1. ENGINEERING ASPECTS OF BIODIESEL PRODUCTION PROCESS
Nurhan Turgut Dunford
Oklahoma State University
Department of Biosystems and Agricultural Engineering

2. Outline Introduction Transesterification Esterification
Homogeneous catalysis
Heterogeneous catalysis
Enzymatic conversion
Conversion without a catalyst
Lipid hydrotreating
Planning for production
Site selection

3. Petroleum
A naturally occurring oil that contains mainly hydrocarbons with some other elements such as sulphur, oxygen and nitrogen
Gasoline: A mixture of hydrocarbons containing 5-8 carbon atoms, boiling point oC
Kerosine (paraffin oil): A mixture of hydrocarbons containing carbon atoms, boiling point oC
Diesel oil: A mixture of hydrocarbons containing carbon atoms, boiling point oC

4. Petroleum Diesel A fuel derived from the distillation of crude oil
It is heavier than gasoline but lighter than engine oil and heavy  oils.  
Diesel fuel is generally  separated into two fuels: diesel number 1 and diesel number 2.  Diesel number 1 is similar to kerosene  and is lighter than diesel number 2.   While diesel number 2 is sold most of the time, diesel number 1 is sold  during winter in very cold climates because it doesn’t cloud or gel as easily  as diesel number 2.
Diesel fuel is ignited in an internal combustion engine cylinder by the heat of air under high compression in contrast to motor gasoline, which is ignited by electrical spark.

5. Definition of Biodiesel
“A fuel comprised of mono-alkyl-ester of long chain fatty acids derived from vegetable oils or animal fat designated B100”
Biodiesel safety:

6. Why Biodiesel?
Can be used in existing diesel engines without modification.
Can be blended in at any ratio with petroleum diesel.
Similar Btu/gal as petroleum diesel.
Also eliminates the huge cost of revamping the nationwide fuel distribution infrastructure.
Reduces CO2 emission.
Average Density and Heating Value of Biodiesel and Diesel Fuel
Fuel Density, g/cm3 Net Heating Value Avg., Btu/gal. % Difference vs.
No. 2 Diesel Avg.
No. 2 Diesel ,500
Biodiesel (B100) , %
B20 Blend (B20) * ,259* %*
B2 Blend (B2) * ,276* %*
* Calculated Values from those of No. 2 Diesel and Biodiesel (B100)

7. Triacylglyceride + C H OH HOOCR HOOCR’ HOOCR” 3H O GLYCEROL2 O
GLYCEROL
FATTY ACIDS
TRIGLYCERIDES
WATER

8. Fatty Acid Molecular Structure

9. Saturated Fatty Acids

10. Monounsaturated Fatty Acids

11. Polyunsaturated Fatty Acids

12. R - COOH + R1- OH R – COO - R1 + H2O
Esterification
R - COOH + R1- OH R – COO - R1 + H2O
Fatty Acid Alcohol Catalyst Ester/biodiesel Water
Methanol safety:

13. Transesterification
Triacylglyceride Alcohol Esters/Biodiesel Glycerine
Wheat is an excellent crop for application of the biorefinery concept.
R1, R2, R3 are hydrocarbon chains on fatty acids and
R’ is the alkyl group on an alcohol molecule

14. Homogeneous Catalysis
Acid or Base Catalysis
Dryer
Biodiesel
Oil/fat
Reactor
Biodiesel
Alcohol/
catalyst
Separator
Wash
Column
Glycerine + Alcohol
Water
Alcohol
Glycerine + Water
+Alcohol
Glycerine
Recovery
Alcohol
Recovery
Glycerine
Glycerine + Water

15. Homogeneous Catalyst Options
Base Catalysts: NaOH, KOH, Na/K-Methoxide
Acid Catalysts: H2SO4, H3PO4, CaCO3
Lipase Enzymes

16. Base Catalyzed Conversions
Base catalyzed processes dominate current commercial production
Sensitive to water and free fatty acids
Typical alcohol to oil ratio varies between 6:1 and 10:1 (mole ratio)
Typical catalyst concentrations (w/w, %)
NaOH/KOH %
Na-Methoxide 0.5% or less

