Algae Energy

204 Pages·2010·1.82 MB·English

Green Energy and Technology
Ayhan Demirbas · M. Fatih Demirbas
Algae Energy
Algae as a New Source of Biodiesel
123
AyhanDemirbas M.FatihDemirbas
ProfessorofEnergyTechnology SilaScienceandEnergyUnlimitedCompany
SirnakUniversity UniversityMah.
Sirnak 24AkifSaruhanCad.,MekanSok.
Turkey 61080Trabzon
Turkey
ISSN 1865-3529
ISBN 978-1-84996-049-6 e-ISBN 978-1-84996-050-2
DOI 10.1007/978-1-84996-050-2
SpringerLondonDordrechtHeidelbergNewYork
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Preface
This book examines the production of algae culture and usage of algal biomass
conversion products. In this book, the modern biomass-based transportation fuels
biodiesel, bio-oil, biomethane, biohydrogen,and high-value-addedproducts from
algaearebrieflyreviewed.Themostsignificantdistinguishingcharacteristicofalgal
oilisitsyieldand,hence,itsbiodieselyield.Accordingtosomeestimates,theyield
(per acre) of oil from algae is over 200 times the yield from the best-performing
plant/vegetableoils.Thelipidandfattyacidcontentsofmicroalgaevaryinaccor-
dancewithcultureconditions.Theavailabilityofalgaeandtheadvantagesofalgal
oilforbiodieselproductionhavebeeninvestigated.
BillionsofyearsagotheEarth’satmospherewasfilledwithCO .Thustherewas
2
no life on Earth.Life on Earthstarted with Cyanobacteriaand algae.These hum-
blephotosyntheticorganismssuckedouttheatmosphericCO andstartedreleasing
2
oxygen.Asaresult,thelevelsofCO starteddecreasingtosuchanextentthatlife
2
evolvedonEarth.Onceagainthesesmallestoforganismsarepoisedtosaveusfrom
thethreatofglobalwarming.
Inthe contextofclimatic changesandsoaringpricesfora barrelof petroleum,
biofuels are now being presented as a renewable energyalternative. Presently, re-
search is being done on microscopic algae, or microalgae, which are particularly
rich in oils and whose yield per hectare is considerably higher than that of sun-
flowerorrapeseed.Algaewillbecomethemostimportantbiofuelsourceinthenear
future.Microalgaeappeartobetheonlysourceofrenewablebiodieselthatiscapa-
ble of meetingthe globaldemandfor transportfuels. Microalgaeare theoretically
averypromisingsourceofbiodiesel.
Algae are the fastest-growing plants in the world. Industrial reactors for algal
culture are open ponds, photobioreactors,and closed systems. Algae are very im-
portantasabiomasssourceandwillsomedaybecompetitiveasa sourceforbio-
fuel.Differentspeciesofalgaemaybebettersuitedfordifferenttypesoffuel.Algae
canbegrownalmostanywhere,evenonsewageorsaltwater,anddoesnotrequire
fertile land or food crops, and processing requiresless energythan the algae pro-
vides. Algae can be a replacement for oil-based fuels, one that is more effective
v
vi Preface
andhasnodisadvantages.Algaeareamongthefastest-growingplantsintheworld,
and about50% of their weight is oil. This lipid oil can be used to make biodiesel
forcars, trucks,andairplanes.Microalgaehavemuchfaster growthratesthan ter-
restrial crops. the per unit area yield of oil from algae is estimated to be between
20,000 and 80,000L per acre per year; this is 7 to 31 times greater than the next
bestcrop,palmoil.Mostcurrentresearchonoilextractionisfocusedonmicroalgae
to produce biodiesel from algal oil. Algal oil is processed into biodiesel as easily
asoilderivedfromland-basedcrops.Algaebiomasscanplayanimportantrolein
solvingtheproblemoffoodorbiofuelsinthenearfuture.
Microalgaecontainoils,orlipids,thatcanbeconvertedintobiodiesel.Theidea
ofusingmicroalgaetoproducefuelisnotnew,butithasreceivedrenewedattention
recently in the search forsustainable energy.Biodiesel is typicallyproducedfrom
plantoils,buttherearewidelyvoicedconcernsaboutthesustainabilityofthisprac-
tice. Biodieselproducedfrommicroalgaeisbeinginvestigatedasanalternativeto
usingconventionalcropssuchasrapeseed;microalgaetypicallyproducemoreoil,
consumelessspace,andcouldbegrownonlandunsuitableforagriculture.
