Grant agreement number EIE/06/191/SI2.448381 · 2014-08-11 · Grant agreement number...

“A strategy for the sustainable use of wood and its implementation as base for legislative measures on regional level”

Grant agreement number EIE/06/191/SI2.448381 Deliverable D.3.4. Concept for raw material collection and processing March 2008

Project ASTWOOD.-“A strategy for the sustainable use of wood and its implementation as base for legislative measures on regional level” WP3.- Concept Development D3.4.- Concept for raw material collection and processing

Full name and address of author for all correspondence.- Ms. Angelika Rubick ofi – Austrian Research Institute for Chemistry and Technology Brehmstrasse 14a 1110 Vienna Austria Phone: +43(1)798 16 01-590 – Fax: +43(1)798 16 01-480 [email protected] Full name and address of each co-author.- Mr. Martin Englisch ofi – Austrian Research Institute for Chemistry and Technology Brehmstrasse 14a 1110 Vienna Austria Phone: +43(1)798 16 01-490 – Fax: +43(1)798 16 01-480 [email protected]

mailto:[email protected]

http://www.ofi.at/


http://www.ofi.at/

1 Definitions .....................................................................................................6 2 Purpose.........................................................................................................8 3 Basics............................................................................................................8 3.1 Prices of raw material wood ........................................................................12 4 Forest management ....................................................................................14 4.1 Methods of logging......................................................................................14 4.2 Methods of harvesting.................................................................................16 5 Harvester.....................................................................................................18 5.1 Prices of harvesters ....................................................................................19 5.2 Costs of automated harvesting ...................................................................22 6 Bundling ......................................................................................................23 7 Transportation within the forest...................................................................24 8 Forwarder....................................................................................................24 9 Skidder ........................................................................................................26 10 Cable skidding.............................................................................................27 11 Forest tractors .............................................................................................29 12 Combined machines ...................................................................................30 12.1 Harwarder ...................................................................................................30 12.2 Harvesting processor with cable skidder.....................................................31 13 Storage area ...............................................................................................32 14 Transportation of Biomass ..........................................................................33 15 Forest fuels (log wood, wood chips)............................................................34 15.1 Production and Quality................................................................................34 15.2 Energy content of wood ..............................................................................37 15.3 Log wood.....................................................................................................38 15.4 Wood chips .................................................................................................39 16 Compacted wood (pellets, briquettes).........................................................47 16.1 Wood briquettes, bark briquettes ................................................................47 16.2 Wood pellets ...............................................................................................48 16.3 Industrial pellets ..........................................................................................56 16.4 Security of supply........................................................................................56

17 Other solid biofuels .....................................................................................57 18 Individual Concepts for Sierra da Gata, Belovo and Cova da Beira ...........59 18.1 Sierra da Gata - Spain ................................................................................59 18.2 Cova da Beira - Portugal.............................................................................60 18.3 Belovo - Bulgaria.........................................................................................62 19 Figures ........................................................................................................63 20 Tables .........................................................................................................64 21 Sources.......................................................................................................64

1 DEFINITIONS

Forest management: whole system how a forest is treated

Logging: process of forest management; includes cutting of trees and transportation of the tim-

ber to the forest roads

Harvesting process of cutting trees, removing the branches and sometimes/partly the bark

Wood processing industry: industries that need wood as a raw material like saw mills, furni-

ture production, paper industry. Often they produce wood residues that are used for energy sup-

ply by themselves or serve as a raw material for e.g. pellet or briquette production, chip board

production,...

Energy wood or firewood: mainly wood of low quality, used for energy production. Differen-

tiation between planted trees only for the purpose of energy production and biomass as a by-

product of forest management, gardening or wood processing.

Raw energy wood: untreated, cut timber without branches; with or without bark. Gained from

thinning, storm damages or similar.

BHD (breast height diameter): a scale unit in forestry and by definition the diameter measured

at a height of 1,30 m.

fm (Festmeter/solid cubic meter): a scale unit used in forestry and by definition one cubic

meter (1m3) wood.

efm (Ernte Festmeter): a scale unit in forestry and by definition harvested wood with bark

Spar/Round timber/round wood: cut wood on a specific length.

PSH15: means the productive machine work per hour inclusive a break of 15 minutes.

Srm: a scale unit used in forestry and by definition one cubic meter (1m3) chipped wood.

Wood chips: mechanical chipped wood, with or without bark; obtained from energy wood;

differenced into fine, middle or rough wood chips.

Wood pellets: compressed wood made of pure, untreated wood from by-products of the timber

industry and forestry without addition of synthetic binding agents.

Net-calorific value (also lower heating value): quantity of heat liberated by the complete combustion of a unit of fuel when the water produced is assumed to remain as a vapour and the heat is not recovered

Gross calorific value (also higher heating value) quantity of heat liberated by the complete

combustion of a unit of fuel when the water produced is assumed to remain as a liquid and the

heat is not recovered

2 PURPOSE

Wood was always used as an energy source. In recent times it gets an increasingly important

role in sustainable energy supply. Therefore more effective but also ecological technologies for

forest management, wood processing and biomass heating applications have been developed.

The present concept will provide a state of the art overview over common harvesting and proc-

essing technologies of wood. On the other side it will suggest possibilities for each participating

region, based on the delivered information and plans of the municipalities. The aim is to show

practical ways how the regions may organise their forest management and how to handle their

biomass fuel demand. On the other hand the concept will give examples of alternatives that are

useful in case of changing circumstances or for other countries or municipalities.

3 BASICS

There are some general rules concerning forest management

- Wood that could be processed into higher value-added products should not be counted

as bioenergy potential - first to product than to energy!

- Wood processing provides possibilities for climate protection as well as for the creation

of jobs and prosperity - positive socioeconomic and environmental aspects!

- Manufacturing should also take place as close as possible to raw material reserves and

the markets (end-users) - development of market (biomass applications) leads to

short distances!

- Forest management may increase timber value and produce solid biofuels (cleaning for-

ests, thinning) - investment creates new value chains but management must be sus-

tainable!

Figure 1 Common value chain for forest “products”, wood processing industry and wood fuels

Saw mill products and residues

Forest „products“

Trunks high quality Trunks low quality Branches

Saw dust Bark Wood chips Log wood

Pellets

Timber

Log wood

Recovered wood Big application e.g. district

Small application <1MW

Residues - compost

Wood fuel production: - chipping - splitting - pelletising

Saw mill

Competitors for raw materials: • Paper Industry • Board industry • Mulch, animal bed-

ding production • Agriculture

Roar/Garden Forest

Figure 1 shows a common value chain for forest “products”, wood processing industry and wood fuels. Usual forest products:

- round wood / spar with high quality for wood processing industry (saw mill)

Figure 2: round wood / spar with high quality [54]

- trunks with low quality e.g. too thin, buckled or damaged used for wood chip production

Figure 3: trunks with low quality [54]

- small twigs and branches partly remain in the forest (fertiliser) partly used for wood chip pro-

duction

Figure 4: twigs and branches [54]

- log wood (length of 25- 50 cm) used as fuel

Figure 5: log wood [54]

Round wood with high quality is often sold to saw mills for timber production. The residues of wood

processing processes like sawing or planning are valuable raw materials for other industries.

Usual saw mill products and residues:

- timber (product)

[54]

Figure 6: timber

- saw dust (residue) used as raw material for pellet production

- [54] Figure 7 saw dust

- wood chips (residue) chipped parts of the trunk with or without bark that remain after sawing,

see Figure 8

cross-cut ends

s

timber

Figure 8 Spar or round timber [40]

endings with or without bark

labs with or without bark

- bark (residue) chipped after debarking process

Figure 9 bark [54]

The residues from the sawmills and the low quality round wood of the forest can be used as raw material

for biomass fuels. The price of these residues depends on the availability and the competition at the

market.

Usual competitors for raw materials:

- Paper Industry

- Board industry

- Mulch, animal bedding production

A forest has to fulfil many different functions:

- recreation (vacations, sport,...)

- environmental protection (soil, water, air/climate,...)

- protection (avalanches, erosion,..)

- wildlife habitat (flora and fauna, biodiversity,...)

- economy (job creation, production of marketable goods)

To preserve forests and their functions, it’s very important to perform forest management in a sustain-

able way. How to treat a forest depends on many criteria like landscape, climate, tree population,... and

must be planned with specialists (it’s not part of the present concept).

3.1 PRICES OF RAW MATERIAL WOOD

Because forest management is a long-term project, the measures have to be planned for decades. A criti-

cal parameter is the earnings, which a forest owner has to calculate. Figure 10 shows the changes in

prices for examples of wood as raw material.

