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Avai lab le at www.sc iencedi rect .com

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Productivity and cost of mechanized energy wood harvestingin Northern Scotland

Dominik Roser*, Lauri Sikanen, Antti Asikainen, Heikki Parikka, Kari Vaatainen

Finnish Forest Research Institute, PO Box 68, FI 80101 Joensuu, Finland

a r t i c l e i n f o

Article history:

Received 9 May 2011

Accepted 14 June 2011

Available online 7 July 2011

Keywords:

Forest biomass

Scotland

Energy wood harvesting

Productivity

Supply chain design

* Corresponding author. Tel.: þ358 10 211 32E-mail address: dominik.roser@metla.fi (D

0961-9534/$ e see front matter ª 2011 Elsevdoi:10.1016/j.biombioe.2011.06.028

a b s t r a c t

At present, the utilization of timber in the Northern part of the Scottish Highlands is low

due to a lack of a wood utilizing industry. As a consequence, the majority of forest owners

do not receive any income from timber and in some cases stumpage prices can even be

negative. At the same time, increasing prices of oil, gas and electricity pose a great chal-

lenge for local industries and homeowners. The establishment of wood fueled heating

systems is therefore expected to improve the situation and at the same time create

a market for the local timber resources. Consequently, a local energy source to produce

heat and electricity at a competitive price would have positive benefits for both local

industries and forest owners. Due to the current lack of competition, roundwood could be

chipped for fuel, which has many associated benefits compared to the harvesting and

chipping of logging residues. It is the aim of this research to apply existing Finnish know-

how in regards to wood fuel harvesting in order to develop and investigate the price level of

sustainable and local wood fuel supply chains.

To determine the most suitable supply chain for forest fuels, various research methods

were applied. An estimation of the forest resources in the Wick area was the first step of

the research. The different cost components of the supply chain such as cutting, for-

warding and chipping were then calculated based on Finnish experiences and adapted to

conditions in Northern Scotland. Detailed transportation distance calculations and cost of

transportation were calculated using GIS tools.

Of the various supply chain designs considered, chipping at the landing seems to be the

most suitable option. Chipping the roundwood at a central terminal would also be feasible;

however, a suitable site would have to be identified since chipping of the material at the

heating plant is not an option. Calculations indicate that forest chips can be delivered

starting from approximately 20 VMWh�1 within a 50 km transportation distance when

chipping is at roadside. If the transportation distance is 100 km wood chips could be

delivered at approximately 23 VMWh�1. Results from the GIS analysis indicate that

a sufficient supply of raw material will be available in the future. According to these

calculations forest fuels can be a competitive energy source for heat and electricity

production in Northern Scotland.

ª 2011 Elsevier Ltd. All rights reserved.

66.. Roser).

ier Ltd. All rights reserved.

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 4 5 7 0e4 5 8 0 4571

1. Introduction and transportation) cannot be simply transferred from one

At present, international agreements and national strategies

emphasize the use of renewable energy resources in Europe. A

major share of that increase could be based onwood resources

[1]. One of the obstacles for an increased use of wood energy

sources is that expertise is dispersed and the development

requires the commitment of several stakeholders. Utilizing

local wood energy resources can helpmeet national strategies

and maximize rural development benefits to local communi-

ties. In addition, local users of wood fuel linked to local

resources could reduce transport costs and create the poten-

tial for affordable energy in areas affected by fuel poverty.

In the Northern parts of the Scottish Highland, active tree

planting programmes several decades ago have created

a rapidly growing forest resource. The main species are

Lodgepole pine (Pinus contorta) and Sitka spruce (Picea sitch-

ensis). Currently, a large share of those forests is in the

succession phase, and thinnings as well as final fellings are

needed to maintain forest health. In some places, mono-

culture lodgepole pine stands are planned to be clear cut in

order to establish newmixed species forests or for restoration

of the original peatlands. The standing volume of softwoods in

Scotland is estimated to increase from the current 6 hm3 to

9 hm3 by 2015 [2]. However, the technical and physical quali-

ties of timber are low and long transportation distances to

wood processing industries strain the economics. A signifi-

cant share of this resource is located in the Highlands, where

the industrial demand for wood is very limited.

