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Current Sawdust Use
Research in Eastern Kentucky
Tom Keene UK - PPS
Dr. Darrell Taulbee UK - CAER
Stakeholders
Tom Keene/Ray Smith – UK Dept. of Plant and Soil Sciences
Darrell Taulbee/Shiela Medina – UK Center for Applied Energy Research
Kenya Stump – Kentucky Energy and Environment Cabinet
David Crews – East Kentucky Power Cooperative
Greg Wells – Valley View Hardwoods/Green Tree Forest
Problem Statement• Valley View Hardwoods looking for a viable and
beneficial use for ~30k tons/yr sawdust
– Sawdust off take to paper mill declining
Increased landfill costs
• During test burn of switchgrass at Spurlock in 2011,
the biggest technical challenge faced was processing
and delivering the switchgrass to the boiler.
Objective• Convert green sawdust from mills near Morehead,
KY to a form that can be economically processed,
transported and burned at EKPC’s Spurlock
Station(Unit #3 – 268 MW circulating fluidized bed combustor)
Objective
• To support Kentucky’s timber mill industry
– Identify and demonstrate a viable method to
convert green sawdust into a form suitable for
processing at a coal-fired utility without
requiring modification of existing equipment
Considerations
• Sawdust fuel must be cost competitive with coal
on a Btu basis
• Green sawdust has high moisture content (~40%)
and low bulk density
Difficult to form into briquettes or pucks
Doesn’t handle well in existing equipment
Low heating value
High transport cost
From Greg Wells
• Valley View Hardwoods
– $10/ton to transport sawdust from Morehead
to Spurlock
– $41.50/ton to landfill
– $5.70/ton to send to Domtar
– Break even to send to Glatfelter
• $31.50/ton more to landfill than to transport to Spurlock
Evaluation Method
Wood Samples Evaluated
– Green Sawdust – Valley View
o As received (5,640 Btu/lb)
o Air-dried
– Kiln-dried Sawdust - BPM
o 8.9% Moisture (7,760 Btu/lb)
– Kiln-dried Wood Shavings – Harold White Lumber
o 8.3% Moisture (7,670 Btu/lb)
Coal Fines Evaluated
– Perry County Coal - 13.9% moisture
– Alden Resources – 6.7% Moisture
– River View – 10.7%
– River Trading
o As Rec’d – 10.2% moisture
o Air dried – 4.0% moisture
Binders Evaluated
• No binder
• Lignosulfonate (with and w/o lime)
• Lime kiln dust
• Slaked lime
• Kaolinite
• Wheat starch
• Corn starch
• Silica fume
• Different plant residue streams
What Worked? - Very Little!136 Formulations Tested
Sawdust only (no coal or binder)
– Unable to make pucks with 100% green sawdust
– Pucks could be formed if feedstock moisture was reduced to about 28% or
less
Three methods to produce biomass-only pucks were identified
1.Blended green sawdust with kiln-dried sawdust or wood shavings
o Very limited availability of dry sawdust or shavings – normally used on
site or marketed
2.Air-dried green sawdust to less than about 28% moisture
3.Blended a fibrous plant residue with up to 50% green sawdust
o Plant wastes are also biomass (renewable)
What Worked?
• Sawdust blended with coal fines
– Unable to form pucks with green sawdust and coal fines
without adding a binder ($$$)
o Wheat starch worked best but even when adding up to 3%
starch (~$15/t), could only add about 20% green sawdust
– Made durable pucks with coal and up to 70% air-dried
sawdust and 2% wheat starch (21-10)
– Also made excellent pucks with a 1:1:1 blend of green
sawdust, coal fines, and a plant residue byproduct (26-1)
What do We think?
Not enough kiln-dried sawdust or shavings are
available to be a viable option
Binders are expensive
Two Scenarios
1. Locate the production facility adjacent to Spurlock
– Make fuel pellets that contain coal
2. Locate the production facility in Morehead
– Make pellets that contain only biomass (SD or SD/plant
residue)
Locate Plant Next Door to Spurlock
• Transport green sawdust to Spurlock and pelletize with
coal and 1) plant residue byproduct or 2) mildly dried
sawdust and1-2% starch
– Steam for drying sawdust can be purchased from Spurlock
– Coal delivery and handling facilities are in place
– EKPC permitted to buy pellets that contain at least 51% coal
• The cost of the steam needed to reduce sawdust moisture
from 40% to 25% is ~$3.50/ton
– The partially dried sawdust has a higher calorific value
• A 10 tph indirect steam dryer estimated to be around $1M
Produce Biomass Pellets in Morehead
• Biomass-only fuel pellets:
– Partially dry the green sawdust and make SD-only pucks
– Or find significant source of plant residue byproduct to blend
and pelletize with the green sawdust
– Biomass pellets cannot be sold to Spurlock as fuel
o Must rely on avoided landfill cost ($31/t) and renewable
energy credits (RECs - ??$) to be viable.
• Go with a direct dryer (flash or rotary drum)
– Generally lower capital but higher operating costs than
steam dryers
Short Summary
• Biomass-only pucks can be made with green sawdust
by blending with plant residue byproduct or by
partially drying the green sawdust
• Pucks can be made with green sawdust and coal by
blending with plant residue byproduct or by partially
drying the green sawdust and adding a binder
Pucks to bring to meeting
• Show pucks made with
– gsd and adsd (40/6027% M, 21-4)
– GSD and plant waste (75 adsd/25 plant
residue -> 27-6)
– ADSD/Coal 2% WG (21-10)
– GSD/adds/ADRT (26-1)
Proposed Solution
Phase I: Laboratory Evaluations
Produce pucks/briquettes made from:
1. Blends of green and kiln-dried sawdust
2. Blends of sawdust and coal fines
3. Others materials (residue)
Phase 2: Production Run
• Identify preferred approach
oDurability, feasibility, cost
• Produce sufficient tonnage to conduct a
meaningful test at Spurlock Station
Scale of Operations
• Location (Spurlock or Morehead)
• Capital Cost
• Equipment
• Drying Cost (if any?)
• Labor
• Marketing
• Etc….
Questions
Source: SSEB – American Energy Security Study