Figure 10: Development of costs for wood as

Saw dust

a raw material [1]

Firewood

Round wood

4 FOREST MANAGEMENT

In the present concept forest management includes following steps:

- Logging – cutting the trees and transport of the trunks/round wood to the forest roads

- Transportation – the trunks or round wood and the residues are collected at the forest roads and

transported to the place where further processing is conducted (splitting, chipping, de-

barking,...)

Storing – within all steps storing might be necessary. It’s possible to store the raw material locally in

small, or central in big areas that are mostly paved. In any case it’s important to protect the wood from

beetles and fire. A certain storage time (e.g. one summer season) does also increase the value of the

wood because of decreasing water content.

4.1 METHODS OF LOGGING

Two different methods of logging can be distinguished:

Manual logging

Figure 11: Logging [41]

The trees are cut by hand (chain saw). For moving the trunks a device is needed, e.g. animals, forestry

tractors, cable machines. This method of course was used in former times and although it seems quite

old-fashioned, under certain circumstances, it’s still the only way how forest management could be per-

formed. This method is slowly, but very gentle to the environment.

Especially in protected areas, steep areas where no heavy, technical equipment can be used or in forests

with trees with a big diameter (more than 90cm) the manual harvesting / logging is the first choice. In

case of thinning, when only few trees have to be cut, the manual logging is still economic.

Automatically logging

Within this method the harvesting and transportation is automated. Usually for cutting the trees and

removing the branches a harvester or forest tractor is used. To transport the trunks to the forest roads

there are many possibilities e.g. forest tractors, forwarders, cable machines,...

When using heavy equipment the terrain shouldn’t be too steep (below 40%). The automatically logging

is economical in case of certain methods of harvesting, especially when a big amount of trees have to be

cut.

Figure 12: Harvester

Figure 13: Forwarder

Figure 14: Harwarder [22]

4.2 METHODS OF HARVESTING

There are different methods to harvest wood regarding the forest, depending on the particular objectives,

species of trees and conditions:

[5]

[41]

The clear-cut method is a system where all of the trees are cut and

the open area is usually re-planted with seedlings. This process is

repeated every 20 to 50 years and produces more residues than the

other methods. Clear-cut works well for regenerating species (for

example southern pines and heavy wood), where seedlings need a lot

of sunlight. This method is very critical, if it isn’t planed by experts,

because it can cause serious damage to the biodiversity.

[5]

The seed- tree method is a system, where every 10 to 15 ha, healthy

and well- formed trees are left after harvesting. This provides a natural

source of seeds for the re-growing forest. Compared to the clear-cut,

the cost for re-planting can be saved. On the other hand the wide

spread trees are more influenced by environmental stress like storms,

lightning or beetles. Like the clear-cut method, this method is also

appropriated for species that need much of sunlight.

[5]

The shelter wood method is designed to remove only certain trees. The

new growth is under the protection of the remaining trees, this provides

a natural regeneration process. This system causes higher harvesting

costs than the first two options, the earnings are depending of the num-

ber of cut trees.

The method is used for shade tolerant species as well as trees that need

sunlight.

[5]

In the selection method, individual trees or small groups of trees are

harvested. This guarantees a minimal damage to the remaining forest

stand, furthermore natural seeds will decrease the costs for re-

cultivating. When semi- or automatically harvesting-methods are used,

forest roads are required, because the moving space is limited. This

method is suitable for species that grow very well under shady condi-

tions (such as beech and other hardwood and fir).

Thinning is another type of selective harvesting. Single trees or rows of trees of poor quality are re-

moved. This method doesn’t aim to create a new forest stand, but to provide more space for growing

trees of better quality.

Harvesting costs are influenced by:

• Sizes and types of equipment that is used

• Size and total volume of harvested wood (harvesting method)

• The distance to the processing plant (e.g.: saw mill, heating plant,...)

The shelter wood, selection and thinning method need more manpower, that means they are more cost

intensive. On the other hand they are a sustainable way to preserve forests for a long time.

5 HARVESTER

These machines came original from Scandinavia, where large forested areas have to be managed. The

common machines are wheel harvester and caterpillar harvester, but there are also special types like

walking harvester.

Figure 15 Wheel harvester

[6]

Figure 16: Caterpillar harvester

[6]

Figure 17: Walking harvester [15]

Harvesters are used for cutting trees (in a range of 6 to 15 m) and removing the branches automatically.

They are able to work on slopes up to 40 %. The most common type is the wheel harvester, it’s also the

“cheapest” solution. The caterpillar and especially the walking harvester are designed for special pur-

pose, for slopes up to 70 %.

To transport the round wood an additional tool is needed e.g. a forwarder, cable machine,…

The characteristics of different sizes of harvesters are shown in Table 1:

Table 1: Characteristics of different sizes of harvesters [7]

Small class Middle class Big class

Output < 70 kW from 70 to 140 kW

> 140 kW

Purpose for the first and second

thinning

for thinning and final

harvest

for final harvest

Diameter of trees 15 - 35 cm 20 - 45 cm 30 - 65 cm

Productivity 3- 5 fm per hour 4 - 8 fm No data available

Operation limit min. 7000 fm/year min.15.000 fm/year min. 20.000 fm/year

Fuel Diesel Diesel Diesel

5.1 PRICES OF HARVESTERS

The prices of harvesters depend on:

• Model of harvester

• Required productivity

• Additional equipment

Table 2 and Table 3 show some examples of typical harvester. The mentioned prices include the com-

mon equipment for cutting trees, exclusive taxes and delivery.

Table 2: Wheel harvesters (state of 2008)

Type of Harvester with

standard equipment

Supplier Price [€] Image

ROTTNE H-8

with ROTTNE EGS 402

104 kW

max. diameter: 40 cm

KOPA Forstmaschinen-

Handels- und Reparatur

GmbH; Germany

www.kopa-

forstmaschinen.de

247.000

[9]

http://www.kopa-forstmaschinen.de/


PONSSE Beaver with

PONSSE H53

129 kW

diameter:

5 - 60 cm

Wahlers Forsttechnik

GmbH; Germany

www.wahlers-

forsttechnik.de

305.000

[10]

VALMET 901. 3

4WD and 6WD

with KOMATSU Valmet

350

140 kW


Komatsu Forest GmbH;

Germany

www.forstmaschinen-

service.at

311.600-

329.200

[11]

VALMET 911. 3 6WD

with Valmet 360. 2

150 – 170 kW



Germany

www.forstmaschinen-

service.at

381.800

[11]

HSM 405 H1 6WD

with CTL 453

172 kW


HSM Hohenloher Spezi-

al-Maschinenbau GmbH

& Co; Germany

Internet: www.hsm-

forstmaschinen.de

347.450

[12]

http://www.wahlers-forsttechnik.de/

http://www.wahlers-forsttechnik.de/

http://www.forstmaschinen-service.at/




http://www.hsm-forstmaschinen.de/


ROTTNE H20

187 kW

diameter: 50 – 70 cm



GmbH, Germany

www.kopa-

forstmaschinen.de

390.000

[9]

VALMET 941. 1

201 kW



Germany

www.forstmaschinen-

service.at

470.700

[11]

Table 3: Caterpillar harvester (state of 2008)

Type of Harvester with

standard equipment

Supplier Price [€] Image

VALMET 911. 3 X3M

with the KOMATSU

Valmet 360.2

165 kW

max. diamter: 65 cm


Germany

www.forstmaschinen-

service.at

415.800

[11]







5.2 COSTS OF AUTOMATED HARVESTING

To decide what kind of harvester suites best more parameters have to be considered. These factors have

significant influence on the investment and pay back.

• Topography

• Species of trees

• Diameter of trees

• Density of forest

• Method of harvesting

• Skill of the forest workers

• Operation hours

Depending on the average diameter of the trees usually felling with a harvester is more economical than

manual harvesting. Figure 18 shows a comparison between different harvesting methods (manual- or

felling with harvester, no investment costs are included).

€/Efm without

bark

BHD (c

Figure 18: Comparison of costs of differe

Manual with employees Manual with seasonal workers Automated

m)

nt harvesting methods [1]

6 BUNDLING

Bundling is a quite new technology that was developed in Scandinavia. It is designed for automatically

forest management to facilitate the transport of voluminous forest residues. Bundling is used to arrange

branches and wood residues to bundles, which can easily be moved out of the forest. It’s possible to

store the whole bundles to reduce the water contend of the wood, before chipping.

