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Our
Presentation
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- Only about 1/2 of a citrus fruit
is juice
with the remainder becoming waste
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- n An average of
5 million tons (wet) of citrus processing residues were generated
annually from over 11 million tons of annual citrus production in
Florida between 1993-2004 with even higher amounts produced in Brazil
- Since 2004,
the citrus residue production dropped to about 3.0- 3.5 million tons
(wet) annually due to hurricane and pest damage, but the Florida
industry is recovering
- Current
practice to handle the waste is to dry and market dried citrus pulp
pellets (CPP) as a cattle feed
- Citrus
processing residue is rich in simple and complex carbohydrates making
it a good cattle feed, but it is low in protein
- Until 2007,
the value of CPP ($40 - $80/ ton) has been about equal or less than the
production costs ($60 - $100/ton)
- The increase
in the price of corn along with other factors have now increased the
value of CPP to approximately $170/ton
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Citrus Pulp Pellets
A. large market, cheap
storage and
transportation
B. Low price ( 2-10¢/lb
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C. Limited or no
diversification into other
products and markets
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| Composition
of Citrus Processing Residue
Approximately: 75-80%
Water
0.5-1.4%
Citrus oil
20-25% Dry
matter
Dry
matter contains:
23
- 28% simple sugars
8
- 10% cellulose
8
- 12% hemi cellulose
20 %
pectin
20 %
mix of flavonoids
limonoids
organic
acids
protein
minerals
8-10
% cutin, waxes
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Why
Ethanol?
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Ethanol is one of the
few products which can
consume the large volume of CPW
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Market development is
not required
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The value of ethanol
exceeds the value of
CPP even on sugar basis
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Fuel ethanol price is
$2.20-2.80/gal( i.e.
33-43¢/lb or 17-21¢/lb sugar)
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Potable ethanol ≥
$3.80/gal
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No fuel ethanol produced
in Florida, yet
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Challenges
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Accomplishments
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Pilot
scale plant consuming up to 1-2 ton CPW/hr has been developed and
operated for two seasons.
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Three
US Patents have been awarded for the innovative process and
it’s parts:
US Patent 7,721,980 B1, May 25,2010 US Patent 7,879,379 B1, Feb. 1
,2011 US Patent, awarded Oct. 2012, in press
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Limonene
removal to ≤ 0.05% (≥ 95% removal) has been achieved.
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Sterilized
and disintegrated CPW mush has been prepared, hydrolyzed and fermented
in simultaneous saccharification and fermentation process.
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Enzyme
cost has been lowered by more than an order of magnitude to about
50¢/gal ethanol.
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Novel
distillation column for stripping of ethanol from viscous (6,000-30,000
cP), fermented CPW has been developed.
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Stripping
of ethanol from CPW and it’s rectification to 95%
concentration has been developed at the pilot scale level. Cars were
driven using ethanol from CPW as a fuel.
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Blending
of simulated stillage with CPW and it’s incorporation into
feed mill operation has been demonstrated.
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Pretreated
CPW and stillage were fed to cattle with excellent acceptance and no
ill effects.
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CPW
from oranges, grapefruit and tangerines has been successfully processed
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Production Costs of Citrus Ethanol 1,2
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Cost
Per Gallon
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Citrus Peel ($0/ton)
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$
0.00
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Chemicals,
Enzymes
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$
0.835
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Utilities (steam,el. )
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$
0.628
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Labor, Supplies &
Overhead Expense
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$
0.156
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Capital Depreciation
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$
0.301
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| Drying of Residues |
$
1.40 |
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Total Cost
1 Includes
limonene
costs
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$
3.32
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Products
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Value
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Ethanol (1 gallon)
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$
2.25
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Limonene (1.7-3.4 lb
@$2.00/lb)
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$
3.40-6.80
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Dried Pulp Pellet
(38
lb @$150/ dry ton)
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$
2.85
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Total Value
2Size:
1,792 tons of fruit/day
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$
8.50-11.90
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Effect
of Plant Size
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Cost comparison
Citrus Pulp
Pellets
Ethanol & Co-products
Cost/dry ton
CPW
$ 0
Pressing & Drying
$100
Income/dry ton
CPP
$170
Limonene
$ 30
Total
$ 200
Net
Income/dry ton
$ 100 |
Cost/dry ton
CPW
$ 0
Total Prod. Costs
$ 116
Income/dry ton
CPP
$ 112
Limonene
(@ $2/lb) $ 120-260
Ethanol
(@ $2.25/gal) $ 79-101
Total $
311-473
Net
income/dry ton
$ 195-357
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Alternative Ethanol
Process
3-6
lb limonene
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Potential Products from
CPW
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Value Added Co-products
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Higher
value than cattle feed; $0.30-10.00/lb
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Possible
elimination of drying of stillage
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Positive
economic impact
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In
some cases products and markets need to be developed
Accomplishments
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Recombinant
bacteria for fermentation of residual C5 and C6 sugars are being
developed in collaboration with Prof L. Ingram at Univ. of Florida. A
50% increase in ethanol yield, concentration and income from ethanol is
possible and waste treatment will be simplified.
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A
new method for preparation and recovery of pectic fragments has been
developed. The fragments have a value as ion exchangers and
precipitants for heavy metal ions.
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Conclusions
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CPW
is a suitable raw material for the production of fuel or potable grade
ethanol
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Coproduction
of ethanol, limonene and cattle feed is economically attractive at
current prices and relatively small (0.2-1.0 x 106 gal
ethanol/season)
plant sizes
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Significant
decrease in VOC emissions is achievable through better limonene recovery
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Development
of value added co-products from stillage provides additional
opportunities
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GOING FORWARD
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Scale
up to a commercial level
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Formation
of strategic partnerships with citrus processors and ethanol producers
or chemical companies
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Energy
(steam) savings through integration of processing steps
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Increase
in ethanol yield and concentration by application of recombinant
microorganisms
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Extension
of the ethanol production season by the utilization of sweet sorghum
juice
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Development
of additional co-products
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The
process may be suitable for other pectin rich residues, such as sugar
beet pulp or apple pumice
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