This document discusses small-scale cassava-based ethanol production systems in Africa. It outlines a potential system using smallholder agroforestry with integrated food, feed, and fuel production. Cassava and other crops would be grown and processed at community centers into products like ethanol for cooking fuel. Enzymes play a key role in converting cassava starch into fermentable sugars and finally ethanol. Novozymes enzymes are suitable and the company can provide technical assistance for such projects.

2. Novozymes in brief

3. Two different pathways:
1. Large scale cassava focused production systems like
in Asia producing ethanol for use a e.g. transport fuel
2. Small scale – e.g. integrated agro-forestry systems
producing ethanol for use in cook-stoves, as well as
misc. food, feed and other energy products
Cassava based ethanol in an African context

4. 1. Reduce deforestation due to charcoal production
2. Reduce accidents and negative health effects relating
to indoor use of kerosene, wood or charcoal
3. Improve access to affordable energy
4. Stimulate local agriculture through
smallholder/outgrower schemes
Benefits of small scale agro-forestry systems
producing ethanol to replace charcoal

5. • 100% family sector growers
– Agro-forestry systems
– Degraded & abandoned plots
– Diverse mix of trees and crops
– Increased food quantity and quality
– Raw materials for energy products
• Community pre-processing centres
– Buying, training, technical assistance, pre-
processing, storage, logistics
• Fruit & Veg  consumed locally
• Cassava  dried chips
• Oilseeds  raw plant oil
• Beans  dried & packed for cities
• Waste  animal feed and biofertilizer
• BioProcessing Centre
– Production of ethanol
• Household cooking fuel
– Production of Pure Plant Oil
• Diesel substitute in converted generators
• Cookstove Manufacturing Facility
5
Outline of a potential smallholder/outgrower
based system

6. Smallholder agro-forestry concept with
integrated food, feed and fuel production

7. The Fuel Ethanol Process

8. Raw Materials for Ethanol Production
• Ethanol can be fermented from sugars
• Sugars can be produced by enzymes from starchy
raw materials
• Starchy raw materials can be any cereal grains or
starchy plant roots
• Examples:
• Corn, wheat, millet, sorghum, rye, barley, rice,
cassava

9. Starch in cassava
Protein
middle
lamella
Outer wall
(β-Glucan and
pentosan)
Inner cell wall
(β-Glucan)
Starch
granules
Protein
matrix

10. General overview of starch conversion to ethanol

11. 3 types of enzymes required
1. Viscosity reducing enzymes
– Viscozyme Cassava R
– Viscozyme cassava C
2. Alpha-Amylase
– Liquozyme SC, SC DS and 4X
3. Gluco-Amylase
– Spirizyme Fuel
– Spirizyme Ultra
– Spirizyme Excel

12. Three stages where enzymes are added
Milling /Slurry make up Cooking Fermentation
Type of
enzyme
added
Viscosity reducing enzyme Alpha-Amylase Gluco-Amylase
Enzyme
name
1. Viscozyme cassava R
2. Viscozyme cassava C
1. Liquozyme SC
2. Liquozyme SCDS
1. Spirizyme fuel
2. Spirizyme ultra
3. Spirizyme Excel
Main
Purpose
Reduce viscosity due to non
starch polymers
1. Reduce viscosity due to starch
polymers
2. Converts starch to dextrin
To convert dextrin to
glucose
Other
Benefits
1. Enable mash to be
pumped
2. Avoids gel formation
3. Lower heating and cooling
cost
1. Processes starch to be suitable for
fermentation
2. Enables better mixing of enzymes
3. Avoids gel formation
Enables yeast to
consume the glucose
and generate ethanol
Working
Temp
50-55°C 84-86°C 32-35°C

13. Ethanol yield from starch: Cassava example
Yields from 1 ton raw material
Cassava Roots Chips Starch
% Starch 25 65 85
100% theoretical
Ethanol, litres 180 468 612
93% efficiency
Ethanol, litres 167 435 569

14. Milling & Cook: Slurry formation and initial
breakdown of starch
1. Grind cassava into smaller particles (flour)
– Increase surface area (accessibility to the enzyme)
2. Mix flour with water to form a slurry
– Form a uniform mixture
– Add enzymes to reduce viscosity
– Add enzymes to start transformation of flour into dextrin
3. Cook slurry at high temperature use jet or steam
– Flour absorbs the hot water and becomes “mash”
– Mash becomes thick (viscous) – becomes gelatinized
4. Hold at temperature
– Allow time for enzymes to break starch into short chain dextrins

15. Initial breakdown of starch into shorter dextrin
chains
Alpha-Amylase enzyme randomly cleaves large chain
dextrins into a mixture of shorter chain dextrins
Alpha-amylase
Shorter dextrin chains
Large
Dextrin chains
DP6
DP4
DP3
DP2

16. Further breakdown of dextrins into
fermentable sugars: Two main process options
• Pre-fermentation saccharification
– Pre-fermentation saccharification in separate tank for a few
hours at optimal conditions
• Simultaneous saccharification and fermentation
– Sugars are generated with the yeast present
– Occurs at typical fermentation conditions
Saccharification: Breakdown of dextrins into glucose

17. What does Gluco-Amylase do?
Gluco-Amylase breaks short chain dextrins into simple
fermentable sugars that yeast can convert into ethanol
Long chain sugarsLong chain sugars
(Dextrins)(Dextrins)
SimpleSimple
sugarssugars

18. Typical cost breakdown for cassava-based ethanol
production – example from Asia

19. How Novozymes can assist you
• Provide enzymes solutions designed for starchy
raw materials – and including for cassava
• Share our vast global process experience with
our customers
• Continuously develop new enzymes and process
technologies

20. Thank You
for your attention
Please visit our website
www.bioenergy.novozymes.com
Technical service contact: HXL@novozymes.com