BIOMASS CONVERSION TO BIO-FUELS
ChE 481
Lecture 2
LECTURER:
MANUEL GARCIA-PEREZ , Ph.D.
Department of Biological Systems Engineering
205 L.J. Smith Hall, Phone number: 509-335-7758
e-mail: mgarcia-perez@wsu.edu
LECTURE OUTLINE
A.- INTRODUCTION TO ETHANOL PRODUCTION
B.- ETHANOL FROM SUGARCANE
C.- CELLULOSIC ETHANOL
A.- INTRODUCCION TO ETHANOL PRODUCTION
Growth of the ethanol manufacturing capacity:
Driven by blending mandates, subsidies and tax
incentives enacted at the government level.
http://www.marketresearchanalyst.com/2008/01/26/world-ethanol-production-forecast-2008-2012/
A.- INTRODUCCION TO ETHANOL PRODUCTION
World Ethanol Production
60 % derived from sugar Crops
30 % derived from grains (mostly corn)
7 % derived from ethylene (synthetic ethanol)
3 % bio-conversion of other feedstocks
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
B.- ETHANOL FROM SUGARCANE
Sugar Cane Yield
http://en.wikipedia.org/wiki/File:SugarcaneYield.png
A.- INTRODUCCION TO ETHANOL PRODUCTION
Although the basic process of ethanol production
from sugar cane has not changed greatly for several
decades, significant improvements were made
throughout the 1980s and 1990s.
Mackay, Australia
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
B.- ETHANOL FROM SUGARCANE
Production of Ethanol in Brazil
Total cost of ethanol from sugarcane: $ 0.81/gal
Total Cultivated Land devoted to sugarcane: 7.4 million
acres (10 % of cultivated land)
Total Production: 4.2 BG ethanol
The fiber in the stalks and leaves is used to generate
process steam and electricity in the sugar mill. In
addition, the liquid effluent (vinasse) is used as a
fertilizer and irrigation supply to the cane fields,
thereby eliminating cost of waste water treatment.
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
B.- ETHANOL FROM SUGARCANE
The Brazilian industry serves as a model in several
ways:
(1) The starting material is extremely cost
effective.
(2) The output can be quickly and cheaply adapted
to changing market demands (ethanol or sugar).
(3) The process is continuously optimized through
research and development as exemplified by the
significant economies already achieved by this
industry.
B.- ETHANOL FROM SUGARCANE
The Sugarcane Plant: Sugarcane is a
tropical grass belonging to the same
tribe (Andropogoneae) as sorghum,
and corn (maize). Modern sugarcane
is a complex hybrid of two or more
of the five species of the genus
Saccharum. New Guinea is the
original home of Saccharum
officinarum.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
Sucrose (Saccharose): The sugar
of household and industry is
sucrose, the most common
sugar in the plant kingdom.
Sucrose is the reservoir for the
energy captured from the sun by
the sugarcane leaves through
photosynthesis, and sugarcane is
the most efficient energy fixer
per ton in the plant world.
