Microalgae Biofuels and Carbon Biofuels and Carbon...  Microalgae Biofuels and Carbon Cycling Prepared

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  • Microalgae Biofuels and Carbon Cycling

    Prepared for the 2009 Annual Conference GA A&WMA

    Umakanta Jena

    &

    Nisha Vaidyanathan

    Biorefining and Carbon Cycling Program

    Department of Biological & Agricultural Engineering

    The University of Georgia

  • Why Biomass?

    Broad Problems: (1) Energy crisis and (2) global warming

    U.S energy consumption 97 quads

    (2001).

    20 million bbl oil/ day, 55% imported, will

    increase to 68% by 2025.

    3% of total energy (2.9 quads) comes

    from biomass.

    National Target:

    30% energy from biomass by 2030, 35

    billion gallons of biofuel by 2017.

    (USDA-DOE, 2005)

    Need an increase in the biomass use for energy by five times.

  • U.S. leads among the producers of green house gas (GHG)

    emissions in the world

    2. Global warming

  • Highest biomass productivity, 100 g/m2/day

    (365 tones/ha/yr against 70 tones/ha/yr for energy cane).

    No competition with food unlike other biofuels

    Uses waste water for growth (waste water treatment media)

    Net GHG reduction as it is carbon neutral

    (1.6-1.8 g of CO2 needed for biosynthesis of 1 g dry algalbiomass).

    Why Microalgae ?

  • Production of biomass

    Cultivation

    Harvesting

    Processing of biomass

    Algae to biofuel: Major challenges

  • Attributes of Algae Production Costs

    Algae Production

    Costs

    Major purchased equipment

    Installation

    Building

    InfrastructureFertilizers

    Labor

    Electricity

    Water OtherCO2

  • (Chisti, 2008;

    Shen, 2009)

  • Present Algae Cultivation Systems-Open Ponds (suspended algae cultivation)

    (Shen, 2009)

  • Photobioreactors for suspended algae cultivation

    (Tredici, 1999)

  • Immobilized algae cultivation systemsfor Attached algae

    Enclosure methods :(a) cells in a polymer matrix sheet; (b) cells in a gel bead

    Non enclosure methods- Algal Turf Scrubber Technology developed for attached algae cultivation

    (Shen, 2009)

  • Dewatering or harvesting

    Low productivities

    Improper mixing of water

    Contamination

    Predation

    Highly technical and hence least economical

  • A substrate material. Cells grow attached on

    this substrate. Initial attachment by

    bacteria. Algae starts dominating

    the substrate with the help of bacteria.

    Mature biomat formation with highest dominance by algae. (Adey, 1980)

  • To develop an advanced cultivation system for algal biomat production using high strength industrial wastewater for bioremediation, carbon cycling and bioenergy applications.

  • Standard reactor configuration

  • Attached algae cultivation systems at UGA Bioconversion laboratory

  • Preliminary experimental details

    Substrates- Geotextile and polymer materials

    Growth media- Tap water and industrial wastewater.

    Months: April-July 2009

    pH of water- 7.5

    Span of each experiment- 21 days

  • Results and discussion

    S1-Substrate 1 (Polymer material)S2-Substrate 2 (Geotextile material)

    0

    5

    10

    15

    20

    25

    S1 S2 S1 S2 S1 S2 S1 S2

    Mixed culture A Ulothrix Mixed culture B

    g/m

    /d

    ay

    Biomass Productivity

    Harvest1 Harvest2 Harvest3

    Tap WaterDalton Utilities Raw Water

  • VARIABLES

    GROWTH MEDIA

    TAP WATER INDUSTRIAL WASTEWATER

    1.Microbial consortia Chlamydomonas, Diatoms, Thin

    filaments, Bacteria

    Oscillatoria, Diatoms, Ulothrix,

    Chlamydomonas, Nostoc,

    Characium sp., Anabaena, Thin

    filaments, Bacteria

    2.Productivity

    (g/m2/day) 7.7 15.0

    3. Structural Compositions (%)

    Carbohydrates 17 25.0

    Proteins 44.0 41.5

    Lipids 3.2 8.8

  • 35

    7.67

    0.6

    49.8

    Algae grown with tap water

    46

    8.49.5

    0.77

    35.33

    Algae grown with

    industrial wastewater

    Carbon (%)

    Hydrogen (%)

    Nitrogen (%)

    Sulphur (%)

    Other (%)

  • Nutrient removal potential

    - Efficient wastewater treatment with

    83% nitrogen, 47% ammonia and 76%

    phosphate removals.

    - Low water evaporation losses from

    reservoir.

    0

    20

    40

    60

    80

    100

    0 1 2 3 4 5 6 7

    %re

    mo

    val

    Time (days)

    %Nitrogen removal

    %removal

    0

    20

    40

    60

    80

    100

    0 1 2 3 4 5 6 7

    %re

    mo

    val

    Time (days)

    %Ammonia removal

    %removal

    0

    20

    40

    60

    80

    100

    0 1 2 3 4 5 6 7

    %re

    mo

    val

    Time (days)

    %Phosphate removal

    %removal

  • Future work

    Improve the reactor configuration to an

    advanced and robust system.

    Experiment different optimizing

    conditions for best biomat productivity.

