Wood Pellets

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Wood Pellets for BioPower in

the US and in the EU

Anthony Baldridge, Tina Dreaden, Matyas Kosa, Kathy Woody, Christina YoungArt J. Ragauskas

07-14-2009Georgia Institute of Technology

Department of Chemistry and Biochemistry



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Outline

What is BioPower?

Effect on ClimateChange

Forces that accelerate

BioPower research Wood pellets

Production facilities

Markets for wood pellets Chemical composition

ProspectsRagauskas, A. J. et al. (2006) Science 311, 484-489



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Biopower

Renewable biomass→ energy/ electricity

Biomass can be virgin or waste Forests

Cultivated land

Sewage

Agricultural crop &

forestry residues

Petrou, E. C. and Pappis, C. P. (2009) Energy and Fuels 23, 1055-1066

http://www.ipst.gatech.edu/faculty_new/faculty_bios/ragauskas/ragauskas_biofuels_1.html



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Why biopower?

Considerations:

worldwide energy

demand expected togrow by > 50% by 2025

rising oil prices

global climate change economic downturn in U.S.

Biopower from biofuels:

Decrease greenhouse gas emissions (CO2 & CH4) Shift dependence away from foreign petroleum

Economic capital

Ragauskas, A. J. et al. (2006) Science 311, 484-489Koh, L. P. and Ghazoul, J. (2008) Biological Conservation 141, 2450-2460

http://www.ipst.gatech.edu/faculty_new/faculty_bios/ragauskas/ragauskas_biofuels_today.html



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Biopower applications

Electricity production

Gas & coal fired power plants Residential space heating

Pellet burning fireplaces

Transportation fuels

Personal & mass transportation

Junginger, M. et al . (2008) Biomass and Bioenergy 32, 717-729

http://www.ipst.gatech.edu/faculty_new/faculty_bios/ragauskas/ragauskas_biofuels_today.html



66Image taken from: www.ornl.gov

Biopower Cycle



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Greenhouse gas emissions are of great concern.

Finding ways to decrease amount of emitted CO2 ,CH4 , and other gases is needed.

Biopower addresses these by:

Using sources that can produce a “carbonneutral” system/cycle

Use of animal waste can reduce pollution and

methane emission

Biomass (wood) use prevents wildfires which:

Globally are 40% of gross global CO2

emissions

Allows for controlled combustion uses(180%) more efficient

Motivates forest understory gathering of wood material

Environmental Impacts of Cycle

http://www.ipst.gatech.edu/faculty_new/faculty_bios/ragauskas/ragauskas_biofuels.html



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Power Choices and Climate

Change By adapting current

methods emitted CO2

and other greenhousegases could greatly

diminish. Currently, wood pellets

are gaining use in cofiring plants that use

coal. Biopower production is

rising in the UnitedStates and Europe.

Substitution of fossil fuel with biomass/ biopowerdecreases net emissions by 750% (note figure).

Image taken from: http://www.uscg.mil/d1/sfoSouthwestHarbor/Innovation/images/pellet_enviro.jpg

http://www.eia.doe.gov/cneaf/solar.renewables/page/biomass/biomass.gif



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Categories of biofuels

Solid biofuels

Pellets, sewage, wood

Liquid biofuels Biodiesel (i.e., long-chain fatty acids),

bioethanol, biobutanol, green diesel

Gaseous biofuels Thermal or microbial degradation of biomass used

to form biogas, i.e. CH4 or H2

Petrou, E. C. and Pappis, C. P. (2009) Energy and Fuels 23, 1055-1066

ethanol

methyl-palmitate



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Pertinent research

Plant biochemistry & genetics increased yield, resistance,

sustainability

Biorefineries: conversion &fractionation of raw materials(polysaccharides & lignin) to products Direct energy, transportation fuels,

chemical products (solvents, plastics,fragrances)

Production of biofuels Cost reduction & efficiency

Ragauskas, A. J. et al. (2006) Science 311, 484-489



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Biopower support

Global: International Energy Agency (IEA)

Bioenergy Task 40 (2003) Develop bioenergy trade to secure supply & demand in a

sustainable way

National: Obama’s Economic Stimulus (2009) $54 billion towards green energy (research, tax cuts, etc.)

