MICROALGAE BIODIESEL AS A SUBSTITUTE FOR JET FUEL

of MICROALGAE BIODIESEL AS A SUBSTITUTE FOR JET FUELby Chandan Sohi With dwindling petroleum resources, the need for alternate fuel resources has becomeimmense.. Although many such fuels

Chandan Sohi B.S., University of California, Davis, 2005

Chandan Sohi ALL RIGHTS RESERVED

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I certify that this student has met the requirements for format contained in the University format manual, and that this thesis is suitable for shelving in the Library and credit is to be awarded for the thesis.

, Department Chair _

Susan Holl, Ph.D Date

Department of Mechanical Engineering

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of MICROALGAE BIODIESEL AS A SUBSTITUTE FOR JET FUEL

by Chandan Sohi

With dwindling petroleum resources, the need for alternate fuel resources has becomeimmense Any new fuel source needs to be home grown, economically feasible, andenvironmentally friendly Although many such fuels are available for groundtransportation, such as ethanol, there are not many options for alternate aviation fuels.One possible replacement fuel for jet fuel is biodiesel Biodiesel has many similarproperties to jet fuel, such as energy density and specific energy However, productionissues, low temperature properties, oxidative degradation provide significant challengesfor implementation of biodiesel as an aviation fuel This author studied these challenges

by examining biodiesel produced from microalgae feedstock The high production rates

of microalgae make it an ideal feedstock Furthermore, the growth of microalgae doesnot require arable land for growth Hence, it does not figure into the land concerns of the

“fuel vs food” debate The author examined methods of improving low temperatureproperties such as winterization and additives For fighting oxidative degradation, thisauthor examined research evaluating the procedure of adding antioxidants to lengthenoxidative stability The study concluded that although pure microalgae biodiesel fuelwould meet the criteria of being home grown, economically feasible, andenvironmentally friendly, the implementation of the fuel is still several years away.However, blends of petroleum diesel and microalgae biodiesel containing up to 30-vol%biodiesel can be implemented due to the better fuel properties of petroleum diesel

List of Tables vii

List of Figures viii

Chapter 1 INTRODUCTION ……… ……… 1

1.1 Need for Alternative Fuels 2

1.2 Choosing a Fuel 5

2 BIOFUELS… 7

2.1 Brief History 7

2.2 Biomass……….… 9

2.3 Biofuel Sources……… … … 9

2.4 Production of Biofuels……… … 11

2.5 Benefits and Impacts……… ………… 17

3 WHY MICROALGAE BIODIESEL? 20

3.1 Production 20

3.2 Fuel Properties 23

4 PRODUCTION 31

4.1 Strain Selection 31

4.2 Production Technologies 33

4.3 Harvesting 38

4.4 Conversion Technologies 38

4.5 Microalgae Biodiesel Pathways 43

5 AVIATION CHALLENGES 48

5.1 Low Temperature Properties 48

5.2 Oxidative Degradation 58

6 PRODUCTION 60

Bibliography…… …….………….… 63

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3.1 Oil Yields of Feedstock Crops……….……… 22

3.2 Characteristics of Different Fuel Types ………….……….……… 24

3.3 Comparison of Biodiesel vs Conventional Jet Fuel……….… 26

4.1 Lipid Content of Many Microalgae Species……… 32

4.2 Expected Yield for Pyrolysis Conversion Process……… 42

5.1 Effects of Winterization on Fatty Acid Composition of Long Chain Methyl

Ester……… 52

5.2 Effects of Additives on Cloud Point and Pour Point Properties of Biodiesel

Based Fuels……….……… 55

5.3 Effects of Additives on Kinematic Viscosity of Biodiesel Based Fuels… 57

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1.1 Annual Energy Consumption Values for Selected Countries.……….4

