Pearson BioEnergy, Inc

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Bio-Energy From Mesquite on Texas Rangelands Jim
Ansley Texas Agricultural Experiment
Station Vernon, TX
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Much of the Southern Prairie (USA) Today
Advanced woody plant (i.e., brush) encroachment
reduces herbaceous (forage) production, reduces
off-site water yields, and interferes with
livestock gathering
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Increasing Mesquite Cover Reduces Grass Yields
This chart shows how C4 (warm season) mid-grass
production in interspaces between mesquite
declines sharply when mesquite cover exceeds 30
(from Ansley et al 2004 J. Range Mgt 5749-57
full article can be found in the publications
list on Dr. Ansleys web site)
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Costly Brush Treatment Options
Mechanical 50-80/acre Herbicides
15-25/acre Fire 5/acre (but limited as to when
and where it can be used)
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Overall Objective Determine the feasibility of
developing a bio-energy industry in rural Texas
based on rangeland woody plants Emphasis is on
Honey Mesquite but other shrubs could be used,
depending on size, density and access
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Mesquite as a BioFuel Source
Drought hardy fixes own nitrogen can grow on
dry, nutrient poor soils
Requires no cultivation, seeding, fertilizing, or
irrigation
Resprouts vigorously after an aboveground
disturbance (i.e., top-kill)
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Managing Mesquite Harvest for Multiple Benefits
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Potential Uses of Mesquite Biomass
Furniture Particle Board Cooking Chips
Wood Products
Feedstock for Combustion
Fire Wood Electricity
Mesquite
Ethanol Biodiesel Other Biofuels
Feedstock for Liquid Fuels
Plastics Polymers
BioProducts
Yellow Area currently emphasized by Dr.
Ansleys project
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WHY ETHANOL???
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How Is Petroleum Used? United States
Type of Use
Percent of Total Use
Cars and Trucks 66 Jets and
Airplanes 10 Power Plants lt10
Energy Sources for Power Plants Coal (56)
Nuclear (21) Gas (10) Hydroelectric
(10) Other (3) Where we need the most help
is fuel for vehicles ETHANOL!!
Source Richard Heinberg, The Partys Over,
Gabriola, B.C., Canada
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Mesquite BioFuel Research Needs
Harvest Technology
Ethanol Conversion
Ecological Effects
Supply
Grasses Soils Wildlife Nutrient Cycling Water
Yield
Size/Mass/Density Relationships Regrowth
Rates Regional Supply
Grinding Gasification Optimum Refinery
Locations Economics
Cutting Lifting Baling Transport
Waste Disposal Energy Balance Water Balance
Yellow Research areas currently emphasized at
Vernon Blue Process being developed by private
industry cooperators
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Mesquite Supply There are 51 million acres of
mesquite in Texas (SCS 1984 SCS is now
NRCS) Scifres (1980) estimates 56 million
acres Of this total, about 30 million acres are
moderate to dense mesquite
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Mesquite Distribution In Texas (SCS,1984)
Texas Mesquite Supply 30 million acres of
moderate to dense mesquite Pink and yellow areas
have highest density
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Mesquite Supply Summary
15 million acres available for harvest (if leave
the remaining 15 million acres for wildlife
habitat)
Estimated wood yield 12 tons per acre in
moderately dense stand (240 trees/ac x 100 lbs
per tree).
Assume 80-85 harvest efficiency Yield 10
tons/acre
10 years regrowth needed before re-harvest in
north Texas. Important to understand we need to
manage the regrowth and not kill the tree.
Note Mesquite standing crop and regrowth yield
estimates are based on data recently collected at
TAES in Vernon. These data are not yet published.
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Harvesting Technology Two Phase Process 1.
Cutting (Felling) 2. Collecting
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• Harvesting
• Technology
• Cutting- (Felling)

Machines such as this Barko 775C Specialized
cutter heads Wood debris left Little damage to
grasses or soils
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Harvesting Technology - Collecting -
Recently constructed a harvester to collect the
wood mulch (Patent pending)
The harvester is pulled and powered by one of the
brush cutter machines. Requires gt100 hp.