17. Acid Catalyzed Conversions
Direct esterification, oils with high free fatty acid content or for making esters from soap stock
Requires water removal
Requires high alcohol:free fatty acid ratio, i.e. 40:1
Requires large amount of catalyst (5-25%)

18. Homogeneous Catalysis Alcohol + Base Catalyst
Two-Step Process
Dryer
Biodiesel
Alcohol + Catalyst
Alcohol + Base Catalyst
Oil/fat
Biodiesel
Acid
Reactor
Alcohol/
Acid catalyst
Base
Reactor
Separator
Wash
Column
Glycerine +
Alcohol
Water
Alcohol
Glycerine
Recovery
Glycerine +
Alcohol + Water
Alcohol
Recovery
Glycerine
Glycerine +
Water

19. Heterogeneous Catalysis
Biodiesel
Alcohol
Glycerine
Glycerine
Alcohol
Oil/fat
Glycerine

20. Heteregeneous Catalysts
Sulfated zirconia and tungstated zirconia are typical
examples of superacids
Sulfonic resins such as Nafion® NR50, sulphated zirconia (SZ), and tungstated zirconia (WZ), have sufficient acid site strength to catalyze biodiesel-forming transesterification reactions as efficiently as sulfuric acid.
Many types of heterogeneous catalysts, such as alkaline earth metal oxides, various alkaline metal compounds supported on alumina or zeolite can catalyze transesterification reactions. The order of activity among alkaline earth oxide catalysts is BaO > SrO > CaO > MgO

21. Heterogeneous Esterfip-H Process Highlights
Continuous technology based on solid catalyst
High glycerol purity >98%
Very high ester yield: close to 100%
No waste production of low-value fatty acids
No waste saline streams that require disposal
Much lower catalyst requirements (per ton of FAME) compared with other processes

22. Enzymatic Conversion Lipases are used as catalyst
Reactor
Enzyme
Biodiesel
Oil + Alcohol
Separator
Glycerine
Lipases are used as catalyst
Immobilized or free enzymes

23. Comparison of Enzyme and Base Catalysis
Catalyst Base Enzyme
Reaction temperature °C OoC
Free fatty acids Saponified products Methyl esters
in raw materials (soap formation)
Water in raw materials Interference with No influence
the reaction
Yield of methyl esters Normal Higher
Recovery of glycerol Difficult Easy
Purification of methyl esters Repeated washing None
Catalyst cost Cheap Relatively
expensive

24. Batch vs Continuous System
Batch process is better suited to smaller plants (<1 million gallons/year)
Batch process provides operation flexibility
Continuous process allows use of high volume separation systems hence increases throughput

25. Transesterification Time
At ambient temperature (70F and 21oC) reaction takes 4-8 h to reach completion
Higher temperature will decrease reaction times but this requires pressure vessel because boiling point of methanol is 148F (65oC)
High shear mixing and co-solvent use accelerates reaction rates

26. Non-Catalytic Conversions
Supercritical fluids
Co-solvent systems

27. Non-Catalytic Conversion Supercritical Methanol
Biodiesel
Alcohol
Oil/fat
High pressure
&
temperature
reactor
Separator
Alcohol
Separator
oC,
atm ( psi),
alcohol:oil 42:1
3-5 min reaction time
Glycerine

28. Non-Catalytic Conversion Co-Solvent Process
Biox Process
Uses an inert co-solvents (tetrahydrofuran, MTBE-methyl tert-butyl ether, ) that generate an oil-rich one-phase system.
This reaction is 95% complete in ten minutes at ambient temperatures.
No catalyst is required.
Alcohol
Oil

29. Phase Separation Required density difference for phase separation 0.1
Specific Gravity
Methanol 0.79
Biodiesel 0.88
Soybean oil 0.92
Catalyst 0.97
Glycerine 1.28
“Good reaction” as much methanol as possible
“Good phase separation” min. methanol

30. SuperCetane
Several reactions occur in the process, including: hydrocracking (breaking apart of large triglyceride molecules), hydrotreating (removal of oxygen), and hydrogenation (saturation of double bonds). A conventional commercial refinery hydrotreating catalyst is used in the process and hydrogen is the only other input.
Feedstocks: canola oil, soya oil, yellow grease, animal tallow and tall oil (a by-product of the kraft pulping process).
Cetane number (a measure of ignition quality) of around 100 – which is comparable to commercial cetane additives. The specific gravity of SuperCetane is similar to regular diesel while its viscosity is similar to biodiesel. It is 97% biodegradable as compared to 45% for regular diesel.