Composition of Sugarcane and Juice
solids
Sucrose
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
Harvesting: The goal of harvest is to deliver sugarcane stalks of
good quality to the mill. Quality, measured by sucrose and trash
content, is reduced by: damaging cane, increasing trash in
delivered cane, and delaying cane delivery. The removal of cane
tops is highly desirable in the harvesting operation. Cane tops and
leaves have little sucrose but are high in starch and reducing
sugars. These tops and leaves lower sugar yields in the boiling
house.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
Harvesting: The top is most effectively removed by hand
cutting, the harvesting method of choice in most of the
sugarcane world. Because of labor shortage, in many
developed nations the entire crop has been mechanically
harvested for several decades. So far, the combine
machine is only efficient for standing straight cane.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
Block-flow diagram of the ethanol production process from sugarcane
Sugarcane
Cleaning
Sand, dirt, metals
Extraction
of Sugars
Sugarcane Bagasse
Juice Treatment
Clarified juice
Juice Concentration
Juice Sterilization
Yeast
Fermentation
Centrifugation
Yeast Treatment
Fermentation
Gases
Wine
Adsorption
CO2
Distillation and
Rectification
2nd grade Alcohol ,
Vinasse, Fusel oil
Dehydratation
Anhydrous Bioethanol
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
FLOW DIAGRAM OF RAW SUGAR FACTORY
Imbibition water
Cane
Bagasse
MILLING PLANT
Vacuum
Phosphate
JUICE PURIFICATION
MUD
FILTRATION
EVAPORATION
Final Molasses
Raw Sugar
CRYSTALLISATION
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
http://www.msfsugar.com.au/irm/Company/ShowPage.aspx?CPID=1076&EID=36187078
B.- ETHANOL FROM SUGARCANE
Block-flow diagram of the ethanol production process from sugarcane
Sugarcane
Cleaning
Sand, dirt, metals
Extraction
of Sugars
Sugarcane Bagasse
Juice Treatment
Clarified juice
Juice Concentration
Juice Sterilization
Yeast
Fermentation
Centrifugation
Yeast Treatment
Fermentation
Gases
Wine
Adsorption
CO2
Distillation and
Rectification
2nd grade Alcohol ,
Vinasse, Fusel oil
Dehydratation
Anhydrous
Bioethanol
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
CLEANING
Cane - cleaning Equipment:
Necessary where mechanical
harvesting prevails. The cane on
the carrier is deluged with warm
water from the condenser
system
delivered
through
nozzles at high pressures. The
wastewater, carrying the mud
and much of the trash, is led off
to the drainage system or is
separately treated before final
discharge.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
CLEANING AND EXTRACTION OF SUGARS
The preparation of the cane for milling is accomplished in
several ways:
1.- By revolving cane knives that cut the cane into chips
but extract no juice.
2.- By shredders that tear the cane into shreds but
extract no juice
3.- By crushers that break and crush the structure of the
cane, extracting a large proportion of the juice.
4.- By combinations of any or all the means just
enumerated
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
EXTRACTION OF THE JUICE
Revolving cane knives
Chopper fibrizer
Tongaat shredder
Shredder side
Shredder feeding
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
Block-flow diagram of the ethanol production process from sugarcane
Sugarcane
Cleaning
Sand, dirt, metals
Extraction
of Sugars
Sugarcane Bagasse
Juice Treatment
Clarified juice
Juice Concentration
Juice Sterilization
Yeast
Fermentation
Centrifugation
Yeast Treatment
Fermentation
Gases
Wine
Adsorption
CO2
Distillation and
Rectification
2nd grade Alcohol ,
Vinasse, Fusel oil
Dehydratation
Anhydrous
Bioethanol
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
EXTRACTION OF THE JUICE
Crushers: Crushers in general consist of two
(occasionally three) deeply grooved rollers that crush or
break the cane, expressing from 40-70 % of the juice.
The classical combination of three rollers arranged in
triangular form is the standard milling unit for the
industry.
B.- ETHANOL FROM SUGARCANE
EXTRACTION OF THE JUICE
Compound imbition is used in all modern installations. As
a rule the water or juice is applied to the bagasse as it
issues from between the rolls with the idea that the
bagasse will adsorb the liquid like a sponge in expanding.
Cane
Compound imbition
Crushers
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
Block-flow diagram of the ethanol production process from sugarcane
Sugarcane
Cleaning
Sand, dirt, metals
Extraction
of Sugars
Sugarcane Bagasse
Juice Treatment
Clarified juice
Juice Concentration
Juice Sterilization
Yeast
Fermentation
Centrifugation
Yeast Treatment
Fermentation
Gases
Wine
Adsorption
CO2
Distillation and
Rectification
2nd grade Alcohol ,
Vinasse, Fusel oil
Dehydratation
Anhydrous
Bioethanol
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
PURIFICATION OF THE JUICE
Preliminary pretreatment: The juice from
the mills is subjected to a coarse straining
and further removal of suspended solids.