The majority of forest owners do not receive any income

from timber and in some cases stumpage prices can be even

negative due to the long transportation distances. At the same

time, increasing prices of oil, gas and electricity pose a great

challenge for local industries and homeowners. The estab-

lishment of wood fuel based heating systems offers possibil-

ities to improve the situation. Increased energy use of timber

may create new local markets for the wood resources.

Another key issue constraining wood fuel market devel-

opment at themoment is confidence. Users lack confidence in

and knowledge about existing supply chains, but their devel-

opment will not proliferate until there is further evidence of

demand for wood fuels.

Contrary to Scotland, Finland already has large variation of

different wood fuel supply chains from small farm-scale to

large industrial combined heat and power plants. From the

early 1990s Finland has promoted the use of wood fuel via

several research and development programmes. In 2004,

2.7 hm3 of forest chips were used in power plants and small

farm-scale boilers whereas in 2000, only 0.9 hm3were used [3].

The successful setup of forest fuel supply chains calls for

the active participation of stakeholders from various back-

grounds and experiences. Finland, which has put lots of

efforts into the development of both large- and small-scale

forest fuel supply chains, has undergone rapid development

[4]. Through the course of that development many mistakes

have been made and lessons were learned. Today, other

regions and countries can benefit from those experiences and

mistakes that have already been made and can be avoided.

However, supply chains (system including logging, chipping

country to another, but they need to be tailored to fit to the

local circumstances and conditions. It is very important to

find out what the local technology is and what is being

currently used. It may be best to use systems that local prac-

titioners are already used to. As a result, technology has to be

chosen based on local conditions and availability of skilled

operators or entrepreneurs. As a result of technology transfer,

new systems and models are constantly being developed and

there is a mutual benefit for the involved stakeholders since

all of them are learning from each other.

Consequently, a local energy source, managed on a sustain-

able basis, to produce heat and electricity at a competitive

price would have positive benefits for both local industries and

forest owners. Due to the current lack of competition, round-

wood could be chipped for fuel, which has many associated

benefits compared to the harvesting and chipping of logging

residues.

Several small-scale wood fuel boilers have already been

installed across the Scottish Highlands. However, there is

a lack of experience when it comes to the supply of larger

installations in the range from 1 to 10 MW. Already existing

timber procurement chains and experienced workers should

be utilized as much as possible to ensure fuel supply.

Timber harvesting and wood procurement has developed

very fast over the last three decades in Nordic countries [5]. At

present, the harvestereforwarder systemhas proven to be the

most profitable and productive harvesting system for the cut-

to length method in Nordic conditions and the degree of

mechanization is close to 100% [6]. In the UK, the cut-to-length

system based on the harvester-forwarder system is also used

commonly and the overall mechanization is approximately

90% [1]. Woodfuels are creating a new market for wood. Thi-

s opens the possibility to utilize roundwood for energy

production.

Over the last decade, harvester and forwarder productivity

has been investigated in numerous studies inNordic countries

[7e12] and also in the UK [13,14].

There have also been various studies dealing with the

harvesting of small diameter trees timber [15e22] but further

research is needed to investigate applicability of harvesters

and energy wood harvesting systems in other countries with

different tree species, terrains and varying operational envi-

ronment. Additional information is needed to promote

a further expansion of the use of bioenergy in other European

countries as well.

The objective of this study was to estimate the feasibility

and cost level of selected supply chains for forest chips in the

Northern parts of the Scottish Highlands. Variations of the

supply chain, resulting from alternative location of chipping

were also compared.

2. Materials and methods

In this study the biomass harvested originated from clear cuts

and it was assumed that conventional purpose built single

grip harvesters and conventional forwarders would be used to

transport timber to the roadside. Once timber is at the

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 4 5 7 0e4 5 8 04572

roadside, three options for further processing of the material

are available. Timber can either be chipped at the roadside or

transported to a terminal where it is chipped and the wood

chips are then transported to the end user, or chipped at the

end use facility. The structure of the considered options is

presented in Fig. 1.

The most suitable harvesting and chipping method was

determined by evaluating four different aspects of forest

energy harvesting, namely:

- natural conditions;

- social considerations in relation to forest energy entrepre-

neurship and structure of supply;

- the limitations set by the combustion technology and their

effects on the harvesting chain; and

- finally the properties of the fuel itself (Fig. 1).

