algae to energy_powerpoint

8/13/2019 Algae to Energy_powerpoint

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Microalgae Grownicroalgae Grownin Photobioreactorsn Photobioreactorsfor Mass Productionor Mass Productionoff Biofueliofuel


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Need for Sustainableeed for SustainableEnergynergy

The Price of Energy is Going UPThe Price of Energy is Going UP Oil reserves are depletingOil reserves are depleting

World demand for energy is increasingWorld demand for energy is increasing

Economic Stability/National SecurityEconomic Stability/National Security Not good to have energy dependence on foreignNot good to have energy dependence on foreign

countriescountries

Global WarmingGlobal Warming Fossil fuels release greenhouse gasesFossil fuels release greenhouse gases


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Oil Yield Comparisonil Yield Comparison

2.52.54.54.558,70058,700MicroalgaeMicroalgaecc1.11.122136,900136,900MicroalgaeMicroalgaebb

2424454559505950Oil palmOil palm

5454999926892689CoconutCoconut

777714014018921892JatrophaJatropha

12212222322311901190CanolaCanola

326326594594446446SoybeanSoybean

84684615401540172172CornCorn

Percent of existingPercent of existing

US croppingUS cropping areaareaaaLand areaLand area

needed (Mneeded (M ha)ha)aaOil yieldOil yield

(L/ha)(L/ha)CropCrop

a For meeting 50% of all transport fuel needs of the United States.

b 70% oil (by wt) in biomass.c 30% oil (by wt) in biomass.


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http://www.emerging-

markets.com/biodi

esel/default.asp


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Advantages of Algaedvantages of Algae

High Quality BiodieselHigh Quality Biodiesel Cold filter plugging pointCold filter plugging point

comparable to #2 dieselcomparable to #2 diesel22

NoNo PhosphatidesPhosphatides, as in, as inbiodiesel from plantsbiodiesel from plants33

Can capture COCan capture CO22 fromfrom

exhaust streamsexhaust streams

Less Land is RequiredMore biomass is obtainedContains higher concentrations

of lipids than terrestrial plants


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Oil Content of Someil Content of SomeMicroalgaeicroalgae5 Microalga Oil content (% dry wt)

Botryococcus braunii 2575 Chlorella sp. 2832

Crypthecodinium cohnii 20

Cylindrotheca sp. 1637

Dunaliella primolecta 23

Isochrysis sp. 2533

Monallanthus salina >20

Nannochloris sp. 2035

Nannochloropsis sp. 3168

Neochloris oleoabundans 3554

Nitzschia sp. 4547

Phaeodactylum tricornutum 2030

Schizochytrium sp. 5077

Tetraselmis sueica 1523


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Algae Production Methodslgae Production Methods Raceway PondsRaceway Ponds

Open system, used forOpen system, used for

production of algae forproduction of algae for

health foodhealth food

PhotobioreactorsPhotobioreactors

Maximize algae growthMaximize algae growth

with controlled conditionswith controlled conditions


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Photobioreactor Variationshotobioreactor Variations


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Maximize the Biomassaximize the BiomassProduction Rate,roduction Rate, g/L/L-d

Equal to the product of the dilution rateEqual to the product of the dilution rateand effluent biomass concentration.and effluent biomass concentration.

Defined as the ratio of the incoming flow rateDefined as the ratio of the incoming flow rate

to the reactor volumeto the reactor volume

Dilution rate is equal to the specificDilution rate is equal to the specific

growth rate at steady stategrowth rate at steady state


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Design Considerationsesign Considerations

Effects of Solar IrradianceEffects of Solar Irradiance Solar inhibitionSolar inhibition

Mass Transfer of Gases Through FluidMass Transfer of Gases Through Fluid

COCO22 supply and Osupply and O22 removalremoval Cell Damage from Shear StressCell Damage from Shear Stress

For high flow ratesFor high flow rates

Nutrient Addition, pH and TemperatureNutrient Addition, pH and TemperatureControlControl


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Solar Irradiance andolar Irradiance andInhibitionnhibition

Dissolved OxygenDissolved Oxygenis directly related tois directly related to

photosyntheticphotosynthetic

activity.activity.

PhotoinhibitionPhotoinhibition

causes decline incauses decline in

photosyntheticphotosynthetic

activity at midday.activity at midday.


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Solution toolution to Photoinhibitionhotoinhibition

Increase cycleIncrease cyclefrequency of fluidfrequency of fluid

between dark andbetween dark and

light zones.light zones.

Cycle frequency isCycle frequency is

increased byincreased by

increasing the fluidincreasing the fluid

velocity.velocity.


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COO2 Bubblingubbling - MassassTransferransfer

Carbon dioxide needs toCarbon dioxide needs to

be added continuouslybe added continuously

COCO22 can be consumed at acan be consumed at a

rate of 26 g COrate of 26 g CO22/m/m33--hh

Oxygen produced duringOxygen produced duringphotosynthesis needs tophotosynthesis needs to

be removed.be removed.