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Harvest Test Trials
Typical Test Stands 50-70 canopy cover 250-350
trees per acre Avg. tree height 3-4 m
Time 2 hours per acre (0.4 for felling) (1.6
for collecting)
Daily Rate One Harvester 4-5 acres
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Harvest Test Trials
Total Fuel Use Dense Stand (300 tr/ac) 23
gallons per acre Moderate Stand (140 tr/ac) 16
gallons per acre
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Ecological Effects of Harvesting
Mesquite stump
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Wood-to-Ethanol Conversion
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Ethanol Cellulose Chemistry
Wood Cellulose Lignin Cellulose has thousands
of 6-carbon chain glucose residues linked by
oxygen bridges (C6H12O6 x thousands) Lignin has
combinations of phenolic subunits such as
coniferyl alcohol that have 6-carbon benzene
rings (C10H12O3 x thousands)
Ethanol Ethanol by comparison is a very simply
2-carbon molecule (C2H5OH ). It has a higher
percentage of hydrogen (13) than cellulose or
lignin (7).
H
H
H
OH
C
C
H
H
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Wood-To-Ethanol Yields
We are working with private companies that are
developing cellulosic ethanol technologies. The
details of these processes are proprietary so we
are unable to provide these data in this
presentation. However, for the purposes of
projections, we will assume ultimately a 150
gallon per ton yield. Currently, fermentation of
1 ton of corn yields about 100 gallons of
ethanol. Cellulosic materials such as wood or
grass may have higher yields but the technology
for conversion of cellulosic materials to ethanol
is not currently available. The maximum possible
ethanol yield from one ton of dry wood is about
300 gallons. This is based on the amount of
carbon in wood plus the addition of extra
hydrogen because there is a greater percentage of
hydrogen in ethanol than in wood.
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Regional Projections These projections are based
on a cellulosic refinery that can yield 5 million
gallons of ethanol per year. Currently, this is
well below the corn ethanol standard of 50-100
million gallons annually. However, with a
feedstock source such as mesquite we have to take
into consideration the transport costs of the
feedstock. Therefore, a lower yielding refinery
is needed to minimize transport costs.
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Wood and Acreage Per Refinery 5 Million Gallon
Per Year
Commercial plant - 5 million gallons ethanol per
year gt Assume 150 gallon per ton yield (this
is not yet commercially available) gt Need
about 34,000 tons mesquite feedstock per year
gt If refinery runs 340 days per year, need 100
tons per day. gt Therefore, need to harvest 10
acres per day.
3,400 acres of mesquite needed per year (assuming
10 tons per acre and 34,000 tons per
year). Re-harvest every 10 years. Therefore to
indefinitely sustain such a refinery, one needs
10 x 3,400 or about 34,000 acres. This assumes
that the mesquite regrowth is allowed to
grow!! If we add 15,000 acres for brush
sculpting for wildlife habitat, the total acreage
needed for the harvest system is about 50,000.
Travel distance from wood source to refinery lt 10
miles. It is ESSENTIAL that refineries are small
capacity and located near the feedstock source to
minimize travel distance.
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Rural Economic Development
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Will It Make A Dent in Texas Oil Use?
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Note Regarding Data Sources This presentation
represents the combined efforts of Dr. Ansleys
research at the Texas Agricultural Experiment
Station near Vernon and data generated by
industry collaborators. All projections
regarding mesquite availability and the costs to
harvest mesquite have been developed by Dr.
Ansley either through field measurements or
reference to available literature.
Wood-to-ethanol yields (i.e., gallons of ethanol
per ton of mesquite wood) are considered
estimates at this time and are used only to
generate regional projections. It should be
emphasized that this represents a very
preliminary projection and is subject to
continual modification in the future as more data
are gathered. No commercial refinery using
cellulosic conversion technology has yet been
constructed. If you have questions please
contact me at r-ansley_at_tamu.edu Thank you for
your interest.