BTC PTEC Biodiesel Workshop

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BTC PTEC Biodiesel Workshop

• August 7 8, 2006
• Session 7 Feed stock and biodiesel quality

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Agenda for session

• Feedstocks for biodiesel
• US and WA feedstocks
• Oil yields for different sources
• Comparison of feedstocks
• Feedstock preparation
• Feedstock quality issues and tests
• Comparison of biodiesel from different feedstocks
• Evaluation of biodiesel quality

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Feedstocks for biodiesel

• Vegetable oils (most volume)
• Soybean
• Rapeseed
• Palm
• Animal fats (lower cost)
• Rendering plants
• Spent oils (lowest cost, so far)
• Yellow and grey grease

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Some US feedstocks
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Vegetable oil production in WA(Armstrong, 2005)

• WA crops (millions of planted acres)
• 2.3 in wheat
• 0.337 in barley
• 0.0077 in canola
• 100,000 acres needed for a 5 million gallons/year
  canola/mustard biodiesel plant
• Not promising due to
• Closest crushing facility is in Montana
• Low current market prices
• Little experience with oil crops

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Vegetable oil yields
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Vegetable oil yeilds

• US
• Soybean oil (0.4 T oil/ha, 20 yield from seeds)
• Canola and mustard oil (40 yield from seeds)
• Europe
• Rapeseed oil (0.5 T/ha, 40 yield from seeds)
• Sunflower oil (0.5 T/ha)
• Tropics
• Palm oil (4 T/ha)

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Comparison of feedstocks

• Vegetable oil
• Unrefined (high phospholipid content) un-degummed
  oils have separation problems in the process
• Refined (better product)
• Animal fats
• Lower cost
• Higher concentrations of saturated FA
• Biodiesel products may have higher freezing
  points
• Higher cetane numbers

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Comparison of feedstocks

• Spent oils
• Trap grease (odor, moisture and color problems
  for this low cost feedstock)
• Brown grease (FFA gt 15)
• Yellow grease (FFA lt 15)
• Cheaper

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Prices
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Feedstock preparation

• Harvesting
• Crushing and pressing to separate the oil
• Filtration
• Removal of gums (phosphatides 1.5 to 2.5 and
  unsaponifiable matter 1.6)
• Removal of free fatty acids (0.3 0.7, soybean
  oil)
• Bleaching and deodorizing

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Feedstock quality issues

• Free fatty acids (variable)
• Phosphorus (may be 600 900 ppm in soybean oil
• Sulfur (usually low, lt 3 5 ppm in vegetable oil
  but may be higher in animal fats, 40 50 ppm)
• Iodine value (level of saturation)
• Water (variable)
• Solids (should be filtered, 100 micron)

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Feedstock quality tests

• Fatty acids
• Specific gravity
• Refractive index
• Iodine number
• Saponification number
• Color

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Free fatty acid concentrations

• Refined vegetable oil lt 0.05
• Crude soybean oil 0.3 0.7
• Yellow grease 2 7
• Animal fat 5 30
• Trap grease 75 100

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Comparison of feedstocksFatty Acid Profile
(major FA)
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Problems in feedstocks due to

• Free fatty acids (can react with catalyst to make
  it ineffective)
• Phosphorus (ASTM fuel limitation of 10 ppm)
• Sulfur (ASTM fuel limitation of 15 ppm)
• Water (can deactivate the catalyst interfere with
  the reaction and methanol recovery)

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Processing High FFA Feedstocks

• High FFA from animal stock and spent grease
• Mainly acid catalyst to form esters (forms water)
  so that FFA lt0.5, followed by normal base
  catalyst transesterification
• Or just do normal transesterification and live
  with results (loss of FFA and possible emulsion
  formation) for low FFA levels

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Comparison of B100 from different feedstocks
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Product quality tests

• ASTM D6751 tests
• BQ-9000 tests
• Others
• Physical properties
• Iodine number

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ASTM D6751 Biodiesel Standard
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Product quality issues

• Quality of the feedstock
• Fatty acid composition
• Contaminants (solids, moisture)
• Processing
• Chemicals used (nature and purity)
• Completeness of reaction
• Tri, di, mon glyceride products for incomplete
  reaction
• Contaminants
• Clean up steps (Water wash or Magnesol)
• Post production
• Filtration (5 micron)

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Product quality

• Glycerols (easily removed by washing)
• Total glycerol lt 0.24
• Free glycerol lt 0.02
• Monoglycerols have low solubility in product
• Alcohol
• Biodiesel may have 4 5 alcohol
• lt 0.1 indirectly due to flash point limit
• Small amounts will not affect engine
• Catalyst
• sulfated ash lt 0.02 limit
• Mostly removed with glycerin phase