The different cost components of the supply chain such as

cutting, forwarding and chipping were calculated based on

experiences in Finland and modified for conditions in

Northern Scotland. Detailed transportation distance calcula-

tions and cost of transportation were calculated using GIS

tools such as ArcGis� and cost calculators.

All machines hourly cost calculations presented in this

study were based on new machines and equipment. The

productivity data used in this study is based on established

Finnish supply chains.

2.1. Long distance transportation

In this study, long distance transportation was assumed to be

truck based with a maximum payload of 27 t. The hourly

operating cost of the trucks in Scotlandwas calculated to be 90

Euros, based on [23,24]. Values used in the hourly cost calcu-

lations of a Scottish timber truck are presented in Table 1.

Loading and unloading times in the case of roundwood

transportation to the end use facility were assumed to be 0.62

and 0.58 h per load, respectively, based on Nurminen [25]. The

driving speed as a function of distance was also calculated

Organizing the supply

Harvesting and forwarding roundwood to roadside storage

Chipping at roadside

Transporting chips

Transporting roundwood

Comminution at terminal Transporting chips

End use facility

Comminution at end

use facility

Fig. 1 e Production stages of different supply chains.

according to Nurminen [25]. However, driving speed was

reduced by 25% since it was assumed that road conditions in

Scotland do not allow as fast a driving speed as in Finland. By

summarizing the results of loading, unloading, driving empty

and loaded, the total roundtrip time was calculated in 5 km

intervals from 1 to 195 km. In addition, delay times of 0.32 h

per load were added to account for breaks and other inter-

ruptions. The total roundtrip time was then multiplied with

the hourly operation cost of the truck and then divided by the

payload of the truck in order to receive the cost in Euros per

tonne.

In the case of roadside chipping, it was assumed that

a mobile chipper would chip directly into the load space of the

chip truck. The maximum volume of the chip truck was

calculated by converting the maximum payload of the truck

namely 27 t into solidm3 (33 m3) and then converting the solid

m3 into loosem3.Asa result themaximumamounta chip truck

could carry in Scottish conditions would be 82.5 m3 loose.

The same hourly cost of 90 Euros was used for the wood-

chips truck. However, the loading time at the roadside was

based on the productivity of the chipper (1.3 h per truck load).

Unloading was assumed to be 30 min and weighing of the

truck before and after unloading was assumed to be 3 min.

The driving speed as a function of distance was calculated

according to the driving speed functions of Ranta [26] and

Halonen and Vesisenaho [27]. Time for driving empty and

loaded was calculated by dividing the amount of kilometers

with the respective driving speed. The same reduction factor

of 0.75 as in long distance transportation was used to account

for the slower driving speeds. By adding the results of loading,

unloading, weighing, driving empty and loaded the total

roundtrip time was calculated in 5 km intervals from 1 to

195 km. In addition extra delay times of 10%were added to the

total time to account for problems associated when intro-

ducing a new type of technology.

When using a chipping terminal the extra unloading at the

terminal and loading of the chips into the chip truck has to be

considered. It was assumed that the chipper blows chips

directly into the wood chips van. The chipping/loading time

was assumed to be 1 h due to the higher efficiency of terminal

operations compared to roadside chipping. The functions for

driving speeds, loading, unloading and delays were the same

as for the alternative of chipping at roadside. The location of

the terminal was assumed to be 5 km from the heating plant.

2.2. Logging costs

Since it was assumed that roundwoodwould be used for wood

chips production, harvesting and forwarding costs or normal

roundwood harvesting were assumed. Harvesting costs per

tonne were based on Finnish work study data. An average

value of 12.2 V t�1 was used. Forwarding costs are based on

long-term average Finnish productivity data [28]. In this study

an average forwarding cost of 7.0 V t�1 was used. In total,

harvesting and forwarding costs amounted to 19.2 V t�1.

2.3. Chipping costs

It was assumed that the moisture content of raw material at

chipping after storage would be approximately 40% based on

Table 1 e Cost details of Scottish timber truck.