2.1 Current Biofuel Pathways.……….……… …… 8

2.2 Two-Stage Gasification……….……….……….…….12

2.3 Alcohol Fermentation……….……….…….15

2.4 Anaerobic Digestion……….…… 16

2.5 Percent Reduction in Pollutants for Biodiesel as Compared to Petroleum Based Diesel……… ………….…… 18

3.1 Mass of Fuel vs Volume of Fuel per Unit Energy……… 25

4.1 Tubular Bioreactors……….……… 35

4.2 Algal Biomass Conversion Pathways……… ….… 39

4.3 Transesterification Process……….…… 45

4.4 Current and Emerging Pathways for Biofuels……… 46

4.5 Microalgal Biofuel Production Cycle……… 47

5.1 Airplane Fuel System………….……… 49

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Chapter 1 INTRODUCTION Purpose of the StudyOne of the most pressing political/economic needs faced today is the need toreduce our dependence on foreign oil There are several new options available asalternatives to gasoline for ground transportation Over time, as new technology andprocesses are developed, our dependence on gasoline will become negligible Some ofthis will come through better fuel cell technology for hybrid or electric vehicles whileother improvements will come through continuous development of biofuels Today wehave biofuels such as ethanol and biodiesel available in the marketplace Currentlyethanol displaces 2% of all gasoline Further advances in technology will allow us toproduce the ethanol out of cellulosic material, which will further decrease ourdependence on gasoline [1].

However, we still do not have a suitable replacement for jet fuel The prevalentalternative fuel options for ground transportation are not suitable for the aviationindustry For airplanes, the specific energy, energy density, and the low temperature fuelproperties for any alternative option are quite important Ethanol does not have thespecific energy or energy density that is suitable for aircrafts Biodiesel has suitableenergy density (about 80% that of jet fuel) however it has a propensity to freeze at thelow temperatures that airplanes are likely to encounter at high altitude cruising Anotherlimitation that biofuels face is the production capacity of these fuels The amount of

biofuel presently produced is very limited In order to increase production of biofuels,more land and resources will need redirection These resources would need shifting fromuse for crops whose primary function is to provide food to crops whose primary function

is of feedstock to produce biofuels Redirection of only a limited amount of theseresources is possible, before the redirection starts hampering food production and causingshortages in food supply Hence, biofuel feedstock crops that do not require arable landneed further investigation Technology for production of these alternative fuels need to

be developed and improved

1.1 Need for Alternative Fuels

Political, economic, and environmental issues that have risen over the past severaldecades have brought fourth the need for alternative jet fuels that are home grown,economically viable, and environmentally clean

The need for alternative fuel sources first came to the forefront during the energycrisis of the 1970’s During this period, most of the industrialized economies wereheavily dependent on crude oil The oil supply along with the oil prices were at the timecontrolled heavily by the Organization Petroleum Exporting Countries (OPEC) In 1973,the US government decided to re-supply the Israeli military during the Yom Kippur War

A move that did not go down well with the Arab nations, so as a response theOrganization of Arab Petroleum Exporting Countries (OAPEC) a large portion of OPECdecided to place an oil embargo on the United States thus limiting oil supplies andsending oil prices skywards The oil embargo highlighted the United States’ dependence

on foreign oil and the need for alternate fuel sources to guarantee its political autonomy[2]

Politics is just one of the reasons for the need for alternate fuels There are otherconsiderations as well Supply chain issues due to war, terrorism, or weather can alsobring about a severe hike in oil prices In August of 2005, there was an interruption in oilsupply due to Hurricane Katrina Ports in the region were not able to receive foreign oilshipments and refineries and pipelines had to be shutdown This disruption in oilhighlights the need for more fuel sources to lessen the impact of disruption in supply offuel from one particular region With other fuel options available, the disruption in oilsupplies could have not been as drastic and the economic affect not been as severe [2].The availability of additional fuel sources will also help dampen the affects of depletingoil reserves and an increasing demand With emerging economies such as China andIndia having more demand for fuel sources, the rate of depletion for the fossil fuelsources should go up (Figure 1.1) With a crowded market place for fuel sources, thecompetition for fuel should be extreme with the prices for crude oil going up drastically[3]

Additional motivations for the need for alternate energy sources includeenvironmental factors There are air quality and global climate concerns that underlinethe need for more environmentally friendly fuel source Aviation emissions such as NOx,

CO, and unburned hydrocarbons can lead to ozone and smog problems This degradation

Figure 1.1: Annual Energy Consumption Values for Selected Countries [3]

in air quality can cause health issues relating to the respiratory and cardiovascularsystems Global climate considerations are also important when discussing alternatefuels There is a need to decrease the life-cycle CO2 emissions CO2 is one of the leadingsources of global warming Since 1900, average temperatures have risen 1.5 °F and sealevels have risen over seven inches If CO2 emissions are not drastically controlled, therecan be drastic planetary changes such as frequent severe weather, higher temperatures,higher sea levels, glacier retreats, and habitat and eco-system losses [4].

