Shifting wood between material and energy use: Modeling the effects of substitution

Abstract

Wood as a renewable material is relevant for climate change mitigation: Carbon sequestration in forests and carbon storage in harvested wood products (HWPs) contribute to carbon reduction in the atmosphere, and the substitution of carbon-intensive products with wood products can reduce greenhouse gas (GHG) emissions. Since wood is a limited resource, it must be used efficiently and sustainably. Shifting wood from one application to another might result in decreased GHG emissions due to substitution effects. However, which wood application will lead to a GHG emission reduction is currently unknown. This study investigates the effects of shifting wood between applications and the resulting substitution effects from a system perspective. A system dynamics model describes the wood utilization system of Austria, including the value chains from the forest to wood-processing industries and the substitution that takes place in these industries. These value chains are associated with the global warming potential. Seven wood utilization scenarios shifting between material use and use for energy are simulated. The results show that wood shifts lead to both a substitution effect (emission reduction) in industries where wood utilization is increased and a counter effect (emission increase) where wood is replaced. The two effects potentially outweigh each other partly, leading to comparatively small net effects. However, carbon sequestration in HWPs and future changes in substitution effects might lead to additional effects. To substantially contribute to climate change mitigation, alternatives other than shifting wood between material and energy value chains need to be found within the wood utilization system.