Max load 55 t Base truck, value 91,000 V

Pay load 27 t Equipments 10,000 V

Driving days 200 d year�1 Trailer 27,000 V

Loads per day 3 loads day�1 Crane 30,000 V

Time per load 3 h load�1 Wage of the driver 18 V h�1

Average transportation distance 60 km Indirect wage costs 60 %

Kilometers per year 64,800 km Wage costs total 51,322 V a�1

Lifetime of truck 6 a Depreciation 17,973 V a�1

Lifetime of trailer 8 a Interest 5 %

Lifetime of crane 8 a Insurances 5200 V a�1

Fuel consumption 45 L (100 km)�1 Transportation fees 4500 V a�1

Tire lifetime before first coating 140,000 km Overheads 4000 V a�1

Operating hours 1620 h load�1 Management 2918 V a�1

Fuel price 1 V l�1 Other uses 5000 km a�1

Lubricants 2354 V a�1 Fixed costs total 41,685 V a�1

Repair/service 13,455 V a�1 Risk 4 %

Tires coating cost 117 V coating�1 Total costs 145,870 V a�1

Variable costs total 47,023 V a�1 Cost per hour 90 V h�1

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 4 5 7 0e4 5 8 0 4573

the results of the drying trials of Hillebrand and Nurmi [29]. A

separate cost calculationwas carried out to determine the cost

of chipping using a medium sized chipper. The chipping costs

varied slightly depending on the location of the chipper. In

these calculations, a similar chipper was used at roadside,

plant or terminal. However, it was assumed to work more

effectively (10%) at the terminal or plant due to more efficient

feeding of the chipper. The cost calculation was based on cost

calculators for energywood developed by Laitila [30]. The

values used to determine the cost of chipping at roadside are

presented in Table 2.

2.4. Overheads and VAT

Based on Finnish experiences overheads were estimated to

10% of the transportation, logging and chipping costs. VAT

was also added to the price of chips. The current level of VAT

in the UK for wood fuel is 5%.

2.5. GIS data analysis

2.5.1. Forest dataThe forest area data consisted of 715 individual stand

compartments. Some of the compartments covered the whole

forest area of a farm and in some cases compartments were

more accurately mapped stands. Despite the size of

a compartment in the calculations it was assumed that the

planting year is always the same for the whole compartment.

Altogether the forest area consisted of over 350 km2. The

mean size of a compartment or a forest in the calculationswas

about 50 ha.

As an attribute, all the compartments had the harvesting

period (5 years each) from a given plan that could be con-

nected only with the mean data that had been calculated for

each period. The actual planting dates were missing for

a remarkable part of the data.

The topology of the forest data was validated in using GIS

software so that overlapping wasn’t allowed. The data

contained some areas twice, probably a result of merging

several sources. In corrections, newer and more detailed data

were preferred before older and coarsely digitized. New areas

for all compartments were calculated. The corrections

decreased the total nominal forest area by 7 km2.

The procedure used in the calculations for all areas is that

all timber is calculated as energy wood. For a part of the area

(private sector) there was information about the locations of

the poorest stands of Lodgepole Pine, where quality is too low

to get logs for lumber. However, there was a lack of this

information the entire state owned forests so that the infor-

mation couldn’t be used in the first stage of the calculations.

2.5.2. Road dataA roads network theme layer Integrated Transport Network�from the Ordnance Survey was purchased for the project. In

addition to that forest tracks of the area of interest had been

digitized manually and a few new tracks from that data were

added to Ordnance Survey road data.

The Highland North Agreed Routes Map [31] was used as

a background map in GIS. The roads that were marked

“excluded road” were not used in the route optimization.

However, all private roads and roads marked “consultation

road” were allowed to use.

2.5.3. Forwarding distancesThe method used was as follows; the first calculation was

distances to the nearest road from all points evenly distrib-

uted over the whole forest area. Then, means of these

distances inside each compartment were calculated. These

direct mean distances were then multiplied by a winding

factor to get estimates of realistic forwarding distances for

each compartment.

A new point layer with 50 m distance between points was

created covering the whole area of interest. Points that lay

inside forest compartments were found using a spatial join

with a rule “points completely inside areas”, and were

exported into a new point layer. The centroid points of the

Table 2 e Cost calculation details for chipping at roadside.