High oxygen concentrationHigh oxygen concentration

inhibits growthinhibits growth PhotooxidationPhotooxidation can damagecan damage

cellscellsInfluence of the oxygen molar fraction in the injected gas on: (a) the

steady-state biomass concentration; and (b) the photosynthetic

activity (i.e. the volumetric oxygen generation rate) in indoor cultures.The dilution rate and the irradiance level were 0.025 h1 and 300 E

m2 s1, respectively. 1


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COO2 Bubblingubbling Effect offfect ofFluid Velocityluid Velocity

Superficial fluid velocity is related to gas velocity and bubbleSuperficial fluid velocity is related to gas velocity and bubblediameterdiameter

Cycling frequency between light and dark zones is dependent onCycling frequency between light and dark zones is dependent onfluid velocityfluid velocity

Shearing damage to cells results from increased radial velocityShearing damage to cells results from increased radial velocity High radial velocity decreases length of microHigh radial velocity decreases length of micro--eddieseddies

So does increasing the tube diameterSo does increasing the tube diameter


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Nutrient Addition, pH andutrient Addition, pH andTemperature Controlemperature Control Algae require nitrogen and phosphorousAlgae require nitrogen and phosphorous

Ammonia is the preferred nitrogen sourceAmmonia is the preferred nitrogen source

Conjunction with WWTPConjunction with WWTP

Optimal pH is between 7.5 and 8.5Optimal pH is between 7.5 and 8.5

Nutrient addition increases pHNutrient addition increases pH Sufficient COSufficient CO22 must be added to keep the pH from increasingmust be added to keep the pH from increasing

too muchtoo much

Optimal temperature is between 20 and 30COptimal temperature is between 20 and 30C

Maintained with heat exchangers and cooling waterMaintained with heat exchangers and cooling water

Especially important at night to reduce losses due toEspecially important at night to reduce losses due to

respirationrespiration


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Converting Algae to Fuelonverting Algae to Fuel TransesterificationTransesterification

Most common method of converting vegetable oil toMost common method of converting vegetable oil tobiodieselbiodiesel

Requires the algal suspension first be harvested, dried,Requires the algal suspension first be harvested, dried,and pressed for oiland pressed for oil


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Converting Algae to Fuelonverting Algae to Fuel ThermochemicalThermochemical

LiquefactionLiquefaction

Can be appliedCan be applieddirectly to algaldirectly to algal

suspensionsuspension

Uses highUses high

temperature andtemperature and

pressurizedpressurized

nitrogen tonitrogen to

evaporate waterevaporate water CHCH22ClCl22 CatalystCatalyst

SeparatesSeparates

BiodieselBiodiesel


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ThermochemicalhermochemicalLiquefaction of B.iquefaction of B. brauniiraunii

Heating energy for liquefaction: 6.69Heating energy for liquefaction: 6.69MJ/kgMJ/kg

For a biomass concentration of 0.5 g/LFor a biomass concentration of 0.5 g/L

produced from raceway pondsproduced from raceway ponds Heating value of oil produced: 45.9 MJ/kgHeating value of oil produced: 45.9 MJ/kg

Concentration in photobioreactors: 6.6g/LConcentration in photobioreactors: 6.6g/L

Much less energy required on kg basisMuch less energy required on kg basis


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Achieved Rates ofchieved Rates ofProductivity forroductivity for P t r i c o r n u t um

11-1.192.3812890.050.5200

160.6511.082.712110.040.3220

160.06382.045.128600.040.3220

160.06281.764.423190.040.3220

160.6841.666.623660.0250.3220

Source, HzPb,

g/L-d

Cb,

g/L

IwmD, h-1UL

m/s

Volume

L


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Energy Yieldnergy Yield Maximum tube length = 80 mMaximum tube length = 80 m

Maximum tube diameter = 0.1 mMaximum tube diameter = 0.1 m

So maximum volume of single reactor = 628.3 L = 0.6283 mSo maximum volume of single reactor = 628.3 L = 0.6283 m33

Assume oil production rate = 2Assume oil production rate = 2 g/Lg/L--dd * 50% oil content = 1* 50% oil content = 1 g/Lg/L--dd ==1 kg/m1 kg/m33--dd

If 270 tubes can fit on one acre, than 62,000 kg of oil/acre couIf 270 tubes can fit on one acre, than 62,000 kg of oil/acre couldld

be produced.be produced. Or (density = 0.864 kg/L) 71,759 L =Or (density = 0.864 kg/L) 71,759 L = 19,136 gal/acre19,136 gal/acre


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Wowow

Almost 20,000 gallons/acre of oil that mayAlmost 20,000 gallons/acre of oil that maypotentially be produced with current technologypotentially be produced with current technology

WithWith thermochemicalthermochemical liquefaction, the energyliquefaction, the energyrequired to extract oil is minimalrequired to extract oil is minimal

Main Constraint: Huge Capital InvestmentMain Constraint: Huge Capital Investmentreactor tubes, water pumps, gas pumps,reactor tubes, water pumps, gas pumps,

autoclave for liquefaction.autoclave for liquefaction. Economies of ScaleEconomies of Scale How long before oilHow long before oil

production pays for infrastructure investment?production pays for infrastructure investment?

algae to energy_powerpoint

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