1.2 Choosing a Fuel

There is certain criterion that is important in the search for alternative fuel sourcesfor the aviation industry This criterion includes “drop in” factor of the fuel, productioncapability, efficiency gains and losses, physical and chemical properties of the fuel, CO2life cycle analysis, infrastructure requirements, and aircraft design issues andmaneuverability The “drop-in” fuel term refers to fuels capable of blending with ordirectly replacing jet fuel without any major changes to aircraft design or presentinfrastructure and without a sacrifice in airplane maneuverability Hence, the “drop-in”factor of the fuel is very important in picking a suitable alternative to jet fuel

There are many alternative fuel options available Some of these are long term,some short term, and some considered as “drop-in” solutions The options availableinclude Synthetic Fuels (Jet A and Synthetic Paraffinic Kerosene), Biofuels (Ethanol,Butanol, Biodiesel, Biokerosene, Biojet), and Cryogenic Fuels (Liquid Hydrogen andLiquid Methane) These fuels must be studied thoroughly and their advantages and

disadvantages as a “drop-in” fuel correctly deciphered Cryogenic fuels are a long-termsolution for aviation fuels Design changes along with technological advances to theairplanes will be necessary to utilize these fuels Such fuel technology is at the least acouple decades away from fruition [5] Biofuels are a better option as replacement for jetfuel then synthetic fuels due to the high levels of CO2 emissions during the production ofsynthetic fuels Hence, this author decided to focus this research on the biofuels, andmore specifically microalgae based biodiesel in particular

This author will look at the biodiesel with an emphasis towards aviation use Thisthesis will compare the properties of biodiesel with those of conventional jet fuel.Discussion performed on the advantages and disadvantages of microalgae as a feedstockand biodiesel as a fuel Examination of the factors preventing the fuel from becoming a

“drop-in” fuel conducted For biodiesel, these factors include production capacity andlow temperature properties of biodiesel Production pathways for microalgae basedbiofuels need examination, areas of improvement and concerns identified

Chapter 2BIOFUELS

A better understanding of biofuels is required before performing any discussion

on the topic It is important to understand their history, sources, and the technologynecessary to manufacture them This section will give a brief overview on these topics Itwill examine different traditional biofuel pathways (Figure 2.1) that use varyingconversion processes to convert biomass sources into biofuels

2.1 Brief History

Man has been using biofuels for thousands of years It is not until as recent astwo hundred years, that fossil fuels became available to the world and have since becomeprevalent The contributing factor behind such a change was the need of hightemperatures for iron smelting Up until the industrial revolution, the smelting processprimarily used charcoal Coal had remained largely unsuitable for this function due to itsimpurities and variable nature However, with the introduction of coal-charcoal, a fuel,

in the early 1700 has changed all that Coal-charcoal, now called coke, started replacingcharcoal as the primary fuel source By the end of the 19th century, coal was in widedemand across the industrialized countries The 20th century would see this demand forcoal go up five folds even with the introduction of other fuel sources such as oil andnatural gas

It was not until the late 1970’s, after the oil crisis, that man has had a renewedinterest in biofuels The shortage of oil during the time showed us our dependency on

Figure 2.1: Current Biofuel Pathways [6]

fossil fuels Hence, extensive research funding has gone towards finding alternate fuelsources that are environmentally clean, sustainable, and reliable Scientists and engineershave also been looking to develop the technology to go with these fuels Currentlyseveral different biofuels are available in the marketplace Among them are ethanol,butanol, propanol, and biodiesel (fatty acid methyl ester) [7]

2.2 Biomass

Biofuels are fuels formed from biomass, biological material made up of living orrecently living things Through photosynthesis, the biological material is able to procurewater and carbon dioxide and use the energy produced by the sun to convert them intoorganic compounds such as sugars The chemical reaction below illustrates this process:

6CO2 + 6H2O + light energy → C6H12O6 + 6O2

The reaction shows how a plant (biological material) is able to gain water, carbondioxide, and energy through the sun and convert it into glucose and oxygen Duringcombustion, the oxygen is used and energy release as heat [7]

not grown primarily as a source for food The relatively clean nature of the biofuelsproduced from these crops coupled with the desire to find domestic sources of oil haveprimarily led to the popularization of energy crops There are two primary types ofenergy crops; these are woody crops and agricultural crops

