Resource efficiency of multifunctional wood cascade chains using LCA and exergy analysis, exemplified by a case study for Germany

- Cascading wood significantly decreases resource consumption.
- Cascading wood can improve resource efficiency of wood utilization.
- Exergy is a viable method for resource efficiency analysis of cascading systems.

Driven by the scarcity of non-renewable resources and a growing environmental awareness in Germany, the demand for wood could likely exceed its sustainable supply within the next decades. In response to this development, cascading, i. e. the sequential use of one unit of material in material applications with energy generation as final step, is expected to enhance the resource efficiency of wood utilization. In this context, the objective of this paper is to determine the resource consumption and resource efficiency of wood cascading compared to the use of primary wood to provide the same multiple functions. To account for resource use and calculate the efficiency, exergy analysis was applied. The exergy of a material is the potential work that can be obtained from the material in the natural environment. By using Exergy Flow Analysis, key drivers of exergy dissipation and thus hotspots for improvement were identified. Exergetic Life Cycle Assessment was applied to determine resource use and the resource efficiency at a life cycle level. The results indicate that cascading leads to less resource consumption compared to the use of primary wood, indicated by higher resource efficiency (46% vs. 21%) at life cycle level. The main resource saving potential through cascading arises from avoiding primary production in forestry systems. In conclusion, cascading reduces the primary resource extraction and makes wood utilization highly efficient. Exergy analysis proved to be a viable method to study the resource use of multifunctional cascading systems, although showing some limitations with respect to land use accounting.