Price/tractor/base machine 76,765 V Productivity

Price/chipper 145,000 V Small size wood (delimbed) 25 m3 h�1

Price/loader 40,000 V Pulpwood 35 m3 h�1

Lifetime/tractor 10 a Whole tree (with branches) 20 m3 h�1

Lifetime/chipper 7 a Annual work amount

Lifetime/loader 10 a Small size wood (delimbed) 10,000 m3

Scrap value of tractor 15 % Pulpwood 20,000 m3

Scrap value of chipper 20 % Fixed costs

Scrap value of loader 15 % Total depreciation 26496.5 V

Management and overheads 5800 V a�1 Interest 15414.0 V

Insurances 2000 V a�1 Insurance 2000.0 V

Risk 5 % Management and overheads 5800.0 V

Interest rate 5 % Fixed costs total 49710.4 V

Salary of the workers 18 V h�1 Variable costs

Social expenses % 60 % Salaries 36534.9 V

Price/fuel 1.0 V l�1 Fuels and oils 45257.1 V

Fuel consumption (chipping) 40.5 l h�1 Maintenance 10470.6 V

Fuel consumption (transfer) 30 l h�1 Traveling 9500.0 V

Translocation 100 km 4 h Risk 7573.7 V

Translocation cost/km 1.5 V km�1 Variable costs total 109336.3 V

Hydraulic oil 1.8 V l�1 Total yearly costs 159046.7 V a�1

Hydraulic oil consumption 0.1 V h�1 Total costs/E15hour 148.8 Vh�1

Motor oil 1.2 V l�1 Unit cost 5.3 Vm3

Motor oil consumption 0.086 L h�1 Wood density 650.0 kgm3

Maintenance 50% of depreciation 10470.6 V a�1 Cost/t at 40% MC 8.3 V t�1

Work travel 25000 km Moisture content of wood 40.0 %

Travel compensation 0.38 V km�1 Energy content of wood

Effective work hours 971 h a�1 Timber with bark 1.86 MWhm3

Working hours/shift 8 h shift�1 Cost per energy content 2.85 VMWh�1

Workdays/month 15 day/month

Maintenance time 97.1 h a�1

Transfer time 100 h a�1

Other working times 100 h a�1

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 4 5 7 0e4 5 8 04574

compartments were then merged with this point layer to

ensure at least one calculation point inside every compart-

ment in the dataset (some of the compartments were pretty

small, 1000 m2, and the largest covered over 20 km2). In the

procedure, the compartment identification was given to all

points inside any compartment as an attribute.

For the calculation of the forwarding distances, there was

at least one calculation point in all areas, and about 8001

points in the biggest area. The high amount of calculation

points with a very detailed road network lead to a computer

intensive analysis. The ArcMap� “Near”-function was used to

determine the distance from each point to a point of the

nearest road.

The forwarding distance for each compartment was

calculated as a mean of these distances from points lying

inside compartment in question. The mean distances were

multiplied with a winding factor of 1.3 to get the estimates for

the actual forwarding distances. The calculationmethod used

here leads to several stockpiles along roadside, as it would be

the case in the true action as well. For the biggest compart-

ments, that covered whole forest farms, in some cases

according to the calculations the stockpiles would be along

several separate roads with even different routes to the heat

plant in Wick. However, one long transport distance was used

for each compartment as a whole.

When a compartment is situated near a road, its area is

small or it is having a narrow but long shape, themethod used

here could lead to a calculated forwarding distance that is too

short for the practical operation. These cases have been

handled by correcting the forwarding distance to an accept-

able level without taking into account what had been the

cause. The distances under 50 m have been considered to be

too short, so the calculated distances have been corrected

with the following formula:

forwarding distanceðmÞ ¼ fðxÞfðxÞ ¼ xþ ½25� x=2�; when x � 50fðxÞ ¼ x; when x > 50

where x¼ calculated mean distance; constant 25 (m)¼ the

half of the distance between the points in uniform point layer.

2.5.4. Long distance transportation and road data GISRoad haulage distances for each compartment were calcu-

lated along the road network. As the data consisted of 715

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 4 5 7 0e4 5 8 0 4575

compartments of different sizes there were >715 dissimilar

transport distances and routes to be optimized. Transport

distances were calculated from each compartment’s geo-

graphical center point (centroid) to the destination.

The ArcGIS Network Analyst was used to calculate the

routes to Wick from the points on the road that were nearest

to the forest center points. In the route optimization road

hierarchy was set so that the main roads were used as much

as possible.