The two most widely grown energy crops are sugarcane and corn These cropsare ideal due to their high yield Other examples of energy crops are those crops that arecultivated mainly for their oily seeds These crops include sunflowers and soybeans [7]

2.3.2 Wastes

There are many types of wastes that can be used as bioenergy sources Thesewastes include wood residues, temperate crop wastes, tropical crop wastes, animalwastes, municipal solid wastes, landfill gasses, and commercial and industrial wastes.Wood residue accumulates largely through trimming of plants and trees Thesetrimmings are often times not utilized

Temperate crop wastes include residues from wheat and corn The residue fromthese plants measures to more than one billion tones per year In large yield areas ofthese crops, the residue remains largely unused Contrastingly, tropical crop wastes comemainly from residues of tropical food crops such as rice (rice husks) and sugar canes(Bagasse) Animal wastes, such as manure, sewage sludge, and poultry litter, andmunicipal solid wastes are treated and converted into biofuels Landfill gases generated

by municipal solid wastes, are also a source of bioenergy [7]

2.4 Production of Biofuels

It is possible to transform biomass directly into solid, liquid, and gaseous fuelsthrough different processes These processes can be divided into thermo-chemical,physical-chemical, and bio-chemical conversion processes

2.4.1 Thermo-chemical Process

One of the main ways to convert solid biofuels into solid, liquid, and gaseousenergy carriers is thermo-chemical conversion There are three main types of thermo-chemical processes They are gasification, carbonization, and pyrolysis Often timesthese conversion processes work in unison An example of this is the biomassgasification process (Figure 2.2) This two-stage process initially requires pyrolysisbefore actual gasification takes place

2.4.1.1 Gasification

Gasification is the process of transforming solid biofuels into gaseous energycarriers During this process, solid biofuel is reacted at high temperatures with oxygen-containing substance such as air The resultant of this process is syngas, or synthetic gas.The produced syngas has many uses such as heat and power generation Alternate energycarriers are also created using syngas Fischer-Tropsch method transforms the syntheticgas into fuels such as methanol and hydrogen [7]

2.4.1.2 Pyrolysis

Pyrolysis is the process of converting solid biofuels into liquid products The processinvolves decomposition of the biomaterial through the addition of heat without the

Figure 2.2: Two-Stage Gasification [3]

presence of oxygen [8] The process can result in gaseous, liquid, and solid byproducts.

It is imperative that the biomaterial does not burn so that gasification is minimal and theresulting byproduct is a liquid fuel The liquid product of pyrolysis, bio-oil, generally hasabout half the energy value of crude It also requires further processing to remove acidcontaminants Bio-oils can be used for can be used for heat and power generation as well

as fuel for transportation [7]

2.4.1.3 Carbonization

The third thermo-chemical process is carbonization During Carbonization,organic substance (biomaterial) decomposes and transform into carbon or carbon creatingresidue The process insures the maximum output of solid reaction products such ascharcoal The process is quite similar to gasification and pyrolysis; however, this processresults in the largest byproduct of the conversion being solid Heat and power generationactivities often utilize the resulting solid biomass that is generally charcoal [8]

2.4.2 Physical-chemical Conversion

Physical-chemical conversion requires biomass (oil seeds) containing vegetableoil or fat The initial step of the process separates the liquid part of the oil from the solidpart through mechanical pressing However, the same result is plausible by extractionusing a solvent Generally, physical-chemical conversion uses both processes First, theoil seeds go through the mechanical press and later the extracted with the use of asolvent The resulting oil is a viable byproduct; however, chemical conversion is alsoavailable to turn the resulting into Fatty Acid Methyl Ester [8]

2.4.3 Bio-chemical Conversion

Bio-chemical conversion uses living organisms or their product to convertbiomaterials into biofuels There are three types of bio-chemical conversion processes;alcohol fermentation, anaerobic digestion, and aerobic fermentation

2.4.3.1 Alcohol Fermentation

Alcohol fermentation takes sugar, starch, or cellulose containing biomass andconverts it into an alcohol and carbon dioxide (Figure 2.3) The process involves usingmicro-organisms, generally yeast, to break down the sugars The next step involvesseparating ethanol from the rest of the byproducts Engines and combined heat andpower plants (cogeneration) are two uses for this pure ethanol fuel Alternatively,blending ethanol with gasoline provides a substitute fuel for gasoline Currently this fuel

is available containing up to 85% ethanol However, blends of a larger percentage ofethanol should be available in the future with more research and development oftechnology that is able to utilize the fuel [8]