31. AVRO Diesel TM Process
( combines mild thermal cracking with esterification. This process is being patented by the CANMET Energy Technology Centre – Ottawa.
Feedstock: waste animal fats, cooking greases, and trap grease that are 'too contaminated' for a conventional trans-esterification process, and produces clean diesel fuel.
The process yields 65 to 75 wt%
hydrocarbons/methyl-esters mixtures
suitable for diesel fuel blending.

32. ConocoPhillips/Tyson Renewable Diesel
The production technology for renewable diesel uses a thermal depolymerization process to co-process animal fat with hydrocarbon feedstock.
The fuel is chemically equivalent to the diesel produced from hydrocarbon feedstocks and can be transported directly through existing pipelines to distribution terminals.

33. Biodiesel DryWashTM Adsorbent purification
Magnesium Silicate (Magnesol D-Sol)
Removes both particles and soluble impurities
Excess methanol flash evaporated

34. Ion Exchange Dry Wash
Ion exchange resin is used for biodiesel cleaning.
Greenline & Rohm-Haas Corporation collaboration: Ion-exchange resin known as Amberlite.
Amberlite looks very much like coffee grounds and functions much like coffee grounds in a percolator. The biodiesel fuel enters the top of the percolator and trickles down through the cylinder of Amberlite.
The final product is pure and dry.
The resin needs replacing at the rate of about 1 metric ton for every 250,000 gallons of biodiesel processed.

35. Technology Providers Desmet Ballestra North America
Westfalia Separator, Inc.
Crown Irons Works
Lurgi PSI 

36. Reading Material
University of Idaho-Questions

37. Questions Define biodiesel
What are the three components that are required for making biodiesel?
What are the advantages and disadvantages of using ethanol instead of methanol for biodiesel production?
What are the most common catalysts (acid and base) used for biodiesel production?
Name two reactions that are used for biodiesel production and highlight differences
Compare energy contents of biodisel and petroleum diesel
Name two biodiesel production techniques which do not require a catalyst

40. Biodiesel Production Facilities in the US
Smallest capacity: 50,000 gallons/year, recycled cooking oil
Largest capacity: 37.5 Million gallons/year, soybean
Earth Biofuels Inc, Durant, OK, 10 Million gallons/year, multifeed stock
Green Country Biodiesel Inc., Chelsea, OK, 2.5 Million gallons/year, soybean

41. Biodiesel Industry Expansion
Largest Capacity:100 Million gallons/year
Smallest Capacity: 250,000 gallons/year
ADM, 85 Million gallons/year, canola oil
Best Energy Solutions LLC, Tulsa, OK, 1 Million gallons/year

42. Planning* Location Biodiesel Marketing Feedstock Sourcing
Glycerine Outlet
Process Plant Size
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

43. Location*
Minimizing the freight cost for feedstock and biodiesel will be critical to survive.
How much biodiesel can be sold in a 200 mile radius?
How much competition or potential competition exists in a 200 mile radius?
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

44. Feedstock Sourcing*
Do you have control of your own feedstock supply (as an oilseed crusher or animal fats renderer)?
If you are dependent on an external supply, how many potential suppliers are within a 200 mile radius?
Can you sign a long-term contract with one of these suppliers to insure adequate feedstock?
Will the feedstock suppliers in the area deliver by truck or rail, and at what frequency?
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

45. Glycerin Outlet* Where are the closest potential buyers of glycerin?
What quality of crude glycerin (H2O, MeOH, soap, FFA, salt etc) will they purchase, and at what price relative to USP grade refined glycerin?
Will the glycerin refiners in the area want delivery by truck or rail, and at what frequency?
Do you need to install your own glycerin refinery?
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