The cumulative sum of forest areas according to long

distance transport distances was calculated with Microsoft

Excel�. Also the cumulative sums for each harvesting period

by long distance transport was calculated: variables that were

scrutinized in a given cutting plan were: harvesting areas (ha),

total harvested wood (m3), logs (m3) and small diameter

material (m3).

3. Results

The available forest area around Wick increases evenly with

increased transportation distance (Figs. 2 and 3). Within the

assumed 100 km maximum transportation distance, approx-

imately 330 km2 of forest land are available.

The cumulative sums for each harvesting period by long

distance transport were calculated. Fig. 4 shows that the

harvestable volumes during the next 6 years are relatively low

when compared with the period starting from the year 2012.

Due to the low supporting capacity of the soil in the Scot-

tish Highlands it is not possible to use terrain chippers or

harvest logging residues. Due to the lack of competition for

timber in the Scottish Highland, roundwood can be used for

forest chips. Roundwood harvesting also offers the favor that

experienced forest harvesting entrepreneurs already exist.

The establishment of a supply chain for forest fuel is

assumed to have a positive effect on the general attitude

towards forest fuels. There are a number of suitable utilization

places and also a developed support scheme in place and

therefore it is expected that investment in wood chip boilers

will increase in the future. When many smaller customers

demand forest chips, chipping of the raw material at the

utilization place is expensive. Further, in and close to resi-

dential areas, limits on noise levels and lack of suitable space

rules out the option to chip at the location of the end user.

Therefore, chipping at the roadside or terminal remained as

options providing the necessary flexibility. In the end, the

05000

10000150002000025000300003500040000

0 20 40 60 80 100 120km

ha

Fig. 2 e Cumulative area of forests in the Northern

Highlands by transportation distance from Wick.

difficulty to find a suitable location and the extra handling

costs at a terminal made chipping at roadside the only viable

alternative.

The combustion technology provides the fuel quality

requirements. At the same time several users of forest chips at

different scales provide the possibility to produce chips at

different scales. In the case of one large-scale customer and

several medium to small-scale customers it can be assumed

that particularly on the farm scale chips will also be produced

for individual farms. If a gasification system should be chosen,

even higher requirements in regards to fuel quality particu-

larly moisture content has to be considered. In general, the

high moisture content (50e55%) of the raw material after

felling is one of the greatest challenges. It is essential that the

timber is stored in order to reduce themoisture content. From

a logistics perspective chipping at roadside is therefore also

the most suitable alternative. Based on evaluating different

aspects for forest energy harvesting it was determined that

chipping at roadside is the most suitable method for the

production of chips from forests (Fig. 5).

Fig. 6 illustrates that the transportation cost per tonne is

very sensitive to the transportation distance. Natural drying of

timber has a positive effect on the costs if they are monitored

according to the energy content, i.e. MWh. Fresh timber can be

assumed to have a moisture content of approximately 50%

which means that the energy content is about 2.3 MWh t�1.

When timber dries to 40% moisture content, the energy

density per tonne increases up to 2.8e2.9 MWh t�1 [32,33]. Due

to the lower moisture content of the material, the shares of

chipping and transportation are smaller in the total cost

structure, when the unit costs are presented in MWh (Fig. 7).

A comparison of costs depending on the location of chip-

ping is given in Fig. 8. Chipping at plant is the cheapest option,

but not in many cases not possible if the plant is located in

a densely populated urban area. Roadside chipping is the next

cheapest option up to a transportation distance of 100 km.

With long transportation distances the extra costs of terminal

handling can be compensated by more effective roundwood

transportation. However, that is the case only when terminal

is relatively near the plant, in this specific case, 5 km.

4. Discussion

The currently available data on the growing stock may be

a significant underestimate of the available wood according to

forestry professionals [34]. However, the best available data

were used and updating can easily be done as better data

becomes available. On the other hand, the possible underes-

timation of growing stock thus means that the forest fuel

potential described above can be seen as a conservative

minimum estimate of the potential. In addition, to meet local

fuel demands, some stands planned to be harvested in the

2012e2016 could be harvested already in the coming six years.

Alternative fuel sources, such as logging or thinning residues,

could also be utilized. Finally, the Northern parts of the Scot-

tish Highlands are close to a deep sea harbor. This offers the

possibility to import timber and other fuel resources as

a backup from other parts of Europe in the case of temporary

local wood fuel shortages. Benefits and challenges of marine

Fig. 3 e Road transportation distance to Wick in the Northern Highlands.

