Microalgae Conversion into Liquid Fuel

James Manganaro Adeniyi Lawal

Stevens Institute of Technology Dept. of Chemical Engineering & Materials Science Presentation for Association of Consulting Chemists and Chemical Engineers December 10, 2014

1

Outline • General energy picture • Biofuels – Why algae?

• Discussion of algae – Growth – Harvest – Extraction of AO – Hydrotreatment of AO – Economics

2

From Princetion Plasma Physics Lab (PPPL) Total energy: (gas, oil & electric, etc)

Energy Consumption by Type

Fuel Type

US (2011) Consumption, Quads

Coal

20

Nat. Gas

25

Petroleum

35

Nuclear

8

Renewable

9

Total

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Fossil Fuels: 83% of total World consumption: 81% Fossil fuels Total world consumption: ~500 quad (17 TW) Total solar insolation: 170,000 TW

Quad = 1015 BTU/yr

1 TW = 1012 watts

US Annual Energy Review http://www.eia.gov/totalenergy/data/annual/pdf/aer.pdf

5

Current CO2 level in atmos. = 395.28 ppm as of Sept 2014 http://co2now.org/currentco2/co2-now/

7

Renewable Power: • Solar (PV and thermal) • Wind Renewable Fuel: • Biofuels

From www.iter.org

10

1000 MW Power Plant Coal vs. Fusion

Coal Fired Plant

Fuel

Coal

9,000 T/day

Fusion Reactor

D2 6Li

1.0 lb/day 3.0 lb/day (equivalent to 1.5 lb/day of T 2)

½ lb/day of neutrons enter blanket Waste

CO2 SO2 NO2

30,000 T/day 600 T/day 80 T/day What about Hg?

From Princeton Plasma Physics Lab

4He

4.0 lb/day

Why interest in renewable fuels? • National security

• Renewability • Economics • CO2 emission reduction 12

13

Advantages of Liquid Biofuel for transportation

• High energy density fuel (60x compared to Nihydride, 30x Li-ion batteries - accounting for efficiencies of gas an electric engines). • Easily handled, fits into existing infrastructure • CO2 mitigating compared to crude oil

Biofuel Classification by Generation Generation

Example

Feedstock

Edible Feedstock ?

Process

1st

EtOH

Sugars, starch

Yes

Fermentation

2nd

Gasoline

Lignocellulose No

Biogas, Pyrolysis/Reforming/FisherTropsch

3rd

Diesel

CO2

Algae to biodiesel or diesel

No

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Energy Independence and Security Act (EISA) of 2007 The Mandate

• Renewable Fuel Standard (RFS1, 2005) – expanded the RFS program to include diesel, in addition to gasoline; – increased the volume of renewable fuel required to be blended into transportation fuel from 9 billion gallons in 2008 to 36 bgal/y by 2022; – established new categories of renewable fuel, and set separate volume requirements by 2022 for each one. • cap of 15 bgal/y for corn-starch ethanol • at least 16 bgal/y from cellulosic biofuels (biogas is now included) • 5 bgal/y from other

– required EPA to apply lifecycle greenhouse gas standards. Each category of renewable fuel emits fewer greenhouse gases than the petroleum fuel it replaces (e.g., fuel derived from algae needs to reduce GHG emissions by 50% at least). – These standards are reviewed & amended once every year

Renewable Fuel Standard (RFS): Overview and Issues Randy Schnepf, Brent D. Yacobucci March 14, 2013

http://www.epa.gov/otaq/fuels/renewablefuels/index.htm

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Other Sugar Sources

Overview of Some of the Biofuels Industry Corn Crop

Starch Extraction

Starch Conversion to Sugar

Fermenation

Conversion to Sugar

Fermenation

EtOH

Crop residue Other Lignocellulose Sources Other Biomass, e.g., sewage sludge, manure, etc

Lignocellulose

EtOH Pelletized Fuel

Pyrolysis or High Pressure Liquefaction

PO

Heavy fuel oils (e.g. #4)

PO Biogas

Possible Chemicals Extraction

Digestion

Chemicals

Hydrodeoxygenation

H2S, H2O

Refinery

H2 PO upgrading

Catalytic Cracking

High Value Fuels

Crude Oil

Reforming

H2

Emusification

Fuel

Diesel oil Reforming

Vegetable Oil Animal fat Algae

H2/CO

Biodiesel oil Transesterification Glycerin MeOH

Fischer Tropsch

Diesel Fuel

Advantages of Algae: • Greatest aerial productivity • Greatest CO2 capture capacity • Uses non-arable land • Can use saline water • Continuous harvest • Production of triglycerides allows easy conversion to diesel