Local: Georgia Power will convert coal-fired power

plant to burn wood chips (2009) One of largest biomass power plant in U.S.

Junginger, M. et al . (2008) Biomass and Bioenergy 32, 717-729Department of Energy, www.doe.gov

http://www.georgiapower.com/nuclear/plantmitchell.asp



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What are Wood Pellets?

Made from

wood

waste

(e.g. sawdust and wood chips)

Densified wood particles:

less then 10% moisture

Cylindrical

Diameter: 6‐12

mm

Length: 5‐30 mm




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Applications of Wood Pellets

Household use

Central heating boilers:Heat transferred towater heater and heatdistribution system for entire home

Hartmann, D.; et al. Biomass and Bioenergy 1999, 16 , 397.

Combined Heat and Power (CHP)Plants

Woody biomass-fueled power plants

Co-firing wood pellets and coal:wood pellets partially substitute

for coal, decreasing net CO2 andSO2 emissions with respect toburning straight coal.

Stoves: Provideheating andcooking for a

single room

Fiedler, F. Renewable and Sustainable Energy Reviews 2004, 8 , 201.

http://www.pelletheat.org/3/residential/burningFuel.html



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Production process overview

Holm, J. K.; et al. Energy & Fuels 2006, 20, 2686‐2694.

Raw wood waste

Pelletisation Wood pellets


(pellet-press or die)

milling

drying



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Pellet Production

Wang, C.; Yan, J. International Journal of Green Energy 2005, 2, 91‐107.

Cooling Pellet Transport/ Storage

Drying and Processing

Raw Material

Pelletisation

(Compression of Pellets)

After the raw material is dried, it is extruded through cylindrical channels. Thefriction between the raw material and the press results in compression of thewood into pellets.




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Compression of Wood Pellets

Obernberger, I. et al. Biomass and Bioenergy , 2004, 27 , 653; Holm, J. K. et al. Energy & Fuels 2006, 20 , 2686-2694.

• Dense particles give longer burn times andhigher energy efficiency

• Lower transportation costs• Increases storage capacity

Vs.

Compressing pellets requires energy so why make densified wood pellets?




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Current Production Plants in the

Southeast

Image taken from: http://www.pelletheat.org/3/residentail/fuelAvaliablity.cfm#south



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Current Production Plants in Europe

Image taken from: http://www.bioenergyinternational.com



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Market for wood pellets

Depends on:

Availability (cost of transport) Heating-value/cost ratio compared to other fuels

Possible consumers:

Energy suppliers Commercial/Industrial

Residential

Creating demand for equipment used in productionand consumption of pellets



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Heating Value vs. Cost in the US

Pellet Fuels Institute

www.pelletheat.org



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Energy Suppliers

Biomass is the only truly “carbon neutral” energy DOE: 45x109 kWh/y from biomass in US

1 MWh of biomass power -> 1.6 t of CO2 emission isavoided, hence substituting “new” carbon releasewith recycling CO2 => reduction of 30x106 t/y

Oglethorpe as an example: Building: 3, 100 MW biomass electric generating plants by

2015 Fuel: process round wood, primary manufacturing residue,

harvest residue

400-500x106 $/facility with 40 jobs in each NRECA, Green Power, Ag Energy Working: 25% of energy

from renewable locally grown sources

Department of Energy (DOE)USA Biomass

Oglethorpe PowerNational Rural Electric Cooperative Association

Green Power EMCAg Energy Working Group



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Other Markets

Commercial/Industrial: Examples: Theater (Elma, WA), manufacturing facility (Claremont, NH), farm (Sutton, Quebec),

prison (Walla Walla, WA) Residential:

Over 1 million homes using pellet stoves in the US, in 2008 (www.pelletfuel.org)

Equipment: For pelletizing: mills, grinders, dryers, pelletizing, packaging For consumers: silos, stoves, boilers



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General Chemical Properties of

Pellets high density ensures high heating value and

steady combustion behavior lower water content -> better heating value

lower ash content -> avoid slag

binding agent, preferably natural like corn or maize starch to improve pellet formation

avoid chemical glues which contribute to pollution

F. Fiedler, The State of the Art of Small Scale Pellet-Based Heating Systems and Relevant Regulations inSweden, Austria, and Germany.



