a techno-economic analysis of open pond microalgae

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A techno-economic analysis of open pond microalgae

biofuels productionJ.R. Benemann1,

I.C. Woertz1,2, and T.J. Lundquist1,21MicroBio Engineering, Inc., and

1,2California Polytechnic State University, San Luis Obispo, California, USA

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Photographs Allowed (or ask for presentation][email protected]

Photographs Allowed (or ask for presentation][email protected]

J. Benemann, July 20, St. Louis, MO, Algal BBB

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Abstract Abstract This techno-economic analysis is for a projected near-term 400 ha (1,000 acre) production system in S. California. The 4 ha (10 acre) raceway ponds are paddle wheel mixed; harvesting is by continuous settling (90% efficiency), followed by gravity thickening, solar drying, and hexane extraction of algal oils in a central facility.

A productivity of 80 metric tons/ha-yr and a 25% extractable triglyceride content, ~50,000 barrels oil/year, is assumed. Biogas generated from residual biomass is used to generate electricity, with digester effluents recycled for nutrients (C, N, P, etc.) , with make-up water and nutrients supplied from local municipal wastewaters..

The engineering designs and construction costs, based on agricultural engineering practices, are estimated at ~$100 million with operating costs of $6 million per year (after sale of electricity of ~$1 million/yr), or $300/barrel (without wastewater treatment credits). Of this $60/bbl are for labor and $20/bbl for transport to/from the remote oil extraction facility. An on-site extraction process is needed.

The main value of such studies is to help focus R&D on key limiting factors and promising approaches for future cost reductions.J. Benemann, July 20, St. Louis, MO, Algal BBB

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We need a crystal ball…


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Biofuels Digest, Jim Lane, June 21, 2011, Paris Air ShowUK-NY in 1 hour: algae-powered rocket plane

Biofuels Digest, Jim Lane, June 21, 2011, Paris Air ShowUK-NY in 1 hour: algae-powered rocket plane

Airbus - Demo will fly by 2020!


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9Roof of MIT Building~ 1950

Inoculum Tubes

Plastic bag-type photobioreactors (PBRs)

First algal mass culture project (for Chlorella)


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Algae mass culture was first investigated over fifty years ago Carnegie Institute of Washington Algae for Food Project

Jack Myers Bessel Kok

Algae mass culture was first investigated over fifty years ago Carnegie Institute of Washington Algae for Food Project

Jack Myers Bessel Kok2006, Austin, Tx

Burlew (ed.) Algae Culture from Laboratory to Pilot Plant, 1953

1956, Stanford

First algae mass culture studies on MIT rooftop


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40 ha design based on 1950’s MIT rooftop plant40 ha design based on 1950’s MIT rooftop plant

Fisher (1956), A.D. Little Co. carried out an engineering design-cost estimate for a 40 hectare system of plastic tubes estimating (2008 $) capital cost >$1.25 million/ha Still ~ what we estimate now for PBRs (best case) Thus PBRs not considered herein J. Benemann, July 20, St. Louis, MO, Algal BBB

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What is the alternative to high cost PBRs? “High Rate Ponds”: shallow raceway mixed ponds.

Developed by Prof. Oswald, UC Berkeley early 1950s. First practical application, with recirculation

pump mixing, in early 1960’s at a municipal wastewater treatment plant (Concord, CA)


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During the 1950s Prof. W.J. Oswald pioneered “high rate ponds” (HRPs) for low-cost waste water treatment and biofuels production : shallow, raceway, slowly mixed ponds (paddle wheel mixing intruduced in 1970s)J. Benemann, July 20, St. Louis, MO, Algal BBB

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U.C. Berkeley, Richmond Field Station,Sanitary Engineering Research Lab. ca 1976

1st use paddle-wheels for mixing large ponds (and of “bioflocculation” harvesting)

Microactinium


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THE MAJOR ISSUES IN MICROALGAE CULTIVATION (Most already well enough known in the 1950’s]

THE MAJOR ISSUES IN MICROALGAE CULTIVATION (Most already well enough known in the 1950’s]

• Production Systems: Ponds vs. photobioreactors • Productivity (solar conversion efficiency) g/m2-day or

tons biomass/hectare-yr, how to maximize (light dilution) • Oil production: very high content after N or Si limitation

BUT very low productivity – a still unresolved problem• CO2 sources (need), supply, transfer (a very dismal topic) • Mixing – why mix, how much to mix, what energy input? • Harvesting – how, costs (< 500 ppm, <50 micron cells)• Cultivation – selected strains, grazers, weed algae, etc.• Processing – how dry, make biogas (oil extraction later)


