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Wood and wood-based fuels are used to produce one-fi h of all the energy used in Finland. Fuel is increasingly collected also from forests, and new technologies are continuously developed to do the work. When logs are sent to a pulp mill, a forest machine remains at the logging site to collect and compress the slash into cigarshaped bundles that are then transported to the combustion plant. Stumps are also uprooted and chipped. Some of the branches and treetops are chipped already in the forest. "In essence, the plant can meet the district heating needs of the entire city of Rauma. The town also sells electricity," says Pertti Asunmaa, Vice President and General Manager of UPM Rauma Mill. The city owns close to one-third of the biofuel combustion plant, and it receives an equal share of the energy. The rest is used by the paper mill. Biomass combustion has evolved in Finland largely alongside the forest industry. energy, in other words, its own combustion plant. The most important fuels have long been coal and oil. "The old boilers can burn only a fraction of the biofuels. Our new boiler combusts them 100 per cent," says Asunmaa. The boiler was supplied in 2006 by Kvaerner Power, previously part of Aker Kvaerner Group, which has since merged with Metso, a global engineering and technology corporation known for its pulping lines and paper machines. Metso's fluidised bed boiler technology can also be used to combust non-woodbased biomass, including many kinds of industrial sludge and recycled fuels (such as sorted, solid waste from companies and municipalities). In fact, about 40 per cent of Metso's energy business already comes from outside the forest industry. Metso Power's Pertti Petänen, Manager of Power Generation Systems, believes the markets will continue to grow as energy consumption increases and emissions limits tighten. "In principle, the markets are unlimited when measuring the need for utilising renewable energy sources. How the investments will be realised is another matter." Big output with low investments The size of a biomass combustion plant is usually dictated by the biomass supply. If the energy demand exceeds the supply, the boiler can also combust other fuels, like peat or coal. In the future, burning more economical biomasses may become necessary, because biomass prices are rising right along with other fuel prices. Petänen says the biggest challenge at the moment is having knowledge about the different kinds of biofuels and knowhow in co-firing areas that are Metso's strengths. "However, biomass combustion is not the only future solution," Petänen notes. Metso is also researching other ways to produce energy competitively and in an eco-friendly way. For example, drying and gasifying biomass produces a raw material for oil and gasoline. Gasification itself also generates heat. As a producer and consumer of fuel, UPM Rauma has brought its own contribution to the development work. Wood bark and slash make their way to the boiler via a new drying plant. Moisture is reduced by one-third, resulting in a 10 per cent increase in energy output. But where does the energy for the drying process come from? From the mill's waste heat, of course. Biomarkets are growing The general manager is also familiar with joint ventures from other paper mills. In fact, biomass combustion has evolved in Finland largely alongside the forest industry. The black liquor cooking chemicals and wood material waste at pulp mills has been combusted for decades now, and the energy generated by the combustion has been used to power mill operations. Today's recovery boilers even produce surplus energy for use by a neighbouring paper mill or for the local district heating network. Even so, a paper mill needs additional 12 FOCUS
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