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Fuel Properties as a Function of

Chemical Constituents

Ideally, wood pellets should contain chemically untreated material

that is free of additives However, sometimes this is not the case what results in pollutant

emissions, deposit formations, and corrosion issues

Emission - increased contents of N, Cl, and S as well as heavymetals

Corrosion - increased heavy metals and Cl contaminate ash

Deposit formation - increased K - negative effect on ash melting

and contributes to higher aerosol formation

I. Obernberger, G. Thek, Physical Characterization and Chemical Composition of Densified Biomass Fuelswith Regard to their Combustion Behavior, Proceedings of 1st World Conference on Pellets, Sept. 2002,Stockholm, Sweden, ISBN 91-631-2833-0, pg. 115-122.

Ch i l C i i f d ll



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Chemical Composition of Wood Pellets

(General Analysis)

parameter unitaverage

valueminimum maximum

standard

deviationdiameter D mm 7.1 5.9 10.2 1.2length mm 16.1 8.6 29.6 5.2bulk density kg/m3 591 520 640 39

particle density kg/dm3 1.18 1.03 1.3 0.06water content wt.% (w.b.) 7.7 5.7 9 0.9ash content wt.% (d.b.) 0.51 0.17 1.61 0.3GCV MJ/kg (d.b.) 20.3 19.8 20.7 0.2NCV MJ/kg (d.b.) 19 18.6 19.4 2C wt.% (d.b.) 50.3 49.5 51.9 0.6H wt.% (d.b.) 5.7 5.5 6.1 0.2

N wt.% (d.b.) 0.22 0.2 0.64 0.1S mg/kg (d.b.) 278 52 1,922 454Cl mg/kg (d.b.) 48 10 126 27K mg/kg (d.b.) 493 302 1,180 252abrasion wt.% (w.b.) 4.05 0.58 12.53 3.52starch content wt.% (d.b.) 0.22 0 1 0.42

Cd mg/kg (d.b.) 0.14 0.06 0.2 0.03Pb mg/kg (d.b.) 0.43 0.07 2 0.44Zn mg/kg (d.b.) 13.2 9.3 25.4 3.6Cr mg/kg (d.b.) 0.6 0.1 3 0.8Cu mg/kg (d.b.) 1.1 0.7 2.7 0.5

Table/data adapted from: I. Obernberger, G. Thek, Physical Characterization and Chemical Composition of DensifiedBiomass Fuels with Regard to their Combustion Behavior, Proceedings of 1st World Conference on Pellets, Sept. 2002,Stockholm, Sweden, ISBN 91-631-2833-0, pg. 115-122.

38 densified biofuels werestudied (60%) were woodpellets collected from 30

different producerslocated in Austria, Spain,

Sweden, Italy, CzechRepublic, and Norway



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Example: Wood Pellets, Sweden

Fuel pellets production in Sweden is mainly from sawdust and planar shavings of Scots pine and Norway spruce

Pellets were analyzed for moisture and composition

M. Arshadi, R. Gref, P. Geladi, S.-A., Dahlqvist, T. Lestander, The Influence of Raw Material Characteristics onthe Industrial Pelletizing Process and Pellet Quality, Fuel Processing Technology, 89 (2008), 1442-1447.

Run MoistureContent (%)

Fresh pinefraction (%)

Stored pinefraction (%)

Spurcefraction (%)

S1 10 45 45 10S2 8.2 100 0 0S3 11.7 100 0 0

S4 11.7 80 0 20S5 8.2 80 0 20S6 10 45 45 10S7 11.7 0 80 20S8 8.2 0 80 20

S9 8.2 0 100 0S10 11.7 0 100 0S11 10 45 45 10S12 8.2 50 50 0



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Pellet Standards Ensure Quality

F. Fiedler, The State of the Art of Small Scale Pellet-Based Heating Systems and Relevant Regulations inSwedent, Austria, and Germany.

