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Emerging Ethanol Production Technologies
Presented by:Steffen Mueller
Ken Copenhaver
University of Illinois at ChicagoEnergy Resources Center
Presented to:CRC Workshop on Life Cycle Analysis of Biofuels
Argonne, ILOctober 21, 2009
IntroductionOver the years modern ethanol plants have started to adopt technologies that transform the industry into integrated biorefineries producing– multiple fuel, – feed, and – bioplastic products
These technologies also alter the energy and environmental impact including the Global Warming Impact “GWI”, and co-product balance from corn ethanol productionEmerging technologies can be grouped into– corn farming technologies– ethanol processing technologies
Base Process – Corn FarmingCorn is produced by – combining the corn hybrid appropriate for the soil
and climate conditions, with the corn transgenic traits desired for herbicide tolerance or pest control
– and the corresponding agro-economic practice (including fertilizer, pesticide, herbicide, tillage, irrigation, and other practices)
The harvested corn is stored on farm or shipped directly to the ethanol plant or to a grain elevator first and then to the ethanol plant for processing.
Base Process – Ethanol ProcessingOnce arrived at the ethanol plant the traditional dry mill process consists of the following steps: – Corn is ground and slurried with water and enzymes– Cooking of the slurry to gelatinize and liquefy the starch– The mash is cooled and another enzyme is added to
convert the starch into fermentable sugars – The yeast is added to ferment the sugars to ethanol and
carbon dioxide, followed by distillation and dehydration– Besides ethanol a typical plant also processes the non-
fermentable nutrients (protein, fat, and fiber) which are processed into animal feeds such as distillers dried grain with solubles (DDGS) or wet distillers grains with solubles (WDGS)
Base Energy Requirements – Corn FarmingCorn production takes approximately between 5,000 and 20,000 Btu/bushel of energy
Main energy requirements: – Farm equipment fuel (tractor, combine, etc.) – Irrigation, Corn drying, Seed production
Separately, N-fertilizer:– Energy to produce N fertilizer and other
chemicals– N2O Emissions from fertilizer application
Base Energy Requirements – Ethanol ProcessingOver the last 8 years, the natural gas consumption at dry mill ethanol plants has been steadily decreasing The 2001 Ethanol Plant Development Handbook quotes a natural gas use of 40,000 Btu per denatured gallon (Higher Heating Value or HHV) and 1.4 kWh/gal of electricity (assumes 100% DDGS drying) In 2006, ICM, Inc. a major ethanol plant process developer provided process guarantees for new natural gas fired ethanol plants in the range of 32,000-34,000 Btu per denatured gallon (thermal energy) and 0.75 kWh/gal (electricity) with 100% DDGS drying and 22,000 to 24,000 Btu per denatured gallon without DDGS drying
Base Energy Requirements – Ethanol Processing
Today, the natural gas energy consumption of a modern ethanol plant is even lower A recent energy balance conducted at the Illinois River Energy Center (IRE) documented – a natural gas consumption of 29,000 Btu per denatured
gallon (30,000 Btu per anhydrous gallon) and – 0.69 kWh per denatured gallon (0.71 per anhydrous
gallon) of electricityWe are currently conducting a new industry survey of energy consumption at ethanol plants.Yields are ~2.73 gallons of ethanol per bushel and 5.7 lbs DDGS per gallon
Ethanol Storage
Cooking
Distillation
Fermentation
Ethanol
Centrifuge
Evaporator D
ryer
Grinding
Whole
Stillage
ThinStillage
DDGS
WDGS
WetCake
Syrup/SolublesC
orn
Thermal Energy
Electric Energy
Farm Energy
Chemicals
Corn Traits
Ethanol Base ProcessCorn Production
Ethanol Processing
Molecular S
ieve
Corn Production -What are the New Technologies?
GPS Tracking with Auto-Steer
Soil Testing and Remote Sensing for Nitrogen Inputs
Use of Nitrification Inhibitors
Use of GEO (genetically enhanced organism) corn
Use of No-Till Practices
Ethanol Processing –What are the New Technologies?
Dry Mill Corn FractionationCorn Oil ExtractionCombined Heat and PowerCold Cook Process (aka raw starch hydrolysis)New Boilers and Motors Anaerobic DigestersBiomass Combustion/GasificationOther Renewable Energy
In the following we will showcase some of these technologies…
Dry Mill Corn FractionationFractionation separates the corn kernel into its components: the pericarp, the endosperm, the germ, and the tip cap.
The endosperm contains 92 to 96% of the starch, the germ contains close to half of the oil, and the pericarp and the tip cap (collectively called bran) consist primarily of cellulose/fiber.
By separating these parts, multiple co-products are possible: – The endosperm is processed into ethanol and a higher
protein, higher value animal feed, – the germ into food grade corn oil. – The bran can be converted into cellulose ethanol, or a
feed product, or a biomass energy feedstock.
