Abstract
In the alpine Autonomous Province of Bolzano (NE Italy), about 40% of the biomass used for bioenergy production is currently imported. This share is expected to further increase in the near future owing to growing renewable energy needs. The residual biomass harvestable from the local agronomic sector, mostly based on the cultivation of apple, is a promising option to supply relatively cheap bioenergy feedstock. In this study, we investigate the use of woody residues from apple orchards (apple orchard's woody residues, AWRs) for the production of bioenergy using the life cycle assessment (LCA) methodology. The system boundaries include the harvesting and chipping of AWRs, their transport to the energy plant and conversion into heat and power in a gasification unit. The life cycle inventory (LCI) data rely on field measurements for AWRs harvesting and chipping operations, as well as for their chemical and energy characterization. In the life cycle impact assessment (LCIA) phase, we consider various environmental impact categories like climate change, acidification, fossil depletion, and others. We benchmark the outcomes with two alternative reference systems based on fossils fuels. Our results show that the energy production using AWRs generally presents better environmental indicators than the reference systems, although some trade-offs exist. For instance, hereas the bioenergy system saves up to about 85% of greenhouse gas (GHG) emissions and about 95% of nonrenewable resources, it is usually associated with higher toxicity impact potentials.