Table 4: Characteristics of typical bundles and bundling machines [13]

Diameter of the bundle Approx. 80 cm

Standard size of a bundle Approx. 3,20 m

Wood chips of one bundle Approx. 1,4 Srm

Weight of one bundle 600 – 800 kg

Content of energy depending on water content Approx. 1000 kWh

Capacity of the bundling machine 10 – 30 bundles/hour

Costs of the bundling process 10 – 20 Euros/ bundle

As examples for bundling machines two types are shown:

The “WoodPack” from Valmet combines a bundling

machine with a forwarder. The two different tools

can me mounted separately.

Figure 19: Bundling machine “Wood pack” [14]

The second type of bundling machine the

“Fiberpack” from Timberjack is mounted on a truck.

Figure 20: Bundling machine “Fiberpack” [15]

7 TRANSPORTATION WITHIN THE FOREST

After cutting, the trees have to be transported to the forest roads. Usually skidder trails are established

within the forest. The wood and the residues are collected at these trails and are transported afterwards

to the forest roads. To move the trunks a device is needed, e.g. animals, forestry tractors, cable systems,

forwarders or skidders.

Table 5 shows the difference of operation costs for examples of logging.

Table 5: Costs of extraction using different systems (figure only available in combination wit bundling) [16]

Operation Euro/ t

Bunching and logging with horses 43

Logging and bundling with a cable system 31

Logging and bundling with forwarder and tractor 11

8 FORWARDER

The forwarder is designed for transportation of timber. It uses a crane for loading the cut trees or resi-

dues on a trailer. The forwarder is able to transport wood up to 18 tons. These heavy vehicles can cause

damages to the soil, when they are moved in the forest especially on soft grounds. Like the harvester the

forwarders operation is limited to the slope (max. 50%).

Table 6 shows some examples of typical forwarders. The mentioned prices include the common equip-

ment, exclusive taxes and delivery.

Table 6: Forwarders (state of 2008) [17]

Type Supplier Price [€] Image

ROTTNE Solid F9-6

104 kW

max. 9 t



GmbH; Germany

www.kopa-

forstmaschinen.de

172.000

[9]



HSM 208 F

107 kW

max. 9 t



& Co; Germany

www.hsm-

forstmaschinen.de

200.900

[12]

VALMET 830. 3

99 kW

max. 9 t


Germany

www.forstmaschinen-

service.at

204.300

[11]

ROTTNE Solid F12

122 kW

max. 12 t



GmbH; Germany

www.kopa-

forstmaschinen.de

204.900

[9]

VALMET 840. 3

125 kW

max. 12 t


Germany

www.forstmaschinen-

service.at

223.900

[11]

HSM 904F Kombi

130 kW

max. 12 t



& Co; Germany www.hsm-forstmaschinen.de

272.600-

281.500

[12]











ROTTNE Solid F14

122 kW

max. 14 t



GmbH; Germany

www.kopa-

forstmaschinen.de

199.900

[9]

VALMET 860. 3

140 kW

max. 14 t


Germany

www.forstmaschinen-

service.at

249.700

[11]

VALMET 890. 3

170 kW

max. 18 t


Germany

www.forstmaschinen-

service.at

302.300

[11]

9 SKIDDER

Skidders are similar to a tractor, but especially adapted to forest work. They are equipped with a crane

or a cable to handle the trunks. Skidders are relatively “cheap” compared to other forest equipment,

that’s the reason, why they are often used.

When using a skidder, it’s important to be careful, because while pulling the trunks damages to remain-

ing trees can be caused. Table 7 shows some examples of typical forwarder. The mentioned prices in-

clude the common equipment, exclusive taxes and delivery.







Table 7: Skidders (state of 2003) [19]

Type Supplier Price [€] Image

FORCAR FC 200

Skidder

133 kW

HERZOG Forsttechnik;

Swiss

www.herzog-

forsttechnik.ch

174.414

[19]

TIGERCAT 625

Skidder

164 kW

Waldburg Forstmaschi-

nen Wolfegg; Germany

www.wfw-forstmaschinen.de

No information

[19]

10 CABLE SKIDDING

Cable skidding is a special kind of transportation of trunks, where a cable is tightened within the forest

(max. length 900 m). The trunks are completely lifted from the ground, that is the reason why the cable

skidding is very sensitive to the forest. This method is mainly used in steep or impassable areas, or in

protected forests.

Figure 21: Cable skidding

http://www.herzog-forsttechnik.ch/

http://www.herzog-forsttechnik.ch/

http://www.wfw-forstmaschinen.de/

http://www.wfw-forstmaschinen.de/

Table 8 shows some key data of an example for a cable skidder (TST 400) combined with a harvester

(Keto 150), depending on the diameter and the slope gradient.

Figure 22: Keto 150 [43] Figure 23: TST 400 [42]

Table 8: Key data of the cable skidder TST 400 and processor Keto 150 [21]

Key data and efficiency

Efm without bark (for example: spruce) 62, 95

Average BHD (cm) 19,5

Slope gradient % 48

Efficiency of Efm / hour 3,45

Table 9 gives an example of a cost calculation when using the above mentioned combination.

Table 9: Cost calculation of the TST and Keto 150 [21]

Cost calculation

Efficiency of Efm w.b./ hour 3,45

Costs of a hour machine work in Euro

(when felling manual)

59,20

Labour costs for two man in Euro/ hour 44.-

Operating costs in Euro/ hour 103,20

Euro/ Efm 29,90

11 FOREST TRACTORS

A very simple way to start with forest management is upgrading a farming tractor used in agriculture.

Therefore different kind of additional equipment is offered. Commonly the forest tractor is combined

with manual harvesting.

Figure 24: Forest tractor [48]

Additional equipment:

Harvesting processor

[47]

Shield and winch

[44]

Crane and shield

[45]

Lay in trailer

[46]

12 COMBINED MACHINES

To facilitate forest management the combination between harvesting and transportation are in use. There

are numerous possibilities. Two examples are mentioned below.

12.1 HARWARDER

The harwarder combines a harvester with a forwarder.

Figure 25: Harwarder [22]

As an example Table 10 shows a cost calculation of a harwarder (Buffalo Dual”). Compared to above

mentioned equipment the harwarder is quite expansive.

Table 10: Cost calculation of the harwarder “Buffalo Dual” (state of 2005 and 2008) [23]

Indications Value Unit

Investment 342.000 Euro

Annually utilization 1.500 Euro/ PSH15

Cost of materials 95,5 Euro/ PSH15

Labour costs 27,8 Euro/ PSH15

Operation costs 123,3 Euro/ PSH15

12.2 HARVESTING PROCESSOR WITH CABLE SKIDDER

Frequently a harvesting processor is combined with a cable skidder, especially when there is a high

slope gradient in the forest (thus cable machines are often used in the mountains). The cut trees are

transported with the cable skidder to a forest road. There a processor removes the branches and cut the

trunks similar to a harvester into round wood.

Figure 26: Combination of cable machine with harvesting processor [20]

Especially with expansive equipment the operating hours are very important. Only when the for-

est machines are used the maximum of possible hours they can be operated economically.

13 STORAGE AREA

To ensure continuous biomass fuel supply and optimal utilisation of the production plants, the raw mate-

rial and the produced biomass fuels have to be stored. Another aspect is the “easy” way of increasing the

wood quality by storing it to reduce the water contend.

A storage area for biomass has to fulfil some infrastructural requirements, e.g.:

- dry, clean and plane/paved ground

- sheltered areas

- good ventilation for drying the biomass

- in distance to the forest (fire protection,...)

- with additional equipment like e.g. sprinkler systems for beetle protection

- loading possibilities and truck access

Figure 27: Biomass storage – good example

Figure 28: Biomass storage – bad example

14 TRANSPORTATION OF BIOMASS

A significant part of the costs of forest management are caused by transportation. One of the main rea-

sons is the big volume of biomass residues. That’s the reason why the reduction of the volume and fur-

thermore the compression of the raw material is an important question.

Wood and woodparts Slash Round woodBundles Chips

Figure 29: Transportation of wood of the same energy content [35]

It’s neither economical nor ecological to transport voluminous biomass for long distances.

Cost of trans-port (€/MWh)

Residues of wood, left in the forest Trees of thinning Spar Wood chips

Distance

Figure 30: Transportation costs [35]

For starting a business it may be necessary to sell the biomass fuels especially wood chips at distanced

markets. But in long term planning it must be the aim to develop local demand. Therefore the coopera-

tion with boiler manufacturer and local government is very important.

15 FOREST FUELS (LOG WOOD, WOOD CHIPS)

15.1 PRODUCTION AND QUALITY

In many cases firewood is a by-product in timber production. Some firewood products, e.g. forest wood

chips and logwood are produced in forestry. Other wood fuels are produced in the wood processing in-

dustry, e.g. cutter chips, cross-cut ends, edgings, sawdust or wood pellets and briquettes. The use of

woods solely for the production of energy sources can be found in the traditional production of log-

wood, especially when any technical use of the wood is not possible. Comparatively young and cur-

rently limited to a few production areas is the plantation of short rotation forests (e.g. willow and poplar)

which is technically attributed to agriculture.