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Cyanotech Co.Open, raceway ponds, algae plant in Hawaii. Red ponds for Haematococcus pluvialis for astaxanthin, others Spirulina J. Benemann, July 20, St. Louis, MO, Algal BBB

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Bird baths – a selective

environement for Haematococcus

pluvialis

Bird baths – a selective

environement for Haematococcus

pluvialis


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Raceway paddle wheel mixed high rate open ponds now the main (>99%) commercial production systems for microalgae

Spirulina


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Biodiesel Power Plant with CO2 Scrubber, 320 kW output can provide all the CO2 needed

and most (~80%) of power needed

Biodiesel Power Plant with CO2 Scrubber, 320 kW output can provide all the CO2 needed

and most (~80%) of power needed


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Open ponds only option for algal biofuels production or wastewater treatment.

Design specs:25-35 cm deep20-30 cm/sec mixDilute 20-40%/d~7.5-8.5 pH range

Paddle wheel

One Question: how large can we make them?


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Ponds, Christchurch NZ 5 hectares, 4 ponds Largest algae for biofuels project in world. Investigator: Dr. Rupert Craggs at NIWA

LOWEST COST BIOFUELS PRODUCTION SYSTEM

Sump for CO2 transfer

Paddle wheel

Lamellar settler harvesting


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Schematic of 1.25 ha ponds [Rupert Craggs, NIWA, NZ)Schematic of 1.25 ha ponds [Rupert Craggs, NIWA, NZ)


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What might algae biomass cost to produce?Techno-economic studies of open pond production suggest low costs possible

What might algae biomass cost to produce?Techno-economic studies of open pond production suggest low costs possible

Benemann, J.R. P. Pursoff, & W.J. Oswald, 1978. Engineering Design and Cost Analysis of a Large-Scale Microalgae Biomass System, Final Report US DOE. NTIS #H CP/T1605-01UC-61 (for methane only)

Benemann, J.R., R.P. Goebel, J.C. Weissman, & D.C. Augenstein 1982.Microalgae as a source of liquid fuels. Final Report U.S.DOE BER

Weissman, J.C., & R.P. Goebel, 1987. Design and analysis of microalgal open pond systems for the purpose of producing fuels Report to US DOE- SERI (fo the Aquatic Species Program)

Benemann, J.R. & W.J., Oswald 1996, Systems and economic analysis of microalgae ponds for conversion of CO2 to biomass. Report to US DOE-NETL (National Technology Energy Laboratory)

Lundquist, T., I. Woertz, N. Quinn and J. Benemann, 2010 (see next)Conclusion: algae biofuels maybe possible BUT NEED VERY HIGH

PRODUCTIVITIES, AND MANY OTHER FAVORABLE ASSUMPTIONS J. Benemann, July 20, St. Louis, MO, Algal BBB

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Productivity during a continuous

cultivation period of 18 months

>50 t ha-1 year-

PE: ~1.5%(Mario Tredici talk at this Conference)

Tetraselmis Oscillatoria

.

.

.

Straub et al. (eds.) Energy from Biomass (1982)Straub et al. (eds.) Energy from Biomass (1982)


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Productivity of Ponds in Calabria (M. Tredici]Productivity of Ponds in Calabria (M. Tredici]m2-d


One of better examples annual productivity with open ponds

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J. Sheehan, P. Roessler, T. Dunahay, J. Weissman J. Benemann(Principal Investigator)

Paul Roessler now at Synthetic Genomics(funded by ExxonMobil where Joe Weissman is)


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REQUIREMENT FOR COMMERCIAL PRODUCTION: Basic Schematic of Algae Biofuels Production

based on wastewater inputs for water/nutrients

REQUIREMENT FOR COMMERCIAL PRODUCTION: Basic Schematic of Algae Biofuels Production

based on wastewater inputs for water/nutrients

Lundquist, T., I. Woertz, N. Quinn and J. Benemann, 2010 “A Realistic Technology and Engineering Assessment of Algae Biofuel Production”, Energy Biosciences Inst., U.C. Berkeley


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Location of the Proposed Project (Imperial County, California

Location of the Proposed Project (Imperial County, California

Imperial Valley


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Coachella Valley

Imperial Valley

Earthrise


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Assumed maximum hourly productivities to size CO2 supply ducts, blowers, spargers etc.

Assumed maximum hourly productivities to size CO2 supply ducts, blowers, spargers etc.

