The increased demand for bioenergy has led to a need to find new sources of bioenergy. An interesting resource in this area could be tree stumps from final felling. The aim of this project is to compare production of forest chips from residues with chips from stumps in a life cycle assessment perspective. This will provide further knowledge of the environmental burden of the system in terms of resource use, energy and carbon balance.
The arguments for bioenergy are many, one of the most important being that they are renewable and would therefore signify decreased greenhouse gas emissions. Nevertheless, it is important to point out that production of bioenergy gives rise to emissions of greenhouse gases through the use of fossil fuels. In addition, the carbon stock in forest soil could decrease when residues and stumps are harvested since this leads to less forest litter. This decrease could be compared with emissions of CO2. Because of this, fossil carbon from the use of fossil fuel and carbon from forest biomass will both be included in the study.
The resource use and emissions generated by the system will be collected and analysed, from the production of inputs such as energy and other ancillary materials until the biomass is processed. Life cycle assessment (LCA) methodology will be used for the evaluation. The study will focus on the most common methods of harvesting and transporting forest slash, but since stump harvesting still is in the experimental stage, a future possible harvest system will be studied. The study is being carried out by the Swedish University of Agriculture and the Forest Research Institute of Sweden. The Swedish Energy Agency and the Swedish University of Agriculture are funding the study.