Measurements for firewood

1 solid cubic meter 1 m³ wood

1 stacked cubic meter 1 m³ stacked firewood incl. air space

1 bulk cubic meter 1 m³ bulk firewood (log wood, wood chips, sawdust, ect.)

stacked m³ bulk m³ bulk m³

bulk m³

log wood wood chips

unit of measurement product range

solid m³

round timber

stacked m³

log wood stacked bulk G 30

„fine“ G 50

„medium“1 solid m³ round timber 1 1,40 1,20 2,00 2,50 3,00 1 stacked m³ log wood, 1 m length 0,70 1 0,80 1,40 (1,75) (2,10)

1 stacked m³ log wood, cut 0,85 1,20 1 1,70

1 bulk m³ log wood, cut 0,50 0,70 0,60 1 1 bulk m³ (forest)-wood chips G 30 „fine“ 0,40 (0,55) 1 1,20

1 bulk m³ (forest)-wood chips G 50 „medium“ 0,33 (0,50) 0,80 1

1 ton of wood chips (G 30) are equivalent to approx. 4 bulk m³ softwood (spruce)

when moisture content is 25 % 3 bulk m³ hardwood (beech)

Table 11: Conversion rates for a common product range of firewood (simplified calculation) [48]

In the past in Austria various conversion factors were used by different institutions (e.g. Statistik Aus-

tria, Austrian Energy Agency, governmental departments). Since March 2007 recommended conversion

factors exist which are used countrywide. An Excel-calculation sheet and an instruction manual are

available free of charge: www.klimaaktiv.at → klima:aktiv Programmübersicht → Erneuerbare Energie

→ energieholz → Downloads → Grundlagen. As an example the conversion factors for forest wood

chips for the use in small and medium-scale systems up to 500 kW nominal output (see Table 11) are

presented. It is based on the following assumptions:

• 35 % average moisture content

• calorific value, gross density and material shrinkage for a mixed range of hardwood and soft-

wood weighted aliquot to the average allocation of wood types used in Austria according to

ÖWI 2000/02

• wood chips G30 with a bulk density of 0.4 solid cubic meter per bulk cubic meter

If the area of application for the forest wood chips is not apparent from the data source (systems up to

500 KW, systems > 500 kW), the calculation can be simplified – according to a customary approach

(see Table 12) - using a bulk density of wood chips G30 of 0.4 solid cubic meter per bulk cubic meter or

2.5 bulk cubic meter per solid cubic meter. For energetic assessment of wood fuels that have been as-

sessed on a dry basis (absolute dry, 0% moisture content), the conversion to wet basis (variable moisture

content) would be necessary to avoid an overestimation of the energy content of the fuel.

fuel

moisture

content

(%)

bulk m³ solid m³ ton, wet

basis

(ton, dry

basis)

heating

value

(GJ)

heating

value

(MWh)

per..

35 1,000 0,400 0,256 0,167 2,921 0,811 bulk m³

2,500 1,000 0,641 0,417 7,302 2,028 solid m³

3,906 1,560 1,000 0,650 11,393 3,065 ton, wet

basis

wood

chips,

G30,

hardwood

and soft-

wood

(mixed) 5,988 2,398 1,538 1,000 18,846 5,235

(ton, dry

basis)

Table 12: Recommended conversion rates for wood chips (small- and medium scale systems up to 500 kw nominal output)

http://www.klimaaktiv.at/

The recommended conversion matrix for pellets is based on the following assumptions

• 8 % average moisture content

• Basic raw material for pelletising in Austria is mainly spruce

• 6 mm pellets with ca. 650 kg/m³ bulk density

For the energetic assessment of pellets that have been assessed on a dry basis (absolute dry, 0% moisture

content), the conversion to wet basis (variable moisture content) would be necessary to avoid an overes-

timation of the energy content of the fuel.

fuel

moisture

content

(%)

bulk m³ solid m³ ton, wet

basis

(ton, dry

basis)

heating

value

(GJ)

heating

value

(MWh)

per..

8 1,000 1,455 0,652 0,600 11,272 3,131 bulk m³

0,687 1,000 0,448 0,413 7,750 2,153 solid m³

1,534 2,232 1,000 0,920 17,284 4,801 ton, wet

basis

pellets

softwood

(spruce)

1,667 2,421 1,087 1,000 19,000 5,278 (ton, dry

basis)

Table 13: Recommended conversion rates for pellets

15.2 ENERGY CONTENT OF WOOD

The calorific value of wood depends on:

• Moisture content (%) – mass of water / total mass

• Density (kg/m³) of the wood – depends on tree species

Wood Condition Moisture Content Net Calorific Value

fresh wood 50 – 60 % 2,0 kWh / kg

stored over one summer 25 – 35 % 3,4 kWh / kg

stored over several years 15 – 25 % 4,0 kWh / kg

Table 14: Calorific value of wood depending on moisture content

Calorific value

[kWh/kg] 5,0

6,0
4,6 4,0 4,0 2,0
3,0
2,2
70 65 60 0,0

1,0

0 5 10 15 20 25 30 35 40 45 50 55

Moisture content [%] Fresh wood Wood logs

Stored for 2-3 years Pellets

Figure 31: Calorific value depending on the moisture content

1110

13001370 1400 1440

15701670 1675

1810 1850 1870 18902040

0

250

500

750

1000

1250

1500

1750

2000

Rob

inie

robi

nia

Eich

eoa

k

Papp

el

Fich

te

Tann

e

Lä Esch

in kWh

fir

spru

ce

popl

ar eas

h

Buc

hebe

ech

Birk

ebi

rch

Aho

rnm

aple

rche

larc

h

Kie

fer

pine

Wei

dew

illow

Erle

alde

r

Figure 32: Calorific value of one cubic meter of wood at a moisture content of 20% depending on tree species

15.3 LOG WOOD

Log wood is defined in the Austrian standards ÖNorm M 7104 and M 7132. Log wood is mainly sup-

plied by small-scale agriculture and forestry or by self-supply. It can be differentiated between hard

wood and soft wood. Classification is also done according to the size. Log wood is ready for use fire-

wood which is cut into the appropriate length. The most common lengths are: 25 cm, 33 cm, 50 cm, 100

cm.

The measuring unit for sections of trees and branches in the length of one meter is “stacked cubic me-

ter”. One stacked cubic meter relates to a stack of wood of 1m x 1m x 1m and is equivalent to 0.7 solid

cubic meters. One solid cubic meter equals one cubic meter of wood (without air space). One stacked

cubic meter of air-dry hardwood weighs 450 to 550 kg, depending on the type of wood. The weight of

air-dry softwood ranges from 350 to 450 kg. Depending on the efficiency of the furnace, this is equiva-

lent to an amount of heating oil of 190 to 230 l for hardwood and 160 to 200 l for softwood.

An important quality characteristic in addition to size and type of wood is moisture. Fresh cut wood is

usually stacked and dried in pieces in the length of one meter with good aeration.

After 1 – 2 years storage time it is in an “air dried” condition with a moisture content of 15 – 20 % (hard

wood dries more slowly than soft wood, especially long is the drying time for oak). For quality reasons

firewood should be stored for at least two years in a sunny, well aerated place. The combustion of fresh

cut or moist wood in boiler provides little energy and can harm the furnace.

15.4 WOOD CHIPS

Wood chips or cutter chips are mechanically chopped wood with or without bark usually up to a length

of 15 cm. It usually refers to matchbox-sized pieces of wood which are produced from small dimen-

sioned wood (wood with a low diameter, e.g. material from thinning, branches, treetops) or other woods

using various types of chippers. Wood chips made of sawmill by-products are called industrial wood

chips.

The measuring unit for wood chips is bulk cubic meter. Depending on type of wood, size and moisture

content, one bulk cubic meter is equivalent to 200 – 300 kg. The energy content of wood chips with a

moisture content of 40% ranges between 2.5 and 4.0 GJ/bulk m³.

Compared to log wood, wood chips have the following benefits:

• Processing and handling is considerably easier due to automatic processing.

• Transport, storage and feeding of the furnace are simplified by automatic transport systems.

• The fuel feed from the storage room to the boiler can be automated – heat production can be

controlled automatically

• Wood chips can be used with higher moisture (up to 60% moisture). However this is only pos-

sible in specifically designed combustion plants, usually for medium- and large-scale systems,

e.g. district heating plants.