Even after cane cleaning operations, juices
may average 2-4 % insoluble solids, and
wet weather 6-7 % is not uncommon. The
material is mostly soil, sand, and ground
rock that is not removed by preliminary
screening. Continuous type settling devices
in use in several factories are effective in
removing coarser particles, but not clay
and fine soil.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers
and their Chemists.12th Edition, 1993, John Wiley & Sons, Inc
45o DSM juice screen
B.- ETHANOL FROM SUGARCANE
Block-flow diagram of the ethanol production process from sugarcane
Sugarcane
Cleaning
Sand, dirt, metals
Extraction
of Sugars
Sugarcane Bagasse
Juice Treatment
Clarified juice
Juice Concentration
Juice Sterilization
Yeast
Fermentation
Centrifugation
Yeast Treatment
Fermentation
Gases
Wine
Adsorption
CO2
Distillation and
Rectification
2nd grade Alcohol ,
Vinasse, Fusel oil
Dehydratation
Anhydrous
Bioethanol
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
RAW SUGAR PROCESS AND EXTRACTION OF JUICE
Purification of Juice (Clarification): The dark-green juice
from the mills is ACID AND TURBID. The clarification
process, designed to remove both soluble and insoluble
impurities, universally employs LIME and HEAT as the
clarifying agents. Milk of lime, about 0.5 kg CaO per ton of
cane, NEUTRALIZES THE NATURAL ACIDITY OF THE JUICE,
forming insoluble lime salts, mostly calcium phosphate.
Heating the limed juice to boiling (95 oC) or slightly above
COAGULATE THE ALBUMIN AND SOME OF THE FATS,
WAXES, AND GUMS, and the precipitate thus formed
entraps suspended solids as well as finer particles. The muds
separate from the clear juice by sedimentation. The muds
are filtered on rotary drum vacuum filters.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
PURIFICATION OF THE JUICE
Function of a Clarifier: The function of
a clarifier is to separate the INSOLUBLE
PARTICLES FROM THE LIMES JUICE. The
effectiveness of such removal is very
often termed “turbidity reduction”. A
good clarifier should not only produce
good juice clarity, but also should have
short retention time and more efficient
mud removal. Any accumulation of
mud that is not definitely scraped away
will crust over rapidly and cool to a
temperature that permits bacterial
action and souring, resulting in sugar
losses.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
Block-flow diagram of the ethanol production process from sugarcane
Sugarcane
Cleaning
Sand, dirt, metals
Extraction
of Sugars
Sugarcane Bagasse
Juice Treatment
Clarified juice
Juice Concentration
Juice Sterilization
Yeast
Fermentation
Centrifugation
Yeast Treatment
Fermentation
Gases
Wine
Adsorption
CO2
Distillation and
Rectification
2nd grade Alcohol ,
Vinasse, Fusel oil
Dehydratation
Anhydrous
Bioethanol
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
JUICE CONCENTRATION
Evaporation: The clarified juice, having much the same
composition as the raw extracted juice except for the precipitated
impurities removed by the lime treatment, CONTAINS ABOUT 85 %
WATER. Two-thirds of this water is evaporated in vacuum multiple
effects consisting on a succession of (four or five) vacuum boiling
cells or “bodies” arranged in series so that each succeeding body
has a higher vacuum, and therefore BOILD AT LOWER
TEMPERATURE. The vapors from one body can thus boil the juice
in the next one. By this system the steam introduced into the first
body does multiple effect evaporation. The vapor from the final
body goes into a condenser. Only part of the juice is concentrated
up to 65 % sucrose, and final juice contains around 22 % sucrose.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
EVAPORATION
Evaporator Types: A variety of multipleeffect evaporator types are used for raw
sugar manufacture and refining. Calandria
vessels are used in raw sugar manufacture.
Long tube vertical rising film units are used
for clarified juice evaporation in sugar
manufacture.
In order to avoid contamination in
fermentation, juice is sterilized and cooled till
fermentation temperature (28 oC)
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their
Chemists.12th Edition, 1993, John Wiley & Sons, Inc
B.- ETHANOL FROM SUGARCANE
EVAPORATION
Multiple Effect Evaporator
Vacuum
Steam
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley &
Sons, Inc
B.- ETHANOL FROM SUGARCANE
Block-flow diagram of the ethanol production process from sugarcane
Sugarcane
Cleaning
Sand, dirt, metals
Extraction
of Sugars
Sugarcane Bagasse
Juice Treatment
Clarified juice
Juice Concentration
Juice Sterilization
Yeast
Fermentation
Centrifugation
Yeast Treatment
Fermentation
Gases
Wine
Adsorption
CO2
Distillation and
Rectification
2nd grade Alcohol ,
Vinasse, Fusel oil
Dehydratation
Anhydrous
Bioethanol
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
PRODUCTION OF ETHANOL
Ethyl alcohol can be produced from the sterilized juice. The
fermentation results from the action of yeast, which first inverts
the sucrose (to glucose and fructose) by the action of invertase
secreted by the yeast. Then the yeast converts the invert sugar to
ethyl alcohol and carbon dioxide. Fermentation is carried out at
28 oC to obtain wine with ethanol content of around 10 mass %.
