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Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash Chand Formerly , Professor & Head: Department of Biochemical Engineering & Biotechnology Indian Institute of Technology Delhi Hauz Khas, New Delhi - 110 016
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Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Mar 29, 2020

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Page 1: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Techno-economic Appraisal of

Alternative Feed-stocks for

Bioconversion to Ethanol:

Subhash Chand

Formerly , Professor & Head:

Department of Biochemical Engineering & Biotechnology

Indian Institute of Technology Delhi

Hauz Khas, New Delhi - 110 016

Page 2: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Ethanol as a Chemical Feedstock:

Characteristic Features:

• Bioconversion route vs Chemical Synthesis

• Biphasic demand curve

• Represents highest product concentration

among microbial bioconversion products

Page 3: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Chemical vs Biochemical Routes

Chemical Synthesis:

CH2= CH2+ H2O C2H5OH

- Keq= 0.15 at 300C and 70 atm.

Pressure

- 100 % carbon conversion

(recycling)

- 0.61 kg C2H4/kg ethanol

Bioconversion:

C6H12O6 2C2H5OH +2CO2

(Yeast/ Bacteria)

- Carbon conversion : 66.7%

- Fermentation efficiency>85%

- Glucose required / kg ethanol:

1.96 kg

- Raw Materials: molasses,

sugar cane juice, corn, agro-

residues (lignocellulosics)

etc.

- Uses biomass based

renewable feed stocks

Page 4: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Bioconversion of Glucose to Ethanol

Glucose 2NAD+ + 2Ethanol

2Pyruvate + 2NADH +H+ + 2 Acetaldehyde

2CO2

Page 5: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Elastic (Industrial/fuel

alcohol, Animal feed

antibiotic)

Price

Quantity

Inelastic (potable alcohol ,

Human antibiotics)

Biphasic demand curve

Page 6: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

2. Starch based raw materials

- Cereal grains

(corn, spoiled wheat / rice/

sorghum)

- Tubers

(Low grade potatoes,

tapioca)

Potential feedstocks for

bio-conversion to ethanol

1. Sugar containing raw

materials

- Sugarcane juice

- Molasses

- Mahua flowers

- Sugar beets

3. Lignocellulosic Agro-residues:

Wheat / Rice Straw, Bagasse etc.

Alternative uses (?)

Page 7: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Ethanol Production in India – current scenario

• Total number of

distilleries: 356

• Distilleries affiliated

to sugar mills: 141

• Installed capacity:

4230 m lit. (based on

molasses)

• Current production:

2600 m lit.

• Present

consumption: 2000 m

lit.

• Availability for

blending: 600 m lit.

• Demand

(5% blend): 1300 m lit.

• Demand

(10% bend): 2600 m lit.

Page 8: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Bioprocess criteria:

• High rate of substrate utilization

• High ethanol productivity

• Ethanol concentration in the brew > 8.5%

• Reduction in the volume and strength of effluent

• Automation and reduction in down time

Raw Material (s) Biocatalyst

Bioprocess

TechnologyDistillation

Effluent treatment and water recycling

Page 9: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Ethanol from Saccharine Feedstocks

Page 10: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Ethanol production from substrates

containing starch

(Misselhorn, K. 1979 in Dellweg, H (ed), 4th Symposium Technische Microbiologie Berlin

Page 11: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Energy (MJ/l of pure ethanol) required to produce

absolute alcohol…

Process stage Substrate

Beets Cane Starchy raw materials

Digestion/Hydrolysi

s

Batch 4-5 - 7-8

Continuous - - 2

Cane Mill - 1.1-1.5 -

Extraction 0.8-1 2-3 -

Fermentation

Batch 0.06 0.06 0.06

Continuous 0.1 0.1 0.1

Distillation

Single-staged 10-13 10-13 10-13

Optimized 5-7 5-7 5-7

Process

Conventional 16 13 19

Optimized 7 7 8

(Misselhorn, 1979)

Page 12: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Bioconversion of different

raw materials to ethanol

Raw material Crop yield

T/ ha./yr.

