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

²/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 6.04±0.02

Volatiles 80.70±0.05

Ashes 6.60±0.05

Fixed carbon 15.25±0.06

Ultimate analysis (%)

C 45.16±0.19

H 7.14±0.20

N 10.56±0.04

S 0.74±0.01

Higher heating value, (HHV) in MJ/kg 20.52±0.23

* Biochemical composition, (%)

Protein 68.64±0.26

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 -->

A b u n d a n c e

T I C : J 1 N C 3 5 0 . D \ d a t a . m s

2 . 9 8 4

3 . 6 7 3

4 . 5 2 4 5 . 4 1 2

8 . 2 9 2

1 0 . 1 9 5

1 1 . 9 6 3

1 2 . 4 9 4

1 4 . 3 0 3

1 5 . 8 7 1

1 7 . 3 0 51 7 . 3 9 21 7 . 4 7 01 7 . 5 3 2

1 8 . 5 4 9

1 9 . 4 9 2

2 0 . 0 5 72 0 . 4 7 82 0 . 5 4 62 0 . 8 2 9

2 1 . 2 7 8

2 1 . 3 4 62 2 . 1 1 0

2 2 . 4 1 6

2 2 . 8 4 32 3 . 4 0 9

2 3 . 6 4 8

2 3 . 8 3 7

2 4 . 0 5 02 5 . 4 9 22 5 . 5 6 9

2 5 . 9 6 12 6 . 3 8 52 6 . 7 8 12 6 . 9 3 2

2 8 . 1 8 0

2 8 . 2 5 0

Hexadecanoic acid

PhenolsIndolesFuran

Pentanones

Pentadecence

BenzenamineCyclohexanol

Pentadecanoic acidAlkanes

Carboxylic acids

Styrene

Majority of the compounds of bio-crude (Phenol, furan, styrene, indole,

alkanes, benzene, cyclohexane) are basic components of the petroleum

crude oil.

Results: Other co-products

0

10

20

30

40

50

60

70

80

Carbon dioxide Carbon

monoxide

Hydrogen Methane Methyl acetylene

%

Spirulina Mixed algae

0

5

10

15

20

25

Sp/Cat5/30 min Sp/Cat5/60 min SP/NC/60 min MA/NC/60 min

Treatments

Yie

ld,

g/k

g o

f alg

ae

Ethanol Formate Succinate

Gas analysis

CO2 is the major product.

H2, CH4 and C2H5 are high

energy value gases and

can be used as fuel gas

Aqueous phase

analysis

Ethanol, formate and

succinates are the major

products, can be used

as fuels/ chemicals

Major conclusions

Microalgae have potential for biofuel in the form of biocrude that has similar fuel properties as the petroleum crude oil.

About 25-30% and 36-48% biocrude could be produced from spirulina platensis via pyrolysis and TCL respectively .

Benefits: Conceptual microalgae biorefineries

Algae cultivation

and harvesting

Microalgae TCC

Processing

SyngasBiocrude Solid/ char

Land use

(Fertilizer)

Carbon

catalysts

UpgradingTransesterification Upgrading

BiodieselTransport

fuel

Upgrading

Combustion for

maintaining

temperature and

CO2 level

Aqueous phase

Recycled

water

Industrial Waste waterCO2

Chemicals

Social

(Biofuels,

new jobs, science

& technology)

Environment

(GHG reduction,

water quality)

Economic

(New business

Opportunities)

Is the concept sustainable ??

Acknowledgements

United States Department of Energy

Dalton Utilities, GA

UGA Biorefining and Carbon Cycling Program

Dr K C Das

Dr Senthil Chinnasamy

Dr Ashish Bhatnagar

Joby Miller

THANK YOU !!!

QUESTIONS?

Methodology: Product Separation

Microalgae

Liq

uefa

ctio

n

Gas

Reaction mixture

Water soluble

Aqueous phase Bio-crude

Water insoluble

Washing with water and filtration

Acetone soluble

Washing with acetone and filtration

Acetone insoluble

Solid residue

Evaporation Drying

100biomassstartingofWeight

biocrudeofWeight(%)yieldBiocrude

100biomassstartingofWeight

gasofWeight(%)yieldGas

100biomassstartingofWeight

residuesolidofWeight(%)yieldSolid

solid)gascrude(bioofyield%100(%)yieldOthers

Methodology: response terms

100valueHeatbiomassstartingofWeight

valueHeatresiduesolidofWeightvalueHeatbiomassstartingofWeight(%)CCE

Carbon conversion efficiency (CCE)

(1) Computer connected to thermocouples, (2) Carrier gas cylinder, (3) Mass flow

controller (4) Oven, (5) Pyrolysis reactor, (6) Thermocouples , (7) Condensing traps

2

1

3

45

6

7

Batch Pyrolysis Experimental Set up

Vent

Results: Effect of time and temperature

0

5

10

15

20

25

30

35

40

45

50

Non-catalytic Na2CO3 NiOTreatments

Bio

-cru

de y

ield

, %

10% organic concentration

20% organic concentraion

0

5

10

15

20

25

30

35

40

45

50

Non-catalytic Na2CO3Treatments

Bio

-cru

de y

ield

, %

30 min reaction time

60 min reaction time

Biocrude yield was 48%

maximum.

The yield increased with

1) Increase in reaction time

2) Decrease in organic solid

concentration

Biocrude yield was the

lowest for NiO used as

catalyst .

Na2CO3 has shown higher

yield than other treatments

Bio-oil

Char as Soil

conditioner

Pyrolysis Process

Heating Biomass

in absence of oxygenGaseous products