Small Scale NZ Biofuel TechnoEconomic Investigation

1
Small Scale NZ Biofuel Techno-Economic
Investigation

• VISHESH ACHARYA
• MASTER OF ENGINEERING
• DR. BRENT YOUNG
• CHEMICAL AND MATERIALS ENGINEERING
• UNIVERSITY OF AUCKLAND

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OVERVIEW

• Introduction to Bio Ethanol
• Benefits of Blending Ethanol with Petrol
• Bio Ethanol Manufacturing Process
• Classification of feedstock
• Potential of various Starch, Sugar and Cellulosic
  materials as Feedstock in NZ
• Conclusions

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What is Bio Ethanol?

• Alcohol based liquid fuel made from agricultural
  bio mass
• Produced by fermenting sugar from Energy crops
• EU, USA and Brazil mandate a minimum ethanol
  blend.
• NZ govt mandates selling a minimum of 0.25 of
  all fuel sold to be that of Bio fuels, starting
  2008

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Benefits of Blending Ethanol with Petrol

• Contains 35 mole percent O2
• Acts as an oxygenate facilitates combustion to
  a greater extent
• Increases energy efficiency by 1

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Manufacturing Process
ENZYMES
Feedstock
HYDROLYSIS
ENZYMES
50 EtOH
95 EtOH
YEAST
AZEOPTROPIC
10 EtOH
DEHYDRATOR
FERMENTATION
BEER STRIPPER
RECTIFIER
99.6 FUEL GRADE ETHANOL
SOLIDS
WATER
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Classification of Feedstock

• Classified into 3 types depending upon the
  constituent sugars
• SACCHARINE Directly fermentable 6 and 12 C
  sugars
• Glucose, Fructose and Maltose
• E.g. Sugar cane, Sugar beet, Whey, etc.
• STARCH Carbohydrates such as Starch
  and Inulin
• E.g. Maize, Wheat, Potatoes, etc.
• CELLULOSE Common material in plants
• Primary constituent of plant cell wall
• Wood, wood waste, paper, straw, etc.

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SACHHARINE Fruits Molasses
STARCH Grains Potatoes
CELLULOSE DRY Green
MILLING
PRE TREATMENT
SHREDDING
MASHING
MASHING
DILUTION
DILUTION
DILUTION
LIQUEFACTION
HYDROLYSIS
HYDROLYSIS
FERMENTATION
DISTILLATION
DEHYDRATION
DENATURING
STORAGE
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Starch Crops

• Maize, Wheat, Barley and Milo (Sorghum) are the
  most extensively used Starch based feedstock
• Maize is the most widely used feedstock
• Current annual production of Maize based ethanol
  is 20 Billion L

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Ethanol from Maize

• Ethanol from Maize is produced by 2 methods
• Dry Milling
• Ethanol - Primary product
• Distiller Dried Grains and Solubles (DDGS) and
  CO2 Secondary Products
• Typical yields 460 L EtOH/T Maize
• 380 kg DDGS/T Maize

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Dry Milling Process for the production of Ethanol
from Maize Henderson, C. (2006)
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Ethanol from Maize

• 2. Wet Milling
• Gluten Feed, Starch, Corn oil, Corn Germ and Corn
  Syrup Liquid Primary products.
• Starch is further hydrolysed and fermented to
  Ethanol
• Typical Yield 440 L EtOH / T Dry Maize
• Yield lower than Dry milling as some starch is
  lost in co-products.
• Process more complex than Dry milling
• Hence, requires higher capital investment

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Wet Milling Process for the production of Ethanol
from Maize Henderson, C. (2006)
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Ethanol from NZ Maize

• 150,000 tonne Maize grown on 13,000 Ha. of land
• NZ Maize yield 12.5 t/Ha (U.S. Maize yield 8
  t/Ha)
• Energy input for un-irrigated arable Maize
  farming in NZ 1683 MJ / t Maize
• Avg. US Maize farming input 2425 MJ / t Maize

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Cost Ethanol from NZ Maize

• Potential Yield 397 L EtOH / t Maize
• Dry Mill Process, 95 ML/yr
• 90.3 NZc/L EtOH
• Maize sourced from within 100km _at_ NZ10/t
• Wet Mill Process, 95 ML/yr
• 76.6 NZc/L EtOH
• Maize sourced from within 100km _at_ NZ10/t
• Ethanol made using Geothermal Steam to be cheaper
  by 4.5 NZc/L

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Ethanol from Sugar Crops

• Sugar Cane and Sugar Beet widely used Ethanol
  feedstocks
• Brazil produced 4.5b Gallons of Ethanol in 2006
• Contains Sucrose which can be directly fermented
  into Ethanol
• Hence, processes are relatively simpler and more
  cost effective
• Sugar Cane is of particular interest
• Has high ethanol yield 7750 L/Ha (Corn 2750
  L/Ha)
• Shorter fermentation period of 6-10 hours (Corn
  48 - 72 hrs)

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Ethanol from Waste Products Cellulosic Waste

• Cellulosic materials most abundant and
  potentially cheap feedstock for ethanol
  production
• Includes wastes from agriculture, forest and
  municipal solid waste.
• Potential to exploit 290,000 t.p.a of landfilled
  paper waste and 430,000 t.p.a. of cereal straw.
• Manufacturing cost estimated at NZ0.7-NZ1.30/ L
  EtOH
• Technology currently exists on Lab. scale only

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Ethanol from Potato Processing Waste

• 500,000 t.p.a grown on 20 of total arable farm
  land
• Solid potato waste accounts for about 20 of
  potato crop
• Potatoes have a high fermentable carbohydrate
  content of 20 w/w
• Starch from 150,000 tonne potato waste can be
  potentially converted to 1.5 MML of ethanol
• Estimated production cost NZ1.4-1.5 / L EtOH
• Co-processing with other feedstock likely to
  reduce these costs by 50c to NZ0.9-1.0 / L EtOH

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Ethanol from Fruit Crop Waste Kiwi fruit

• Kiwi fruit has very high content of Starch,
  Fructose and Sucrose.
• Fermentable sugar content estimated as 8(w/w).
• Average ethanol yield of 44 L EtOH/t kiwi fruit.
• Cost of making ethanol from kiwi fruit, in an
  already existing ethanol plant is estimated at
  NZ0.7-0.8/ L EtOH

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Conclusions

• NZ grows several agricultural products that have
  the potential to be converted into bio ethanol
• Sugars crops such as Sugar cane are easier to
  process than Starch crops such as Maize.
• Ethanol can be produced in NZ at the cost of
  NZ0.7-1.0/L EtOH depending upon the feedstock
  used.

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Acknowledgement

• Foundation of Research Science and Technology
  (FRST) for their generous financial support
• Derek Turnbull, Steve Holmes
• Tamaki Controls Ltd.
• Project Mentors