Alcohol yield

L/T

Productivity

L/ha/yr

-Sugarcane

-Sugar beet

-Molasses

-Potato

-Cassava

-Sorghum (dry)

-Corn (dry)

60-100

30-60

--

15-30

10-20

2-5.5

3-7.5

60-80

50-110

225-300

80-120

150-200

340-400

360-400

5000-6000

3000-4000

--

2000-3000

2000-3000

1000-2000

1500-2000

Page 13: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Bioconversion of

Lignocellulosics to Ethanol

• Selection of Appropriate Feedstock

• Pretreatment and Delignification

• Saccharification / Hydrolysis

• Fermentation to Ethanol

• Recovery and Purification

• Process Integration, Techno-economic

evaluation and Scale Up

Page 14: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Cellulose to ethanol : process inhibition

pattern

( C6)n n1C6 + n2C12 2nCH3CH2OH + 2nCO2

[A] n = n1 + n2

[C] [B]

[A] :Sugars ( Glucose & Cellobiose) inhibit cellulase enzyme ( Saccharification)

[B] : Ethanol inhibits alcoholic fermentation

[C] : Ethanol inhibits cellulase enzyme ( Saccharification)

[D] : Accumulation of cellobiose reduces the yield of fermentable sugars.

[D]

Page 15: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Sweet Sorghum- a potential crop

• An alternative to sugar cane

• Production of high biomass yield

• High %age of fermentable sugars and

organics

• Shorter growth period

• Tolerance to draught stress

• Low fertilizer requirement

• Provides grains for additional ethanol

productivity

Page 16: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Sweet Sorghum ( Sorghum bicolor L.)

• Released by IARI in 1996; single cut variety ; 120-150

days cycle time ( mid June – Oct end) ; rain fed &

requires low fertilizers input.

• Total plant biomass yield : 620 Q /ha

• Dry matter : 35% w/w ( 217 Q /ha)

• Juice recovery : 27900 l/ha

• Total fermentable sugars : 15.8 % w/v ( 4408 kg/ha)

• Sorghum bagasse : 186 Q /ha (dry wt.)

• Sorghum grain : 12.5 Q /ha

SSG 601 PC 009 PCH 106 PC 121 PC 023

* Courtesy Dr. S. Solomon , Dept. of Genetics IARI,New Delhi

Page 17: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Sweet Sorghum- Sorghum bicolor

Page 18: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Sweet Sorghum:

- Stalks → Juice → Ethanol

- Bagasse → SSF → Ethanol

+

Residues

- Grains → Liquefaction → Saccharification

Ethanol

Page 19: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Sorghum grains

Milling

α-amylase ↓ Ca++, pH 6.0, 900C, 2.5 h

Solubilized starch + Residue

Liquefaction

Page 20: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Saccharification of liquified sorghum

grain in an IME packed bed reactor

• Enzyme : Amylo 300 L (crude

AMG + pullulanase

• Substrate: 30 % (DS) enzyme

liquified syrup

• Carrier: Activated bagasse

• pH: 4.5

• Temperature: 50 0 ± 10C

• Specific activity: 1000 IU/g

• Km (approx.): 3.0x 10-4 M

• Packed bed volume: 800 ml

• Residence time: 3.5 hours

Page 21: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Activated sorghum bagasse matrix

-OH + CH2-CH-CH2 Cl (epichlorohydrin)

-O- CH2-CH2-CH2 + HCl

-O- CH2-CH-CH2

O

1 N ONaH, 60 0 C, 30 min

O

NH2 (CH2)6NH2, pH 11, 60 0 C, 2h

(hexamethylene diamine)

OH NH (CH2)6

NH2

aminohexyl matrix

Page 22: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Bioconversion of Sorghum juice and

saccharified grains

0

1

2

3

4

5

6

7

8

9

0

30

60

90

120

150

180

0 5 10 15 20 25 30 35

Su

ga

r c

on

c. (g

/l)

Time (hr.)

ethanol conc. % (v/v) Sugar conc.(mg/ml)

Ethanol

conc. (v/v)

Page 23: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Delignification of bagasse

Sugarcane / Sorghum bagasse

(1 kg dry wt.)