Dry Mill Fractionation
Feed Products– High Protein Distillers Dried Grains. The low oil and bran
content in the now degermed and debraned corn stream allows production of a high protein animal feed (HPDDG) that is commercially sold as 37-44% protein
– Corn Gluten Feed. Mixing deoiled germ, bran, and syrup results in a feed product that is sold as 20% protein
– Bran Cake. Mixing bran and syrup results in a feed product that is sold as bran cake
Dry Mill FractionationCellulose Ethanol from Corn Kernel– Bran conversion to cellulose ethanol utilizes
specific enzymes which can convert corn kernel fibers into fermentable sugars
– Technology can increase the ethanol yield from a bushel of corn by between 4-10%[
– Challenges are to develop affordable enzymes, and concentrated process streams
– The technology increases overall yield at constant conversion efficiencies
Dry Mill FractionationIf all products are dried to approx. 10% moisture, the thermal energy savings over the base process from either producing HPDDG combined with Corn Gluten Feed or from producing HPDDG combined with Bran Cake is 18%
On the electric side, the hammer mills in traditional dry mill processes are replaced by roller mills increasing electricity use to approx. 1 kWh/gal electricity
Dry Mill Fractionation
Yields on AverageEthanol: 2.64 gal/buHPDDG: 2.6 lbs/galCorn Gluten Feed: 3.7 lbs/galCorn Oil: 0.75 lbs/buBase Energy Requirements (relative to 30,000 Btu/gal Base Plant: 24,720 Btu/gal, 1 kWh/gal
Dry Mill FractionationKey Technology Providers:– Buhler Inc., Ocrim/Delta-T, Cereal Process Technologies,
MOR Technologies, Satake USA, Crown Iron Works Renessen LLC (joint venture between Cargill and Monsanto; process name: Extrax), ICM via Applied Milling (“Total Kernel Optimization”), FCStone Carbon LLC with Maize Processing Innovators Inc (licensing University of Illinois’ Quick Germ Quick Fiber technology)
Current Plants Employing Technology:Renew Energy, Jefferson, Wisconsin (using the CPT Process)Pilot Plant in Eddyville, Iowa (using the Extrax Process)Didion Milling, Johnson Creek, WisconsinBadger State Ethanol, Monroe, WisconsinIllinois River Energy, Rochelle, Illinois (in development)
Ethanol Storage
Cooking
Distillation
Fermentation
Ethanol
Centrifuge
Evaporator D
ryer
Fractionation Unit
Whole
Stillage
ThinStillage
HPDDG
Bran Cake
Syrup/SolublesC
orn
Corn Oil
Thermal Energy
Electric Energy
Dry Mill Fractionation
Bran Feed Products
Farm Energy
Chemicals
Corn Traits
WetCake
Bran EnergyFeedstock
Corn Gluten Feed
Molecular S
ieve
Corn Oil ExtractionBesides fractionation corn oil can also be removed from the kernel using centrifuges either before or after the ethanol distillation process
Corn oil removed before distillation => food grade product, corn oil removed after distillation => fuel product
Manufacturers quote an extraction rate of about 3-4% by volume:– a 100 million gallon per year ethanol plant can produce
an additional 3-4 million gallons of corn oil.
The resulting deoiled/debranned DDGS can be of equal value to the feed industry.
Corn Oil Extraction
Thermal energy requirements are unchanged from the base process.
However, VOC emissions during the drying process are reduced.
Electricity needs will increase by about 10% to operate the centrifuges for oil extraction.
Corn Oil ExtractionThe COPE process developed by Prairie Gold Inc. uses a different approach and extracts the corn oil prior to the fermentation by percolating ethanol back through the ground corn meal.
This extraction process produces food grade corn oil as well as the protein “zein” that can be used for biodegradable products and plastics.
Ethanol Storage
Cooking
Distillation
Fermentation
Ethanol
Centrifuge
Evaporator D
ryer
Grinding
Whole
Stillage
ThinStillage
DDGS
WDGS
Syrup/SolublesC
orn
CornOil
Extraction
Corn OilThermal Energy
Electric Energy
Corn Oil ExtractionFarm Energy
Chemicals
Corn Traits
WetCake
CornOil
Extraction
COPEZein/Oil
Extraction
Bio Plastics
Molecular S
ieve
Corn Oil ExtractionKey Technology Providers: – Greenshift Corporation– Primafuel Solutions– Prairie Gold, Inc.
Installations:– Little Sioux Corn Processors, Marcus, Iowa (Greenshift
system)– Utica Energy, LLC, Oshkosh, WI (Greenshift system, corn
oil extracted an converted into biodiesel)– Western NY Energy, LLC, Medina, New York (Greenshift
system, corn oil extracted and converted into biodiesel)– Amaizing Energy LLC, Denison, Iowa (Primafuel system)
Combined Heat and PowerCombined heat and power systems generate electricity and useful thermal energy from the same fuel source
Natural gas fired CHP systems consist of a boiler with a steam turbine or a combustion turbine with a heat recovery system and a steam turbine
Biomass and Coal fired CHP systems consist of a solid fuel boiler and a steam turbine
The thermal energy generated from a CHP system is used to meet cooking, distillation, drying needs of the plant.