46. Process Plant Size*
What plant size will meet the short and long term needs of the local biodiesel market?
How does local feedstock availability limit plant size?
What minimum plant size is required to provide a competitive conversion cost in the long-term?
How much equity and debt financing is available to build the plant, and how much capacity can that buy?
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

47. Plant Site Selection* Transportation Proximity Utility Connections
Specific Parcel of Land
Shared Infrastructure
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

48. Transportation Proximity*
Is the site adjacent to an active freight rail system?
Does the site, or can the site, have a rail siding installed with sufficient length of track?
At what frequency are rail switches possible, and how will the rail cars be moved for loading/unloading?
Is the site in close proximity to a highway?
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

49. Utility Connections*
Does the site have sufficient power supply available?
Does the site have sufficient water supply available (to meet fire protection demand)?
Does the site have a sewer connection that can take the plant waste water?
Does the plant have natural gas supply available?
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

50. Land*
Does the site have sufficient space for the process plant (with surrounding safe area), tank farm, utility building, office building, rail siding and truck route?
Does the site have sufficient extra space for a future biodiesel plant expansion or glycerine refinery?
Is the site long enough for the rail siding to hold a sufficient number of cars?
Any environmental & construction permitting issues?
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

51. Infrastructure*
Does the site already have a process plant staff (management, marketing, purchasing, maintenance and quality control) that can be shared to offset conversion costs?
Does the site already feedstock tanks to reduce feedstock (freight) costs?
Does the site already have utilities that can be shared?
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

52. Critical Parameters* Safety Quality Downtime/Uptime Operating Costs
Capital Costs
* Chris Mitchell – Biodiesel Product Manager Desmet Ballestra North America

53. Safety*
Biodiesel plants use a considerable quantity of highly flammable liquid (methanol) & corrosive material (sodium methoxide).
The process plant must be designed as a hazardous area environment with the hazardous areas within and adjacent to the process building defined by NFPA-497 (NFPA-National Fire Protection Association).
The methanol and sodium methoxide storage tanks must be designed in accordance with NFPA 30.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

54. Safety*
Special Class 1, Division 1, Group D and Class 1, Division 2, Group D explosion proof electrical design is required as per NFPA-70 to minimize a source of ignition.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

55. Quality*
All biodiesel leaving the facility must meet ASTM (American Society of Testing and  Materials) specs at a minimum.
Biodiesel leaving the facility should meet specs as agreed to with the buyer.
Biodiesel should also be transported in clean vessels.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

56. Quality*
Biodiesel should be analyzed before being sent to storage.
A biodiesel plant should have a fully equipped lab with a qualified chemist that understands the chemistry and unit processes in the plant well enough to trouble-shoot feedstock & process issues and give the operations staff feedback.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

57. Downtime*
Plants are often stopped for lack of feedstock, biodiesel and crude glycerine sales, sufficient storage or loading & unloading logistics.
Plants also suffer from quality problems which require significant rework, and resultant loss of production time.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

58. Uptime*
A biodiesel plant should operate a minimum of 8,000 hours per year at its design rate (>90% uptime).
The fixed costs of capital and semi-fixed costs of manpower need to be spread out upon a full production schedule to minimize conversion costs.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

60. Operating Costs*
Approximately 85% of operating cost of a biodiesel plant is for feedstock.
Producing your own feedstock to insure supply at a fair price, and minimizing the freight to deliver the feedstock to the biodiesel plant, are both critical factors in controlling profitability.
An alternative to controlling supply is to have a flexible process to handle multiple feedstock sources (such as soybean oil, poultry fat or yellow grease).
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

62. Operating Costs*
Total conversion costs range from $0.30 to $0.50 per gallon depending on technology and plant size.
Chemical consumptions, utility consumptions and maintenance costs (50-75% of the conversion cost) are more a function of the technology than plant size.
Selecting automated, continuous or semi-continuous process technology is a critical factor in controlling plant profitability.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

63. Operating Costs*
Total conversion costs range from $0.30 to $0.50 per gallon depending on technology and plant size.
Manpower, taxes, insurance and depreciation (25-50% of conversion cost) are more a function of plant size than technology.
Selecting a plant large enough to take advantage of economy of scale (capital & manpower) is a critical factor in controlling plant profitability.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

