Harvesting Technology of Forest residues for fuel in the USA and Finland

This work has been carried out in Biomass Feedstock Development Program in Oak Ridge National Laboratory (ORNL) during 1.9.2001-31.08.2002. The work and the final report has been made by Dr. Arvo Leinonen who has been working as a visiting research scientist for ORNL. The main focus of this work has been to collect and assemble information on the methods and economics associated with collection of wood residues for bioenergy from natural forest systems and from short-rotation fiber production systems. Additionally, information on bioenergy crop development approaches and projected economics has been collected and summarized. Comparisons have been made between the USA and Finnish biomass production and collection technologies to evaluate possible technology transfer opportunities. In the USA currently 3.5-4.5 million dry tons (15.3-19.6 TWh in 50 % moisture content) of whole tree chips utilized for fuel annually at the moment. Forest residues are mainly utilized in the electricity power sector. There are no subsidies for utilizing wood for fuel. The use of forest residues has an important social and economical impact on the rural areas offering industrial jobs which in general are decreasing in these regions. There is a huge forest residue potential to increase the use of forest residues for fuel, 23.8-44.8 million dry short tons (103.8-195.3 TWh). Also smallwood, if harvested for fuel, has a potential of 17.0-65.0 million dry short tons (74.1-283.4 TWh in 50 % moisture content). The biggest possibility to utilize forest residues for fuel is co-firing in coal fired power plants. Small municipal cogeneration (20 MWth) power plants in the Northern areas would also be economical and possible users for forest residues. The harvesting technologies in the USA are effective, but there is still potential to intensify them. It would be justified to start a R&D program to intensify the use of forest residues for fuel for different end users. In Finland the use of forest residues in 2000 was only 0.46 million dry short ton (2.0 TWh in 50 moisture content), which was only about 2.5 % of the total wood fuel use. In Finland there are also lots of forest residue resources to be utilized for fuel, 6.5-7.4 million dry short tons (25.8-31.6 TWh, 50 w-%). The target is to increase the use of forest residues up to 2.3 million dry short tons (10 million MWh, 50 w-%) by the year 2010. The aim is supported by intensive R&D work on forest residues harvesting and use. The use of forest residues for fuel has been competitive with other fuels because of investment aids for constructing wood fired power plants, subsidies for harvesting wood from thinnings and excise taxes for fossil fuels. The production costs of forest residues are higher in Finland than in the USA. To intensify the harvesting of forest residues the whole-tree technology using feller bunchers and skidders should be tested in Finnish conditions especially from thinnings on hard lands. The environmental impacts of forest residues for fuel are low and do not hinder utilizing them. The use of forest residues from final felling areas helps to reforest the stand.