Usingmicroalgaeasasourceofbiofuelscouldmeanthatenormousculturesof
algaearegrownforcommercialproduction,whichwouldrequirelargequantitiesof
fertilizers.Whilemicroalgaeareestimatedtobecapableofproducing10to20times
morebiodieselthanrapeseed,theyneed55to111timesmorenitrogenfertilizer–
8to16tons/ha/year.
Thisbookonalgaeenergyattemptstoaddresstheneedsofenergyresearchers,
chemicalengineers,chemicalengineeringstudents,energyresourcespecialists,en-
gineers, agriculturists, crop cultivators, and others interested in practical tools for
pursuingtheirinterestsinrelationtobioenergy.Eachchapterinthebookstartswith
basicexplanationssuitableforgeneralreadersandendswithin-depthscientificde-
tailssuitableforexpertreaders.Generalreadersincludepeopleinterestedinlearn-
ingaboutsolutionstocurrentfuelandenvironmentalcrises.Expertreadersinclude
chemists, chemical engineers, fuel engineers, agricultural engineers, farming spe-
cialists,biologists,fuelprocessors,policymakers,environmentalists,environmental
engineers, automobile engineers, college students, research faculty, etc. The book
may even be adopted as a textbook for college courses that deal with renewable
energyorsustainability.
Trabzon,TURKEY(September2009) AyhanDemirbas
MuhammetDemirbas
Contents
1 Introduction................................................... 1
1.1 Introduction ............................................... 1
1.2 EnergyDemandandAvailability.............................. 2
1.2.1 FossilEnergySources ................................ 3
1.2.2 RenewableEnergySources............................ 10
1.3 PresentEnergySituation .................................... 12
1.3.1 EnergyProductionandFutureEnergyScenarios .......... 12
1.3.2 FutureEnergyScenarios .............................. 13
References..................................................... 26
2 GreenEnergyFacilities ......................................... 29
2.1 Introduction ............................................... 29
2.2 BiomassFeedstocks ........................................ 30
2.3 GreenEnergy.............................................. 31
2.4 ImportanceofBiomass...................................... 32
2.5 ProductionofFuelsandChemicalsfromBiomass ............... 36
References..................................................... 46
3 Biofuels ....................................................... 49
3.1 Introduction ............................................... 49
3.2 ImportanceofBiofuels...................................... 51
3.3 Bioethanol ................................................ 54
3.4 Biodiesel ................................................. 56
3.5 Bio-oil ................................................... 59
3.6 Biogas.................................................... 61
3.7 Fischer–TropshLiquidsfromBiorenewableFeedstocks........... 64
3.8 Biohydrogen .............................................. 69
3.9 OtherLiquidBiofuels....................................... 70
3.9.1 Glycerol-basedFuelOxygenatesforBiodiesel
andDieselFuelBlends ............................... 70
3.9.2 P-seriesFuels ....................................... 71
vii
viii Contents
3.9.3 DimethylEther ...................................... 71
3.9.4 OtherBio-oxygenatedLiquidFuels..................... 72
References..................................................... 72
4 AlgaeTechnology .............................................. 75
4.1 Introduction ............................................... 75
4.1.1 DefinitionofAlgalTerms ............................. 76
4.2 ProductionSystems......................................... 77
4.2.1 HarvestingMicroalgae................................ 79
4.2.2 Photobioreactors..................................... 80
4.2.3 Open-pondSystems.................................. 83
4.2.4 ClosedandHybridSystems ........................... 87
4.3 ProductionCosts ........................................... 89
References..................................................... 93
5 EnergyfromAlgae ............................................. 97
5.1 Introduction ............................................... 97
5.1.1 HistoricalPerspective ................................ 99
5.2 Biofuels .................................................. 99
5.2.1 Biodiesel ...........................................102
5.2.2 Bioalcohol..........................................104
5.2.3 Costs,Prices,andEconomicImpactsofBiofuels..........106
5.2.4 EnvironmentalImpactsofBiofuels .....................110
5.2.5 CombustionEfficienciesofBiofuels ....................113
5.2.6 Bio-oil .............................................117
5.2.7 Biomethane.........................................119
5.2.8 ProductionofBio-oilandHydrogenbyPyrolysis .........120