Special Challenges to Algae: • Process complexity (growth, harvest, extraction) • Resulting economics – (co-products appear necessary) Scale of Production of Algae: • Estimated aerial productivity of 0.2 bbl HTAO/day/acre (3,500 gal of AO/ac/yr) • To supply 10% of US daily transportation fuel demand, need 1.4x106 bbl/day. • Therefore: need 7x106 acres or 11,000 sq. miles which is a square 105 miles on a side (this is 4% the area of Texas) to supply 10% daily transportation demand. Comments: - Canada grows 12 million acres of canola - Texas is 0.27x106 sq. miles - Sahara desert covers more than 3.5x106 sq. miles. - AO = algal oil; HTAO = hydrotreated AO 20

Design Basis 1. 2. 3. 4. 5. 6.

Production rate of 1000 bbl/d (15.3 Mgal/yr) of HTAO. Capital cost estimate based on Davis et al. For the parameters chosen, the area productivity is 25 g (algae dry wt)/m^2/day. This is taken as being uniform throughout the year. AO assumed to be composed only of acylglycerides and free fatty acids. Only 1.1% of AO is taken to go to nutraceuticals. Post extracted algae residue (PEAR) goes to animal feed. –

A viable alternative to animal feed, not considered here, is digestion of this biomass to produce methane for electricity generation.

7.

A carbon reduction credit of $5/T is taken. This, however, has only a small effect being $0.01/gal. 8. On-stream time of 100% 9. Return on investment of 10% 10. Hydrotreater efficiency of 90%

21

High Rate Algal Ponds with No Inoculation Ponds (e.g., Lundquist, et al) Recycle water, nutrients, and fresh water

Algae conc. of 0.05% entering Flow

Paddle Motor for paddles

CO2 sparging sumps

Flow

Many identical ponds here

To harvest and extraction

Chlorella Vulgaris

Nannochlorpsis salina

22

From Jose Olivares LANL

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Production of Purified Algal Oil: Growth, Harvest, & Extraction sunlight   CH 2O + O2 Photosynthetic Reaction: CO 2 + H 2O  decomposition

Production of Purified Algal Oil: Growth, Harvest, & Extraction– Section 1 Growth

Evaporation & H2O to Vent Gases Sun replace (containing Light Evap O2)

CO2 Capture

4 2

Water make up Nutrients 3a From Waste water treatment

1

Extraction Make-up Hexane

Flue gas from power plant

Vent to atmos

Harvest

Pond feed 1a

4a

Flocculant

8a

Hexane recycle 9a

Conditioning Agents Acid (H2SO4)

9

Deemulsifier

4b 5c

Culture of Algae in Ponds

5

Algae Slurry Split

5b

7

Flocc

6

Thickening

Centrifugation

6b

11

Conditioning

8

Contacting/ Extraction

10

Organic Phase Gravity 12 Separation

80 C 30 min

3

Aqueous recycle

Used as inoculant 5a

18 Aqueous recycle

Recycle Water Holding & Adjustment 17 Waste purge

Aqueous recycle

5d 6a 14

Heat to 80 C pH=2, 60 min

Aqueous recycle

Aqueous Phase & Suspended Solids

Wash water

Heat

12a Solid/Liquid Separation Recovered hexane

16 Additives

Algal Oil Distillation 13 to hydrotreatment

Post extracted algae residue

15

Steam Stripper

15a

conden ser

Fresh H2O for use as wash water

Dryer

Animal feed 15b

Steam

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Growth-Harvest-Extraction Spreadsheet: Input & Some Output Algae Growth, Harvesting, & AO Extraction Total flow rate thru pond or reactor, gpm Feed broth algae concentration, g (dry wt)/L Retention time in pond or reactor, hr Algae doubling time, hr Pond depth, ft Algae gross composition oil, % of dry wt water solubles, % of dry wt Insolubles, % dry wt Efficiency of CO2 utilization, % CO2 usage, lb CO2/lb algae Oxygen production, lb O2/lb algae(dry) Net Evaportion rate, inch/yr Theor N nutrient required, wt% of aglae dry wt Theor P nutrient required, wt% of aglae dry wt % excess nutrient fed to pond Weight of nitrogen fed to pond as NH3 in pond feed, lb/h Weight of phosphorous fed to pond as DAP in pond feed, lb/h Purge rate (of strm#17) % of strms 5d,6a & 14 Conc of algae in floc thickener exit (strm 6), wt % Conc of algae in centrifuge exit (strm 6b), wt %