Compared to log wood, wood chips have the following drawbacks:

• Mechanical equipment is required for the production of wood chips. Usually it can only be pro-

duced by commercial suppliers, self-supply is virtually impossible for the private end-user.

• The storage of moist wood chips can cause biological decomposition processes and mould.

Apart from unpleasant odour, this can be harmful to one’s health. Therefore only dry, high qual-

ity wood chips should be used in small-scale combustion appliances. In large scale combustion

plants combustion plants this danger is counteracted by high turnover and/or appropriate storing

of the fuel (storage in piles with a height of several meters as wells as compaction)

A classification can be made according to the European Technical Specification CEN/TS 14961. Apart

from information about fuel characteristics and commercial size and packing this specification also re-

quires information about the origin of the wood. Established and practically applied in Austria is a clas-

sification of wood chips according to ÖNORM M 7133. Classification is carried out according to the

parameters size, moisture content, bulk density and ash content as shown in Table 15.

Wood Chip Classes

Description Size distribution1 Maximal Size of Single Chips

G 30 Fine wood chips with a nominal length of 30 mm

Maximum of 20 % smaller than 2,8 mm or larger than 16 mm

Width 3 cm. Length 8,5 cm

G 50 Medium wood chips with a nominal length of 50 mm

Maximum of respectively 20 % smaller than 5,6 mm or larger than 31,5 mm

Width 5 cm. Length 12 cm

G 100 Coarse wood chips with a nominal length of 100 mm

Maximum of respectively 20 % smaller than 11,2 mm or larger than 63 mm

Width 10 cm. Length 25 cm

Moisture Content2

Class Limits Explanation

W 20 W ≤ 20% Air dried wood chips

W 30 20% < w ≤ 30% Storable wood chips

W 35 30% < w ≤ 35% Limited storable wood chips

W 40 35% < w ≤ 40% Moist wood chips

W 50 40% < w ≤ 50% Fresh wood chips

Bulk Density3


S 160 < 160 kg/m³ Low bulk density

S 200 160 – 200 kg/m³ Medium bulk density

S 250 > 200 kg/m³ High bulk density

Ash Content


A 1 ≤ 0,5 % Wood chips with low proportion of bark

A 2 0,5 % < a ≤ 2 % Wood chips with increased proportion of bark

Table 15: Classification of wood chips according to ÖNORM M 7133 1)..The sizes mentioned refer to the standardized mesh size of the sieves used for the analysis 2) 3)... refer to dry basis

According to ÖNORM M 7133 the fine fraction (< 1mm) must not be higher than 4 % at most, i.e. saw-

dust, swarf and the like must not added to any wood chip mix and should not - except for adequate tech-

nical suitability - be burnt in wood chip boilers.

In larger facilities up to district heating plants and in commercial combustion plants –other wood prod-

ucts like sawdust, other wood residues with or without adhesives and coating, shredded scrap wood,

bark and very moist wood chips can be utilized, depending on the type of appliance type and notice of

approval. This is common practice and is mainly done for economic reasons.

Harmful emissions are expected to be in a range that is environmentally not relevant, provided that the

combustion appliances is adapted for those fuels.

Energy content of wood chips (W 30, G 30) based on volume 1 bulk m³ spruce / fir 750 kWh 1 bulk m³ larch 960 kWh 1 bulk m³ pine 879 kWh 1 bulk m³ beech / oak 1057 kWh

1 stacked m³ wood ≈ 1.75 bulk m³ wood chips

1 solid m³ wood ≈ 2.50 bulk m³ wood chips

Calorific value equivalents oil – wood: 1.000 litre heating oil are equal to: • ~ 5 – 6 stacked m³ hardwood

• ~ 7 – 8 stacked m³ softwood

• ~ 10 – 15 bulk m³ wood chips Wood chip production

Depending on the purpose and the amount size of biomass that have to be treated, there are different

kinds of chipper. In general the mobile and the stationary can be distinguished. There ate two common

processes to produce wood chips within forest management.

Chipping in the forest with a mobile chipper

1. Harvesting in the forest

2. Transportation of the residues to the forest road

3. Chipping at the forest road with a mobile chipper

4. Transport of the wood chips to e.g.: heating plant

Figure 33

1

: Chipping

2

in the forest [4]

3

4

Chipping at the storage area/heating plant with a mobile or stationary chipper

1. Harvesting in the forest

2. Transportation of the residues to the forest road

3. Transportation of the residues to the storage area/plant

4. Chipping at the storage area/plant with a big- sized chipper

5. Transport of the wood chips to the production plant (optional)

2 1

Figure 34: Chipping at the storage area/plant [4]

Table 16: Examples of mobile chippers offered by Eschlböck (state 2008) [27]

Type with maximum diameter of wood (cm)

Amount of wood chips (Srm)

Price [€] Image

Biber 2 max. diameter: 14 cm

ex 300 10.000

[28]

3

4

Biber 7 max. diameter: 35 cm

ex 5.000 32.000

[28]

Biber 80 ZK max. diameter: 55 cm

ex 50.000 150.000

[28]

Biber 80 S max. diameter: 55 cm

ex 50.000 190.000

[28]

Figure 35: Stationary chipping plant [54]

Wood chip production costs

The prices of chippers range from € 10.000.- (15 kW) to € 550.000.- (480 kW). Small chippers are used

directly on the forest road after the harvest. More powerful and therefore bigger chippers (up to

100.000) are used at a loading station (also in the forest). The mentioned prices represent the situation in

2008.

- small chippers ( 25-60 kW ), which are operated only by one man, are available from 4.000.- to

13.000.- Euro.

- medium sized chippers ( up to 250 kW ) are available from 30.000.- to 62.000.- Euro.

- large chippers ( up to 480 kW) are available from 180.000.- to 550.000.- Euro.

The prices of stationary chippers, which are used directly at the power plant can reach from 25.000.- to

200.000.- Euro. Depending on the equipment the prices vary in a quite wide range. In the lower price

category there are only chippers, which are only able to chip saw residues or bark. Their capacity is

usually limited with 400 kilo. Real stationary chippers (200- 315 kW), which are able to chip whole

wood, may cost between 160.000.- and 200.000.- Euro.

There are no sales tax and separate equipment in the prices included. The prices depend on the sort of

model, the power range, the efficiency and separate equipment. For special needs an estimation of costs

is given from the dealer.

Personal required

Mobile chippers can be self-fed (with the help of a crane) or operated by only one person (required only

for small chippers). For chipping in the forest only one person is needed for operating and controlling

the chipping machine.

For chipping at the power plant, two persons are necessary: one person to monitor the chipping process

and the other one to manage the logistics of the processed wood.

Maintenance costs

The price of wood chips is about 18.- Euro per bulk volume (Srm = one cubic meter heaped up chips).

Chips as a residual from the saw mills are cheaper than chips gained in the forest. The costs for saw

chips are 7.- Euro Srm with bark and 9.- Euro Srm without bark.

The costs for chipping and transportation are about 10 to 18.- Euro so the essential costs arise by trans-

portation. Due to this fact only small transportation distances (20-50 km) to the power plant are profit-

able.

(state of 2005)

The price of the chips mainly depends on the calorific value respectively on the water content of the

wood chips. So the lower the water content, the higher the price of the chips. So there is a motivation to

produce high- quality wood chips.

The operation costs for chipping range from 180.- to 250.- Euro per hour.

Additional costs of chipping are demonstrated in the next table:

Variable Costs Unit

Labour costs ∼0,50 Euro/ Srm

Chipping costs of a mobile chipper

2,50- 4,00 Euro/ Srm

Chipping costs of a stationary chipper

∼8,50 Euro/ Srm

Operation costs of a truck+ driver

∼41,00 Euro/ Srm

Travel costs of the truck ∼1,00 Euro/ km

Average load of chips on a truck

80 Srm

Average load of chips on a container

72 Srm

Average load of log wood on a truck

26 or 65

fm/ truck carriage Srm/ truck carriage

Loading time of chips on a truck with attachment

1,00 hour

Loading time of wood chips on a container

0,50 hour

Table 17: Additional costs of chipping

Production capacity

Stationary chippers, which are positioned at a power plant achieve an efficiency of 2,5 to 5,0 tons TM (=

dry wood mass) per hour.

Mobile chippers manage to process 3,5 to 8 tons TM per hour. They achieve a capacity of 110 Srm/

hour.

16 COMPACTED WOOD (PELLETS, BRIQUETTES)

Wood pellets and wood briquettes are summarized under the term compacted wood. Those are fuels of

different size and shape produced by compaction of wood shavings. The product characteristics and

quality requirements are specified in ÖNORM M 7135 and in the European Technical Specification

CEN/TS 14961, annex A for pellets for small-scale systems. Wood pellets and briquettes are produced

on industrial scale.