C12H22O11 + H2O + invertase = C6H12O6 + C H O
6 12 6
(Sucrose)
(Fructose)
(Glucose)
C6H12O6 = 2 C2H5OH + 2 CO2
(invert
(ethyl
(carbon
sugar)
alcohol)
dioxide)
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley & Sons,
Inc
B.- ETHANOL FROM SUGARCANE
Block-flow diagram of the ethanol production process from sugarcane
Sugarcane
Cleaning
Sand, dirt, metals
Extraction
of Sugars
Sugarcane Bagasse
Juice Treatment
Clarified juice
Juice Concentration
Juice Sterilization
Yeast
Fermentation
Centrifugation
Yeast Treatment
Fermentation
Gases
Wine
Adsorption
CO2
Distillation and
Rectification
2nd grade Alcohol ,
Vinasse, Fusel oil
Dehydratation
Anhydrous
Bioethanol
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
CONVENTIONAL DISTILLATION SYSTEM
Consist of a distillation column
comprised by columns A, A1,
and D and a rectification
column comprised by columns
B and B1. Pressure on the
distillation columns range from
133.8 to 152.5 kPa, and from
116 to 135 kPa in the
rectification columns.
Dias MOS, Modesto M, Ensinas AV, Nebra SA, Filho RM, Rossell CEV: Improving bio-ethanol production from sugarcane: evaluation of distillation thermal integration and
cogeneration systems. Energy xxx (2010) 1-13
B.- ETHANOL FROM SUGARCANE
Micro-distillery: Microdistilleries have been developed by Brazil as small
factories producing hydratated ethyl alcohol. This is an ultra-simple and
comparatively inexpensive distillery which could be installed easily on any
farm.
Fermentation
tanks
Micro-distillery flowsheet
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley & Sons,
Inc
B.- ETHANOL FROM SUGARCANE
BAGASSE
Bagasse is the byproduct or residue of milling cane. Bagasse
amounts to one-third of the cane ground. It supplies the fuel
for the generation of steam in the raw factories. Most modern
factories have an excess of bagasse during the regular grinding
season.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley & Sons,
Inc
B.- ETHANOL FROM SUGARCANE
BAGASSE
The fuel value of dry bagasse is 8350 BTU/lb. The actual fuel value of bagasse
burned on the grates depends on the moisture present. When bagasse
contains moisture at the 53-54 % level, its heating value is reduced, and so is
boiler efficiency. By pre-drying the bagasse using waste heat in the boiler flue
gas, reducing the moisture to 46-47 %, not only may a great saving of
supplementary fuel be expected, but also some 10-15 % of excess bagasse from
total production may be available for other industrial purposes.
Schematic diagram of the pneumatic
bagasse drying system
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley & Sons,
Inc
B.- ETHANOL FROM SUGARCANE
BAGASSE
Steam
Boiler:
The
steam
consumption per ton of cane
varies widely depending on
different factory equipment and
product quality (450-550 kg
steam/t cane). The most marked
advanced in bagasse burning in
the past 20 years has been the
growing used of spreader stokers,
particularly in connection with
boilers of large capacity.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley & Sons,
B.- ETHANOL FROM SUGARCANE
BAGASSE
Bagasse Boards: It is now being used in practically all
types of reconstituted panelboard, e..g., insulation
board, process hardboard (wet or dry process),
particleboard, and medium density board. The board
forms by the process known in pulp handling as
“felting” the strength of the board being due solely to
the interweaving and entangling of the fiber. As the
wet board comes from the forming machine, it is fed
into a continuous hot-air drier, from which it emerges
finished in a continuous sheet 12 ft wide, cut by saws
into convenient sizes. Particle board is made from
small pieces of lignocellulosic material with an
organic binder agent under heat, pressure, or other
treatments.