238,981 0.5 120 120 0.83 30 29 41 95 2.0 1.07 43 9.2 1.3 15 6,863 3,800 10 2 12

Conditioning H2SO4 dosage, lb 100% acid/lb slurry Wt ratio of hexane to algae (dry wt) Efficiency of oil recovery, % Moisture content of biomass, strm 15, wt% Moisture content of dryed biomass, strm 15b, wt% H2O usage, lb H2O/lb algae Algal Exit conc, g/L Algal recycle ratio (stm5a/stm5b) Fraction of total feed flow that is recycled Total Pond volume, gal Algal area productivity, g(dry wt algae)/m^2/day Algal volumetric productivity, g(dry wt algae)/L/day Total Area of pond, ac Algae production rate,g/h Algae production rate, lb/h Algae production rate, lb/day Annual production, ton algae/ac/y Algal oil production rate, gal/yr/ac Algal oil production rate, Mgal/yr Algal oil production rate, bbl/day/ac HTAO oil to refinery rate, bbl/day

0.005 5 95 85 10 0.333 1.00 1.00 0.50 1.721E+09 25.3 0.10 6,363 27,100,438 59,693 1,432,622 41 3,467 22.1 0.23 1,000

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Hydrotreater Reactions Algal Oil (AO ):

+ MAG & DAG & FFA

Hydrotreated Algal Oil (HTAO)

where, G = C3H5 (i.e., the glycerin backbone); GH3 = propane; HDCO2 = hydrodecarboxylation; HDO = hydrodeoxygenation; R = fatty acid moiety.

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Hydrotreatment of Algal Oil & Nutraceuticals Processing – Section 2 Compressor H2 Accumulator 600 psig

12 10a

4

Fresh Amine

CO2 removal Spent Amine to Regeneration

Amine Scrubber

Recycle gas H2 from Refinery

Purge gas

11

10 Vapor Cold/High Pressure Separator

3

Off gas

Sour H2O

9

7 Organic phase

4a HEX 2

Preheater 50-60 C

Hydrotreater 2 6a

25 – 30% AO in AO/diesel mixture

P diesel from refinery for AO dilution

1b

6

Pt/Al2O3

Unused AO returned to strm#1b

P=700-1000 psig T = 300 – 360 C LHSV = 0.3 – 2.0 1/h WHSV = 5-7.5 1/h Treat gas ratio = 2000-3000 scf/bbl

HEX 1

Hot/High Pressure Separator

HEX 3

8

Light ends Let down valve

7a

Water

8a

Stripper

Steam

Coke

Lost product (yeild inefficiency)

8b 8c

1c

1 Algal Oil (strm#13 from Sec. 1)

Nutraceutical Processing

1a

Separator 3-phase

Hydrotreated AO/ diesel mixture for blending with refinery hydrotreated diesel

Nutraceuitcals (ω-3, etc.)

P

= high pressure pump

HEX

= heat exchanger

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Hydrotreatment Spreadsheet: Input & Some Output Hydrotreatment of Algal Oil % of AO to nutraceuticals AO Composition: AGs, wt% FFA, wt% H2O, wt% inert, wt% ave mol wt of FA ave moles of double bonds per mole of FA ave acyl number of AGs Ave no. of double bonds per molec of AGs

ave mol wt of AGs Gas purge rate (strm 11), % Frac of FA going to HDCO2 Frac of FA going to HDO Frac FA unreacted (by difference)

1.1 79.0 19.0 1.0 1.0 267 1.44 2.36 3.40 679 10 0.6 0.4 0

Frac of AGs undergoing hydrogenolysis Frac AGs unreacted (by diff) Frac of CO2 generated that goes to RWGS Frac of CO generated that goes to methanation Frac of CO generated that goes to coke Frac of CO generated unreacted(by diff) Fraction of double bonds hydrogenated Excess H2 over theoretical, % Efficiency of hydrogenator, % Gross heating value of purge gas (strm11), MBTU/lb

Wt Ratio of HTAO to AO HTAO to refinery rate, gal/day HTAO to refinery rate, Mgal/stream yr HTAO to refinery rate, bbl/day HTAO to refinery rate, bbl/day/acre Nutraceutical oil annual production, Mlb/y

1 0 0.3 0.2 0.1 0.7 1 30 90 18,987 0.71 42,000 15 1,000 0.16 1.6

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Economics

29

Early 2011 data

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Economics Capital Cost Estimates from literature

Estimate Davis et al [1] Lundquist et al [12] Junker & Faaij [19] Sun et al [7] NREL

Year 2011 2010 2013 2011

Pond lined? no no yes no?