Pellets and briquettes differ from traditional wood fuels (log wood and wood chips) primarily in:

• Low moisture content

• High density

• Low total ash content (exception: bark pellets)

• High energy density

Pellets should only be burnt in appropriate boilers.

16.1 WOOD BRIQUETTES, BARK BRIQUETTES

Wood briquettes are established in the Austrian market and can be obtained from fuel retailers but also

in supermarkets, building centres and do-it-yourself stores. Currently the market is quite saturated.

Wood briquettes are especially suitable for small or only sporadically used room heaters like wood

stoves, sauna heaters or tiled stoves. Due to their high energy content based on volume (high density of

over 1kg/dm³) as well as based on weight (moisture lower than 10 %) and their attractive appearance

customers usually accept the comparatively high prices.

Figure 36: Storage of “attractive” fuel briquettes [50]

Wood briquettes have to be broken into pieces prior to use. They should in no case fill the entire com-

bustion chamber vertically. This could harm the combustion chamber as briquettes expand when heated

or burnt.

Wood briquettes can be found in very different qualities on the market. Good briquettes fulfil the fol-

lowing criteria:

• They are certified according to ÖNORM M 7135 (non-certified products bear, amongst others,

danger of chemical and other Impurity with the implicated environmental risks)

• They have a hole in the middle (significant improvement of combustion behaviour)

• They do not tend to “crumble”

As bark briquettes combust quite slowly, they are particularly suited for maintaining glow in the fire bed

(substitute for charcoal briquettes).

16.2 WOOD PELLETS

Wood pellets are the youngest and most innovative wood fuel, with rapidly increasing use since 1997.

Pellets are made of pure, untreated wood from by-products of the timber industry and forestry without

addition of synthetic binding agents. In Austria more than 90% of the wood used for pelletising is

spruce.

Raw materials for pelletising:

• Shavings from the processing of untreated wood, with low moisture content of approx. 10 %

• Sawdust from the processing of wood without bark

• Other sawmill by-products with low bark content

• Additives based on biomass, e.g. starch, rye flour, corn powder; according to ÖNORM M 7135

the addition of up to maximal 2 % is allowed.

• Water or water vapour

Production

The capacity of 25 major Austrian production facilities is approx. 950,000 tons per year. In fact, about

750,000 tons of pellets will be produced in 2007 (as of June 2007). Due to the existing production ca-

pacities in Austria the supply with high-quality, certified pellets is secured. On the other hand, a multi-

tude of independent suppliers guarantees a market-driven price development in the long run.

Austrian pellet production Austrian pellet demand

tons

Figure 37: Production and consumption in Austria [51]

While the production facilities differ a lot in details, the structure is similar in all facilities and consists

of the following parts:

• Storage for raw materials (silo, hall with pusher plate or other automatic discharge system)

• Drying plant (conveyor or rotary dryer, only necessary for the processing of sawdust)

• Milling (hammer mills,...)

• Metal separation

• Metering unit for additives

• Conditioning (addition of water) and mixer

• Pellet press (flat die or ring die pellet press, see Figure 5; in Austria mainly ring die pellet presses are used)

• Cooling (and drying) system

• Sieving / removal of dust

• Storage of pellets

Figure 38: Flow Chart of a pelleting plant and sectional drawing of a standard pellet press [52]

The layout of a typical plant (flow chart) and a sectional drawing of a standard flat die pellet press are

shown in Figure 38. The pelletising technique originates from the production of compound feed-

ingstuffs. Since the pelletising of wood is considerably more sophisticated than the pelletising of com-

pound feedingstuffs, initially often only pellets in low quality and with a high amount of fines were pro-

duced. Intensive development effort and the demand for higher quality by both customers and heating

appliance manufacturers led to significant further development and improvement of the pelletising tech-

nique.

Production costs

Pellets are produced on industrial scale. The costs are determined by numerous parameters with differ-

ent fluctuation margins, see Figure 39 and Figure 40. The calculations are based on production costs of

73.5 to 94.6 €/t for plants with drying and 52.2 to 81.3 €/t for plants without drying. Depending on the

size of the plant, between 10 and 12 employees have to be calculated.

Without drying

Employees20%

Other costs4%

Storage4%Cooling

1%Pelletising

14%Milling

2% Investment2%

Raw material53%

Figure 39: Average composition of pellets production costs for plants without drying [53]

With drying

Employees13%

Other costs4%Storage

3%Cooling

0%Pelletising

9%Milling4%

Drying30%

Investment3%

Raw material34%

Figure 40: Average composition of pellets production costs for plants with drying [53]

Important criteria for the cost effectiveness of pellet production plants are the capacity utilisation (see

Figure 41) and the size of the plant. Plants with a capacity of less than 5,000 t per year are only profit-

able under very specific circumstances. In the future the total market will mostly be served by large

plants. The size of a plant is limited by the capacity of sawmills and/or availability of raw material (in

terms of transport distances and prices). Transport costs to the customers rise with increasing distance.

s pec

ific

prod

uctio

n co

sts [

€/t p

elle

t]

3 shifts; 7 days/week 2 shifts; 5 days/week

3 shifts; 5 days/week 1 shift; 5 days/week

hours of operation [h per year]

Fig

Ch

Th

8.3

ure 41: Interdependence of production cost and operation hours p.a. [53]

aracteristics of pellets for boilers

• The pellet measures approx. 6 mm in diameter at a length of 1 to 3 cm

• Due to the uniform moisture content of approx. 8 % storage in closed, dry rooms is possible.

• Pellets have a density of approx. 1.2 kg/dm³ with an energy content of about 4.8 kWh/kg at a

moisture content of 8 %.

• The bulk density is 650 kg/m3 on average, i.e. 1000 kg correspond approximately with 1.5 m³.

• Therefore there is not more storage space needed than for an oil storage room.

• Volume of ash less than 0.5 %

• Comprehensive quality guidelines and standards are established, in Austria only pellets certified

according to ÖNORM M 7135 should be bought and sold.

e annual pellet demand of an average single-family house in Austria is about 5,500 kg; this is about

m³ pellets. This amount equals approx. 37 bulk m³ wood chips, 2820 m³ gas or 2700 l heating oil.

Quality assurance and requirements

Why is quality important especially for pellets?

• Pellets compete with established fuels, which have had a steady high quality for years (espe-

cially heating oil and natural gas)

• Pellets are industrial products, when quality is poor, many failures occur at the same time

• The customer segment addressed by pellets usually differs from customers of traditional wood

fuels (pellets are not only used in rural regions or as niche product for environmentally aware

groups).

• Pellet consumers are environmentally conscious (justification for higher investment costs)

o Fuels containing harmful substances are especially negative

o Emissions of heating systems in practical use have to be comparable with values identi-

fied in test facilities. This is only possible with a standardized fuel, which varies only

within narrow limits.

• From the beginning on quality had to be high to avoid a negative reputation, as negative reputa-

tion persists for years (see e.g. quality problems with wood chips in the 1970ies).

• Pellet producers as wells as boiler and stove producers have to explain their customers the need

for certified goods.

Wood pellets are specified internationally by various standards and quality guidelines:

ÖNORM M 7135 DIN 51731 skand. Normen

seit 2006CEN-Normen

ASTM E 870

Normennationale Standards

UZ 38 DINplus

nationale Gütezeichen

HolzpelletsSpezifikationen

Figure 42: Standards and common certification marks for pellets

DIN 51731 HP5 ÖNORM M 7135, HP 1

UZ 38

diameter mm 4 £ D £ 10 4 £ D £ 10 4 £ D £ 10length mm < 50 5*D (1) 5*D (1)

gross density kg/dm³ 1 £ X £ 1,4 ³ 1,12 ± 0,2 ³ 1,12 ± 0,2moisture contend % £ 12 £ 10 £ 10ash contend % £ 1,5 £ 0,5 £ 0,5calorific value (wf) MJ/kg 17,5 £ X £ 19,5 ³ 18 ³ 18sulphur contend % £ 0,08 £ 0,04 £ 0,04nitrogen contend % £ 0,30 £ 0,30 £ 0,30chlorine contend % £ 0,03 £ 0,02 £ 0,02abrasion % – £ 2,3 ± 0,2 £ 2,3 ± 0,2additives % keine < 2 < 2fines % – – – heavy metals mg/kg verschied. – Cr, Cu

(1) max. 20 Gew-% dürfen Längen bis 7,5*D aufweisen(2) max. 20 Gew% bis 45 mm

Table 18: Physical and chemical requirements for wood pellets

In addition to the product standard for wood pellets, there are guidelines for logistics and intermediate

storage, design of storage rooms and requirements for heating appliances in Austria, which together

allow for a comprehensive quality assurance system.

