Consequential life cycle assessment of wood cascading: exemplified for the German waste wood market
Main Presenter: Pia Szichta
Co-Authors: Michael Risse Klaus Richter
Its contribution to the bioeconomy and to climate change mitigation is likely to increase the future demand for wood. In this context, wood cascading represents a promising concept to increase the efficiency of wood utilization. So far, in Germany, material utilization of recovered timber is mostly limited to the production of particleboard due to the specifications of the German Waste Wood Ordinance in particular. Accordingly, wood cascading concepts are still limited to the degradation of the material quality (e.g., dimension). However, several studies have shown increasing potentials for material-preserving, solid wood cascading. Increasing solid wood cascading will lead to a change in the utilization of recovered timber assortments. Despite intensive research on wood cascading systems, the induced environmental consequences on German market level remain still unclear. Therefore, a consequential life cycle assessment (CLCA) on the example of increased solid wood cascading was conducted.
In the cascading system, one ton of recovered solid timber from construction is processed into glulam as first step, which is, at the end of its lifetime, further processed into particle board twice, followed by final incineration for energy purposes. Due to the extended time horizon (>75 years) resulting from the sequential utilization of wood, prospective aspects (e.g., concerning future energy systems) had to be considered. Thus, the system was distributed into four time steps.
Using the combination of the future availabilities of recovered timber and CLCA, the potential environmental impacts of wood cascading were determined on German market level. The environmental impacts arising in the cascade system are based on induced market shifts (e.g., shift from energetic to material utilization in the first time step) and depend on the products that are manufactured in the respective time steps. As a result, different marginal technologies are included in the system, varying with regard to the time step.
Overall, preliminary results indicate that the implementation of cascade use is beneficial from an environmental perspective. Since the emissions in the cascade system are distributed over the extended time horizon, a dynamic life cycle assessment could further be carried out to enable a differentiated analysis of the environmental impacts.