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