65. Capital Costs*
Process equipment only accounts for 25-35% of total capital cost in a typical biodiesel plant.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

67. Capital Costs*
Total capital costs for 1-5 mgy biodiesel plants** are typically in the range of $1.75-$1.25 / annual gallon.
Total capital costs for mgy biodiesel plants** are typically in the range of $1.00-$0.75 / annual gallon.
Total capital costs for mgy biodiesel plants** are typically in the range of $0.75-$0.50 / annual gallon.
** Tank farm included / pretreatment not included.
* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

68. Biodiesel Fuel Specification ASTM D 6751-06
Property
Method
Min
Max
Flash point, ºC
ASTM D 93
130.0 –
Water & sediment, %vol
ASTM D 2709
0.050
Kin. Viscosity (40ºC), mm²/s
ASTM D 445
1.9
6.0
Sulfated ash, %mass
ASTM D 874
0.020
Sulfur, %mass
ASTM D 5453
(S15)
0.05 (S500)
Copper strip corrosion
ASTM D 130
No. 3
Cetane number
ASTM D 613 47
Cloud point, ºC ASTM—
ASTM D 2500
Report
ASTM: American Society of Testing and  Materials.

69. Biodiesel Fuel Specification ASTM D 6751-06
Property
Method
Min
Max
Carbon residue, %mass
ASTM D 4530 –
0.050
Acid no., mg KOH/g
ASTM D 664
0.50
Free glycerin, %mass
ASTM D 6584
0.020
Total glycerin, %mass
0.240
Phosphorus, %mass
ASTM D 4951
0.001
Distillation temp., ºC
Atm. equiv. temp., 90% recovered
ASTM D 1160
360
Sodium & potassium, combined, ppm
UOP 391 5

70. Biodiesel Quality Assurance
Testing in accordance with fuel specifications is time consuming and expensive
In North America, the “BQ-9000” program helps assure quality in biodiesel fuel

71. Biodiesel Quality Assurance BQ-9000 Program
National Biodiesel Accreditation Program
Endorsed by NBB & Canadian Renewable Fuels Association
Cooperative & voluntary program for accreditation of biodiesel producers & marketers
Open to manufacturers, marketers & distributors of biodiesel & blends in the U.S. & Canada
Combines ASTM D 6751 standard with quality systems program including practices for storage, sampling, testing, blending, shipping, distribution & fuel management

72. Biodiesel Quality Assurance BQ-9000 Program
National Biodiesel Accreditation Committee
(NABC) is a fully autonomous committee of NBB
Designed & implemented BQ-9000 program
Responsible for developing improvements
Program objectives:
Promote commercial success & acceptance of biodiesel
Help assure biodiesel is produced to & maintained at industry standard, ASTM D 6751
Avoid redundant testing during production & distribution
Provide mechanism to track biodiesel in distribution chain
Reduce probability of “out of spec” fuel reaching the market

73. Biodiesel Quality Assurance BQ-9000 Program
Program Accreditation
Open to companies actively or planning to produce, distribute or market biodiesel in “neat” or blended formulations
Requires formal review & audit of capacity of applicant to produce or market biodiesel that meets ASTM D 6751 standards
Once it is awarded, it is held for two years
Following two-year period, company undergoes recertification audit to extend accreditation

74. Biodiesel Quality Assurance BQ-9000 Program
Accredited Producer
Entity engaged in production and/or distribution & sale of biodiesel and/or biodiesel blends of B2 or greater
Successfully met accreditation requirements
Accredited producers, as of July 2006.
Accredited Producers: AGP, Cargill, Eastman Chemical (AR Ops), Griffin Industries, Huish Detergents, Imperial Western Products, Johann Haltermann, Organic Fuels, Peter Cremer NA, SoyMor Biodiesel, West Central, World Energy Alternatives

75. Biodiesel Quality Assurance BQ-9000 Program
Certified Marketer
Entity undertaking to sell or resell biodiesel or biodiesel blends
Successfully met accreditation requirements
Certified marketers, as of July 2006.
Certified Marketers: Peter Cremer NA, Sprague Energy