0.51

2.4

3.54 4

3.53

2.4

10.5

3

0

1

2

3

4

5

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Alga

l Biom

ass P

rodu

ctivity

(g/m

2/hr

)


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Lundquist et al. 2010: Capital & operating cost estimates based mainly on agricultural, less on

civil & not on chemical engineering practices

Lundquist et al. 2010: Capital & operating cost estimates based mainly on agricultural, less on

civil & not on chemical engineering practices• Construction techniques based on prior experience• RS Means Construction Cost Data 2008• Also from recent S. California wastewater projects• Operating costs from wastewater treatment plants

BOTTOM LINE: Algal oil production (no wastewater treatment credits) costs would be ~$300/barrel oil. J. Benemann, July 20, St. Louis, MO, Algal BBB

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Detailed C, N and Water Mass Balance, 400 ha system, wastewater make-up (full view)

Detailed C, N and Water Mass Balance, 400 ha system, wastewater make-up (full view)

(Ave) (Max) (Ave) (Max) (Ave) (Max) (Ave) (Max)Q (m3/d) 296,000 349,000 Q (m3/d) 32,400 44,200 Q (m3/d) 305,000 360,000 Q (m3/d) 9,150 10,800Biomass (kg/d) 5,080 7,250 CO2 (kg/d) 36,000 51,750 Biomass (kg/d) 5,240 7,470 Biomass (kg/d) 157 224 (Ave) (Max)C (kg/d) 2,420 3,440 CO2-C (kg/d) 9,720 13,973 C (kg/d) 2,490 3,550 C (kg/d) 75 106 Q (m3/d) 3,040 4,330N (kg/d) 2,650 4,190 N (kg/d) 406 507 N (kg/d) 2,730 4,320 N (kg/d) 82 130 N (kg/d) 1,180 1,690

(Ave) (Max) (Ave) (Max) (Ave) (Max) (Ave) (Max)Q (m3/d) 44,700 59,300 Q (m3/d) 312,000 368,000 Q (m3/d) 6,640 9,470 Q (m3/d) 3,160 4,500C (kg/d) 1,740 2,310 Biomass (kg/d) 105,000 149,000 Biomass (kg/d) 99,600 142,000 Biomass (kg/d) 94,700 135,000N (kg/d) 1,560 2,080 C (kg/d) 49,800 71,000 C (kg/d) 47,300 67,400 C (kg/d) 45,000 64,100

N (kg/d) 7,710 9,640 N (kg/d) 4,980 7,100 N (kg/d) 4,730 6,740

(Ave) (Max) (Ave) (Max) (Ave) (Max) (Ave) (Max) (Ave) (Max)Q (m3/d) 3,560 5,070 CO2 (kg/d) 144,000 207,000 CH4 (kg/d) 28,400 41,100 Q (m3/d) 3,490 4,970 Q (m3/d) 118 169Biomass (kg/d) 38,900 55,400 CO2-C (kg/d) 38,880 55,890 CH4-C (kg/d) 21,280 30,790 Biomass (kg/d) 4,980 7,100 Biomass (kg/d) 94,700 135,000C (kg/d) 16,600 23,700 C (kg/d) 2,370 3,370 C (kg/d) 45,000 64,100N (kg/d) 3,800 5,410 N (kg/d) 249 355 N (kg/d) 3,550 5,060

(Ave) (Max) (Ave) (Max)Q (m3/d) 35,100 50,000CO2 (kg/d) 22,400 32,000 (Ave) (Max)CH4 (kg/d) 15,400 21,900 Q (m3/d) 22 31CTotal (kg/d) 17,600 25,100

(Ave) (Max) Q (m3/d) Q (m3/d)Q (m3/d) 72 103 Biomass (kg/d) Biomass (kg/d)Biomass (kg/d) 71,000 101,000 C (kg/d) C (kg/d)C (kg/d) 33,700 48,100 N (kg/d) N (kg/d)N (kg/d) 3,550 5,060

Q (m3/d)Oil (kg/d)Oil (bbl/d)C (kg/d)

Spent Algae

Evaporation/ Volatilization

Flue Gas

Make-Up Wastewater

Algae Settling Supernatant

Digester Effluent

BlowdownSupernatant of Algae Settling

Total Effluent

Natural Gas

7271,00033,7003,550

2623,700

16211,200

Spent Algae

Electricity From Nat Gas (MWh/d)

130 189

Electricity From Biogas (MWh/d)

71 101

Dried Algae

Unrefined Oil from 1 400-ha Site

3,55045,00078,900

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Supernatant of Gravity Thickener

Subnatant of Gravity Thickener

Evaporation

Subnatant of Algae Settling

Electricity Biogas

Dried Algae Flakes

Algae High Rate Ponds

Generator

2° Clarifier Algae Gravity Thickener

Anaerobic Digester

Flash Dryer & Silo at Pond Site

Centralized Solvent Extraction Facility

Drying Beds

Silo at Pond Site

Mass Balance of Carbon, Nitrogen, and Water for Case 5. (400 ha algae facility)


