp://en.wikipedia.org/wiki/Combined_cyclehttp://en.wikipedia.org/wiki/Gas_turbinehttp://en.wikipedia.org/wiki/Syngashttp://en.wikipedia.org/wiki/Energy_conversion_efficiency

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P. Enthalpy of Formation

1. Consider the reaction

C + O2 CO2

as shown below:

where the reference or standard temperature and pressure are

Tref = 25oC = 298 K

Pref = 1 atm = 101.325 kPa = 14.696 psia

Apply the First Law to the control volume shown assuming negligible changes in kineticand potential energies

If we assign a value of zero (0) to the enthalpy of all the elements at the reference state, T= 298 K,P= 1 atm), then

This term is called the enthalpy of formation at Tref = 25oC,Pref = 1 atm with reference to

the arbitrary state in which the enthalpy of the elements at 298 K, 1 atm is arbitrarily

chosen to be zero. The symbol is . The enthalpy of formation of a substance may be

considered to be the enthalpy at a specified state due to its chemical composition. Theenthalpy of CO2at any other temperature Tis then

Values of of various substances are given in Table A-25, Page 860 in MSBB. Note

that two values are given for water, H2O (g) and H2O (l). The difference between the twovalues is

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Tables of enthalpy values as a function of temperature for N2, O2, H2O, CO, and CO2aregiven in Table A-23, pp 929-932 in MSBB. Values of enthalpies for O, OH, and H2fromCengel and Boles (2008) are provided as an attachment.

Q. First Law Analysis for Reacting Systems

Neglecting changes in kinetic andpotential energies, application ofthe steady state First Law to theControl Volume shown yields:

R. Enthalpy of Combustion and Heating Values

1. Definition

The enthalpy of combustion RPis defined as the difference between the enthalpy of theproducts and the enthalpy of the reactants when completecombustion occurs at a giventemperature and pressure

2. Tabulated values are usually given at T= 298 K,P = 1 atm and the symbol is used

for data at this reference state.

3. Useful for fuel oil and coal, for which data is not available, for which RPis

determined experimentally. Such data is obtained using a bomb calorimeter

4. Heating Value of a Fuel

a. Definition The amount of energy released when a fuel is burned completely in asteady-flow process and the products are returned to the state of reactants, i.e.

Heating Value = ||

i. Higher Heating Value (HHV)

Water in the products is in the liquidform

ii. Lower Heating Value (LHV)

Water in the products is in the vaporform

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HHV=LHV+ (nfg)H2O

S. Adiabatic Flame Temperature, TP

Assumptions:

1. Steady state2. Adiabatic combustionprocess

3. KE = 0

4. PE = 0

5. cv= 0

Under these assumptions the steady state First Law of Thermodynamics is

which may be written as

The resulting outlet temperature is known as the adiabatic flame temperature, Tp.

1. For a given fuel and given T, Pof the reactants, the maximum adiabatic flame temperature

which can be achieved is with a stoichiometric mixture.

2. Therefore, the adiabatic flame temperature can be controlled by the amount of excess air.

3. Because of the nature of the problem, an iterative solution is generally required

T. References

Jeffrey Bennett, Natural Gas to Power Pickups, Wall Street Journal, March 2, 2012.Gene Blevins,Reuters, August 30, 2009.

Y. A. Cengel and M. A. Boles, Thermodynamics: An Engineering Approach, Ideal-GasProperties of H2, H, and OH, 6

thEdition, McGraw-Hill, New York, 2008, pp. 946 & 949.

Rick Curkeet, Wood Combustion Basics, EPA Workshop, March 2, 1011.

Fuels. Wikipedia, (http://en.wikipedia.com,March 17, 2012.
http://en.wikipedia.com/http://en.wikipedia.com/

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Erica Gies, As Ethanol Booms, Critics Warn of Environmental Effects, New York Times,June 24, 2010.

Alex Halperin, Ethanol: Myths and Realities, Business Week, May 19, 2006.

A.C. Hansen, Combustion and Emissions Characteristics of Biodiesel Fuel, CABER,

Department of Agricultural and Biological Engineering, University of Illinois, CABERSeminar, Department

Mackenzie, F.T. and J.A. Mackenzie (1995), Our Changing Planet. Prentice-Hall, UpperSaddle River, NJ, p 288-307. (After Warneck, 1988; Anderson, 1989; Wayne, 1991.http://eesc.columbia.edu/courses/ees/slides/climate/table_1.html.

Michael J. Moran, Howard N. Shapiro, Daisie D. Boettner, and Margaret B. Bailey,Fundamentals of Engineering Thermodynamics, Seventh Edition, John Wiley, New York,2011.

Pure Biodiesel (B-100) from Soybeans, Wikipedia, April 3, 2012 of Agriculture, May 5,2008.

Justin Sullivan, Spot fires Glow after the Station Fire Burned Through, Getty Images,August 30, 2009.

Jon Vidar, AP Photo, August 31, 2009.

U. Example Problems

Attachments

A. U.S. Energy Outlook

B. International Energy Outlook

C. Ideal Gas Properties of H2, O, and OH
http://eesc.columbia.edu/courses/ees/slides/climate/table_1.htmlhttp://eesc.columbia.edu/courses/ees/slides/climate/table_1.html

Documents

136 W14 L 2, 3, 4 Lecture