Chen J.C.P., Chou C.C: Cane Sugar Handbook. A Manual for Cane Sugar Manufacturers and their Chemists.12th Edition, 1993, John Wiley & Sons, Inc
B.- CELLULOSIC ETHANOL
Production of first generation biofuels alone will not be able to
satisfy the world’s growing energy needs.
Giving the limits of corn and sugarcane ethanol, fuel ethanol
production in the long run depend on the use of cellulosic
materials as primary feedstocks. Over 1.3 billion dry tons of
biomass from forest land and agricultural land alone are
potentially available in the US every year. Such an amount is
sufficient to meet more than one third of current demand for
transportation fuels while still meeting food, feed and export
demand. Production from cellulosic material is not yet a
commercial route. Diluted acid hydrolysis, the currently available
technology, has a limited efficiency of 35 %. PRETREATMENT
TECHNOLOGIES ARE NEEDED!
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Simplified Diagram of Cellulosic Ethanol Production
Girard P, Fallot A, Dauric F, Technology state of the Art, Forest Department of CIRAD
C.- CELLULOSIC ETHANOL
Concept 1
SEPARATE ENZYMATIC HYDROLYSIS AND FERMENTATION (SHF)
NEW SYSTEM
Biomass
EXISTING SYSTEM
FERMENTATION AT
PRETREATMENT Sugars
EXISTING CORN
AND
ETHANOL OR SUGAR
HYDROLYSIS
CANE ETHANOL
PLANT
Concept 2
DISTILLATION
Ethanol
SIMULTANEOUS SACCHARIFICATION AND FERMENTATION
Biomass
PRETREATMENT
(Solubilization of
hemicelluloses)
HYDROLYSIS
(Cellulose
hydrolysis using
Acid/enzymes)
FERMENTATION
(Conversion of
sugars to ethanol
by yeast)
Ethanol
DISTILLATION
C.- CELLULOSIC ETHANOL
SEPARATE ENZYMATIC HYDROLYSIS AND FERMENTATION (SHF)
This process consist of two steps: the first step involves the
enzymatic hydrolysis of pretreated cellulose into glucose,
while the second step aims at converting the resulting
glucose into ethanol. Enzymatic hydrolysis can be carried out
under conditions optimum cellulose activity. The optimum
temperature for hydrolysis by cellulase is usually around 50
oC, depending on the specific cellulase.
Main shortcomings of SHF:
1.- The sugars produced strongly inhibit cellulase activity.
2.- Hydrolysis is a lenghty process and a diluted solution of sugar
always bears the risk of contamination even at relatively high
temperatures such as 50 oC.
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
SIMULTANEOUS SACCHARIFICATION AND FERMENTATION (SSF)
Combines the enzymatic hydrolysis of cellulose and the subsequent
fermentation of the cellulose hydrolyzate in a single step. As soon as
cellulose conversion into glucose is initiated, a fermenting microorganism is introduced in the medium and immediately consumes the
produced glucose. Cellobiose and glucose significantly decrease the
activity of cellulase. SSF therefore provides higher ethanol yields and
requires lower amounts of enzyme than SHF, since end product
inhibition from cellobiose and glucose produced by enzymatic
hydrolysis is mitigated.
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
Disadvantages
1.- Cellulase is inhibited by ethanol
2.- Most micro-organisms used for converting cellulosic
biomass (e.g. S. cerevisiae and Z. mobilis) preferentially use
glucose and cannot efficiently utilize xylose and arabinose.
3.- It operates at temperature and pH conditions that
represent a compromise between the optimal of these
parameters for both enzymatic activity and the growth of
the fermenting micro-organisms.
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
PRETREATMENT TECHNOLOGIES
Source: Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
PRETREATMENT TECHNOLOGIES
Ammonia fiber
expansion (AFEX)
Ammonia recycle
percolation (ARP)
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges
and opportunities. November 8, 2010.
C.- CELLULOSIC ETHANOL
HIDROLISIS
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges and opportunities.
November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges and opportunities.
November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges and opportunities.
November 8, 2010.
C.- CELLULOSIC ETHANOL
Degradation of lignocellulosic biomass during pretreatment
and the formation of inhibitory compounds.