Table 4: Pellet standards in Sweden, Austria and Germany1bulk density

2particle in weight % <3mm

3amount must be specified

4type and amount must be specified

Pellet standard Austria

Parameter Unit Class 1 Class 2 Class 3O-Norm

M7135DIN 51731 DIN plus

Diameter (d) mm 25 25 25 4-10 4-10 4-10

Length mm 4 x d 5 x d 6 x d 5 x d 50 5 x d

Density kg/dm3 0.61 0.51 0.51 1.12 1.0-1.4 1.12

Water content % 10 10 12 10 12 10

Abrasion/small particles % 0.82

1.52

1.52 2 - 2.3

Ash content % 0.7 1.5 <1.5 0.5 1.5 0.5

Upper caloric value MJ/kg 16.9 16.9 15.1 18 15.5-19.5 18

Sulphur content % weight 0.08 0.08 3 0.04 0.08 0.04

Nitrogen content % weight 3 3 3 0.3 0.3 0.3

Chlor content % weight 0.02 0.02 3 0.02 0.03 0.02

Additives % 4 4 4 2 - 2

Sweden - SS 187120 Germany



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Future of BioPower in the US

*only corn stover and cereal straw

Chart showing predicted BioPower usage, including wood pelletsversus the predicted cost of logistics for biomass, including: harvest &collection, preprocessing, storage & queuing, transportation & handling

Table shows the predicted growth in biomass production, including:corn stover, switchgrass, cereal straw and woody biomass

DOE, Biomass: Multiyear Program Plan, May 2009DOE, Vision for Bioenergy and Biobased Products in the US, 2006



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Future of BioPower in the EU

2005: 41 TWh/y of electricity from solid biomass and 13 frombiowaste

20% of all energy consumption must come from renewable sourcesby 2020, according to the “Renewable Energy Roadmap”, asaccepted and published by the Commission of the EuropeanCommunities. Their goal of reaching 12% until 2012 most likelywon’t be met however.

Reduce annual fossil fuel consumption by 250 Mtoe annually

600-900 Mt decrease in CO2 emission, saving of 150-200 billioneuro

Communication: Renewable Energy Road Map, Brussels, 10-01-2007



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Main references

Petrou, E. C. and Pappis, C. P. (2009) Energy and Fuels 23, 1055-1066 Ragauskas, A. J. et al. (2006) Science 311, 484-489 Koh, L. P. and Ghazoul, J. (2008) Biological Conservation 141, 2450-2460

Junginger, M. et al . (2008) Biomass and Bioenergy 32, 717-729 Bain, Richard L; Overend, Ralph P. Forest Products Journal. 2002, 52, 2, 12-19

Fiedler, F. Renewable and Sustainable Energy Reviews 2004, 8 , 201

Hartmann, D.; et al. Biomass and Bioenergy 1999, 16 , 397 Holm, J. K.; et al. Energy & Fuels 2006, 20 , 2686-2694

Wang, C.; Yan, J. International Journal of Green Energy 2005, 2 , 91-107 Obernberger, I. et al. Biomass and Bioenergy , 2004, 27 , 653 I. Obernberger, G. Thek, Physical Characterization and Chemical Composition of Densified

Biomass Fuels with Regard to their Combustion Behavior, Proceedings of 1st WorldConference on Pellets, Sept. 2002, Stockholm, Sweden, ISBN 91-631-2833-0, pg. 115-122

M. Arshadi, R. Gref, P. Geladi, S.-A., Dahlqvist, T. Lestander, The Influence of RawMaterial Characteristics on the Industrial Pelletizing Process and Pellet Quality, FuelProcessing Technology, 89 (2008), 1442-1447

Documents

Wood Pellets