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Magnification of Mass Balance, 400 ha system, detail

Magnification of Mass Balance, 400 ha system, detail

(Ave) (Max) (Ave) (Max)Q (m3/d) 32,400 44,200 Q (m3/d) 305,000 360,000CO2 (kg/d) 36,000 51,750 Biomass (kg/d) 5,240 7,470CO2-C (kg/d) 9,720 13,973 C (kg/d) 2,490 3,550N (kg/d) 406 507 N (kg/d) 2,730 4,320

(Ave) (Max)Q (m3/d) 312,000 368,000Biomass (kg/d) 105,000 149,000C (kg/d) 49,800 71,000N (kg/d) 7,710 9,640

(Ave) (Max) (Ave) (Max)CO2 (kg/d) 144,000 207,000 CH4 (kg/d) 28,400 41,100CO2-C (kg/d) 38,880 55,890 CH4-C (kg/d) 21,280 30,790

(Ave) (Max) (Ave) (Max)Q (m3/d) 35,100 50,000CO2 (kg/d) 22,400 32,000CH4 (kg/d) 15,400 21,900


Flue Gas

Supernatant of Algae Settling

Total Effluent

Natural Gas

Electricity From Nat Gas (MWh/d)

130 189

Electricity From 71 101

Electricity Biogas

Algae High Rate Ponds

Generator

2° Clarifier


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High rate ponds 3,410,000Digesters 2,660,000Extraction plant share 2,430,000Drying beds 2,990,000Land 2,350,000Electrical 1,900,000Water piping 1,730,000Biogas turbine 2,000,000Flash dryer 1,020,0002° Clarifiers 1,160,000CO2 delivery 594,000Roads + Fencing 338,000Thickerners 316,000Buildings 120,000Silo storage 109,000Vehicles 100,000Total 23,227,000

Captial CostCAPITAL COST FOR A 100 HECTARE FACILITY

add insurance, engineering, contingencies, management: = $33 million needed to construct a 100-ha facility


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Algae facility staff 694,000 Extraction plant (staff and energy req.) 478,000 Maintenance (2% cap.) 465,000 Administrative staff 375,000 Electricity purchasea 379,000 Biomass haulingb 239,000 Insurance 180,000 Outside lab testing 50,000 Vehicle maintenance 15,000 Lab & office supplies 12,500 Employee training 10,000 Total operating expenses 2,900,000$

Operating Expenses

$~3 million is the annual O&M cost$~3 million is the annual O&M cost


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Technological Advances required for Biofuels Technological Advances required for Biofuels • PRODUCTIVITY INCREASES (ANTENNA SIZE

REDUCTION, see next slide for example)• OIL CONTENT INCREASE (REGULATION)

• CONTROL WEED ALGAE, GRAZERS, OTHER …

• CONTROL PROCESS OF BIOFLOCCULATION

• EXPAND TEMPERATURE LIMITS OF CULTIVATION

• WET EXTRACTION AND PROCESSING

• PRODUCE ANIMAL FEED CO-PRODUCTJ. Benemann, July 20, St. Louis, MO, Algal BBB

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WT CM1

CM2 CM1-1

CM3 CM7

A

To increase productivity

WT MutantJ. Benemann, July 20, St. Louis, MO, Algal BBB

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CHALLENGE: ROTIFERS ( JUST ONE TYPE OF ALGAE GRAZER]Must manage ponds for algal species & culture stability

CHALLENGE: ROTIFERS ( JUST ONE TYPE OF ALGAE GRAZER]Must manage ponds for algal species & culture stability


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Nature already provides what some want to make (using genetic modifications and synthetic biology)

oil globs made by the alga Botryococcus braunii

Nature already provides what some want to make (using genetic modifications and synthetic biology)

oil globs made by the alga Botryococcus braunii


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WHY I AM OPTIMISTIC ABOUT MICROALGAE FUELS: WHY I AM OPTIMISTIC ABOUT MICROALGAE FUELS:

“ We now have wonderful tools”


42We seem to have a few problems going from lab-scale to full-scale productionJ. Benemann, July 20, St. Louis, MO, Algal BBB

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‘On my planet, we only have one real word: Money’(everything else are “helper words”)

‘On my planet, we only have one real word: Money’(everything else are “helper words”)

• Cartoon


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Greg Mitchell, SIO-UC San Diego

SEE YOU IN MINNESOTA, OCT 25-27ALGAL BIOMASS SUMMIT -2011


a techno-economic analysis of open pond microalgae

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