Kajaani University Consortium

CEMIS-Oulu timo.karjalainen@oulu.fi

KUHMO: the perfect example of local bioenergy production

Background

Much more wood energy must be used in the near future to help meet the target of increasing the

share of renewable energy in national energy consumption to 38% in Finland by 2020. The aim of the

national climate and energy strategy is to triple the amount of energy generated currently from

wood chips by 2020. As the statistical data (Fig. 1) indicates, Kainuu is one of the forerunner regions

in the use of wood energy in Finland and the EU. This is based on excellent wood energy knowledge

and production (in harvesting, logistics and production). The consumption of primary energy in the

Kainuu region was 4.7 TWh and no less than 62% was based on renewable energy resources. Up-to-

the-minute statistical data shows that 32% of primary energy consumption in the Kainuu region was

based on solid wood based fuels. It has been estimated that in the municipality of Kuhmo the share

of renewable energy is the highest in the Kainuu region.

Wood directly or indirectly accounts for as much as one third of the total energy used in the Kainuu

region. The largest users of wood energy are companies and district heating plants and power

stations, which produce large quantities of energy from residual wood such as bark, sawdust and

forest chips. The Kainuu region does not have pulp or paper making processes producing black

liquor, which is a typical fuel in some wood industrial regions in Finland.

Figure 1. The share of primary energy consumption in the Kainuu region in 2012.

Renewable electricity

26 %

Wood energy 32% Heat pumps

2%

Other renewables

2%

Heating oil 6%

Peat 9%

Traffic 15%

Motor fuel oil 7%

Kainuu is a very sparsely populated region with an area of 24,453 km2 and population of 80,100. It

has extensive forest energy resources. The forested area is more than two million hectares. The

sustainable cutting plan in the Kainuu region is 4.7 million m3/a. Only one million m3 is processed in

the region and half of the whole potential remains unused. Refining high quality fuels from local

energy resources offers great potential for the development of the region.

From 2008 to 2010 Kuhmo Lämpö Oy and Kuhmo Oy invested a total of 15 million euros in a new

boiler, combustion gas heat recovery system, belt dryer and briquetting lines. A subsidy from the

Ministry of Economy and Employment covered 25% of the cost of the combustion gas heat recovery

system.

City of Kuhmo

Kuhmo is a city of 9,200 inhabitants on the

eastern border of Kainuu, Finland and the

European Union. It lies 100 km from Kajaani

and 65 km from the Russian border checkpoint

Vartius. An ecologically sustainable economy is

respected in Kuhmo. The wood processing

development network Woodpolis is in charge

of the commercialisation process of wood

construction within an international network.

The forests of Kuhmo as well in Kainuu as a whole, have been certified.

District heating in Kuhmo

Like many other municipalities in Finland, Kuhmo utilizes a district heating network in the city

center. The total length of the district heating network is 28 km. The majority of buildings in the

center of Kuhmo are connected to the district heating network. The total volume of buildings with

district heating is more than 770 000 m3 including municipal (town hall, school, etc.) and privately

owned buildings and residences.

Insulated heating pipelines are situated under the streets. Kuhmo city buys district heat energy from

Kuhmon Lämpö Oy and distributes it to private customers. The amount of customers is 490. The

pipeline network is owned by Kuhmo city. Each customer has a heat exchanger and energy

consumption is measured according to customer use. The price of district heat energy is only €63

/MWh and it is the lowest in Kainuu (see fig 2.).

Figure 2. The price of district heat in municipalities in Kainuu 2013.

Close co-operation between the local sawmill and energy company

The energy company and sawmill cooperate extensively and they are situated on the same site.

Their location boasts some advantages (e.g. no fuel transport costs).

Kuhmo Oy (sawmill) founded in 1955, is the largest forestry company in Kainuu and it is privately

owned. The company is a timber expert, using the latest sawing technology. It provides employment

for 135 people.

Kuhmo Oy sawmill uses the two main tree species of the local forests; pine 80% and spruce 20%. The

main suppliers are state forests and local private forest owners. Kuhmo Oy is often the sole buyer for

many forest owners as it can use up to 90% of commercially harvested round wood. This is enabled

by an investment into sawing equipment capable of handling small sized round wood coming from

thinning operations and the tops of trees. The timber comes from the forests of Kainuu and it is

distributed under the trademark URSUS, which is Latin for ‘bear’.

Kuhmon Lämpö Oy (Energy Company) is owned by the municipality of Kuhmo (51%) and Kuhmo Oy

(49%). Kuhmon Lämpö Oy produces energy for Kuhmo Oy, district heat for the municipality of

Kuhmo and electricity for the national grid. Kuhmon Lämpö Oy has three boilers with an efficiency of

18, 12 and 10 MW. 246 GWh of wood-based fuel is used. The use of heavy oil was only 0.7 GWh.

Fuel handling employs three employees around the clock. The 18 MW-boiler is a combined heat and

power unit (CHP). The newest boiler (10 MW) has a combustion gas recovery unit.

Table 1 . The use of fuels in Kuhmon Lämpö Oy 2006 – 2012.

The efficiency of the combustion recovery unit is 3.2.

MW when the boiler is operated at maximum efficiency. The boilers burn moist bark and saw dust

and it is also possible to mix them with dryer fuel if problems occur.

The drying unit is a typical belt dryer where hot air is drawn

through the moist saw dust bed from the top down. The

thickness of the sawdust bed is 17 cm. The speed of the

belt varies according to the target sawdust moisture

content. The process aims to achieve 11% moisture

content.

