Today there are some 160 boilers using biofuels as their only fuel source.

• Forty-nine of these are peat fired CHP plants. Nineteen boilers are black liquor recovery boilers connected to the chemical pulp production in the forest industry.
• Forty-four other boilers are also connected to the forest industry, mainly grate fired and fluidized bed boilers, using bark refuse as their fuel and producing heat and power to the paper mill.
• Seven are fluidized bed boilers, producing heat and power for municipal purposes,
• The rest are smaller sized district heating boilers.

Totally some 5.5 Mtoe p.a. of heat and power is produced. Since Finland doesn´t have any clear dominant fuel source of its own, the country has also a strong tradition in co-firing. The tradition to use biomass as an additional, secondary fuel is, consequently, strong.

Finland is a world leader with respect to know-how on energy production from pulping spent black liquor. Black liquor recovery boilers, designed in Finland, hold a major market share world wide.

The recovery boiler is a complicated combination of a power boiler and a chemical reactor. The main purpose of the recovery boiler is to recover the pulping spent chemicals in a suitable form so that they can be recycled back to the pulping process. At the same time energy is recovered in a conventional steam cycle. The combination of these two processes makes the design and operation of the recovery boiler very challenging.

Traditionally, the recovery boilers have suffered from major slagging fouling and corrosion problems, as well as sulfurous emission problems. With increased detailed knowledge about the physico-chemical processes involved in black liquor combustion many of these problems have been solved. Today the SO₂ emissions, for example, can be driven down to almost zero level without any additional flue gas SO₂ cleaning devices.

Finnish know-how has played an important role also in the development of the fluidized bed technology especially in the field of circulating fluidized bed boilers. Examples of this development work are among others: the Kvaerner Pulping CYMIC CFB and the Foster Wheeler Compact CFB.

In Finland the fluidized bed technology has become especially important in larger (>10 MW_th) plants while grate-firing is still used in smaller heating applications. There are roughly 100 fluidized bed boilers in operation today. The two FBC concepts, bubbling and circulating fluidized beds, have been scaled up to 100 MW_e in industrial applications and large CHP plants. Today the installed capacity of fluidized bed boilers in Finland is 1200 MW_e. But although the largest CHP plant on FBC technology ever in Finland just has been announced (230 MW_e and 320 MW_heat), the current development direction of CHP plants is rather on scaling down than up, since smaller plants makes it feasible to utilise locally available fuels.

Fluidized bed technology is usually marketed as a clean and flexible technology. The flue gas emissions from various types of fluidized bed boilers have been shown to be low and low grade fuels have been succesfully used in FBC plants. The reduction of gaseous emissions have, however, also been shown to be strongly coupled with each other, so that a decrease in one emission component increases another. By detailed studies of how the different emissions form, a good knowledge on how to optimise the emission reduction for most of the harmful components, has been achieved.

Even if the fluidized bed technology is regarded as a fuel flexible system with capacity to handle also low grade and problematic fuels, the technique has its limits. One challenge of the future is to be able to control bed agglomeration in the system. In bed agglomeration, the separate bed particles glue together to bigger agglomerates that disturb the fluidization. This affects the efficiency of the combustion in the boiler. In worst cases the whole bed collapses and an unsceduled shut-down of the boiler is inevitable. An often used way by the operators today to avoid bed agglomeration is to change the bed often enough. This however leads to expence since in certain problematic cases the bed may have to be changed even every second day.

In Finland, as in many other countries, the demand for electricity continues to increase. The development of various types of combined cycle concepts are one way to meet this demand. In Finland biomass gasification has especially attracted attention.

An example of a project where Finnish know-how is involved is the pressurized air-blown biomass IGCC plant in Värnamo in southern Sweden. This demonstration CHP plant is being developed in a joint R&D project by Foster Wheeler Energy International Ltd and Sydkraft Ab. This demo-plant was erected in 1991 and has been in test operation since then for more than 5400 hours. As a fully integrated plant the operational hours add up to 1500 hours. The gasifier is fueled with wood and forest residue chips and produces 6 MW_e to the grid and 9 MW_th to the district heating net.

Another example is the simplified air-blown pressurized gasification concept of the company Carbona Inc. This process is based on the Enviropower gasification technology which originally was developed as the U-gas process. Carbona Inc. will together with Ignifluid Boilers India Ltd deliver a pressurized fluidised bed gasification plant to the 55 MW_e co-generation project of IBIL Energy Systems of Madras, India. The plant will be designed for multifuel operation.

An interesting co-firing demonstration plant using biofuel gasification and fossil fuel combustion is being demonstrated in the city of Lahti in southern Finland. Lahden Lämpövoima Oy has together with Imatran Voima Oy built a 50 MW_th CFB gasification plant connected to a 350MW_th steam boiler, flexibly fired with coal, oil or natural gas. This plant, called Kymijärvi power plant has been producing electricity and district heating for the city of Lahti since January 1998.

The gasifier used is a Foster Wheeler design. The commercially available solutions use dry fuels in the gasifier, but in this demonstration plant the gasifier is fueled with un-dried forest residue, wood chips, peat and recycled waste (REF). The product gas from the gasifier is fired as a supplementary fuel in the steam boiler to replace some of the fossil fuel that otherwise will be used . The consumption of coal in the steam boiler is estimated to be cut by some 45 000 tons/a by this co-firing procedure, which equivalents to a 15-20 % reduction in CO₂ emissions. It is estimated that about 100 boilers in Europe could apply this type of a concept.

The Technology Research Centre of Finland, Tekes, has together with the industry supported the energy research during the past five years by some Euro 300 mn. through different energy research programs. From biomass energy conversion point of view the research programs LIEKKI 2 and BIOENERGIA have been the most important programs where research and development has been carried out. Both of these programs were finalized 1998 and have now been followed up with a number of new research programs.

One is the "TULISIJA" research programme on wood firing technology. This 3 year programme (1997-1999) is focusing on small-scale wood log fired fireplaces and stoves for heating purposes in houses holds. One particular feature of interest in these small scale fireplaces is their ability to store heat. The heat is effectively bound in the the massive construction of the fireplace and then slowly released, thus, producing a pleasant and even heat source over a long period of time. Several enterprises in Finland manufacture these types of wood fired units.

The emission issue has been and still is of great importance in the marketing of fireplaces. The European fireplace standard (CEN TC 295) is under preparation and this will force the developers to construct fireplaces with even lower emission levels than is achieved today. The aim of the TULISIJA programme is to assist the developers and manufacturers in this effort. The detailed research objectives of the program are:

• To produce modelling capabilities for the evaluation of different fireplace designs, with respect to efficiency and emissions. The main emphasis is in the prediction of carbon monoxide (CO) and other unburned gases (C_xH_y) but due weight is also placed on emissions of nitrogen oxides (NO_x) since a number of methods for reducing the emission of unburned gases tend to increase the formation of nitrogen oxides.
• To establish a standardised measuring lab for fireplaces where different fireplace designs may be tested in a standardised manner. This kind of a lab may also serve as a test lab when manufacturers need to obtain approvals for their products for different market areas.

The programme is co-ordinated by Tekes and Åbo Akademi University. In 1998 eight commercial enterprises and four research institutions were participating in the programme:

• Harvia Oy, Kerman Savi Oy, Nunnanlahden Uuni Oy, Optiroc Oy / Finnish Brick Industry Association, Tulikivi Oyj, Tunnelma Uuni Oy, Turun Uunisepät Oy, Puulämpö Suomi Oy.
• Åbo Akademi University, VTT Energy, Technical University of Tampere, VTT Construction Technology.