5.2.9 AnaerobicBiohydrogenProduction.....................125
5.3 LiquefactionofAlgalCells ..................................127
5.3.1 LiquefactionofAlgalCellsbyHexaneExtraction.........129
5.4 High-value-addedProductsfromAlgae ........................131
5.4.1 SmallMolecules.....................................131
5.4.2 Polymers ...........................................132
5.4.3 High-valueOils......................................132
References.....................................................133
6 BiodieselfromAlgae ...........................................139
6.1 Introduction ...............................................139
6.2 BiodieselfromAlgalOil ....................................140
6.2.1 ProductionofBiodieselfromAlgalOils .................144
6.3 PotentialofMicroalgalBiodiesel .............................147
6.4 AcceptabilityofMicroalgalBiodiesel .........................150
6.5 EconomicsofBiodieselProduction ...........................151
6.6 ImprovingEconomicsofMicroalgalBiodiesel ..................153
6.7 AdvantagesandDisadvantagesofBiodieselfromAlgalOil .......153
References.....................................................154
Contents ix
7 Biorefineries...................................................159
7.1 Introduction ...............................................159
7.2 DefinitionsofBiorefinery....................................162
7.2.1 MainTechnicalandNontechnicalGaps
andBarrierstoBiorefineries ...........................164
7.3 HistoricalPerspective .......................................164
7.4 PetroleumRefineryandBiorefinery ...........................168
7.5 RefiningofUpgradedProducts ...............................174
7.6 OpportunitiesforRefiningPyrolysisProducts...................178
References.....................................................180
8 FutureDevelopments...........................................183
8.1 Introduction ...............................................183
8.1.1 WorldTheoreticalLimitofBiomassSupply..............184
8.1.2 High-yieldEnergyCrops..............................185
8.1.3 FoodVersusFuelDelineation..........................186
8.1.4 ThermodynamicEfficiency(ExergyAnalysis) ............187
8.1.5 BiofuelUpgradation..................................187
8.1.6 CarbonCredits ......................................188
8.2 SocialandPoliticalIssues ...................................189
8.2.1 ThePromiseofAlgae:EnergySecurity..................190
8.3 EnvironmentalImpactsofBiomassProduction..................191
References.....................................................193
Index .............................................................195
Chapter 1
Introduction
1.1 Introduction
Energyis defined asthe ability to do work.However,there is no conceptofforce
that includes all definitions of force. For example, the forces that form light en-
ergy,heat(thermal)energy,mechanicalenergy,electricalenergy,magneticenergy,
etc.aredifferent.Therearemanyformsofenergy,buttheyallfallintooneoftwo
categories:kineticandpotential.Electrical,radiant,thermal,motion,andsounden-
ergiesarekinetic;chemical,storedmechanical,nuclear,andgravitationalenergies
are typesof potentialenergy.It can exist in the formof motion.Thisis knownas
kineticenergy.Themotioncanrelatetodifferentthings.Ifthemotionisofalarge
object,thekineticenergyissaidtobemechanical.Ifmovingobjectsareelectrically
charged,theyaresaid toformanelectric current.Ifmovingobjectsareindividual
molecules,therearetwopossibilities.Iftheirmotionisorganizedintowaves,then
their kinetic energy is associated with sound. If their motion is completely disor-
ganized, then their kinetic energyis associated with what we call heat or thermal
energy.Anotherformofkineticenergyislight(andotherformsofelectromagnetic
radiation,likeradiowavesandmicrowaves).Otherformsofenergydonothavethe
formof motion,butthey can cause an increase in motionat a later time. Water at
the top ofa damcan spilloverthe dam.A batterycanproducean electric current
whenitisconnectedtoacircuit.Fuelscanbeburnedtoproduceheat.Allofthese
areexamplesofpotentialenergy.
The world is presently confrontedwith twin crises of fossil fuel depletion and
environmentaldegradation.Toovercometheseproblems,renewableenergyhasre-
centlybeenreceivingincreasedattentiondueto itsenvironmentalbenefitsandthe
factthatitisderivedfromrenewablesourcessuchasvirginorcookedvegetableoils
(bothedibleandnonedible).Theworld’sexcessivedemandforenergy,theoilcrisis,
andthecontinuousincreasein oilpriceshaveled countriestoinvestigatenewand
renewablefuelalternatives.Hence,energysourcessuchassolar,wind,geothermal,
hydro,nuclear,hydrogen,andbiomasshavebeenconsidered.
A.Demirbas,M.FatihDemirbas,AlgaeEnergy 1
DOI10.1007/978-1-84996-050-2,©Springer2010