The humidity of the fuel varies from 50% to 60%. This is

very typical of sawmill by-products which are mainly bark and sawdust when the raw wood is

processed before drying. The boilers in Kuhmon Lämpö Oy are able to use moist wood fuels of this

kind. The humidity of the wood fuels is measured using on-line measuring equipment which is based

on the microwave system (Senfit Oy).

The local energy system concept is shown in fig. 3. Kuhmo Oy produces some 480 000 loose m3 of

different kinds of by-products when processing 800 000 m3 small diameter round wood. The by-

products are sawdust, bark and the residue from timber trimming.

After drying, the sawdust is formed into wood briquettes (capacity 30,000 t/a) and the rest is used as

fuel in the boilers of Kuhmon Lämpö Oy. Most of the wood briquette users are located within 200

km of Kuhmo.

Bark and some of the sawdust is sold to Kuhmon Lämpö Oy and used as boiler fuel. The dry residue

from trimming the timber is mainly sold out for use as a fuel in local smaller boilers.

Year

Heavy fuel

oil

Light fuel

oil

Wood

based fuels

Total

Renewable energy

The share of renewable energy

GWhpa GWhpa GWhpa GWhpa GWhpa %

2006 5.0 0.0 148.0 153.0 148.0 96,7

2008 0.0 2.0 168.9 170.9 168.9 98,8

2010 0 1.0 230.0 231.0 230.0 99,6

2012 0 0.7 246.0 246.7 246.0 99,7

2013 0 0.6 270.0 270.6 270.0 99,8

Sale of energy

District heat for the municipality of Kuhmo network 62 GWh/a

Heat energy to Kuhmo Oy 123 GWh/a (including drying energy for 9 progressive and 20

chamber kilns)

Electricity for Kuhmo Oy or the national grid 24 GWh/a

Figure 3. The energy system concept in Kuhmo.

Technological approach

Combustion technology:

o 18 MW CHP-unit by Ahlströn using Pyroflow technology, 1992

13 MW Heat energy

5 MW Electricity

o 12 MW Rotating grate by Sermet, 2001

o 10 MW Grate boiler by URBAS , 2009

3.2 MW combustion gas heat recovery

Four briquetting lines by Nielsen, 2009

Investment (boiler & saw gas condenser) €5.4 M

Recycling pure wood ash

In 2006, Kuhmon Lämpö Oy initiated the recycling of pure

wood ash. Ever since, wood ash has been recycled and used

as a nutrient in local peat-land forests. Annually, the

company produces some 1000 tonnes of pure wood ash

which is stabilized and dispersed with a dispersal unit

attached to a forest forwarder. This amount of fertilizer is

enough for 140 hectares of forest land. Kuhmon Lämpö Oy

uses the self-stabilization method. The ash is used to

replace virgin raw materials. The target humidity content of ash is 30% in order to achieve optimal

stabilization. The mixing ratio of fly ash and grate ash is 1:1 to achieve the correct mixture.

The quantity of the mixture needed for fertilising the forest is calculated using the data from ash and

needle analysis. On average, the amount of ash spread is four tonnes (TS) per hectare. Stabilization

is carried out by carefully mixing flue and grate ash and then clamping the mixture for some months

in an asphalt field. Kuhmon Lämpö Oy reports to the Finnish Food Safety Authority EVIRA on the

utilization of ash mentioned above. The ash replaces conventional chemical fertilisers used to

fertilise forests. In this way nutrients are returned to the forest.

In Kuhmo, there are also other wood processing companies which buy timber from Kuhmo Oy and

refine it to produce high quality timber such as panels, e.g. AA-puu Oy. This company produces a lot

of cutter shavings, the raw material for M-Pelletti Oy. M-Pelletti makes wood pellets from this raw

material. The company has two pellet presses and its annual pellet capacity is 15 000 tonnes.

Nowadays the company also has a small capacity briquetting machine. M-Pelletti Oy provides

employment for three people. The pellets are distributed via wholesale businesses.

Kuhmo also has some large residential buildings which have outsourced their energy production.

Heat production entrepreneurship is one potential energy business sector. The Veljekset Pääkkönen

Company is a local heating enterprise which produces heat energy for the Kalevala Rehabilitation

Centre (forest chips) and the Kanerva Nursing Home (wood pellets).

Conclusion

It is very important for remote municipalities such as Kuhmo to conduct very close co-operation with

different operators including local companies and the municipal government.

Kuhmo Oy is the largest private enterprise providing employment in Kuhmo and therefore its

operations are extremely important to the regional economy. Cooperation on energy issues

between the City of Kuhmo, Kuhmo Oy and Kuhmon Lämpö Oy has created significant economic

benefits. Cheap energy (both thermal energy and electricity) is crucial to export companies such as

Kuhmo Oy that operate in global markets. The location of operations has its own electricity

distribution network which means that no transmission fee is charged for the electricity sold to

Kuhmo Oy by Kuhmon Lämpö Oy.

The City of Kuhmo also receives cheap district heating for its own properties and for distribution to

private customers.

Natural resources and opportunities must be utilized locally in the best possible way. The nearest

potential power station outside Kuhmo able to use by-products from Kuhmo Oy is located 100 km

away in Kajaani. Recycling wood ash locally also provides an approximate advantage of €100,000/a

in comparison to having to transport ash to the nearest municipal refuse site.

It is important to use local resources as much as possible and to refine by-products to a higher

degree. Local material flows must be connected so that the residue of one company’s process can be

the raw material for another company.

More information

Kuhmon Lämpö Oy: Managing Director Markku Piirainen, markku.piirainen@kloy.inet.fi

Kuhmo Oy: www.kuhmo.eu

City of Kuhmo: www.kuhmo.fi

Regional bioenergy program: Timo Karjalainen, timo.karjalainen@oulu.fi