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 4 5 7 0e4 5 8 04576

transport of timber in Scotland have been investigated and

discussed in a report by the Scottish enterprise in 2006 [35].

However, the raw material availability should improve

already after 2012.

The cost sensitivity in regards to long distance trans-

portation, in particular, has to be carefully considered. Costs

vary significantly depending on the natural conditions, the

contractor employed and the working method, and trans-

portation distance. The number of technological and logistic

options is high and each option has different effects on the

total transportation costs. Another important factor that

should be considered is that in case of chipping at roadside

and chipping at the plant only one type of truck (either chip or

normal roundwood truck) is needed, whereas when chipping

Fig. 4 e Cumulative yearly harvesting volumes by road

transportation distance. Years 2003e2026.

is done at the terminal a timber truck and chip truck are

needed which requires more logistics. A combined truck that

would be able to transport both round wood and chips might

be another possibility.

These calculations presuppose insignificant competition

for the roundwood resources on the East coast of the Scottish

Highlands. If competition should increase, the situationmight

change dramatically and alternative fuel resources such as

thinning residues will have to be considered as well.

The uncertainties described above must be considered.

However it was the aim of this study to investigate the general

cost structure of forest chips for a significant district heating

development (10 MW). Another objective was to find out

whether forest energy harvesting is feasible compared to

other energy options. Even considering the possible errors, the

results indicate that cost of forest fuel harvesting is logistically

and economically feasible compared to alternative energy

sources.

The price of forest fuel in Scotland is high compared to

Finnish and Polish conditions [36,37]. According to Heikkila

et al. [35] the unit costs of fuel chips made from delimbed

small diameter stems is 34.2e37.6 Vm3 solid (VAT 0%) at

a transportation distance of 40 km and terminal or end use

facility chipping. When 5% VAT are added and costs are pre-

sented by MWh, the corresponding figure is 16.5e18.1 V. In

addition four Finnish energy cooperatives were interviewed

[38e41] about the price of chips they pay to the supplier. The

prices delivered to plant varied between 11.4 and 13.5

No terrainchipping

Low bearingcapacity of soil

Lack ofcompetition

High moisturecontent of fuelChip boilersExisting

entrepreneurs

No chippingat plant

Multiplecustomers

Gasification

Harvesters &Forwarders

Drying in theforest

Chipping at roadside

Natural conditions Fuel propertiesSocial Combustion technology

Varying sizeof customers

Big & smallchippers

No harvestingof residues

Roundwoodfor fuel

Loggingresidues areneeded forbrush mat

No space forterminal

No terrainchipping

Low bearingcapacity of soil

Lack ofcompetition

High moisturecontent of fuelChip boilersExisting

entrepreneurs

No chippingat plant

Multiplecustomers

Gasification

Harvesters &Forwarders

Drying in theforest

Chipping at roadside

Varying sizeof customers

Big & smallchippers

No harvestingof residues

Roundwoodfor fuel

Loggingresidues areneeded forbrush mat

No space forterminal

Fig. 5 e Decision support tree for forest energy harvesting in the case of Northern Scotland.

b i om a s s a n d b i o e n e r g y 3 5 ( 2 0 1 1 ) 4 5 7 0e4 5 8 0 4577

VMWh�1. If 5% VAT is added in order to better compare to the

Scottish figures, the price would be 12e14.2 VMWh�1.

Furthermore, it has to be considered, in Finnish conditions,

harvesting of small size trees for energy can be supportedwith

a state subsidy of up to 6 VMWh�1 if this is added to the mill

gate price the actual income of the forest chip supplier could

be up to 22 VMWh�1.

However, results presented for Finland and Poland are

based on small diameter trees where harvesting costs are

much more expensive compared to industrial roundwood

harvesting. Furthermore chipping at plant or end use facilities

were considered in those studies whereas in Scotland chip-

ping at roadside was assumed. If those factors are considered

the price level of forest energy is even higher in Scotland.

Nonetheless, if results from this study are compared to the

general price level of forest fuels in Scotland [40], which is

approximately 30 VMWh�1, results from this study indicate

that forest chips for industrial purposes can definitely be

competitive on the Scottish wood fuel market.