• ÖNORM M 7136

Design of storage rooms

• ÖNORM M 7137

• BVS-Merkblatt Nr. 29

Quality assurance

ÖNORM CEN/TS 15234 „Solid biofuels - Fuel quality assurance”

16.3 INDUSTRIAL PELLETS

Industrial pellets are designed for the use in commercial combustion plants or for the heating of larger

properties. They differ in size and quality requirements from the 6 mm pellets used in small-scale com-

bustion appliance and should never be used in heating systems less than 100 kW. The requirements fol-

low mostly ÖNORM M 7135. If industrial pellets are sold as pellets certified according to ÖNORM M

7135, they have to meet the requirements of class HP 2 mentioned in this standard. Also for the produc-

tion of industrial pellets solely the use of untreated biomass is allowed.

16.4 SECURITY OF SUPPLY

The needed amount of wood pellets can relatively easily be estimated considering the systems set up and

their power. Since 2002 overproduction is increasingly being sold to Germany and Italy where own

capacities are just under construction.

Fundamental for the long-term supply security is the availability of the raw material. Primarily sawdust

and shavings produced by large wood processing plants are used for pelletising. In Austria about 1 mil-

lion tons of sawdust and shavings are available. By now this potential is largely utilised by the produc-

tion of pellets and briquettes and for other uses. Basically all sawmill by-products or wood products that

are chemically untreated and, to a large extent, free of bark, are suitable for the production of wood pel-

lets. They are already used in some larger pellet production plants. In this case additional shredding and

drying facilities are necessary. In the long run the total yearly growth of the Austrian forests presently

not used (approx. 10 million tons) is available. This means that raw material for 750,000 single-family

houses, each with an annual fuel demand of 6 tons of wood pellets, is available, without endangering the

sustainable use of Austrian forests.

17 OTHER SOLID BIOFUELS

In Europe traditionally different solid biofuels are used for the production of energy. While in Northern

and Central Europe wood fuels dominate, agricultural residues are used as fuels in Southern Europe, e.g.

residues from olive pressing and olive kernels in Spain, Italy and Greece. In Denmark straw is burnt in

district heating plants and in Belgium and Dutch power plants imported palm nut shells and the like are

burnt.

In order to fulfil different requirements, to create equal general conditions throughout Europe, to reduce

trade barriers and to force the use of biofuels the European Commission has mandated CEN (European

Committee for Standardization) to standardise biomass fuels. The mandate defines the scope of the pro-

spective standards. For this purpose CEN has formed a technical committee (TC 335) with five work-

shops whose members work intensely on the development of comprehensive regulations (altogether

about 28 standards). In 2004 the first technical specifications (TS) were published, since 2006 the ma-

jority of the standards are available, see Table19. For the time being the technical specifications, which

have the character of prestandards, will complement the Austrian standards but not substitute them.

Presently the standards are revised, from 2008 on they shall be published as EN. From then on Austrian

standards will partly be withdrawn.

ÖNORM CEN/TS 14588 Feste Biobrennstoffe - Terminologie, Definitionen und Beschrei-bungen

ÖNORM CEN/TS 14774-1 Feste Biobrennstoffe - Verfahren zur Bestimmung des Wasserge-halts - Teil 1



ÖNORM CEN/TS 14775 Feste Biobrennstoffe - Verfahren zur Bestimmung des Aschegehalts

ÖNORM CEN/TS 14778-1 Feste Biobrennstoffe - Probenahme (Teil 1: Verfahren zur Probe-nahme)

ÖNORM CEN/TS 14778-2 Feste Biobrennstoffe - Probenahme (Teil 2: Verfahren zur Probe-nahme von Materialien...)

ÖNORM CEN/TS 14779 Feste Biobrennstoffe - Probenahme (Verfahren zur Erstellung von Probenahmeplänen...)

ÖNORM CEN/TS 14780 Feste Biobrennstoffe - Verfahren zur Probenherstellung ÖNORM CEN/TS 14918 Feste Biobrennstoffe - Verfahren zur Bestimmung des Heizwertes ÖNORM CEN/TS 14961 Feste Biobrennstoffe - Brennstoffspezifikationen und -klassen ÖNORM CEN/TS 15103 Feste Biobrennstoffe - Verfahren zur Bestimmung der Schüttdichte

ÖNORM CEN/TS 15104 Feste Biobrennstoffe - Verfahren zur Bestimmung des Gehaltes an C, H und N (...)

ÖNORM CEN/TS 15105 Feste Biobrennstoffe - Verfahren zur bestimmung des wasserlösli-ches Gehaltes an Cl, Na, K

ÖNORM CEN/TS 15148 Feste Biobrennstoffe - Verfahren zur Bestimmung des Gehaltes an flüchtigen Substanzen

ÖNORM CEN/TS 15149-1 Feste Biobrennstoffe - Verfahren zur Bestimmung der Teilchengrö-ßenverteilung - Teil 1



ÖNORM CEN/TS 15150 Feste Biobrennstoffe - Verfahren zur Bestimmung der Teilchendich-te

ÖNORM CEN/TS 15210-1 Feste Biobrennstoffe - Verfahren zur Bestimmung der mechanischen Festigkeit von Pellets...

ÖNORM CEN/TS 15210-2 Feste Biobrennstoffe - Verfahren zur Bestimmung der mechanischen Festigkeit von Pellets...

ÖNORM CEN/TS 15234 Feste Biobrennstoffe - Qualitätssicherung von Brennstoffen

ÖNORM CEN/TS 15289 Feste Biobrennstoffe - Bestimmung des Gesamtgehaltes an Schwefel und Chlor

ÖNORM CEN/TS 15290 Feste Biobrennstoffe - Bestimmung von Hauptelementen

ÖNORM CEN/TS 15296 Feste Biobrennstoffe - Analysenberechnung auf unterschiedliche Bezugsbasen

ÖNORM CEN/TS 15297 Feste Biobrennstoffe - Bestimmung von Spurenelementen

ÖNORM CEN/TS 15370-1 Feste Biobrennstoffe - Verfahren zur Bestimmung des Schmelzver-haltens der Asche - Teil 1

prCEN/TR 15569 (Final Draft) Solid biofuels - A guide for a quality assurance system

Table19: European standards for solid biofuels

The wood pellets for small scale combustion appliances specified in Austria (ÖNORM M 7135) can

currently be found in the European standards in supplement A of ÖNORM CEN/TS 14961: 2004 09 01

„Solid biofuels – Fuel specifications and classes“.

18 INDIVIDUAL CONCEPTS FOR SIERRA DA GATA, BELOVO AND COVA DA BEIRA

Based on the information delivered by the regions concerning the planned biomass application and the

data of previous work packages, suggestions for establishing a collection and processing system have

been developed.

18.1 SIERRA DA GATA - SPAIN

Planned action

The planned application in Spain will be the heating system for a public building in Sierra de Gata. Fur-

thermore they are planning to establish a forest managing plan for the area. They are planning to pro-

mote four “forest stations”, that will be used for managing logging, storing and processing for forest

biomass.

Topography

The average slope is 30%, but the terrain is uneven. If the road EX-205 serves as reference, two well

differentiated areas exist. Toward the north, there is almost forest, but the area is mountainous and most

of the slopes are superior to 30%, there are even areas with slopes steeper than 60%. Toward the south

the slopes are 15-20%, but the land is occupied by Dehesas and agricultural lands.

Existing forest management

There is neither information about the permitted annual cut not a registration of the wooden quantity that

exists in the public or private mountains.

Existing laws or regulations for working in the forest

Laws of protection of mounts exist against forest fires that indicate that in the times of maximum risk of

forest fires, the activities cannot be carried out with heavy machines. Vehicles that are not in official

services are not allowed to drive off road. For forest measures it is necessary to make a plan of fire pre-

vention for properties of more than 100 has and for ones in close surroundings of towns (400 m).

In case of thinning, cutting trees or to burning stubbles on agricultural properties, people have to request

a permission from the Junta de Extremadura, in general the burning at forest lands is forbidden the

whole year. References: Forest Plan of Extremadura, Plan PREIFEX and Plan INFOEX.

