Energy efficiency and the environmental impact of harvesting stumps and logging residues

In a case study, seven different procurement chains of forest energy in Sweden were modelled and the environmental performance was calculated from a Life Cycle Assessment (LCA) perspective. The systems differed with respect to geographical location, the technology employed and resource use (stumps or logging residues). The energy output/input ratio of chips from residues and stumps was in the range 21-48, and the greenhouse gas emissions were 1.5-3.5 g CO2-eq/MJ chips. The systems in southern Sweden were generally more efficient than similar systems in northern Sweden. The forest energy systems based on bundles and stumps rely on immature technologies which have the potential to be improved should there be technical developments of the systems.