Tobacco Biomass
A Potentially Valuable Component of Texas Bioenergy Projects
Great Spirit Bioenergy Partners
Bill Drake
bdrake@ktc.com
Biomass Tobacco Profile
for more info: bdrake@ktc.com
• 50-70 Tons/Acre – the most
conservative case
• NCSU range was low of 20 tons to high of
70 tons/acre
• 100+ tons/acre – reasonable
expectation for Texas
• Given Texas growing season, hours of
sunlight, etc
• Use of higher yield tobacco varieties
100 tons/acre yields 10 – 20+ tons dry weight**
2.5 -5.0 tons sugars - nearly 100% are ideal sugars for biogas & ethanol
Standard biofuel conversion formulas apply
1-2 tons starches
Conversion to biofuel same as corn
4-8 tons cellulose with very favorable biofuel properties
1-4 tons F1 & F2 proteins with complete amino acid profile
** Tobacco variety, growing conditions, harvesting strategy
are all important factors
Basic Tobacco Biofuel Calculations
for more info: bdrake@ktc.com
•
From 100 MT (one acre) of tobacco biomass 10-20% dry weight, or 10-20
tons total breaks out to:
– @ 5.5 MT sugar, @ 2.5 MT starch, @ 8 MT cellulose
• Yields are approximate because of variables like tobacco variety
• Sugars an ideal profile for fermentation
• 90% of total cellulose (7.2 MT) is hemicellulose – lignin is 1.5%
•
Sugar to ethanol – conventional conversion formula (DOE)
– (11,000) X (.47) X (.97) / (6.6) = 760 gallons
•
Starch to ethanol – conventional conversion formula (DOE)
– (5290) X (.90) X (1.11) X (.47) X (.97)/6.6 = 365 gallons ethanol
•
•
So we are at 1125 gallons before we also convert the cellulose to biofuel
Hemicellulose to ethanol (DOE estimates)
– Estimate @100 gallons/ton (using reference data for cellulose from corn stalks) =
720 gallons/acre
• Probably more because tobacco cellulose is 90% hemicellulose and Corn
cellulose is only 28% hemicellulose
• Also tobacco lignin is only 1.5%
•
Provisional total of @ 1845 gallons/acre for 100 tons/acre of tobacco
biomass
– Even at 50 tons/acre we get @920 gallons/acre
Compared With Cellulosic Crops For Biofuel
for more info: bdrake@ktc.com
High fermentable cellulose yields/acre
100 tons fresh tobacco biomass per acre yields 4-8 tons
of dry weight cellulose, characterized by:
The highest proportion of hemicellulose of any
major cellulosic feedstock crop, and
The lowest % lignin of any major cellulosic
feedstock crop
•
•
•
•
Corn Stover
Switchgrass
Sugar Cane
Tobacco
35% Tot. Cellulose
28% hemicellulose
44-51% Tot. Cellulose 42-50% hemicellulose
32-48% Tot. Cellulose 19-24% hemicellulose
40% Tot. Cellulose
90% hemicellulose
16-21% Lignin
13-20% Lignin
23-32% Lignin
1.5% Lignin
Biofuel Feedstock Potential
for more info: bdrake@ktc.com
•
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Tobacco has far greater environmental range
Tobacco has more economic byproducts
Tobacco has more flexible crop management requirements
Tobacco doesn’t displace food crops
– Can be produced on marginal land
– Uses far less land per million gallons of fuel output
•
Compare: 50,000,000 gallon/year ethanol plant
– Requires 178,000 acres of corn @ 100 Bushels/Acre
– At $4.50/bushel feedstock cost is $80 million
– 50 Million Gallon plant would require 50,000 acres of biomass tobacco @ 100
tons/acre
– At $10/ton for biomass tobacco feedstock cost is $50 million
– Even at 50 Tons/acre biomass tobacco would only need 100,000 acres to supply
a 50 million gallon plant
• Processing and operating costs significantly less than corn, grain, cane etc
• Perhaps possible to pay growers in fuel credits, not cash
• Co-locate with tobacco-based biogas electricity, biodiesel, & co-products
processing plants for added revenues & profit centers
Dairy Farm
Biogas-Electricity Installation
www.biogas-nord.com
Tobacco Biogas Electricity Basics –
First Look At This Data
• 1 MW electricity generation
– Requires 5681 m3 CH4 per day
• Proven yield = 550M3/day of total biogas per ton of fresh tobacco
– This from a Virginia/Burley mix; other varieties likely higher yield
• 5681 m3 of methane = 550 m3 biogas/ton MOS tobacco * 55%
(methane content) * 18% (solid matter) * 92 % (biodegradability) =
114 wet tons fresh tobacco/day
• Requires @ 400 acres/year at @ 100 tons/acre
• Ideal substrate composition = 70% tobacco/30% manure
– 2 MW = 56,000 wet tons/year or 560 acres at 100 tons/acre
• Less than 2X acreage of a 1MW plant due to engine efficiencies
– Larger generator engine, more KW per M3 of biogas
– 4 MW = 110,000 wet tons/year or 1100 acres at 100 tons/acre
• Less than 4X acreage of a 1 MW plant due to engine efficiencies
• Relatively small acreage requirement allows rotation from year to
year even in very small communities
Biogas - Unlocking
Value from Waste
F e ed Stock Values
C ow M anure
P ig M anure
P otato Was te
C hic ken M anure
B rewery Was te
G reen C lippings
G ras s S ilage
M aize S ilage
Food S c raps
B ak ery Was te
Fats & G reas e
0
200
400
600
800
1000
Cubic m of gas per t onne of substrate
Tobacco Biomass xxxxxxxxxxxxxxxxxxxx
550 M3/Ton
1200
Potential Model for Rural Texas
Biogas Electric
• Low cost decentralized uninterruptible electricity production
• Existing Rural Electric & Agricultural Coops become electric power
producers
• For local consumption and as export energy product
• Farmers provide biomass for electricity credits and/or cash
• No new grid connections needed
– Unlike wind-generated electricity
– Sell excess into existing grid for urban users
– Operate one plant for power, one plant for revenue?
• Redundancy
– If biomass tobacco supply is interrupted for any reason the biogas
electricity plant can operate on 100% manure
• Reduced capital & operating costs over conventional electric power
generation
• Utilize existing energy distribution infrastructure
• Shortened pay-back period compared with conventional power generation
options
• Power generation independent from rising fuel costs
Complete Rural Energy Solution?
Community Energy Cooperative
• Community owned co-located cooperative biogas electric, smallscale ethanol, biodiesel, and co-product processing plants
• 1100 acres biomass tobacco @ 100 tons/acre for single 4 MW
biogas electricity plant
• All capital and operating costs established
• 8 months to turnkey electricity
• Operates above breakeven selling power to coop members at
$0.12/Kwh after paying growers with electricity credits
– Not calculating tax credits, incentives, grants etc
• 5000 acres biomass tobacco @ 100 tons/acre @ 1500 gallons/acre
= 7.5 million gallons/year (7500 vehicles @ 20,000 miles/year)
– Capital requirements & operating costs TBD
• Ethanol output cost may be > $1/gallon
• Also provides “insurance” for biogas electric facility
– Role of biodiesel needs to be studied – synergies are clear.
– Co-products would add to ‘community energy coop’ bottom line
• Could pay for conversion of all vehicles to use E-85
• Can bioenergy revenues replace property taxes as a revenue source for
government services in small communities?