Concept for collection/logging and processing

Because of fire danger and the slope of the mountainous terrain manual harvesting is recommended. The

optimal harvesting method might be thinning or the selection method, but it have to be planned together

with forest experts in consideration with the regional characteristics. Afterwards the cut wood can be

moved with a forest tractor, or in very steep areas with a cable skidder. The round wood with high qual-

ity can be sold to wood processing industries like saw mills. The trunks with low quality and the

branches can be chipped. It’s important to remove the needles before burning. The forest residues have

to be removed immediately from the forest itself. One interesting possibility might be to collect the resi-

dues next the forest roads while the thinning takes place and chip them with a mobile chipper. The chip-

per can be shared between several municipalities. The wood chips can be stored at the planned “forest

stations”, which are established in distance to the forest areas. The chips may also be sold at these

places.

To reduce the volume of the residues a bundling machine should be considered.

Because in Sierra de Gata there are no biomass applications, it’s advisable to start with wood chip boil-

ers for small buildings. The technology is well known and the fuel can be produced locally (strengthens

the identification with the “new” fuel).

Figure 43: Bundling process

To establish a pellet plant is not advisable at the moment, because in Sierra de Gata there is no big saw

mill industry and significant investment would be needed.

18.2 COVA DA BEIRA - PORTUGAL

Planned action

The planned application in Portugal will be the heating system for a pavilion and Swimming-Pool in

Sabugal. The system is constituted by two boilers with 165 kW of individual power, working during 260

days. This boiler can be powered by grain of olive, almond bark and wood chips

Topography

Regarding the slopes, most of the region has slopes that vary between 0 and 10%, except the counties

covered by mountains of Gardunha, Estrela and the Vale do Côa, where the predominate classes of slope

are higher.


There is no information about the permitted annual cut, but a legislation that regulates the slaughter of

different species under its DBH - diameter at breast height, where these species may be slaughtered

when they reach that measure.


Regulatory Decree No 12/2006

Regional Plan of Planning Forest of Beira Interior. These are some instruments of regional policy that

affects the forest areas and seek to manage and establish specific standards of use, occupation, use and

forestry development, in order to promote and ensure the production of goods and services and the sus-

tained development of these spaces.

The Regional Plan of Planning Forest of Beira Interior (PROF BI) has an approach for integrating func-

tions of production, protection, conservation of habitats, fauna and flora, forest-Grazing, hunting and

fishing in inland waters, recreational and landscape.

These plans aim also to contribute to the development of the proper management of forest areas through

the establishment of an appropriate policy planning regarding the recovery, protection and sustainable

management of forest resources. References: Plan for Prevention Against Fires, PROLUNP - National

Programme of Fight Against Pine Wilt Nematode, Protection of quercus suber and quercus ilex, Good

Practice Forestry

Concept for collection/logging

Because of the close neighbourhood to Sierra de Gata the two regions can be treated similar. In Cova da

Beira the slope is less steep, so it’s easier to use forest machines. But because of the same reasons (fire

danger) it might be advisable to start with manual harvesting. Please see the concept for Sierra de Gata.

An interesting aspect is the population of Eucalyptus. Many people want to get rid of the foreign spe-

cies, so that might be cheep raw material.

18.3 BELOVO - BULGARIA

Planned action

The planned application in Bulgaria will be a heating system for a school in Belovo town. This project

will substitute old, depreciated boilers with a new pellet boiler with a capacity of 500 kW.

Topography

The average slope in the Belovo forest terrain is 30%.


The annual allowable cut for the Belovo forest (public/private) is 50 000 m3.


There is a Forest Law, which regulates all activities related to forests exploitation and recreation in Bul-

garia.

Concept for collection/logging

In Bulgaria the forest areas are very large, therefore it’s important to establish a functional system of

forest roads. Because of the amount of wood and the large diameter of the trees a combination of man-

ual and automated harvesting might be the best possibility in future also complete automated forest

management could be envisaged.

Figure 44: Automated harvesting

In relatively flat areas forest machines like the harvester and the forwarder are a good combination, es-

pecially in case of large forestry regions a good occupancy rate can be reached.

To supply local demand of the region the production of log wood and wood chips might be advisable. In

the case of Belovo because of the amount of wood, bushes and wood residues a stationary chipper will

be good solution. That device can also cope with larger diameter of trees.

19 FIGURES

Figure 1 Common value chain for forest “products”, wood processing industry and wood fuels ............. 9 Figure 2: round wood / spar with high quality ......................................................................................... 10 Figure 3: trunks with low quality ............................................................................................................. 10 Figure 4: twigs and branches.................................................................................................................... 10 Figure 5: log wood ................................................................................................................................... 10 Figure 6: timber........................................................................................................................................ 11 Figure 7 saw dust ..................................................................................................................................... 11 Figure 8 Spar or round timber [40] .......................................................................................................... 11 Figure 9 bark ............................................................................................................................................ 12 Figure 10: Development of costs for wood as a raw material [1] ............................................................ 13 Figure 11: Logging [41] ........................................................................................................................... 14 Figure 12: Harvester................................................................................................................................. 15 Figure 13: Forwarder................................................................................................................................ 15 Figure 14: Harwarder [22]........................................................................................................................ 15 Figure 15 Wheel harvester ....................................................................................................................... 18 Figure 16: Caterpillar harvester................................................................................................................ 18 Figure 17: Walking harvester [15] ........................................................................................................... 18 Figure 18: Comparison of costs of different harvesting methods [1]....................................................... 22 Figure 19: Bundling machine “Wood pack” [14] .................................................................................... 23 Figure 20: Bundling machine “Fiberpack” [15]....................................................................................... 23 Figure 21: Cable skidding ........................................................................................................................ 27 Figure 22: Keto 150 [43].......................................................................................................................... 28 Figure 23: TST 400 [42]........................................................................................................................... 28 Figure 24: Forest tractor [48] ................................................................................................................... 29 Figure 25: Harwarder [22]........................................................................................................................ 30 Figure 26: Combination of cable machine with harvesting processor [20].............................................. 31 Figure 27: Biomass storage – good example ........................................................................................... 32 Figure 28: Biomass storage – bad example.............................................................................................. 32 Figure 29: Transportation of wood of the same energy content [35] ....................................................... 33 Figure 30: Transportation costs [35] ........................................................................................................ 33 Figure 31: Calorific value depending on the moisture content ................................................................ 37 Figure 32: Calorific value of one cubic meter of wood at a moisture content of 20% depending on tree

species ............................................................................................................................................. 38 Figure 33: Chipping in the forest [4]........................................................................................................ 42 Figure 34: Chipping at the storage area/plant [4]..................................................................................... 43 Figure 35: Stationary chipping plant [54] ................................................................................................ 44 Figure 36: Storage of “attractive” fuel briquettes [50]............................................................................. 48 Figure 37: Production and consumption in Austria [51].......................................................................... 49 Figure 38: Flow Chart of a pelleting plant and sectional drawing of a standard flat die pellet press [52]50Figure 39: Average composition of pellets production costs for plants without drying [53]................... 51 Figure 40: Average composition of pellets production costs for plants with drying [53]........................ 52 Figure 41: Interdependence of production cost and operation hours p.a. [53]......................................... 53 Figure 42: Standards and common certification marks for pellets........................................................... 54 Figure 1: Bundling process ...................................................................................................................... 60 Figure 2: Automated harvesting............................................................................................................... 62

20 TABLES

Table 1: Characteristics of different sizes of harvesters [7] ....................................................... 19 Table 2: Wheel harvesters (state of 2008)................................................................................................ 19 Table 3: Caterpillar harvester (state of 2008)........................................................................................... 21 Table 4: Characteristics of typical bundles and bundling machines [13]................................................. 23 Table 5: Costs of extraction using different systems (figure only available in combination wit bundling)

[16] .................................................................................................................................................. 24 Table 6: Forwarders (state of 2008) [17].................................................................................................. 24 Table 7: Skidders (state of 2003) [19]...................................................................................................... 27 Table 8: Key data of the cable skidder TST 400 and processor Keto 150 [21]........................................ 28 Table 9: Cost calculation of the TST and Keto 150 [21] ......................................................................... 28 Table 10: Cost calculation of the harwarder “Buffalo Dual” (state of 2005 and 2008) [23] ................... 31 Table 11: Conversion rates for a common product range of firewood (simplified calculation) [48]....... 34 Table 12: Recommended conversion rates for wood chips (small- and medium scale systems up to 500

kw nominal output).......................................................................................................................... 35 Table 13: Recommended conversion rates for pellets.............................................................................. 36 Table 14: Calorific value of wood depending on moisture content ........................................................ 37 Table 15: Classification of wood chips according to ÖNORM M 7133.................................................. 41 Table 16: Examples of mobile chippers offered by Eschlböck (state 2008) [27] .................................... 43 Table 17: Physical and chemical requirements for wood pellets ............................................................. 55 Table18: European standards for solid biofuels ....................................................................................... 58 21 SOURCES

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