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Wood
Pelleting
Technology
BÜHLER
Stefan Lescae CH – Uzwil, June 2006
► Use of wood pellets as a solid fuel
� common wood pellet sizes: 6 mm (Austria, Germany), 8 mm (Scandinavia)
� burned directly at the stove (e.g. Austria)
� pelletized for transport reasons (volume reduction) (e.g. Sweden)
• spec. volume (raw material): app. 5 – 20 l/kg
• spec. volume (wood pellets): app. 1.5 – 1.7 l/kg
• pellets are transported to large power plants and are ground again due to
burning properties
► Use of wood pellets for cat litter
Why Wood Pelleting?
Stefan Lescae CH – Uzwil, June 2006
Energy Aspects of Wood Pellets
0
2000
4000
6000
8000
10000
12000
14000
Wood
pellets
Peat lutro Wood
lutro
Brown
coal
Hard coal Oil Natural
gas
Net heat of combustion / kWh/t
Lutro = air dried
Energy for production of wood pellets:• 3 - 20 % of net heat of combustion
Stefan Lescae CH – Uzwil, June 2006
0
200
400
600
800
1000
1200
1400
1600
Wood pellets Heating oil Natural gas
Energ
y h
eating c
osts
(household
) for
34200 kW
h / E
uro
• Calculation done for Germany autumn 2002
• Wood pellets: 0.17 € / kg
• Heating oil: 0.37 € / kg
• Natural gas: 0.42 € / m3
Fuel Costs
Stefan Lescae CH – Uzwil, June 2006
Emissions from the Combustion
of Wood Pellets
0
50
100
150
200
250
300
wood pellets heating oil natural gas
SO2
Nox
Fly ash
CO
CO2
Em
issio
ns o
f com
bustion / m
g/m
3 Values based on specific stovesCO2 neutral
Stefan Lescae CH – Uzwil, June 2006
Net Emissions from the Combustion of
Wood Pellets
0
50
100
150
200
250
300
wood pellets heating oil natural gas
SO2
Nox
Fly ash
CO
CO2Net E
mis
sio
ns / m
g/m
3
Values based on specific stoves
Wood pellets are
CO2 neutral
Stefan Lescae CH – Uzwil, June 2006
Stefan Lesca
eCH –Uzw
il, June2006
Fore
st A
rea o
f Specific
Countrie
s
0
10
20
30
40
50
60
70
Japan
Finland
Slovenia
Sweden
Estonia
Canada
Russia
Latvia
Slovakia
Austria
Bulgaria
Czechia
USA
Germany
Switzerland
Romania
Poland
Portugal
France
Norway
Spain
Belgium
Fore
st A
rea / %
Political Motivations for Wood Pellets
Climate protection, Reduction of greenhouse gas CO2
� EU: promotion of renewable energy sources
� Kyoto protocol
� Danish energy policy: reduction of CO2 of 20 % (2005 – 1988)
�….
Security of energy supply� Green paper: European strategy for the security of energy supply
�….
1
2
Stefan Lescae CH – Uzwil, June 2006
Wood Pellets in Future
F U T U R E D E M A N D O N W O O D P E L L E T S F O R F U E L IN E U R O P E
N A T IO N A L
R E G U L A T IO N S
A N D L A W S
C O N S U M E R
B E H A V IO R
C O S T S F O R
W O O D P E L L E T S
W O O D P E L L E T S
F O R P O W E R
P L A N T S
E U G re e n
P a p e r
K y o d o
p ro to c o l
E U W h ite p a p e r
o n R e n e w a b le
E n e rg y S o u rc e s S u b s id ie s ,
ta x e s
C o s ts fo r
w o o d p e lle ts
C o s ts fo r
c o n v e n t io n a l
fu e ls
G re e n h o u s e
e ffe c t
E n v iro n m e n ta l
p ro b le m s
C o s ts fo r r a w
m a te r ia ls
In v e s tm e n t c o s ts fo r
w o o d p e l le t in g
O p e ra t in g c o s ts fo r
w o o d p e lle t in g
S u b s id ie s ,
ta x e s
E m is s io n s o f
w o o d p e lle ts
(C O 2 , a s h ,… )
S u b s id ie s ,
ta x e sC o s ts fo r
c o n v e n t io n a l
fu e ls
C o s ts fo r
w o o d p e lle ts
N a tio n a l
R e g u la t io n s
a n d la w s
C o m fo r t b y
u s in g w o o d
p e lle ts
A v a ila b il i ty o f r a w
m a te r ia ls
E n e rg y p r ic e s
S p a c e fo r
s to ra g e
N a t io n a l
re g u la t io n s a n d
la w s
S e c u r ity o f fu e l
s u p p ly
S e c u r ity o f fu e l
s u p p ly
Stefan Lescae CH – Uzwil, June 2006
Wood Pellets Process
Chipboard industry
Chipboards
wooden slats,
wooden boards,
parquet, furniture,…
Waste wood
Wood pellets (6mm, 8mm)Wood pelleting
process
By-products of wood processing
Wood industry (wood cutting, drying, sawing, grinding, planing,…)
Stefan Lescae CH – Uzwil, June 2006
Wood Pellets Process
Pretreatment (e.g. crushing, sieving,
heavy particle separator)
Drying
Grinding
Conditioning
Pelleting
Cooling
Sieving
Raw material
Wood pellets
Water and steamTransport
Storage
Control
Stefan Lescae CH – Uzwil, June 2006
Wetting
storageSieving
Storage
Bagging
Intake Sieving
Reduction
Pre Drying
Magnetic
GrindingPelleting
Drying
Wood Pellets Production
Stefan Lescae CH – Uzwil, June 2006
8490
101
133
0
20
40
60
80
100
120
140
3 shifts 7 days a week 3 shifts 5 days a week 2 shifts 5 days a week 1 shift 5 days a week
Productions costs depending onannual operation time / Euro/t
Production costs and
annual operation time
Stefan Lescae CH – Uzwil, June 2006
Wood Pellets Factoryexample
Raw Material Intake
Coarse GrindingSieving
Drying
Flat Store for Pellets
Pelleting
Grinding
Stefan Lescae CH – Uzwil, June 2006