    Assess the cost economics of the

    improved bioreactors in comparison open

    pond cultivation systems

  • Next step??Processing of

    Microalgae into fuels

  • Biomass Energy Conversion Routes

    Biomass

    Biochemical

    ConversionDirect Combustion

    Thermochemical

    conversion

    FermentationAnaerobic

    Digestion

    Extraction of

    Hydrocarbons

    Thermo

    Chemical

    Liquefaction

    Pyrolysis Gasification

    Ethanol,

    Acetone,

    Butanol

    Methane,

    Hydrogen

    Biodiesel &

    Value added

    products

    Heat &

    powerBio-oil

    Oil and

    CharcoalFuel Gas

  • What is pyrolysis

    Heating of biomass in absence of oxygen

  • Thermochemical Liquefaction

    Solubility, density, ionic properties, chemical potential, reactivity of water

    change drastically as it approaches towards critical point

    (Matsumura et al, 2006)

    Hydrothermal conversion under high pressure

    Tarry material is the

    precursor to biocrude or bio-

    oil

  • Our research goal

    Investigate the production of bio-oil (biocrude) from

    microalgae by two thermochemical conversion

    processes

  • Compositional Analysis

    Ultimate analysis

    Biocrude

    Se

    pa

    rati

    on

    TCC Process

    Proximate

    Analysis

    Bomb Calorimeter

    Analysis

    GC-MS

    GC Analysis

    Sta

    tistical A

    naly

    sis

    Microalgae

    Gas

    Aqueous phase

    Experimental Methodology

    Solid residue

    HPLC Analysis

    Reactio

    n m

    ixtu

    re

  • 1. N2 gas cylinder, 2. Flow meter, 3. Heating furnace, 4. Reactor,

    5. Thermocouple, 6. Data logger, 7. Sample, 8. Condenser set

    up, 9. Ice bath, 10. Gas vent

    1

    2

    34

    7

    8

    9

    10

    6

    5

    8

    Experimental Set up for Batch Pyrolysis

  • P

    rpm

    Gas sample

    Water in

    7 8

    1 2

    11

    10

    9

    1-Reactor, 2-Heater

    unit 3-Power relay

    4-Pressure sensor

    5-Thermocouple,

    6- Stirrer assembly,

    7- Controllers,

    8- Computer,

    9-Condenser for liquid

    sampling, 10-Valves 11-

    N2 gas cylinder

    3

    4

    5

    6

    10

    10

    10

    Power supply

    Experimental set up for TCL

  • Separation of condensate into three phases using a separatory funnel.

    Product separation

  • Results: Feedstock composition

    Composition Algae feedstock

    Proximate analysis (%)

    Moisture 6.040.02

    Volatiles 80.700.05

    Ashes 6.600.05

    Fixed carbon 15.250.06

    Ultimate analysis (%)

    C 45.160.19

    H 7.140.20

    N 10.560.04

    S 0.740.01

    Higher heating value, (HHV) in MJ/kg 20.520.23

    * Biochemical composition, (%)

    Protein 68.640.26

    Lipids 13.30

  • Results: Product distribution

    Thermochemical LiquefactionPyrolysis process

    Others are the products dissolved in aqueous phase

    %

    Solid,

    39.73

    Gas,

    19.2

    Others,

    17.37

    Biooil,

    23.69

    Solid,

    4.67

    Gas,

    23.6

    Biooil,

    40.56

    Others,

    31.26

  • Results: Biocrude Vs petroleum crude oil

    Biocrude

    from

    Pyrolysis

    Biocrude

    from

    TCL

    Petrocrude

    (Matar and

    Hatch, 2001)

    Elemental analysis

    Carbon, wt% 67.52 74.66 84.6

    Hydrogen, wt% 9.83 10.57 12.8

    Nitrogen, wt% 10.71 7.13 0.4

    Sulfur, wt% 0.45 0.81 1.5

    Oxygen, wt% 11.34 9.63 0.5

    Viscosity, Cp 23.36 82.63 23

    Heating value, MJ/kg 28.03 30.82 42

  • 15

    25

    35

    45

    55

    65

    75

    85

    95

    0 10 20 30 40 50

    Time, Days

    Vis

    co

    sit

    y,

    cP

    Pyrolysis biooil

    TCL biooil

    Storage properties of algal bio oil

    Change in viscosity during storage (measured at 60oC)

  • Results: Analysis of biocrude

    5 . 0 0 1 0 . 0 0 1 5 . 0 0 2 0 . 0 0 2 5 . 0 0 3 0 . 0 00

    1 0 0 0 0 0

    2 0 0 0 0 0

    3 0 0 0 0 0

    4 0 0 0 0 0

    5 0 0 0 0 0

    6 0 0 0 0 0

    7 0 0 0 0 0

    8 0 0 0 0 0

    9 0 0 0 0 0

    1 0 0 0 0 0 0

    1 1 0 0 0 0 0

    1 2 0 0 0 0 0

    1 3 0 0 0 0 0

    1 4 0 0 0 0 0

    1 5 0 0 0 0 0

    1 6 0 0 0 0 0

    1 7 0 0 0 0 0

    1 8 0 0 0 0 0

    1 9 0 0 0 0 0

    2 0 0 0 0 0 0

    T im e --