The introduction of forest energy in countries with weak

timber harvesting and usage traditions is more challenging

0

10

20

30

40

50

60

70

80

1 25 50 75 100 125 150 175

Transportation distance, km

Uni

t cos

t, €/

tonn

e VAT 5%OverheadsTransportationChippingHarvesting

Fig. 6 e Unit cost in V tL1 of forest fuels according to

transportation distance and when chipping is done at

roadside.

compared to countries with a very developed forest industry

and high utilization of timber. One of the possible reasons to

explain that is that in countries with high timber usage,

harvesting operations are either highly mechanized or other

established harvesting systems have been introduced. The

efficient use of existing technology is one of the key

factors when introducing a new technology. Entrepreneurs or

contractors should minimize their experimenting and make

use of already existing and proven technology. The tech-

nology transfer from countries with an established harvest-

ing chain can therefore be of a great benefit where both sides

benefit from each other. The country, where the technology

is transferred from, also benefits through the improvisation

of their own technology by adapting it to new and varying

conditions.

The technology selection process has clearly shown that

the supply chains have to be tailored to local conditions and

the quality of forest fuel to be produced. There are numerous

possibilities to produce forest energy and during our investi-

gations suitable options had to be discounted due to the local

conditions or bottlenecks that could not be foreseen such as

road transportation or carrying capacity of the soil. During the

technology selection process it also became clear that the

cooperation of all stakeholders is essential. The organization

of the combustion technology selection and forest fuel supply

chain should be done parallel and interlinked to minimize the

risk of producing the wrong kind of fuel or not having enough

suitable resources tomeet the demands of the end user. There

is a strong relationship between the selected scale and type of

combustion and the biomass resources and their procurement

chain.

A bottleneck for further development of forest energy is the

lack of developed business models for forest energy

producers. The possibilities to earn money have to be more

visible in order to make forest energy business attractive to

producers. This requires active transfer and adaptation of

already existing business models from countries with an

established and functional market.

0

5

10

15

20

25

30

35

1 25 50 75 100 125 150 175

Transportation distance, km

Uni

t cos

t, €/

MW

h

Chipping at plantChipping at roadsideChipping at terminal

Fig. 8 e Unit cost of energy according to different locations of chipping.

0

5

10

15

20

25

30

1 25 50 75 100 125 150 175

Transportation distance, km

Uni

t cos

t, €/

MW

h VAT 5%OverheadsTransportationChippingHarvesting

Fig. 7 e Unit cost in VMWhL1 of forest fuels when chipping is done at the roadside.

b i om a s s an d b i o e n e r g y 3 5 ( 2 0 1 1 ) 4 5 7 0e4 5 8 04578

One of the challenges in the Northern Highlands, at the

moment, is the dispersed location of the forests and the fact

that there is only one comparatively large user of the

biomass. This limits the large-scale use of forest biomass

and increases the need for costly road transportation.

A possible solution to further increase the utilization rate is

to locate additional wood fuel installations in the future. This

would enable larger investments in the forest energy supply

chains by local entrepreneurs. In return, this would increase

the confidence of the consumer to invest into heating

systems based on forest chips since supply would be

ensured.

This study has shown that forest energy offers an

economically feasible alternative for future energy production

in the Scottish Highlands. This study has been carried out

from the point of view of Finnish forest energy business.

However, the technology was selected to fit local conditions

and demands in Scotland. Still, it may be necessary to adapt

solutions further to the needs of Scottish forest energy

entrepreneurs and energy producers. A major obstacle to

overcome is the local scepticism about the use of forest

energy. The only way to convince those sceptics is by estab-

lishing systems that work on a sustainable basis and without

any major problems.

In an international perspective, Scotland has a favorable

positionwith regards to increasedutilizationof forest fuels.The

biomass base is abundant and the infrastructural conditions

include strong timber harvesting expertise and full mechani-

zation of harvesting operations. Even so, careful holistic plan-

ning of setups and supply chains is required because traditions

of forest fuel utilization areweakand theoptions for organizing

the forest fuel supply chains are numerous.

Acknowledgements

Data collection and preparation of this study were carried out

within the Northern WoodHeat project. Financing and

support of the project by the European Union, Regional

Development Fund and Interreg IIIB Northern Periphery Pro-

gramme are gratefully acknowledged.

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