Harvest equipment? yes yes no yes

Capital Cost $M/1000 acres 40 100 90 85 (estimated)

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Variable Costs

VARIABLE COSTS Growth-harvest-extraction: Raw Materials & Other Costs CO2 nutrient: nitrogen as NH3 nutrient: phosphate as DAP make up water (strms 1 & 4a) flocculant H2SO4 make up hexane deemulsifier TOTAL Raw Mat. Cost Utilities & other costs Electric Steam Cooling water TOTAL Utilities cost Hydrotretment: Raw Materials & Other Costs H2 Catalyst amine solvent TOTAL Raw Mat. Cost Utilities & other costs Electric Steam Cooling water TOTAL Utilities cost

Credits Waste water treatment Waste biomass (animal feed) Hydrotreatment Purge gas fuel credit (strm#11, Sec 2) Nutraceuticals Cost of processing nutraceutical CO2 reduction credit TOTAL credits TOTAL Variable Cost

Price

Usage

Cost

Cost

Units

$/Unit

Unit/bbl

$/bbl

$/gal

lb

0.02

2,865

lb lb k gal lb lb lb lb

0.20

0.05

154 85 0.63

0.12

59.7

57.3 30.9 18.9 0.03 0.0 7.2 0.0 0.0 114.3

1.36 0.74 0.45 0.00 0.00 0.17 0.00 0.00 2.72

KWH k lb k gal

0.08 8.00

366.1 6.9

29.3 55.3

0.70 1.32

84.6

2.01

0.22

Price

Usage

Cost

Cost

Units

$/Unit

Unit/bbl

$/bbl

$/gal

lb lb lb

0.68

11.3

7.7 3.8 0.0 11.5

0.18 0.09

0.0

0.00

0.0

0.00

KWH k lb k gal

0.08 8.00

0.27

Price

Usage

Cost

Cost

Units

$/Unit

Unit/bbl

$/bbl

$/gal

Mgal ton MBTU lb lb T

0 225 3.5 30 6 5

-0.17 -0.46 -0.02 -4.5 4.5 -0.12

0 -104 -0.1 -134.7 26.9 -0.6 -212

0.00 -2.46 -0.002 -3.21 0.64 -0.01 -5.05

-1.6

-0.04

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Base Case Economics Cost Component Raw materials Utilities Fixed costs Capital cost recovery Co-product credits Sales Price= SP w/o co-product credit=

$/gal 2.99 2.01 1.85 2.66 -5.05 4.47 9.06

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Sensitivity Analysis of Base Case to 10% Increase in Parameter

If all the 10% increments were done (in the right direction), there would be a savings in sales price of

$3.45/gal

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If 1.1% of AO were diverted to nutraceuticals, then at 10,000 bbl/day production nutraceuticals would supply 25% of the nutraceutical market

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High Rate Algal Ponds for Waste Water Treatment Table 7c Concentrations of TN and TP Component TN, mg/L TP, mg/L

1 2 3 4 5 6

Conventional activated sludge (secondary) Effluent ~ 25 ~7

Algae Pond Feed with 15% excess nutrients 51 8

Algae Pond Effluent with 15% excess nutrients 7 1

Using a charge to a municipality for tertiary treatment of $500/Mgal would reduce the sales price of HTAO by $2.03/gal for treatment plus an additional credit for savings on nutrient cost of $0.77/gal giving a total credit of $2.80/gal. However, for the production of 1000 bbl/day of HTAO, which is only demonstration scale, waste water from a municipality of 1.4 million population would be required.

• Save on cost of tertiary treatment plant • Can’t produce nutraceuticals and animal feed • Need large population nearby

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Conclusions • • • •

Biofuel (especially algae) is in a nascent state CO2 foot print of prime importance. Need good LCAs. Co-products are necessary for economics With co-product sales, production of HTAO on scale of 1,000 to 10,000 bbl/day may be economical. • A myriad of processing steps have to be improved

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Recommendations • • • • • • •

Generate accurate LCAs Use material-energy-economic spreadsheet as scouting tool Improve doubling time at production scale Build 2 bbl/day pilot plant with nutraceuticals and animal feed or fertilizer subsidizing operation Explore low power dewatering equipment Reduce water content of the wet cakes Does the US need a more vigorous energy policy? Perhaps. The mandate is a good start.

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