Pressure - 4.2 kg/m2

Time - 3 + 1.5 hrs

PulpDelignification: 89-90%

Yield: Sugarcane bagasse 42.0% w/w

Sorghum bagasse 48.5 % w/w

NaOH (0.22 kg)

Water

(5 Lit.)

washing

drying

Pulp compositionSugarcane Sorghum

Cellulose( % w/w) 43.7 38

Hemi cellulose (%w/w) 23 27.3

Lignin (%w/w) 9.8 13.0

Crude Protein(%w/w) 3.5 7.5

Page 24: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

0

5

10

15

20

25

30

35

40

45

0 24 48 72 96 120 144 168 192

En

zym

e A

cti

vit

y ( IU

/ g

so

lid

)

Time ( hr)

Enzyme production by Solid state

fermentation

FPA Activity

beta glucosidase activity

Dry air for 6 hrs.

Page 25: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Production of Cellulase by Trichoderma reesei

0

2

4

6

8

10

12

0 20 40 60 80 100 120 140

Time (hr)

FP

(IU

/ml)

, B

-glu

go

sid

as

e (

IU/m

l), S

P (

mg

/ml)

Soluble ProteinsFilter Paper Activity

B-glucosidase

Page 26: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Production of beta-glucosidase by Aspergillus wentii Pt 2804

0

1

2

3

4

5

6

7

8

9

0 10 20 30 40 50 60

Time ( hr. )

en

zy

me

ac

tiv

ity

(IU

/ml)

B-Glucosidase (IU/ml )

Page 27: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

• Solid/ Liquid (1:5)

• Cellulase: 8 IU/g

• Yeast: 50 mg/g

• Temp. :30oC / 35oC

A schematic diagram of the reactor for

bioconversion of bagasse pulp to ethanol

Page 28: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Bioconversion of pulp to ethanol

S.cerevisae (IMTECH strain)

0

2

4

6

0 4 8 22 26 30 44 48

Time (Hours)

Co

nc

en

tra

tio

n

Glucose (g/l)

Ethanol (% w/v)

Solid / liquid ( 1:8) , FPA: 8 IU/ g pulp, glucosidase: 4 IU/ g pulp,

Yeast : 10 mg/ g pulp, Temp. : 38 oC , pH : 4.8

Page 29: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Spent solids

Buffer

Residue

Fermented

Broth

II

Mixed Enzyme

(Cellulase + -

glucosidase)

Yeast Production System

Delignified Pulp

Sorghum Bagasse

NaOH

EvaporatorIncinerator

Waterrr

Rotary Digester

Pulp Washer

I

Page 30: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Total Utilization of sweet sorghum for ethanol production(Basis : 1 Hectare of Sweet Sorghum cultivation)

Sweet

sorghum

620 Q

Stalk

465 Q

Panicles

93 QLeaves

62 Q

Juice 27900 lit Bagasse180 Q

Fermentation

Saccharification

(PFR)

Distillation

Milling

Hydrolysis

Ethanol

4525 lit

Residues Grain 12.5 Q

Q

Liquefaction

Page 31: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Alternative strategies to enhance

the ethanol production

• Secondary cane juice for

distilleries affiliated to sugar mills

• Use of low grade potatoes

/cereals for scarification &

fermentation

• Sorghum juice & grains

• Mixed feed-stocks

Page 32: Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion … · 2017-08-20 · Techno-economic Appraisal of Alternative Feed-stocks for Bioconversion to Ethanol: Subhash

Bioconversion of a flexible feedstock system (e.g. pretreated lignocellulosics mixed with presaccharified low cost starchy

materials) to ethanol can provide a decentralized and sustainable alternative to meet the growing needs of ethanol as an organic

feed stock in a sustainable manner.