Cellulose
Lignocellulosic
biomass
Hemicellulose
Hexoses
HMF
Pentoses
Levulinic acid
Furfural
Formic acid
Furoic acid
Acetic acid
Ferulic acid
Lignin
Other aldehydes
Other Acids
Other phenols
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
CLASIFICATION OF INHIBITORS BASED ON THEIR CHEMICAL FUNCTIONAL GROUPS
(1) Aldehydes , (2) Ketones, (3) Phenols, (4) Organic acids
Low molecular weight compounds show more toxic effects to
microbes than the high molecular weight compounds. This
property could perhaps be explained by an easier transport of
the smaller molecules via a variety of mechanisms including
passive diffusion.
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
Aldehyde inhibitors (Furfural, phenol aldehydes such as 4-hydoxybenzaldehyde,
coniferyl aldehyde, syringaldehyde and vanillins) are inhibitors to cell grow and
ethanol yield for most yeasts and bacterial strains. Lignin derived aldehydes seems
to be more inhibitor than those derived from cellulose.
Ketone inhibitors: exert a greater inhibitory effect on bacteria such as
thermoanaerobacter mathranii than on yeast in term of reduced grow and ethanol
yield.
Phenols such as cathecol, hydroquinone, and coniferyl alcohol almost completely
inhibit E. coli. However, eugenol and isoeugenol are inhibitory to yeast at low
concentrations. The general toxicity of a phenol compound to yeasts has been
correlated to the degree of its methoxy substitutes ortho to the phenol hydroxy
group. The order of inhibitory effect ranked from strong to weak is as follows: (1)
hydroxyphenol (2) guaiacyl and (3) syringyl.
Organic acids, in general are more toxic to isolates of bacteria than yeats. The
toxicity of organic acids has been correlated with their degree of hydrophobicity,
suggesting the involvement of a hydrophobic target such as the cell membrane.
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
INHIBITORY COMPOUNDS DERIVED FROM LIGNOCELLULOSIC MATERIALS
Overcoming the impact of inhibitory compounds derived from
lignocellulosic biomass is one of the major challenges for a sustainable
biomass to bio-fuels industry. Research and development in this area is
under way in order to develop methods that limit the production of
potential inhibitors produced during the deconstruction of biomass. Each
of the currently available methods has different advantages and
disadvantages.
Remediation Treatments (Detoxification)
Physical
Chemical
Bio-Chemical
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
INHIBITOR REMOVAL METHODS
PHYSICAL: Vacuum evaporation (used to remove the amount of volatile compounds)
(Concentrations of furfural, vanillin, and acetic acid can be reduced from 29 to 100 %)
CHEMICAL: Precipitation of toxic compounds (such as alkali treatment using Ca(OH)2 or
NaOH. By employing overliming the pH of the hydrolysate can be increased to 9 – 10
and subsequently readjusted to an appropriate value using acid addition prior to
microbial fermentation). This method reduces aldehyde and ketone inhibitors,
including furfural and HMF, improves microbial growth and fermentation
performance. The formation of CaSO4 precipitation product must be removed. This
additional step increases costs and generate an additional waste. Activated Carbon:
Level of toxic compounds is reduced.
BIO-CHEMICAL: Enzymatic treatment using peroxides and laccase from the lignolytic
fungus Trametes versicolor has been reported to improve ethanol productivity of a
fermentation process based on willow hemicellulosic hydrolysate. The soft-rot fungus
Trichoderma reesei has been reported to be able to degrade inhibitory compounds in
a hydrolysate after steam pretreatment.
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges and opportunities.
November 8, 2010.
C.- CELLULOSIC ETHANOL
PERSPECTIVE
The main challenges for cellulosic biomass based bio-ethanol
process are:
(1) The utilization of pentoses such as xylose and arabinose
(2) The simultaneous utilization of glucose and pentoses
(3) A lower sensitivity to fermentation inhibitors.
Vertes A.A., Qureshi N, Blaschek H, Yukawa H: Biomass to Biofuels. Strategies for Global Industries.
Wiley 2010
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges and opportunities.
November 8, 2010.
C.- CELLULOSIC ETHANOL
Bura R, Gustafson R: Bioconversion of lignocellulosic biomass to ethanol: Challenges and opportunities.
November 8, 2010.