2.4.3.2 Anaerobic Digestion

Anaerobic digestion creates vapor-saturated gas mixture that is roughly sixty percent

methane and forty percent carbon dioxide (Figure 2.4) During the process, biomaterials

are broken-down by bacteria into biogas Waste and water treatment plants use anaerobicdigestion; however, it also occurs naturally at landfills and bottom of lakes The resulting

biogas useful as an alternative for natural gas, transportation and powergeneration are possible [8]

Figure 2.3: Alcohol Fermentation [3]

Figure 2.4: Anaerobic Digestion [3]

2.5 Benefits and Impacts

There are several benefits and impacts of biofuels The most important of which is itsenvironmentally friendly nature Photosynthesis of carbon dioxide with water createsbiomass This process ends up extracting carbon dioxide from atmosphere However, asbiomass burns during combustion, CO2 releases back into the atmosphere Biofuels haveshown to be significantly more environmentally friendly Fossil fuels on the other handare a result of atmospheric carbon dioxide sequestered in the ground for millions of years

As fossil fuels burn during combustion, previously sequestered carbon dioxide releasesinto the atmosphere [9] Emission studies of combustion of biodiesel as compared topetroleum diesel show significant reduction in pollutants (Figure 2.5) There is up to100% reduction in sulfur dioxide, 80% reduction in carbon monoxide, 67% reduction inunburned hydrocarbons, 47% reduction in particulate matter, and up to 90% reduction inmutagenicity [3] Biofuels are renewable as new crops are grown and waste materialcollected Political and economic reliefs are other benefits of biofuels Biofuels helploosen our reliance on foreign oil and insuring the country’s political autonomy Largenumber of jobs created to manufacture biofuel acts as an economic stimulus

Figure 2.5: Percent Reduction in Pollutants for Biodiesel as Compared to Petroleum

Based Diesel [3]

Some of the drawbacks of biofuels are due to the land use for growing energycrops Since large amounts of crops are necessary to create significant quantities ofbiofuels, the land needed to grow these crops has to come from somewhere Landpreviously allocated towards growing crops for food now grows crops for fuel Doing sowill hamper the food supply Hence, too much land cannot be set aside to grow crops forfuel This limitation on land use really dictates the type of energy crops used for fuelproduction High yield crops are ideal for biofuels New fuels based on algae andhalophytes are being researched and developed that will help eliminate this limitation.

Chapter 3WHY MICROALGAE BIODIESEL?

Biofuels derived from corn, cotton, soybean, mustard seed, sunflower, rapeseed,jatoropha, oil palm, and algae are available in the market Several factors set asidemicroalgae based biodiesel from other fuel options These factors include productioncapacity, energy content, performance, availability, and price In this chapter, microalgaebiodiesel is compared to other options based on the above given criteria This author willattempt to quantify the critical factors and present the results and conclusion

3.1 Production

Production is important because any viable alternative to jet fuel needs to be readilyavailable to the consumers Any disruption in production or supply chains is likely tosend fuel prices skyrocketing Hence, it is extremely important to evaluate thecharacteristics of production that are likely to increase or enhance the production capacity

of a biofuel Microalgae, as a feedstock for production of biofuels, provide severalbenefits over other feedstock; mainly oil yield and land use This section will discuss indetails these benefits and provide a description of challenges faced in large-scaleproduction of microalgae biofuels

3.1.1 Oil Yield

Oil Yield is a very important characteristic when deciding which feedstock to use

to produce biofuels Generally, you need a feedstock with high oil yields because oilyield has a direct correlation with the production capacity of oil Plant oils or lipids are

the starting point to manufacture biodiesel or jet fuel In Table 3.1, a list of oil yields ofvarying biofuel feedstock crops is available Common feedstock crops such as corn andsoybean have oil yields of eighteen and forty eight gallons per acre respectively.Rapeseed has an oil yield of 127 gallons per acre Compared to these numbers, the oilyield for algae is ten to fifty times higher than other terrestrial plants Algae can yieldbetween twelve hundred with technology currently available and ten thousand gallons ofoil per acre with technology available in the future [10]