Combined Heat and PowerThe electricity can be utilized to meet all or a portion of the electric load of the plant with supplemental electricity purchased from the incumbent utility companyCHP systems can achieve significant overall energy savings: With an increase of about 10% in natural gas or coal use plants can offset up to 85% of their electricity needsAbout 10 plants employ this technologyTechnologies are provided by diverse engine, boiler, and turbine manufacturers.
Ethanol Storage
Cooking
Distillation
Fermentation
Ethanol
Centrifuge
Evaporator D
ryer
Grinding
Whole
Stillage
ThinStillage
DDGS
WDGS
Syrup/SolublesC
orn
Combined Heat and Power (CHP)
Combined Heat and PowerFarm Energy
Chemicals
Corn Traits
Electric Energy
Thermal Energy
WetCake
Molecular S
ieve
Electricity Export
Anaerobic Digester Biogas ProductionA modern ethanol plant produces approximately 5 gallon of thin stillage for each gallon of ethanol. An anaerobic digester can convert the thin stillage into biogas that consists approximately 60% of methane
Biogas can be combusted to offset energy needs
Plant base energy requirements will drop from 30,000 to 27,290 Bu/gal since solubles are not dried
Thin stillage can produce approx. 21,000 Btu/gal (HHV) of energy and provide 75% of the plant’s energy.
The trade-off is a reduction in animal feed output to 2.6 lbs/gal DDG plus 0.25 lbs/gal of NPK fertilizer
Anaerobic Digestion with FractionationThermal Needs: 24,720 Btu/gal [base fractionation]-2,710 Btu/gal [no solubles drying]-21,000 Btu [digester]=1,010 Btu/galElectric: 1.03 kWh/gal
Ethanol Yield: slightly lower 2.64 gal/bu
Co-Products: 2.6 lbs/gal HPDDG. Combining fractionation with anaerobic digestion of thin stillage does not enable production of corn gluten feed, but alternatively 0.5 lbs/gal ofbran. Bran may be used as a feed product.
0.25 lbs/gal of NPK fertilizer
Other Energy Saving TechnologiesTechnologies that are currently in various stages of the commercialization process will increase the efficiency of currently utilized energy generating and conversion equipment such:– NEMA Premium Efficient Motors– Superboilers– Distributed Control and Instrumentation Systems
Other Promising Technologies on the Horizon– For example production of ethyl lactate/solvent from
ethanol will alter co-product and energy balance
Example A:GWI Variation of Ethanol Plants by Energy System(model Iowa plant)
Source: Plevin and MuellerEnv. Res. Letters, 2008
Ethanol Storage
Cooking
Distillation
Fermentation
Ethanol
Centrifuge
Evaporator D
ryer
Grinding
Whole
Stillage
ThinStillage
DDGS
WDGS
WetCake
Syrup/SolublesC
orn
Thermal Energy
Electric Energy
Farm Energy
Chemicals
Corn Traits
Ethanol Base ProcessCorn Production
Ethanol Processing
Molecular S
ieve
Corn Production TechnologiesDepending on the employed practice (irrigation, corn drying, equipment vintage) corn production takes approximately between 5,000 and 20,000 Btu/bushel of energy
Several technologies and practices can reduce energy consumption further including:– No till practices under certain conditions reduce tractor
trips across the fields and can save fuel costs– Farm Machinery Technologies Using GPS Tracking
Technology with Auto-Steer reduce overlap along each field pass.• Reduces fuel consumption by about 5%• Reduces seed use and chemicals by about 5%
Corn Production Technologies– Soil Testing and Remote Sensing: Other methods
which allow a more precise application of nitrogen fertilizer include • soil testing to determine nitrogen availability in different parts of the field and
• remotely sensed imagery which can be used in-season to apply N only where needed based on plant vigor
– Nitrification Inhibitors: Work by retarding the formation of Nitrate by nitrifying bacteria => reduced N2O greenhouse gas emissions
Corn Production Technologies
– Use of GEO (genetically enhanced organisms) corn• Use of GEO corn may reduce use of pesticides, herbicides thus reducing the amount of tractor trips across the field.
• Furthermore, GEO corn increases yield thus reducing the energy per bushel spent.
Example B:GWI from N-Inputs to Produce Ethanol at Illinois River Energy Center
Fertilizer as currently applied at IRE at 0.81 lbs/bu results in GWI contribution of ~14 gCO2//MJIn contrast, farms that apply 1.6 lbs/bu would contribute ~24 gCO2//MJFarms that apply 0.6 lbs/bu (theoretical minimum) contribute ~11 gCO2/MJ
Global Warming Impact of IRE Produced Corn Ethanol
0.010.020.030.040.050.060.070.080.090.0
100.0
Gasoline GREETDefault
IRE
gCO
2/MJ
C-Sequestration
IRE Biorefinery
Other Ag andDistributionN Fertilizer
Fertilizer Contribution to GWI of IRE Corn Ethanol
0.05.010.015.020.025.0
0.600.801.001.201.401.60
N Fertilizer Applied in lb/bu
gCO
2e/M
J of
Et
hano
l
Utilization of Advanced N-Application Technologies
Conclusions
Corn ethanol production is continuously improving
Need policies that push advanced ethanol technologies and not discourage ethanol altogether