3.1.2 Land Use

Land use is a very important factor in production capacity For every acre ofarable land used to grow feedstock, there is one less acre of land to grow food Hence, anincrease in production of fuels based on feedstock grown on arable land decreases foodsupply and in turn increases food prices for vegetable oils An estimate of one quarter ofone third of all price increase in vegetables oils results from an increase in production ofenergy from land Since feedstock cost account for a large percentage of biofuel price,any increase in vegetable oil prices sends biofuel prices higher At that point, biodiesel is

no longer competitive with fossil fuels [11]

Microalgae provide a distinct advantage in this aspect It can grow onmarginal/non-arable land Algae grown from twenty to thirty million acres of non-arableland can replace the entire oil supply imported by the United States There is no need touse any arable land for growing feedstock for biofuels Furthermore, any fluctuation invegetable oil prices does not have an impact on biofuels derived from microalgae

Oil Yield Gallons/Acre

One of the main production concerns for producing microalgae based biofuels istechnology Currently microalgae production is performed at a much smaller scale thanthat would be required to replace jet fuel New technology and processes needdevelopment and testing to increase the production capacity of the feedstock The currenttechnology is also very expensive Production of any alternative fuel for replacement ofjet fuel needs to be economically feasible Future technology needs to makeeconomically acceptable so that it does not price the fuel generated out of market due tocost This author will discuss the entire production cycle for producing microalgaebiodiesel in further detail in Chapter 4.

3.2 Fuel Properties

A way to distinguish between possible alternative jet fuels is through fuelproperties of the fuel Determination of how a fuel will affect the airplane’s design,maneuverability and operations need evaluation Since the main purpose of the fuel is toprovide energy, specific energy and energy density are important characteristics of a fuelthat need evaluation before contemplation in any changes in type of fuel Table 3.2 andFig 3.1 provide values for these criteria for varying fuel types In addition to providing

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excess heat, and as hydraulic fluid in engine control systems.

3.2.1 Specific Energy

Specific energy, the energy per unit mass, is dependent on the energy content of thefuel Specific energy is used to asses the lower heating value of the fuel In general, jetfuel provides aircrafts with the necessary energy to propel the aircraft The turbinesconvert the chemical energy present within the fuel into mechanical energy; thusproviding necessary thrust to operate the airplane The reaction between the fuel andoxygen at high temperatures release the chemical energy stored within the fuel Thisreleased energy is the heat of combustion of the fuel If the water formed during thecombustion process is in gaseous form, the heat of combustion is termed as lower heatingvalue, LHV However if the water formed during the combustion process is in condensedliquid state, the heat of combustion is termed as the higher heating value, HHV Sinceaircraft engines generally release water in a vapor phase, we use the LHV as thedetermining factor [12]

Several potential alternative jet fuels tend to contain oxygen These fuels, such asethanol and butanol, tend to have lower LHV then those without oxygen since the oxygenpresent in the fuel molecule does not contribute any energy to the combustion process.Due to the lower LHV, the specific energy of the fuel also tends to be lower

The specific energy of a fuel is an important characteristic in determining the range

of an airplane Aircrafts receive ratings at their maximum take-off weight This take-off

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energy of the fuel, the larger the quantity of fuel (in weight) needed to fly similardistance Hence, reducing the amount of cargo and passengers the airplane can carry Afuel with larger specific energy is able to fly more cargo and passengers and for longerdistances [12].

3.2.2 Energy Density

Similar to specific energy, energy density is also an important characteristic whiledistinguishing between fuels Energy density is the measure of energy per unit volume of

a fuel The design of an airplane limits how much fuel it can carry This limiting factor

in the design is the volume capacity of the fuel tanks of the airplane Fuels with higherenergy density will enable the airplane to have a greater range [12]

3.2.3 Fuel Comparison

This section will provide the advantages and disadvantages of using biodiesel as areplacement fuel for conventional jet fuel This author will evaluate the fuel properties ofbiodiesel against those of jet fuel Areas of technological improvement and futureresearch identified

3.2.3.1 Advantages

Table 3.2 provides values for the specific energy and energy density of the fuels.Generally, a good fuel needs to have high specific energy and high energy density.Currently acceptable jet fuel, Jet A or Jet A-1, has a specific energy of 43.2 MJ/kg and anenergy density of 34.9 MJ/l Setting this as a standard, we look for fuels with similar or

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